bluuebunny/crossref_metadata_2025 huggingface dataset:
Intergovernmental organizations and entrepreneurship: understanding the relationship between the supranational, national, and individual level
Authors: Moore Elizabeth M. , Brandl Kristin , Dau Luis Alfonso
Published: November 2024

Intergovernmental organizations (IGOs), such as the World Trade Organization, the United Nations Trade and Development and the World Bank, promote stability, security and development for member states and their citizens via supranational institutional influences. However, their influence on individuals, especially their entrepreneurial business activities, is unclear. As policymakers decide when more (or less) IGO involvement best serves their countries and citizens, we must better understand the connection of the supranational, national, and individual levels. Thus, we study how IGO membership influences entrepreneurial opportunities and focus on two activities that impact a country’s economy differently: formal and informal entrepreneurship. Moreover, we identify how national institutional ecologies build the bridge between the supranational and the individual level and mediate the relationships. Using a sample of 68 countries, their entrepreneurial environment, and their connection to IGOs, we find that IGO memberships enhance opportunities for entrepreneurship. Moreover, IGOs promote formal entrepreneurial activities while discouraging informal entrepreneurial activities, mediated by the country’s institutional ecology. We combine insights from international relations, institutional theory, and strategic entrepreneurship to highlight how institutions at different levels influence entrepreneurial opportunities and discuss the policy implications of our findings.
Integration of ML methods with CR model-based optical diagnostic for the estimation of electron temperature in Ga laser produced plasma
Authors: Suresh Indhu , Srikar P. S. N. S. R. , Gangwar R. K.
Published: November 2024

Accelerated diagnostic of plasma plays a significant role in controlling and optimizing plasma-mediated processing, particularly for plasma with higher temporal and spatial gradients, such as laser produced plasma (LPP). In the present work, two advanced machine learning (ML) algorithms, random forest regression, and gradient boosting regression are integrated with noninvasive collisional radiative (CR) model-based optical diagnostics to facilitate accurate diagnostics. A comprehensive fine-structure resolved CR model framework is developed by incorporating our consistent cross section data obtained from the Relativistic Distorted Wave method [Suresh et al., “Fully relativistic distorted wave calculations of electron impact excitation of gallium atom: Cross sections relevant for plasma kinetic modelling,” Spectrochim. Acta B: At. Spectrosc. 213, 106860 (2024)]. An extensive dataset of CR model simulated intensities is created to train and test the ML methods. The present CR model is applied to characterize the Gallium LPP coupling with the optical emission spectroscopic measurements of Guo et al. [“Time-resolved spectroscopy analysis of Ga atom in laser induced plasma,” Laser Phys. 19, 1832–1837 (2009)] at different delay times. Further, a detailed correlation study of the line intensity ratios is performed to observe the qualitative behavior of the plasma parameters. The electron temperature results obtained from the CR model, ML, and line ratio methods were compared and found to be in excellent agreement. Overall, the present study demonstrates diagnostic approaches that can benefit the LPP community significantly by providing a rapid understanding of the plasma behavior across various operating conditions.
Mitigating interface damping of metal adhesion layers of nanostructures through bright-dark plasmonic mode coupling
Authors: Wang Lun , Ji Boyu , Xu Yang , Lang Peng , Shao Qi , Peng Siyuan , Yang Ju , Zhao Zhenlong , Song Xiaowei , Lin Jingquan
Published: November 2024

Metal (such as Cr, Ti, etc.) adhesion layers, which are generally used to prevent nanostructures from falling off during electron beam lithography processes, will introduce interface damping, decrease the near-field enhancement, and shorten the dephasing time of localized surface plasmons (LSP). Maintaining metal adhesion layers while alleviating the induced interface damping in nanostructures is crucial for high-performance sensing, surface-enhanced Raman scattering elements, plasmon-based photocathodes, and plasmon-mediated catalysis. Here, we experimentally demonstrated that the mitigation of interface damping of metal adhesion layers can be achieved through the coupling between the bright and dark plasmonic modes of gold nanorods. We attribute the mitigation to stronger confinement across the plasmon energy, which effectively reduces the proportion of plasmon energy injected into the Cr adhesive layers. Compared to weak coupling, the non-radiative damping of plasmonic modes 1 and 2 is reduced by approximately 74% and 85%, respectively, under strong coupling conditions. The experimental results are supported by finite-difference time-domain simulations and are well explained by the calculated interaction potential for different gap sizes. This research will further benefit applications where low interface damping is required, such as the construction of low-threshold nanolasers and ultrasensitive sensing systems.
Inverse stochastic resonance in adaptive small-world neural networks
Authors: Yamakou Marius E. , Zhu Jinjie , Martens Erik A.
Published: November 2024

Inverse stochastic resonance (ISR) is a counterintuitive phenomenon where noise reduces the oscillation frequency of an oscillator to a minimum occurring at an intermediate noise intensity, and sometimes even to the complete absence of oscillations. In neuroscience, ISR was first experimentally verified with cerebellar Purkinje neurons [Buchin et al., PLOS Comput. Biol. 12, e1005000 (2016)]. These experiments showed that ISR enables a locally optimal information transfer between the input and output spike train of neurons. Subsequent studies have further demonstrated the efficiency of information processing and transfer in neural networks with small-world network topology. We have conducted a numerical investigation into the impact of adaptivity on ISR in a small-world network of noisy FitzHugh–Nagumo (FHN) neurons, operating in a bi-metastable regime consisting of a metastable fixed point and a metastable limit cycle. Our results show that the degree of ISR is highly dependent on the value of the FHN model’s timescale separation parameter ε. The network structure undergoes dynamic adaptation via mechanisms of either spike-time-dependent plasticity (STDP) with potentiation-/depression-domination parameter P or homeostatic structural plasticity (HSP) with rewiring frequency F. We demonstrate that both STDP and HSP amplify the effect of ISR when ε lies within the bi-stability region of FHN neurons. Specifically, at larger values of ε within the bi-stability regime, higher rewiring frequencies F are observed to enhance ISR at intermediate (weak) synaptic noise intensities, while values of P consistent with depression-domination (potentiation–domination) consistently enhance (deteriorate) ISR. Moreover, although STDP and HSP control parameters may jointly enhance ISR, P has a greater impact on improving ISR compared to F. Our findings inform future ISR enhancement strategies in noisy artificial neural circuits, aiming to optimize local information transfer between input and output spike trains in neuromorphic systems and prompt venues for experiments in neural networks.
In vivo micro-Raman spectroscopy from an arbitrary-shaped region of interest under simultaneous reflectance confocal imaging guidance
Authors: Wu Zhenguo , Jiang Liwei , Zhao Jianhua , Lui Harvey , Zeng Haishan
Published: November 2024

Confocal Raman spectroscopy (CRS) has been widely used for noninvasive biochemical analysis of biological tissue in vivo. Currently, reflectance confocal microscopy (RCM) has been integrated with CRS as visual guidance for a square-/rectangular-shaped region of interest or a point of interest micro-Raman measurement. However, biological structures often have various morphologies; it is highly desirable to acquire a representative Raman spectrum from and only from the area that covers the whole target biological micro-structure. To achieve this goal, we developed a method to acquire Raman spectrum from a region of interest with any (arbitrary) shape under simultaneous RCM imaging guidance.
Investigation of Elaeocarpus ganitrus seed (EGs) powder as a sustainable composite biomaterial: Effects of particle size on the mechanical, frictional, and thermal properties for potential biomedical applications
Authors: Widodo Rahmat Doni , Rusiyanto Rusiyanto , Kriswanto Kriswanto , Naryanto Rizqi Fitri , Boy Alfres May , Fitriyana Deni Fajar , Siregar Januar Parlaungan , Cionita Tezara , Mamat Rizalman Bin , Jaafar Jamiluddin , Ammarullah Muhammad Imam
Published: November 2024

This study explores the potential of Elaeocarpus ganitrus seed (EGs) powder as a sustainable composite biomaterial, focusing on its particle size effects on the mechanical, frictional, and thermal properties of composite materials for potential biomedical applications such as prosthetics and implants. Composite specimens were produced using the compression hot molding method, utilizing EG powder particles of varying sizes (120, 140, and 200-mesh sieving). The influence of EG powder particle size on key properties was systematically investigated. The findings reveal that reducing the particle size of EGs leads to a decrease in density and hardness of the composite, with the largest particle size (BP1) resulting in the highest density and hardness. Friction coefficient measurements indicated suitability for biomedical applications where surface interaction and wear resistance are critical, such as joint prosthetics. Thermal analysis showed that BP1 exhibited superior thermal stability, with a maximum decomposition temperature (Tmax) exceeding 375 °C. Differential scanning calorimetry identified significant differences in glass transition temperature (Tg) and crystallization temperature (Tc) across specimens. The composites demonstrated exceptional thermal performance, surpassing previous benchmarks for biomaterials in high-temperature environments. The mechanical and thermal characteristics of Specimen BP1—2.725 g/cm3 density, 74 Shore D hardness, 0.159 coefficient of friction, 93.3% total residual, 378.14 °C Tmax, 426.25 °C Tc, and 376.87 °C Tg—suggest its potential for biomedical applications requiring durability and thermal resilience, such as in orthopedic devices and tissue engineering scaffolds.
Exploring advanced microwave strategy for the synthesis of two-dimensional energy materials
Authors: Cai Jingyan , Wu Zhiao , Wang Sangni , Guo Jiayue , Fan Miao , Xu Weilin , Jin Huanyu , Wan Jun
Published: November 2024

The rapid pace of technology and increasing energy demands underscore the urgent need for eco-friendly materials with exceptional energy conversion and storage capabilities. Two-dimensional (2D) energy materials, characterized by unique physicochemical properties, hold great promise in renewable energy conversion, catalysis, and electronics. Nevertheless, conventional synthesis methods often falter in balancing high quality, high yield, and cost-effectiveness, presenting substantial obstacles to their large-scale application. Microwave-assisted synthesis, characterized by its rapid and efficient process, emerges as a promising approach to surmount these limitations. This review meticulously examines the pivotal role of microwave-assisted synthesis in the preparation of 2D materials, highlighting its profound impact on enhancing material quality and production efficiency. By scrutinizing the unique physical properties of microwaves and their applications in material synthesis, the review elucidates the innovative contributions of microwave technology to materials science. Furthermore, it delves into the intricate influence of microwave parameter control on the synthesis process and resultant material properties, offering insight into the potential of microwave technology for the precise modulation of material structure and functionality. This comprehensive analysis underscores microwave-assisted synthesis as a viable solution for overcoming current challenges, thereby advancing the development of high-performance 2D energy materials.
Spreading of graphene oxide suspensions droplets on smooth surfaces
Authors: Quirke J. A. , Möbius M. E.
Published: November 2024

Understanding and predicting the spreading of droplets on solid surfaces is crucial in many applications such as printed electronics and spray coating where the fluid is a suspension and in general non-Newtonian. However, many models that predict the maximum spreading diameter usually only apply to Newtonian fluids. Here, we study experimentally and theoretically the maximum spreading diameter of graphene oxide suspension droplets impacting on a smooth surface for a wide range of concentrations and impact velocities (5≤We≤700, 30≤Re≤2000). As the particle concentration increases the rheological behavior changes from a viscous fluid to a shear-thinning yield stress fluid and the maximum spreading diameter decreases. The rheology for all concentrations is well described by a Herschel–Bulkley model that allows us to determine the characteristic viscosity and corresponding Reynolds number Re during spreading. Analogous to Newtonian fluids, the spreading ratio follows the Re1/5 scaling in the viscous spreading regime. Furthermore, we use this characteristic viscosity to develop an energy balance model that takes into account the viscous dissipation and change in surface energies to find the maximum spread diameter for a given impact velocity. The model contains one non-dimensional parameter α that encodes both the dynamic contact angle during spreading and the droplet shape at maximum spread. Our model is in good agreement with our data at all concentrations and agrees well with literature data on Newtonian fluids. Furthermore, the model gives the correct limits in the viscous and capillary regime and can be solved analytically for Newtonian fluids.
Mathematical modeling of electroosmotically driven peristaltic propulsion due to transverse deflections of two periodically deformable curved tubes of unequal wavelengths
Authors: Yadav Pramod Kumar , Roshan Muhammad
Published: November 2024

The present study aims to investigate the viscid fluid propulsion due to the electroosmosis and transverse deflections of the sinusoidally deformable tubes of unequal wavelengths in the presence of electro-kinetic forces. This situation is estimated from the physical model of physiological fluid flow through a tubular structure in which an artificial flexible tube is being inserted. In this model, both peristaltically deforming tubes are taken in a curved configuration. The flow-governing momentum equations are simplified by the approximation of the long wavelength as compared to the outer tube's radius, whereas the Debye–Hückel approximation is used to simplify the equations that govern the electric potential distribution. Here, the authors have used the DSolve command in the scientific computing software MATHEMATICA 14 to obtain the expressions for electric potential and axial velocity of viscid fluid. In this work, the authors have analyzed the impact of various controlling parameters, such as the electro-physical parameters, curvature parameter, radius ratio, wavelength ratio, and amplitude ratios, on the various flow quantities graphically during the transport of viscid fluid through a curved endoscope. Here, contour plots are also drawn to visualize the streamlines and to observe the impacts of the control parameters on fluid trapping. During the analysis of the results, a noteworthy outcome extracted from the present model is that an increment in electro-physical parameters, such as Helmholtz–Smoluchowski velocity and the Debye–Hückel parameter, are responsible for enhancement in the shear stress at the inner tube's wall and the axial velocity under the influence of electro-kinetic forces. This is because of the electric double layer (EDL) thickness, which gets reduced on strengthening the Debye–Hückel parameter. This reduced EDL thickness is responsible for the enhancement in the axial velocity of the transporting viscid fluid. The present model also suggests that the axial velocity of viscid fluid can be reduced by enhancing the ratio of wavelengths of waves that travel down the walls of the outer curved tube and the inner curved tube. The above-mentioned results can play a significant role in developing and advancing the endoscopes that will be useful in many biomedical processes, such as gastroscopy, colonoscopy, and laparoscopy.
A study on the internal vortex structure within a single-blade pump via numerical methods and particle image velocimetry experiments
Authors: Tan Linwei , Wang Wenrui , Shi Weidong , Yang Yang , Bao Linglei , Wang Chuanlong , Wang Tao , Li Hui
Published: November 2024

This study investigates the performance and internal flow characteristics of a single-blade centrifugal pump through a comprehensive analysis integrating performance tests, Particle Image Velocimetry (PIV) tests, and numerical simulations. Across the operational speed range of 1470–2940 rpm, the predicted pump (head-flow rate curve)performance error between the numerical simulation results and the test results of the pump underrated flow conditions is found to be only 3.4%, demonstrating the high accuracy of the selected numerical method in predicting both performance metrics and internal flow structures. Key findings highlight the presence of significant circumferential and axial secondary flows in the region where the blade wraps back, resulting in the formation of high-intensity vortex structures and subsequent energy dissipation. The interaction of the blade's trailing jet with the volute casing's tongue induces periodic changes in the intensity and spatial size of these vortex structures. Furthermore, pronounced reverse vortex pairs are identified within the volute casing, attributed to axial non-uniformity in impeller outflow. These vortex pairs are associated with the preferential accumulation of solid particles, potentially contributing to wear in the volute casing of single-blade centrifugal pumps. The revelation of the evolution characteristics of vortex structure in single-blade centrifugal pumps provides theoretical support for reducing pressure pulsation and radial force of single-blade centrifugal and provides a potential solution to the technical difficulties of low efficiency and poor stability of single-blade centrifugal pumps. Overall, this study provides valuable insights into optimizing the design and operational efficiency of single-blade centrifugal pumps by elucidating their complex flow dynamics and performance characteristics under varying operational conditions.
Rogue wave patterns in the nonlocal nonlinear Schrödinger equation
Authors: Zhang Guangxiong , Wu Chengfa
Published: November 2024

This paper investigates rogue wave patterns in the nonlocal nonlinear Schrödinger (NLS) equation. Initially, employing the Kadomtsev–Petviashvili reduction method, rogue wave solutions of the nonlocal NLS equation, whose τ function is a 2×2 block matrix, are simplified. Afterward, utilizing the asymptotic analysis approach, we investigate the rogue wave patterns when two free parameters a2m1+1 and b2m2+1 are considerably large and fulfill the condition |a2m1+1|2/(2m1+1)=O(|b2m2+1|1/(2m2+1)). Our findings reveal that under these conditions, rogue wave solutions of the nonlocal NLS equation exhibit novel patterns, which consist of three regions, which are the outer region, the middle region and the inner region. In the outer and middle regions, only single rogue waves with singularities may occur, and their locations are characterized by roots of two polynomials from the Yablonskii–Vorob'ev polynomial hierarchies. In the inner region, a possible lower order rogue wave may appear, which can be singular or regular, depending on the values of m1,m2, the sizes of τ function, and certain free parameters. Finally, the numerical results indicate that the predicted outcomes are in close alignment with real rogue waves.
Research on nonlinear instability of blended-wing-body aircraft based on experimental bifurcation analysis
Authors: Fu Junquan , Shi Zhiwei , Geng Xi , Chen Yongliang
Published: November 2024

Focusing on the nonlinear instability problem of the blended-wing-body aircraft, first, numerical bifurcation analysis is adopted to obtain catastrophe points and branches where the elevator is taken as a continuous parameter. Second, based on virtual flight tests and bifurcation theory, an experimental bifurcation analysis method is developed. Open-loop and closed-loop experiments are carried out, and the corresponding experimental bifurcation diagrams are obtained. The comparative analysis shows that the experimental bifurcation analysis enables the aircraft to make a response that is close to reality under the influence of nonlinear and unsteady aerodynamics and has a more intuitive embodiment of instability characteristics, providing an accurate prediction of departure. The open-loop experiment predicts a sudden longitudinal nose-up at an angle of attack of 7.4°. The closed-loop experiment can transform the open-loop unstable branch into a stable branch. However, roll instability still occurs at a critical angle of attack of 16.0°. These research results provide important dynamic information for the stable flight and the design of the controller.
Enhancing improved advection upstream splitting method on triangular grids: A hybrid approach for improved stability and accuracy in compressible flow simulations
Authors: Mohammadi Adnan , Djavareshkian Mohammad Hassan
Published: November 2024

This paper introduces NAUSM+M+AUFS (New Improved Advection Upstream Splitting Method Plus Artificially Upstream Flux Vector Splitting), a novel hybrid computational scheme for simulating compressible flows on triangular grids. The AUSM+M (Improved Advection Upstream Splitting Method) method is enhanced through two key modifications to boost numerical stability and robustness in high Mach number and hypersonic flows. The first modification redefines the interfacial numerical sound velocity, reducing shock anomalies and improving shock-capturing by integrating velocity and characteristic sound speed parameters. The second modification addresses the insufficiency of the pressure flux dissipation term at supersonic speeds by introducing a formulation that increases dissipation proportionally to the Mach number, thereby enhancing performance in high-speed flows. These enhancements constitute the NAUSM+M method. The NAUSM+M+AUFS scheme combines the strengths of NAUSM+M and AUFS (Artificially Upstream Flux Vector Splitting) methods, particularly in overcoming the limitations of NAUSM+M in handling shock instabilities and the carbuncle phenomenon on structure triangular grids. A dynamic switching function adjusts the weighting between NAUSM+M and AUFS, optimizing accuracy and stability based on local flow conditions. Numerical tests demonstrate that NAUSM+M+AUFS significantly outperforms AUSM+M, NAUSM+M, and AUFS, effectively eliminating the carbuncle phenomenon and providing smooth shock wave contours. In steady flow analysis, the new hybrid method achieves convergence speeds comparable to AUFS and shows 15% to 45% superior convergence accelerating than AUSM+M, depending on the convergence rate. In addition, in steady flow analysis, the accuracy of NAUSM+M+AUFS is 46% better than that of AUFS. This approach represents a significant advancement, offering a robust, accurate, and efficient solution for high-speed aerodynamic simulations, with broad applicability across various compressible flow challenges.
Impact of density ratio on droplet dynamics in pulsating flow
Authors: Kumar Robin , Mukhopadhyay Sudipto
Published: November 2024

Secondary atomization is extensively studied by investigating a droplet subjected to a steady air/gas stream. However, droplets are often subjected to unsteady or pulsating flows, such as in aero-engines or rockets, because of thermo-acoustic instabilities in the combustion chambers. The investigation focuses on the droplet dynamics and breakup in a pulsating flow for a range of density ratios (ρr), 1000 to 10, under sinusoidal airflow of different amplitudes and frequencies as compared to the dynamics in a steady flow. The volume of fluid multiphase model tracks the liquid–gas interface, and the governing equations are solved using the finite volume method. The two-dimensional axisymmetric pulsating simulations demonstrate accuracy comparable to the corresponding three-dimensional simulations at a much lower computational cost and are used for parametric studies. The droplets under the pulsating flow show a wavy surface, and larger vortex structures are observed during the deceleration period. At a high-density ratio (1000), pulsating flow enhances droplet deformation for a faster breakup, with the flow amplitude having more impact than its frequency. For a medium-density ratio (100), where breakup occurs under steady flow, droplet breakup is inhibited in the pulsating flow at low amplitude and high frequency. In the case of a low-density ratio (10), there is no breakup under steady flow, but pulsating flow promotes breakup, except at low amplitude and high frequency. The droplet breakup is always achieved for the highest amplitude, while lower frequencies push the liquid mass from the center of the droplet to the rim.
Raman activities of nitrogen reduction and ammonia oxidation intermediates on the high-entropy alloy CoCuFeMoNi catalytic surface
Authors: B. Araujo Rafael , Thyr Jakob , Bayrak Pehlivan İlknur , Edvinsson Tomas
Published: November 2024

We developed a computational framework to extract the Raman spectra of nitrogen reduction and ammonia oxidation intermediates on high-entropy alloy (HEA) surfaces, integrating density functional theory with microstructural representations to account for the inherent lattice randomness in these materials. As a case study, we computed the Raman activities of intermediates (N2*, NNH*, N*, NH*, and NH3*) and H* adsorption on CoCuFeMoNi HEA surfaces. A comprehensive map of Raman peaks was generated and assigned to specific vibrational modes. The method highlighted the effects of lattice randomness on the Raman spectra compared to those of adsorbates on single-element catalysts. For instance, our results showed that the adsorbed N2 exhibits Raman modes that are dependent on whether the adsorption is vertical or horizontal. These peak differences could serve as unique fingerprints to identify nitrogen reduction reaction pathways. Moreover, it is also possible to detect surface poisoning by hydrogen, a common issue in reductive environments, due to the high-frequency peaks of H* compared to the typical N-metal stretching and bending frequencies. These results provide valuable references for identifying intermediates in nitrogen reduction and ammonia oxidation reactions, offering insights into reaction mechanisms and potential surface poisoning. This approach is generalizable to other reactions and surfaces in catalysis, provided that the relevant intermediates can be identified.
DFT based analysis of pressure driven mechanical, opto-electronic, and thermoelectric properties in lead-free InGeX3 (X = Cl, Br) perovskites for solar energy applications
Authors: Hasan Md. Ratul , Apon Imtiaz Ahamed , Islam Md. Mafidul , Azad Asab Uzzaman , Aminuzzman Md. , Haque Md. Salman
Published: November 2024

Lead halide perovskites have distinct physiochemical properties and demonstrate remarkable power conversion efficiency. We used density functional theory to investigate the electrical, optical, structural, and elastic features of non-toxic InGeCl3 and InGeBr3 halide perovskite compounds at different hydrostatic pressures, from 0 to 8 GPa. InGeCl3 and InGeBr3 halide perovskite exhibit noteworthy changes in their electronic and optical properties under different pressure conditions. When the pressure is 0 GPa, the direct bandgap for InGeCl3 is 0.886 eV, and for InGeBr3 it is 0.536 eV. This gap decreases as the pressure rises. Specifically, InGeBr3 exhibits conducting properties at 3 GPa due to its larger bromine atoms, whereas InGeCl3 requires a higher pressure of 6 GPa to achieve similar conductivity. This type of nature suggests that larger halogen atoms reduce the bandgap more effectively under pressure. As the pressure increases, the behavior of the lattice constant and unit cell volume decreases constantly, from 5.257 and 145.267 Å3 for InGeCl3 to 5.509 and 167.168 Å3 for InGeBr3 at 0 GPa for both compounds. When subjected to pressure, the bonds between In-X and Ge-X atoms experience compression, leading to a decrease in surface area and an enhancement in mechanical strength. Overall, the compounds exhibit characteristics of semiconductors, as evidenced by evaluations of their electrical properties. As pressure increases, the bandgap decreases linearly, narrowing until it aligns with the Fermi level, leading to a transition toward a metallic state. In addition, the pressure induces a rise in the electrical density of states around the Fermi level by displacing valence band electrons in an upward direction. As pressure increases, the electron density peak shifts to lower photon energy values. Notably, InGeCl3 exhibits a more pronounced shift in this peak compared to InGeBr3, indicating greater sensitivity to pressure. In terms of optical properties, both compounds demonstrate significant absorption coefficients in the visible region, suggesting their potential suitability for photovoltaic applications. The dielectric constant, absorption, and reflectivity values all increase gradually as pressure increases. The absorption spectra shift toward longer wavelengths. Furthermore, the mechanical properties analysis reveals that all InGeX3 compounds are mechanically stable up to 8 GPa pressure.
On the electrohydrodynamic jet printing of two-dimensional material-based inks for printed electronics
Authors: Rijo P. C. , Vega E. J. , Galindo-Rosales F. J. , Montanero J. M.
Published: November 2024

Electrohydrodynamic (EHD) jet printing is a well-known advanced manufacturing technique that uses electric fields to generate and control fine jets of fluid for high-precision deposition of materials. This method enables the printing of extremely fine features, making it ideal for applications such as printed electronics. However, little is known about the optimal conditions for achieving consistent jet stability and droplet formation, especially when dealing with complex and volatile fluids laden with two-dimensional (2D) nanoparticles. In this work, we study the electrohydrodynamic printing process of 2D material-based inks using toluene as the main carrier fluid. Adding ethyl cellulose to toluene allows us to increase the stability of the suspensions and establish the steady cone-jet mode of electrospray. A small amount of ethanol increases the fluid conductivity, stabilizing the steady cone-jet mode and reducing the jet diameter. The inks behave as leaky-dielectric, weakly viscoelastic liquids. For this reason, the jet diameter and minimum flow rate obey the scaling laws for electrospray of Newtonian liquids. We determine the optimal parameter conditions for the EHD printing of our inks directly onto a non-conductive substrate. The influence of the substrate's velocity on the width of the printed lines is analyzed. These findings enlarge the knowledge about how to increase the throughput in the EHD jet printing process while controlling the resolution of the printed lines when using volatile solvents, 2D nanomaterials, and non-conductive substrates.
The isolated effect of yield stress in viscoplastic turbulent flow
Authors: Lugarini Alan , Franco Admilson T.
Published: November 2024

Turbulent flows of viscoplastic fluids are present in several industrial and natural applications. The effects of yield stress on this problem have always been studied as a part of a larger physical context, because real viscoplastic materials have many properties that cannot be easily isolated. Direct numerical simulations have recently emerged as a viable tool for investigating non-Newtonian fluid flow in turbulent regimes. In the present work, we solve the turbulent flow of an ideal Bingham fluid, focusing on the isolated effect of yield stress. A numerical scheme for viscoplastic flows was implemented based on the lattice Boltzmann method. An outstanding characteristic of this scheme is the possibility of representing infinite viscosity by setting the relaxation frequency to zero, enabling the representation of the Bingham constitutive equation without artifacts, and producing a more accurate representation of the yield surfaces. In the turbulent channel flow simulations, the friction Reynolds number was fixed at 180, while the Bingham number varied from 0 (Newtonian) to 0.15. It is shown that unyielded portions of material travel along with the flow near the centerline. These unyielded spots do not disappear quickly, but rather have a significant lifetime. Another interesting outcome is that the yield stress increases the turbulence anisotropy, by lowering the spanwise and normal velocity fluctuations, while the streamwise component becomes higher. Reynolds stresses and budgets of turbulent kinetic energy have been analyzed regarding the increased bulk velocities that were found by increasing the yield stress.
Interactions of localized wave and dynamics analysis in the new generalized stochastic fractional potential-KdV equation
Authors: Zhu Yan , Huang Chuyu , He Shengjie , Chen Yun , Zhong Junjiang , Li Junjie , Zhang Runfa
Published: November 2024

In this paper, we investigate the new generalized stochastic fractional potential-Korteweg–de Vries equation, which describes nonlinear optical solitons and photon propagation in circuits and multicomponent plasmas. Inspired by Kolmogorov–Arnold network and our earlier work, we enhance the improved bilinear neural network method by using a large number of activation functions instead of neurons. This method incorporates the concept of simulating more complicated activation functions with fewer parameters, with more diverse activation functions to generate more complex and rare analytical solutions. On this basis, constraints are introduced into the method, reducing a significant amount of computational workload. We also construct neural network architectures, such as “2–3–1,” “2–2–3–1,” “2–3–3–1,” and “2–3–2–1” using this method. Maple software is employed to obtain many exact analytical solutions by selecting appropriate parameters, such as the superposition of double-period lump solutions, lump–rogue wave solutions, and three interaction solutions. The results show that these solutions exhibit more complex waveforms than those obtained by conventional methods, which is of great significance for the electrical systems and multicomponent fluids to which the equation is applied. This novel method shows significant advantages when applied to fractional-order equations and is expected to be increasingly widely used in the study of nonlinear partial differential equations.
Optimization of a novel biomimetic vortex generator structure based on cavitation intensity and stability control
Authors: Huadan Cairang , Liu Zhenwei , Huo Wenzhao , Li Ping
Published: November 2024

Cavitation phenomena in the fields of hydraulic machinery and underwater submersibles have brought numerous negative impacts, such as vibration noise and mechanical damage. To suppress cavitation intensity and reduce the negative effects of cavitation instability, a biomimetic vortex generator (BVG), arranged on the surface of hydrofoils, is proposed in this study. The renormalization group k-ε turbulence model with density correction and the Ffowcs Williams and Hawkings acoustic model are employed. The cavitation intensity and cavitation stability of the BVG hydrofoil at different arrangement densities are analyzed. Cavitation control performance can be enhanced by reducing the spacing between structures on the hydrofoil. However, an excessively high BVG arrangement density may cause large-scale cavities to collapse prematurely, promoting the formation of small-scale cavities. This exacerbates cavitation instability, intensifies high-frequency pressure oscillations, and consequently amplifies noise. To mitigate performance degradation in hydrofoils caused by high-density BVG arrangements, the effects of structural height on the reentrant jet and surface vortices are analyzed. As a result of BVG structural optimization, cavitation intensity is further reduced, and cavitation stability is improved. Compared to the baseline hydrofoil, the time-averaged vapor volume over three cavitation cycles is reduced by 22.68%, the overall sound pressure level at receiver F decreases by 5.7 dB, and the dominant frequency of S3h2 hydrofoil cavitation decreases by 1.87 Hz. Ultimately, the optimization of the BVG structure enhances cavitation stability and significantly reduces high-frequency noise caused by pressure fluctuations on the hydrofoil surface.
Dynamics of a hot flexible cantilever plate under natural convection heat transfer in a square cavity
Authors: Kumar Vivek , Ranjan Aashish , Assam Ashwani , Prabhakaran Deepu
Published: November 2024

This study investigates the fluid-structure interactions of a flapping plate within a square cavity under four distinct boundary conditions, where two opposing walls are heated isothermally, and the others are adiabatic. These configurations are defined as case 1 (cooled side walls), case 2 (cooled top and bottom walls), case 3 (heated bottom and cooled top wall), and case 4 (heated top wall and cooled bottom wall). The effects of non-dimensional parameters, including Rayleigh number (Ra), Cauchy number (Ca), and mass ratio (β) on plate dynamics and convective heat transfer are analyzed. Numerical investigations are executed utilizing the SU2 open-source multi-physics computational fluid dynamics solver, with a fixed Prandtl number (Pr) set at 0.71 and dimensionless temperature difference (ϵ) established at 0.6. The results show that in cases 1 and 4, the plate exhibits no observable unsteadiness, while cases 2 and 3 reveal different oscillatory behavior within certain parameter ranges, including static mode, periodic flapping mode, quasi-periodic flapping mode, and chaotic flapping mode. In particular, the configuration in case 3 possesses higher inherent instability than case 2, causing the earlier onset of Hopf bifurcation. These findings provide valuable insights into the influence of boundary conditions on the behavior of flexible structures in fluid environments, highlighting the critical role of flow instabilities and boundary conditions in determining the dynamic response of the system.
Acoustic holographic lenses for transcranial focusing in an ex vivo human skull
Authors: Zhu Qiuchen , Bu Mengxu , Li Boyi , Jiang Xue , Liu Xin
Published: November 2024

The skull has long been an obstacle for transcranial ultrasound therapy and neuromodulation, leading to waveform distortion and focal points misalignment. In this work, we propose a dual-focus transcranial ultrasound focusing method for ex vivo human skulls to bridge this barrier, which is demonstrated by using a 2 MHz single-element transducer placed outside the occipital bone, coupled to a 3D-printed acoustic holographic lens. The experimental results show that the proposed method allows for achieving high-precision single- and dual-focus ultrasound focusing through human skulls with the maximum target registration error less than one wavelength in water. The in-target ratio spans a range from 72% to 92%, with an average of 80.7%, while the out-of-target ratio varies from 0% to 43.9%, with an average of 18.3%. Additionally, the focal spots are substantially free of the skull-induced distortion, closely matching the ideal ones, and maintain a clearly identifiable circular focus shape. The method opens up a route toward the subsequent applications in clinical research and may enable to implement transcranial ultrasound therapy and neuromodulation.
Effect of injection distance on supersonic combustion under different combustion modes
Authors: Li Fan , Sun Mingbo , Zhao Guoyan , Wang Taiyu , Ma Guangwei , Liu Mingjiang
Published: November 2024

The effect of injection distance on supersonic combustion under different modes in an ethylene-fueled scramjet combustor at Mach 2.52 is experimentally investigated. The study is based on three injectors at injection distances of 42, 21, and 7 mm. As the injection distance increases, a higher equivalence ratio is required to complete the transition from the Scram to Dual mode. The increase in injection distance will cause the reaction zone to move downstream in the Scram mode. However, the opposite is true in the Dual and Ram modes. In addition, the increase in injection distance will intensify the reaction zone oscillation under all modes. Moreover, in the Scram mode, shortening the injection distance will increase the heat release and the oscillation of heat release intensity. In the Dual mode, although shortening the injection distance cannot enhance the heat release, it will decrease the oscillation of heat release intensity. In the Ram mode, increasing the injection distance will enhance the heat release and will hardly increase the oscillation of heat release intensity. Considering the combustion heat release and oscillation, the injection distance should be shortened in the Scram and Dual modes and increased in the Ram mode.
Breather, soliton, multiple-pole, and interaction solutions to the Hirota–Satsuma equation
Authors: Wang Ming , He Guoliang , Xu Tao , Han Yitong
Published: November 2024

In this paper, we investigate serval types of localized waves of the Hirota–Satsuma equation by using the Hirota method. By means of two identities, the bilinear form of the Hirota–Satsuma equation is proposed. Then, the one-, two-, and three-soliton solutions are given explicitly and analyzed. The one-soliton solution could present the type of soliton or antisoliton, which depends on the sign of the wave number. The soliton–soliton, soliton–antisoliton, and antisoliton–antisoliton interactions are analyzed through graphics in the two-soliton solution case. The interactions among three solitons/antisolitons are considered in two cases. On basis of the soliton solutions, we give the conditions of obtaining breather solutions and interaction solutions between breathers and solitons. Multiple-pole solutions are derived by taking the limit of wave numbers and appropriate phase parameters. The dynamics of double- and triple-pole solutions are analyzed.
Numerical investigation of turbulent wake thermal effects on surface ships
Authors: Wu Zhongwan , Gong Jie , Su Junjun
Published: November 2024

To investigate the evolutionary mechanism of the thermal wake of surface ships, this study has proposed a numerical method for the thermal effects of turbulent wake and computed the near-wake fields for three ship schemes. The study indicates that the thermal wake, formed by vortices produced by the ship's movement and the propeller's rotation, propagates in a fine, thread-like pattern, setting it apart from the characteristic V-shaped diffusion of the Kelvin wake. The diffusion of thermal wake is divided into three distinct stages: formation, growth, and maturity. The thermal wakes generated by ships with shaftless rim-driven systems exhibit significantly lower diffusion rates, extents, and intensities compared to those created by ships with propeller propulsion systems. In summer, the center of the thermal wake exhibits a cold peak that is significantly lower than the ambient temperature. A reduction in temperature of greater than 0.05 K was observed for the three design schemes. In contrast, a warm peak that is above the environmental temperature is present at the edge of the wake. As the speed of the ship increases, the duration of each stage of the thermal wake lengthens and the diffusion range expands. When the temperature gradient is larger, the thermal wake becomes more intense. The findings of this study have revealed the evolution mechanisms of thermal effects in the wake of surface ships, thereby contributing to the advancement of knowledge in the fields of hydrodynamics and thermodynamics.
Numerical simulation progress of whole-heart modeling: A review
Authors: Ruan Chang , Zhou Jingyuan , Zhang Zhuo , Li Tao , Chen Lu , Li Zhongyou , Chen Yu
Published: November 2024

Cardiovascular diseases, characterized by high mortality rates, complex etiologies, and challenging prevention and treatment strategies, have become a major focus of public concern. With the advancement of computational numerical simulation technologies, whole-heart modeling has emerged as a crucial direction in cardiovascular engineering research. This review summarizes the progress in numerical simulations of whole-heart models, with a particular emphasis on the modeling and computation of cardiac-related physical fields. Through a retrospective study, this article covers various modeling approaches, including electrophysiological simulations, cardiac mechanics, and fluid–structure interaction models. Advanced theoretical models and numerical techniques are discussed in depth to enhance the accuracy and relevance of the simulations. Currently, numerical simulation techniques for whole-heart modeling have developed a relatively complete theoretical framework to compute key cardiac functions. However, there remains a need for further exploration in multiphysics coupling and high-performance computing to support clinical applications, requiring additional theories and methods. The integration of multiphysics and multiscale modeling is critical for advancing personalized medicine and improving the diagnosis and treatment of cardiovascular diseases. Future research will focus on enhancing computational efficiency and expanding clinical applications.
Analysis of visco-inelastic biphasic fluid flow in wire coating process
Authors: Hegde Soniya , Srikantha N.
Published: November 2024

To ensure the safety of data transmission, wires and fibers undergo a coating process to shield against potential damage. This process is critical in fields such as telecommunications, power transmission, and electronics, where durability and insulation are key factors. The current investigation is focused on the coating process by employing Eyring–Powell fluid in the presence of the magnetic field. The governing equations are developed by employing the biphasic (Buongiorno) model and temperature-dependent thermophysical properties. These equations are subsequently transformed into dimensionless form and tackled numerically. The study extensively explores critical aspects including shear stress rate, flow rate, and heat transfer rate for pertinent parameters. Furthermore, utilizing the response surface methodology, the optimization of shear stress and heat transfer rates in coated wire is pursued. This approach determines optimal levels for the viscosity parameter, Eyring–Powell fluid parameter, and thermophoresis parameter. The analysis concludes that the best outcomes are achieved by minimizing the viscosity parameter while maximizing the Eyring–Powell fluid parameter.