bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary neural networks for learning turbulence closure models with explicit expressions
Authors: Li Haochen , Zhao Yaomin , Waschkowski Fabian , Sandberg Richard D.
Published: May 2024

Developing physical closure models with explicit expressions based on a given dataset is essential to science and engineering. For such symbolic regression tasks, biology-inspired evolutionary algorithms are most widely used. However, typical evolutionary algorithms do not utilize any structural information inherent in training data, which limits their performance in finding accurate model structures and coefficients. By combining one evolutionary algorithm, gene expression programing (GEP), with an artificial neural network (ANN) for symbolic regression, we propose a novel evolutionary neural network method, in which candidate expressions are specifically designed so that they can be transformed between the GEP and ANN structures during training iterations. By combining the GEP's global searching and the ANN's gradient optimization capabilities, efficient and robust convergence to accurate models can be achieved. In addition, sparsity-enhancing strategies have been introduced to improve the interpretability of the trained models. The present method has been tested for finding different physical laws and then applied to turbulence modeling problems with different configurations, showing advantages compared to the existing GEP and ANN methods.
Effect of anisotropic thermal transport on tearing mode stability in negative versus positive triangularity plasmas
Authors: Yang Xu , Liu Yueqiang , Yuan Jiao , Bai Xue , Dong Guanqi , Xia Guoliang , Zhou Lina , He Yuling
Published: May 2024

The combined effects of anisotropic thermal transport and the plasma shaping, including negative triangularity, on the n = 1 (n is the toroidal mode number) tearing mode (TM) stability are numerically investigated utilizing the MARS-F code [Liu et al., Phys. Plasmas 7, 3681–3690 (2000)]. While varying the plasma boundary triangularity, the TM stability is found to be dictated by the competing effects of the Shafranov shift induced stabilization and the bad-curvature induced destabilization. The negative triangularity shape increases the Shafranov shift (stabilizing) in the plasma core but also enlarges bad-curvature regions (destabilizing) near the plasma edge, with the net effect being largely destabilizing for the TM as compared to the positive triangularity counter-part. Large negative triangularity however can also lead to more stabilization for the plasma core-localized TM. Anisotropic thermal transport reduces the stabilizing effect on the TM associated with the favorable averaged curvature, resulting in more unstable core-localized TMs in both negative and positive triangularity plasmas. But the opposite effect can also take place for the edge-localized TM in finite-pressure plasmas with negative triangularity.
The Kirkwood–Bethe hypothesis for bubble dynamics, cavitation, and underwater explosions
Authors: Denner Fabian
Published: May 2024

Pressure-driven bubble dynamics is a major topic of current research in fluid dynamics, driven by innovative medical therapies, sonochemistry, material treatments, and geophysical exploration. First proposed in 1942, the Kirkwood–Bethe hypothesis provides a simple means to close the equations that govern pressure-driven bubble dynamics as well as the resulting flow field and acoustic emissions in spherical symmetry. The models derived from the Kirkwood–Bethe hypothesis can be solved using standard numerical integration methods at a fraction of the computational cost required for fully resolved simulations. Here, the theoretical foundation of the Kirkwood–Bethe hypothesis and contemporary models derived from it are gathered and reviewed, as well as generalized to account for spherically symmetric, cylindrically symmetric, and planar one-dimensional domains. In addition, the underpinning assumptions are clarified and new results that scrutinize the predictive capabilities of the Kirkwood–Bethe hypothesis with respect to the complex acoustic impedance experienced by curved acoustic waves and the formation of shock waves are presented. Although the Kirkwood–Bethe hypothesis is built upon simplifying assumptions and lacks some basic acoustic properties, models derived from it are able to provide accurate predictions under the specific conditions associated with pressure-driven bubble dynamics, cavitation, and underwater explosions.
Prompt extinction of bump-on-tail energy spectra for radiation belt electron phase space density
Authors: Zou Zhengyang , Huang Hanyu , Hu Jiahui , San Wen , Yuan Qitong
Published: May 2024

The bump-on-tail electron flux energy spectral distributions in the Earth's radiation belt are widely observed and have been proven to be generated by plasmaspheric hiss-led wave–particle interactions. Here, we report and discuss the prompt disappearance of them induced by the high solar wind dynamic pressure (Pdyn) combined with substorms on 12–13 March 2014. To remove the potential adiabatic influence, the electron fluxes are all converted to phase space density in the TS04 geomagnetic coordinate. Immediately after the Pdyn reached its maximum accompanied by the intensifying of substorms, the initial bump-on-tail spectra of the phase space density at L* (the third adiabatic invariant) from 3.8 to 4.4 were destroyed and rapidly smoothed to the exponential distributions, with a distinct ascent for lower energy electrons and a sharp decline for higher energy electrons. The balance line between the source and loss processes was located at μ = 50–200 MeV/G (μ is the first adiabatic invariant), which is sensitive to the spatial location. Further investigation of the temporal evolution of the phase space density along with L* and the plasma wave distributions provided evidence that the loss processes dominated at higher L* for electrons at μ ≳ 100 MeV/G, while the source processes became stronger at lower L* for electrons at μ ≲ 10 MeV/G. Our study provides new insight into the rapid change of the radiation belt electron spectral types in response to solar wind disturbances, which could be fully considered in further radiation belt particle modeling.
Informing conservation management of the bilby (Macrotis lagotis) in the Pilbara: a review of research and future directions
Authors: Northover Amy S. , Dziminski Martin A. , Carpenter Fiona M. , Moore Harry A. , Ottewell Kym , Palmer Russell , Gibson Lesley A.
Published: May 2024

For threatened species that occur across multi-use landscapes, a coordinated cross-tenure management approach is desirable to achieve long-term conservation outcomes. To provide a comprehensive understanding of the progress towards achieving conservation priorities for the greater bilby (Macrotis lagotis) in the Pilbara region of Western Australia (WA), and inform ongoing research and funding investment, we review a research program that has focused on the species over the past decade. Priorities were initially established at a stakeholder workshop in 2013, and research targeting key areas has greatly enhanced ecological knowledge of the bilby in the Pilbara and elsewhere in WA. Highlights include the development of a non-invasive scat DNA-based abundance monitoring technique, an improved understanding of habitat use and diet, including the importance of Acacia spp. that host root-dwelling larvae, and the threat posed by introduced predators. Proposed future research directions focus on better understanding habitat requirements and the association between key food resources and fire, evaluating genetic structure and gene flow at the landscape-scale and examining threat interactions. Management to mitigate a range of threats including introduced predators, grazing livestock/feral herbivores and fire is recommended, with consideration for an integrated approach.
Identification of cysteine-rich receptor-like kinase gene family in potato: revealed StCRLK9 in response to heat, salt and drought stresses
Authors: Zameer Roshan , Alwutayd Khairiah Mubarak , Alshehri Dikhnah , Mubarik Muhammad Salman , Li Cheng , Yu Chengde , Li Zhifang
Published: May 2024

The investigation into cysteine-rich receptor-like kinases (CRLKs) holds pivotal significance as these conserved, upstream signalling molecules intricately regulate fundamental biological processes such as plant growth, development and stress adaptation. This study undertakes a comprehensive characterisation of CRLKs in Solanum tuberosum (potato), a staple food crop of immense economic importance. Employing comparative genomics and evolutionary analyses, we identified 10 distinct CRLK genes in potato. Further categorisation into three major groups based on sequence similarity was performed. Each CRLK member in potato was systematically named according to its chromosomal position. Multiple sequence alignment and phylogenetic analyses unveiled conserved gene structures and motifs within the same groups. The genomic distribution of CRLKs was observed across Chromosomes 2–5, 8 and 12. Gene duplication analysis highlighted a noteworthy trend, with most gene pairs exhibiting a Ka/Ks ratio greater than one, indicating positive selection of StCRLKs in potato. Salt and drought stresses significantly impacted peroxidase and catalase activities in potato seedlings. The presence of diverse cis-regulatory elements, including hormone-responsive elements, underscored their involvement in myriad biotic and abiotic stress responses. Interestingly, interactions between the phytohormone auxin and CRLK proteins unveiled a potential auxin-mediated regulatory mechanism. A holistic approach combining transcriptomics and quantitative PCR validation identified StCRLK9 as a potential candidate involved in plant response to heat, salt and drought stresses. This study lays a robust foundation for future research on the functional roles of the CRLK gene family in potatoes, offering valuable insights into their diverse regulatory mechanisms and potential applications in stress management.
The Andes–Amazon–Atlantic pathway: A foundational hydroclimate system for social–ecological system sustainability
Authors: Beveridge Claire F. , Espinoza Jhan-Carlo , Athayde Simone , Correa Sandra Bibiana , Couto Thiago B. A. , Heilpern Sebastian A. , Jenkins Clinton N. , Piland Natalia C. , Utsunomiya Renata , Wongchuig Sly , Anderson Elizabeth P.
Published: May 2024

The Amazon River Basin’s extraordinary social–ecological system is sustained by various water phases, fluxes, and stores that are interconnected across the tropical Andes mountains, Amazon lowlands, and Atlantic Ocean. This “Andes–Amazon–Atlantic” (AAA) pathway is a complex hydroclimatic system linked by the regional water cycle through atmospheric circulation and continental hydrology. Here, we aim to articulate the AAA hydroclimate pathway as a foundational system for research, management, conservation, and governance of aquatic systems of the Amazon Basin. We identify and describe the AAA pathway as an interdependent, multidirectional, and multiscale hydroclimate system. We then present an assessment of recent (1981 to 2020) changes in the AAA pathway, primarily reflecting an acceleration in the rates of hydrologic fluxes (i.e., water cycle intensification). We discuss how the changing AAA pathway orchestrates and impacts social–ecological systems. We conclude with four recommendations for the sustainability of the AAA pathway in ongoing research, management, conservation, and governance.
A journey to your self: The vague definition of immune self and its practical implications
Authors: Koncz Balázs , Balogh Gergő Mihály , Manczinger Máté
Published: May 2024

The identification of immunogenic peptides has become essential in an increasing number of fields in immunology, ranging from tumor immunotherapy to vaccine development. The nature of the adaptive immune response is shaped by the similarity between foreign and self-protein sequences, a concept extensively applied in numerous studies. Can we precisely define the degree of similarity to self? Furthermore, do we accurately define immune self? In the current work, we aim to unravel the conceptual and mechanistic vagueness hindering the assessment of self-similarity. Accordingly, we demonstrate the remarkably low consistency among commonly employed measures and highlight potential avenues for future research.
Patients and mice with deficiency in the SNARE protein SYNTAXIN-11 have a secondary B cell defect
Authors: Kögl Tamara , Chang Hsin-Fang , Staniek Julian , Chiang Samuel C.C. , Thoulass Gudrun , Lao Jessica , Weißert Kristoffer , Dettmer-Monaco Viviane , Geiger Kerstin , Manna Paul T. , Beziat Vivien , Momenilandi Mana , Tu Szu-Min , Keppler Selina J. , Pattu Varsha , Wolf Philipp , Kupferschmid Laurence , Tholen Stefan , Covill Laura E. , Ebert Karolina , Straub Tobias , Groß Miriam , Gather Ruth , Engel Helena , Salzer Ulrich , Schell Christoph , Maier Sarah , Lehmberg Kai , Cornu Tatjana I. , Pircher Hanspeter , Shahrooei Mohammad , Parvaneh Nima , Elling Roland , Rizzi Marta , Bryceson Yenan T. , Ehl Stephan , Aichele Peter , Ammann Sandra
Published: May 2024

SYNTAXIN-11 (STX11) is a SNARE protein that mediates the fusion of cytotoxic granules with the plasma membrane at the immunological synapses of CD8 T or NK cells. Autosomal recessive inheritance of deleterious STX11 variants impairs cytotoxic granule exocytosis, causing familial hemophagocytic lymphohistiocytosis type 4 (FHL-4). In several FHL-4 patients, we also observed hypogammaglobulinemia, elevated frequencies of naive B cells, and increased double-negative DN2:DN1 B cell ratios, indicating a hitherto unrecognized role of STX11 in humoral immunity. Detailed analysis of Stx11-deficient mice revealed impaired CD4 T cell help for B cells, associated with disrupted germinal center formation, reduced isotype class switching, and low antibody avidity. Mechanistically, Stx11−/− CD4 T cells exhibit impaired membrane fusion leading to reduced CD107a and CD40L surface mobilization and diminished IL-2 and IL-10 secretion. Our findings highlight a critical role of STX11 in SNARE-mediated membrane trafficking and vesicle exocytosis in CD4 T cells, important for successful CD4 T cell–B cell interactions. Deficiency in STX11 impairs CD4 T cell–dependent B cell differentiation and humoral responses.
Collective dynamics of liquid sulphur across the polymerisation transition temperature probed by inelastic x-ray scattering
Authors: Hosokawa Shinya , Katayama Yoshinori , Tsutsui Satoshi , Baron Alfred Q R
Published: May 2024

Inelastic x-ray scattering (IXS) experiments on liquid sulphur were carried out below (140 ∘C) and above (180 ∘C) the polymerisation temperatureTλof about 159 ∘C to investigate changes in the collective dynamics of this unique liquid, that exhibits a liquid–liquid transition. As reported earlier, broad longitudinal acoustic excitation signals were observed at both temperatures, and only the width of the quasielastic peaks slightly decreased when the temperature crossed the transition temperature. A model analysis was performed using a generalised Langevin formalism with a memory function having one thermal and two viscoelastic decay channels with the help of simple sparse modelling, and large positive deviations from the hydrodynamic sound velocity by 51%–54% were observed. The fast viscoelastic relaxation timeτµis close to the correlation times of intermolecular stretching and bending motions of local sulphur connections in both ring and chain structures, and is similar to those of other molecular liquids. The small contrasts in the IXS spectra across theλtransition result in large changes in only the slow viscoelastic decay timeταof the memory function. Theταvalue at 140 ∘C matches the mixed internal/external torsional modes of S8molecules well, whereas that at 180 ∘C has no corresponding molecular motion mode. The kinematic viscosity values at theQ→0limit are much smaller than the minimum values of macroscopic shear viscosity, indicating that large changes in relaxation dynamics are expected withQin the GHz and MHz excitation regimes.
A modified two temperature molecular dynamics (2T-MD) model for cascades
Authors: Rojano Andrés , Hunt R J , Crocombette J-P , Murphy S T
Published: May 2024

Two-Temperature molecular dynamics (2T-MD) is a common approach for describing how electrons contribute to the evolution of a damage cascade by addressing their role in the redistribution of energy in the system. However, inaccuracies in 2T-MD’s treatment of the high-energy particles have limited its utilisation. Here, we propose a reformulation of the traditional 2T-MD scheme to overcome this limitation by addressing the spurious double-interaction of high-energy atoms with electrons. We conduct a series of radiation damage cascades for 30, 50, and 100 keV primary knock-on atoms in increasingly large cubic W cells. In the simulations, we employ our modified 2T-MD scheme along with other treatments of electron–phonon coupling to explore their impact on the cascade evolution and the number of remnant defects. The results suggest that with the proposed modification, 2T-MD simulations account for the temperature time evolution during the ballistic phase and remove arbitrary choices, thus providing a better description of the underlying physics of the damage process.
Pendulum with a large bob
Authors: Tadta Kritsada , Tanalikhit Pattarapon , Kanchanapusakit Wittaya
Published: May 2024

By measuring the period of oscillations, a suspended bob is used to determine the local gravitational acceleration g. When modelling the system as either a simple pendulum or a physical pendulum, the measured g is found to be less than the accepted value as the size of the bob increases. With a given bob’s size, the simple pendulum measures g to be slightly higher than the physical pendulum does.
Ultrabright attosecond gamma ray from irradiating solid foil with tailored vortex laser pulse
Authors: Ju L B , Wu C N , Li R , Zhang H , Wu S Z , Yu M Y , Huang T W , Zhou C T , Ruan S C
Published: May 2024

Intense attosecond light sources are required for investigating ultrafast electron dynamics, such as that in molecules and atoms, etc. However, so far the achievable photon energy remains at the keV level, thereby limiting their range of applications. For instance, probing intranuclear dynamics requires photon energies in the gamma-ray regime. We propose here a scheme for generating intense attosecond gamma-ray pulses by irradiating a thin solid-density foil with intense vortex laser. In the interaction, the laser driven-foil electrons are differentially accelerated within a quarter-wave field and become highly bunched. Three-dimensional particle-in-cell simulations show that they can efficiently (with

∼

30
%

energy conversion efficiency) radiate ultrashort (

∼

400

 as), high-flux (

>

10

10

photons per pulse), and ultrabrilliant (up to 1027 photons s−1 mm−2 mrad−2 per 0.1% BW at 1 MeV photon energy) gamma rays. With an x-ray driving laser, the scheme can even produce isolated bright sub-attosecond gamma-ray pulses that are useful for time-resolved nuclear spectroscopy and many other areas.
Comparing the efficiency of fly ash geopolymer attenuation and cement mortar as diagnostic x-ray shielding materials through theory and experiment
Authors: Shalbi Sabri M , Oglat Ammar A , Jaafar M S , Ahmed Naser M
Published: May 2024

This study compared ordinary Portland cement (OPC) and Fine Aggregate Graded Polymer (FAGP) samples mixed with 0%, 5%, 10%, and 15% barium sulfate (BaSO4). Theory using the XCOM program and experiments using x-ray fluorescence (XRF) within a specified energy range of 16–25 keV were used to calculate the samples’ mass attenuation coefficients. The comparison involved calculating the linear attenuation coefficients (μ/ρ) and attenuation coefficients (μ) of the samples. Both theoretical and experimental results show that the FAGP containing 15% BaSO4 at 16.61 keV has the best attenuation. The findings show that BaSO4 improves radiation shielding. A negative association was found between the attenuation coefficient (μ) and the energy level of radiated radiation. The analysis also found significant concordance between experimental and theoretical methods. In conclusion, the XCOM program had slightly higher mass attenuation coefficients, especially at lower energy levels.
Epitaxial analysis of GaInP/AlGaInP red light-emitting diodes with ternary AlGaP quantum barriers for quantum efficiency enhancement
Authors: Anum  , Usman Muhammad , Habib Usman , Ali Shazma
Published: May 2024

We have numerically analyzed Gallium Indium Phosphide (GaInP)/Aluminum Gallium Indium Phosphide (AlGaInP) red light-emitting diodes (LEDs) by utilizing ternary Aluminum Gallium Phosphide (AlGaP) quantum barriers instead of the conventional quaternary AlGaInP quantum barriers. The simulation findings show that the use of AlGaP quantum barriers in AlGaInP red light-emitting diodes leads to a significant increase in both electron and hole concentration in the quantum wells which in turn enhances the rate of radiative recombination compared to conventional (reference) red light-emitting diodes. Furthermore, the proposed LEDs have a substantial decline in efficiency droop from 38% to 32%.
Measurement of the damping coefficient of an elastic rubber band oscillator by a smartphone
Authors: Agliolo Gallitto Aurelio , Battaglia Onofrio Rosario , Fazio Claudio
Published: May 2024

The use of smartphones as laboratory tools for school physics experiments has recently received attention for the possibility of carrying out a wide variety of didactic experiments with low-cost equipments. This article presents a study on a damped oscillator consisting of an elastic rubber loop and a mass. The investigation of the oscillations was conducted by using a smartphone. The experimental data was interpreted by a simple model, obtaining information on the viscoelastic properties of the rubber material.
Quantum support vector machine for multi classification
Authors: Xu Li , Zhang Xiao-yu , Li Ming , Shen Shu-qian
Published: May 2024

Classical machine learning algorithms seem to be totally incapable of processing tremendous data, while quantum machine learning algorithms could deal with big data unhurriedly and provide exponential acceleration over classical counterparts. In this paper, we propose two quantum support vector machine algorithms for multi classification. One is the quantum version of the directed acyclic graph support vector machine. The other one is to use the Grover search algorithm before measurement, which amplifies the amplitude of the phase storing of the classification result. For k classification, the former provides quadratic reduction in computational complexity when classifying. The latter accelerates the training speed significantly and more importantly, the classification result can be read out with a probability of at least 50% using only one measurement. We conduct numerical simulations on two algorithms, and their classification success rates are 96% and 88.7%, respectively.
RFX-mod2 diagnostic capability enhancements for the exploration of multi-magnetic-configurations
Authors: Carraro L. , Zuin M. , Abate D. , Agostinetti P. , Agostini M. , Aprile D. , Barbisan M. , Belpane A. , Berton G. , Bonotto M. , Brombin M. , Cavazzana R. , Cinnirella L. , Ciufo S. , Croci G. , Cordaro L. , D’Isa F. , Dal Bello S. , Dal Molin A. , De Masi G. , Emma G. , Fadone M. , Fassina A. , Fiorucci D. , Franz P. , Grando L. , Guiotto F. , La Matina M. , Marchiori G. , Marconato N. , Mario I. , Marrelli L. , Milazzo R. , Molisani S. , Moresco M. , Muraro A. , Perelli Cippo E. , Peruzzo S. , Porcu P. , Pomaro N. , Puiatti M.E. , Putignano O. , Rigamonti D. , Rigoni Garola A. , Rizzolo A. , Ruffini F. , Scarin P. , Spagnolo S. , Spolaore M. , Taliercio C. , Tardocchi M. , Terranova D. , Ugoletti M. , Valisa M. , Vianello N. , Zaniol B.
Published: May 2024

The RFX-mod2 device, the upgraded version of the previous RFX-mod with a modified magnetic boundary, is presently under realization and will start to be operated in 2025. Significant upgrades of the diagnostic capabilities have been proposed and are under development. These include a largely increased number of in-vessel magnetic and electrostatic sensors, a new fast reciprocating manipulator for the exploration of the edge plasma in a wide range of experimental conditions, the improved Thomson scattering and soft x-ray diagnostics system for a detailed determination of the behavior of the electron temperature profile, new dedicated systems for the space and time resolved analysis of x-ray spectra and neutron rate, a reflectometric diagnostic for real-time determination of plasma position, two diagnostics devoted to the imaging of light impurities and influxes behavior along with arrays of halo current sensors. These diagnostic upgrades will be accompanied by a significant effort to improve the control of the electron density and of the impurity influxes by means of proper treatment of plasma facing components with in-vessel fixed electrodes distributed over the first wall. The described advancements will allow a deeper understanding of physics phenomena in the wide variety of magnetic configurations, including the tokamak, the reversed-field pinch and the Ultra-low q, which can be produced in RFX-mod2 thanks to its flexibility and unique MHD control capabilities.
Automated W7-X sawtooth crashes detection and characterization
Authors: Zanini M. , Aymerich E. , Böckenhoff D. , Merlo A. , Aleynikova K. , Brandt C. , Braune H. , Brunner K.J. , Hirsch M. , Höfel U. , Knauer J. , Laqua H.P. , Marsen S. , Pavone A. , Rahbarnia K. , Schilling J. , Smith T. , Stange T. , Thomsen H. , Wolf R.C. , Zocco A. ,   W7-X Team
Published: May 2024

Sawtooth crashes are observed during ECCD experiments at the superconducting optimized stellarator Wendelstein 7-X. The study and the characterization are necessary in order to understand under which condition ECCD can be driven without posing a risk to experimental operations. The development of automatic tools is crucial to speed up the analysis of extensive datasets. In this work, we report on the first attempt of using a data-driven approach to automatically characterize the sawtooth crashes. Cluster algorithms are applied to the dataset, confirming the existence of two distinct types of crashes. This approach allows to study the two groups separately and underlines the different plasma parameters that influence the sawtooth crash parameters, for instance crash amplitude and period.
Numerical simulation of the slamming effect of regular waves and freak waves on ultra heavy-lift amphibious connector
Authors: Bao Wenqian , Pan Yuxin , Xu Gang
Published: May 2024

The Ultra Heavy-lift Amphibious Connector can be used for sea and land operations. When the amphibious connector opens the bow door, it will inevitably suffer from the combined action of wind, waves, currents, and other factors, resulting in the slamming of the wave on the hatch and various landing ship hull movements in the process. Due to the complexity of the actual UHAC model, in order to save computing resources, this paper selects the external load on the UAHC hatch when it is operated in water when the door is closed. The effects of crest height, draught, and focus position on UHAC slamming under the action of regular waves and freak waves were analyzed. Based on the viscous flow theory, the CFD commercial software FLUENT is used to simulate the interaction between the reduction of regular waves and floating structures. The simulation results are compared with the experimental results to verify the feasibility of the proposed method. Since the published UHAC data cannot be found in the network environment, this paper draws the UHAC based on the only data on the Internet and studies the slamming load of the wave on the UHAC on this basis.
Method for vibration and acoustic radiation analysis of underwater stiffened plates with acoustic coatings
Authors: Wang Jingyao , Li Zhe , Wang Yichuan , Hu Zhuxi
Published: May 2024

Based on the effective medium theory as well as the three-dimensional viscoelastic theory, a semi-analytical model of the three-dimensional underwater vibration and acoustic radiation with cavity-type stiffened plate structures covered with acoustic coatings is established to solve the issues related to underwater vibration and acoustic radiation calculation of the stiffened plate and shell structure with complex acoustic coatings. By comparing the far-field acoustic radiation characteristics of the proposed semi-analytical model and the finite element numerical model, this research verifies the validity and accuracy of the proposed model. On such a basis, this research preliminarily investigates the coupling effect exerted by stiffeners and parent plates in stiffened plates as well as the vibroacoustic characteristics of acoustic coatings, thereby providing a valuable idea for the prediction of vibroacoustic characteristics concerning underwater structures.
Comparison of impulse noise energy distribution from two generations of parachute gun
Authors: Li Jun , Xie Wujun , Li Hui , Huang Guangjun
Published: May 2024

The rocket ejection seat is an advanced life-saving device for fighter pilots. However, it can also produce damaging impulse noise during ejection, which could compromise the pilot’s hearing health, and the manufacturer must assess the noise damage. This study uses Variational Mode Decomposition (VMD) and Hilbert-Huang transform (HHT) to analyze energy-instantaneous distribution over time and frequency-instantaneous and energy contribution of different modes of impulse noise generated by the parachute gun in two generations of rocket ejection seats. The results demonstrate considerable disparities in the energy distribution of impulse noise generated by the parachute gun in the new generation seat compared to the old generation seat. The new generation seat has higher overall energy, more concentrated action time, and a higher energy contribution in the 1-10 kHz frequency range. These findings provide valuable data for the design of the new generation of noise protection equipment for pilots.
The calibration device research for assessing the impact exposure level of rubber balls in architectural acoustics
Authors: Li Yubin , Yan Jianwei , Yu Ling , Wang Rui , Lu An
Published: May 2024

In order to accurately measure the impact exposure level of rubber balls used in architectural acoustics, a calibration device is designed based on a force sensor, signal analyzer, programmable stepper motor and Infinite Impulse Response (IIR) filter. A weighing sensor with a range of 200 kg is selected to match the range of impact forces of rubber balls. The sensor is installed on a specially designed metal base plate of a rubber ball measuring fixture and connected to the signal analyzer. The rubber ball is dropped from a predetermined height in a free-fall manner to impact the sensor, generating an impact waveform. The force exposure level is then calculated by using software algorithms built into the device. The accuracy and reliability of the calibration device are evaluated by conducting repeated measurements on rubber balls and comparing the results with a known standard force exposure level curve. The experimental results demonstrate that the calibration device can consistently and stably measure the force exposure level of rubber balls, showing consistency with the known standard values. However, due to limitations such as a limited variety of measured objects and insufficient measurement repetitions, further research will be conducted to increase the number of tested rubber balls and enhance the device’s capabilities. This will provide technical support for the further development and application of the device.
Measurement method of the transient radiated noise in the reverberant pool
Authors: Yang Liuging , Zhang Jun , Wu Boyue , Wang Jiaheng
Published: May 2024

Transient radiated noise is the primary source of exposure for underwater targets due to its short duration and distinct spectral line characteristics. In order to accurately measure the sound source level of transient radiated noise, a reverberation method of radiated noise measurement based on power averaging processing in the frequency band is proposed. The power of the transient signal is obtained by using time-domain signal autocorrelation technology. The sound source level of the transient radiated noise in the frequency range of 500 kHz to 10 kHz is determined by the reverberant characteristics of the pool. The sound source level of the transient radiated noise in the frequency range of 1 kHz - 10 kHz is compared and measured in the anechoic tank. The deviation of the measurement results is less than 1.5 dB, which confirms the accuracy of the reverberant measurement method.
Experimental design and verification of heat transfer flow in a scaled cabin model under the influence of convective and radiative coupling
Authors: Zhong Yifei , Lan Yuqing , Luo Haining , Zhang Jiagan , Zeng Yu
Published: May 2024

With the development of aircraft towards high altitude, high speed, and long endurance, the influence of aerodynamic and radiant heat on the flow and heat transfer in the cabin has increased. To explore the flow conditions in the cabin under the influence of ventilation, convection, and radiation coupling, a scaled model test was conducted for verification and simulation. According to the scaling principle, a small ventilation box with a scale of 1: 5 was designed to simulate the boundary conditions in grid computing methods by building ventilation, heating, and irradiation systems. The CFD results were compared with experimental results for analysis. The results show that the experimental results of the scaled model are comparable to the flow field of the prototype model, and the experimental measurement data can be used as a reference indicator for evaluating the temperature field inside the model cabin. The comparison between the simulation experiment and the simulation results verifies the applicability of numerical calculation methods to simulate the flow field in the passenger compartment and the rationality of the scaled test technical scheme.
Numerical simulation study on noise pollution of the pressurized gas system in pumped storage power station
Authors: Long Zhe , Shu Lingfeng , Zhang Xiang , Li Chengjun , Huang Jingqian
Published: May 2024

To Investigate the noise pollution caused by pneumatic whistling during the blowdown operation of a pressurized gas storage system in a pumped storage power station, the flow field and sound field distribution of the gas storage tank under blowdown operation are analyzed in detail through full-channel unsteady numerical simulation of the gas storage tank and its supporting facilities. Subsequently, a comprehensive analysis of the noise issue in the gas cylinder was conducted. While investigating the mechanism of noise generation based on the distribution of noise intensity, the precise location of the noise source was pinpointed, providing a reference for the stability research of the exhaust pressurized water system.
Detecting the high/low-speed large-scale structures by a machine learning perspective in turbulent boundary
Authors: Zhang Yujie
Published: May 2024

The current developments in machine learning have facilitated the application of data-driven strategies for predicting the evolution of vortex structures in turbulent boundary layers. This study combines the attached eddy hypothesis with the extreme gradient boosting model to forecast large-scale high/low-speed motion based on a series of input signals. The performance of the trained model, as quantified by the percentage of accurately predicted high/low-speed regions, exhibits variability concerning the deviation between the input velocity fluctuation and the predicted output value at z/δ=0.016, where ‘z’ represents the wall-normal height and ‘δ’ indicates the boundary layer thickness. Our findings underscore the significant potential of machine learning in predicting high/low-speed regions within large-scale motion.
The study of input power of an underwater free-damping ribbed plate in statistical energy analysis
Authors: Guo Zhiwei , Sheng Meiping , Wan Zifei , Wang Qian , Cheng Yipeng
Published: May 2024

To study the vibration characteristics of the free-damping ribbed plate with fluid load under point force excitation in statistical energy analysis (SEA), the theoretical model of input power calculation was established in this research. The simulational results from SEA commercial software validated the correctness of the proposed theoretical model. As inferred from the theoretical model, the added damping layer and ribs significantly affect the effective bending stiffness and area density, and the added fluid load only affects the effective area density. These effective parameters will affect the input power of the fluid-loaded free-damping ribbed plate, resulting in increased input power as a function frequency. The research in this paper could provide theoretical guidance on the vibroacoustic analysis of underwater complex ship structures.
Thermal behavior and dynamics of flow boiling in a pin-fin microchannel
Authors: Huang Haoxiang , Yan Zhe , Pan Zhenhai
Published: May 2024

As the need for effective heat dissipation in specialized systems intensifies, the study of flow boiling in microchannels has gained prominence due to its high efficiency and cost benefits. Utilizing a three-dimensional computational model incorporating the Volume of Fluid (VOF) and Saturated Interfacial Volume (SIV) methodologies, this research scrutinizes the behavior of saturated flow boiling in a microchannel featuring a centrally positioned, heated square cylinder. The analysis focuses on variations in bubble morphology, fluidic behavior, and thermal profiles, revealing that the evaporation of a thin liquid film contributes significantly to heat transfer efficacy. A systematic assessment of temperature gradients, heat transfer coefficients, and liquid film metrics uncovers the critical drivers behind effective heat transfer across different surfaces. Additionally, the study elucidates the role of Reynolds number and initial bubble size, indicating that higher Reynolds numbers thicken the liquid film, reducing heat transfer efficiency, while larger initial bubble diameters thin the liquid film, thereby boosting efficiency. Factors such as thermal boundary layer disruption and superheated fluid absorption further contribute to heat transfer optimization. This investigation enriches the current understanding of phase-change heat transfer dynamics and bubble interactions in microchannel environments equipped with a heated square cylinder.
Study on flow behavior of fresh concrete in elbow using the dense discrete phase approach
Authors: Wu Mingzhuang , Chen Fei , Li Aimin , Sun Guanzhong
Published: May 2024

The presence of an elbow in the pipe during pumping can cause serious problems such as separation and clogging of the concrete. It is difficult to accurately and intuitively observe the internal information of the pump tube. This work used the Dense Discrete Phase Model (DDPM) to investigate the flow behavior of fresh concrete in the elbow. Firstly, the accuracy of the simulation model is verified. Then, the DDPM is used to research the flow behavior of fresh concrete in the elbow at different inlet velocities, and the changing rules of flow velocity, pressure loss, and particle migration are revealed. This work provides a solution to ensure the normal pumping process and effectively predict the pump pressure loss.
Analytical solutions for unsteady fractional maxwell nanofluid flow and mass transfer between two rigid spheres with periodic oscillations
Authors: Shi Jingyun , Liu Chunyan , Bai Yu , Wu Xueke
Published: May 2024

In this paper, we develop axisymmetric squeeze flow and mass transfer of incompressible Maxwell nanofluid between two rigid spheres. The position of the boundary between the two rigid spheres varies periodically with time and space, and the unsteady magnetic field is considered. Analytical solutions are derived for velocity and concentration by using the method of Laplace integral variation. In addition, the radial velocity and concentration distributions are imaged and the relevant parameters are analyzed.
Pressure changes in two-phase flow of gas and liquid in a wellbore
Authors: Tian Jingmeng , Song Xianmin , Li Dan , Cao Guangsheng , Wang Xing , Wang Yahui , Meng Sinuo
Published: May 2024

The phenomenon of high gas-liquid ratio has an impact during the lifting process of oil wells, and it is necessary to study the variation of the two-phase flow of gas and liquid in the wellbore. In this paper, the pressure losses along the wellbore and the coupling pressure losses in the process of gas-liquid two-phase flow in the wellbore were studied through experiments. It was found that with the increase in gas content, the pressure losses gradually decreased, and there was a turning point in the pressure losses within the gas content range of 10-15%. With the increase in flow rate, the pressure losses also increased. The theoretical model was used to calculate the bottom hole pressure values of actual oil wells under different gas contents and flow rates. It was found that in the calculation process, the dominant flow regime is often slug flow. Through experiments and theoretical calculations, the influence of gas content and flow rate on the pressure inside the wellbore was determined, providing guidance for understanding the changes in pressure during the lifting process of oil wells.
Effects of computational domain in underwater explosion numerical simulation on bubble pulsation
Authors: Fang Houlin , Zhang Dezhi , Guo Quanshi , Lu Qiang , Ding Yang , Tao Sihao , Bai Wudong , Liu Cunxu
Published: May 2024

To clarify the influence of the computational domain size on the underwater explosion bubble pulsation, a one-dimensional axisymmetric model of the underwater explosion was established. The computational model was verified using empirical formulas. Further research was conducted on the variation patterns of the bubble pulsation period and maximum radius with changes in the proportional computational domain radius. The results indicate that as the proportional computational domain radius increases, the maximum radius of the bubble and the bubble pulsation period gradually increase and stabilize. The proportional computational domain radius required to achieve stability is related to the static water pressure of the computational domain. Increasing static water pressure makes the required computational domain size for achieving high numerical accuracy smaller. When the proportional computational domain radius reaches around 1600, the calculation results are highly accurate under different static water pressures at different depths of explosion.
Numerical study of the brash ice effects on propeller performance with different advance speeds
Authors: Wen Xiao , Liu Zhenghao , Yang Mengzi , Ding Ju
Published: May 2024

In this paper, the effects of brash ice on propeller performance with different advanced speeds are numerically analysed based on the CFD-DEM method. The results show that in the ice-water environment, the thrust and torque of the propeller oscillate violently due to the interaction between the ice and the propeller, and as the advanced speed increases, the oscillation becomes more and more intense. Moreover, under the blocking effect of sea ice, the average value of the thrust and torque of the propeller obviously increase and cause a large loss of propeller performance under high advance speed conditions, which would seriously affect the ice-breaking ability of polar ships.
Free-field three-transducer spherical-wave reciprocity calibration for hydrophone at hydrostatic pressure of 10 MPa
Authors: Jia Guanghui , Chen Yi , Zhang Dong
Published: May 2024

Free-field three-transducer spherical-wave reciprocity method has been reviewed and employed to calibrate the hydrophone of TC4033 in a high hydrostatic pressure vessel. To reduce the measurement uncertainty, a reciprocal calibration bracket and reciprocal transducers were designed and developed. The calibration bracket can locate the transducers in the high hydrostatic pressure vessel. The reciprocal transducer can reduce the errors caused by the deviation of reciprocity. A correcting sensitivity method based on complex electrical impedance measurement has been described, which can obtain the original open-circuit sensitivity of a hydrophone. It is more accurate than correcting method based on the measurement of extension cable capacitance especially near the resonant frequency range. The TC 4033 hydrophone was calibrated in the one-third octave frequency points from 2 kHz to 200 kHz at a high hydrostatic pressure of 10 MPa. The calibration results were analyzed, and the measurement uncertainty was estimated to be 0.5 dB (k=2).
Stochastic CFD numerical model, algorithm, and simulation on regular wave fields
Authors: Wang Mingyuan , Yu Wei , Yang Yang , Wang Yajun
Published: May 2024

This paper invites higher-order derivative numerical technology to research the stochastic characteristics in regular wave fields. The randomness of the parameters vector was incorporated during the stochastic space establishment, by which, the stochastic CFD numerical model and algorithm were developed in the study. Meantime, Taylor expansion coupled with the perturbation was also utilized to realize the investigation on the random behaviours of the regular wave fields where the perturbative values of the parameters vector included 1%, 2%, and 3%. The results indicated the merit of the stochastic CFD numerical model and algorithm in wave field research.
Parametric optimization of rearview mirror structure based on a multi-island genetic algorithm
Authors: Dong Guoxu , Jiang Hao , Zhang Dongxing , Ma Rui , Xia Jinhao , Jia Wenyu , Xu Xiaomin
Published: May 2024

To quickly find the structural parameters of a particular mirror that produces the least amount of aerodynamic noise, the rearview mirror of a passenger car is taken as the research object and an optimization platform is established based on Isight software in this paper. The mirror structure is parameterized in Sculptor, and several sample models are constructed using the optimal Latin hypercube design (OLHD). Then, by simulating each sample model, the sound pressure level of the Curle source at the side window surface monitoring point was obtained. The relationship between the mirror structure and the wind noise at the point is fitted using the Kriging approximation model after the calculation is completed. Finally, the values at each point decreased when the changes at positions 1, 2, 3, and 4 were 2.5 mm, 3.91 mm, 4.5 mm, and 3.6 mm, and the sound pressure level at monitoring point 4 decreased the most, with a reduction of 3.76 dB in wind noise compared with the original model.
The comparative research on the VPMM experiment and numerical simulation of the SUBOFF model
Authors: Sun Haoyu , Hong Yue , Yu Changli , Zhang Xingming , Ju Xiaoqun
Published: May 2024

To ensure optimal maneuvering performance of underwater vehicles, it is essential to obtain highly precise hydrodynamic coefficients for constructing the equations of motion. The principal approach to acquiring these coefficients is through the Planar Motion Mechanism (PMM) test. The subject of this paper is the SUBOFF full appendage model. To obtain hydrodynamic coefficients related to maneuvering motion, a Vertical Planar Motion Mechanism (VPMM) test is conducted in the circulating water tank. In addition, a numerical simulation of the typical pure heaving and pure pitching maneuverability test is performed for the model by programming its motion UDF using Fluent’s dynamic mesh technology. The test results and calculated hydrodynamic coefficients are compared to the data obtained from the Key Laboratory of Underwater Robotics Technology of Harbin Engineering University. The calculation results show high credibility of the test results of the circulating tank VPMM test. The corresponding numerical simulation has a certain practical engineering accuracy, which can break through the limitations of the test and also provides valuable experience and technical reference for the hydrodynamic prediction of other underwater vehicles.