bluuebunny/crossref_metadata_2025 huggingface dataset:
Scale effects on ship vertical force and trim moment in calm water
Authors: Le Strat Maxime , Terziev Momchil
Published: January 2025

Predicting ship resistance with high accuracy is essential to reduce fuel consumption. Of the two currently available methods, extrapolation from models-scale using towing tank results shows high levels of uncertainty, and while computational fluid dynamics is a promising option to reduce this uncertainty, recent full-scale simulations show persistently high errors. Another way to reduce the uncertainty is to understand the scale effects and devise strategies to account of them. In this paper, we explore the scale effects on ship trim and sinkage through numerical simulations using viscous and linear scaling with three different turbulence models. We demonstrate that the scale effect on sinkage can be neglected. However, between Re = 106 and Re = 108, depending on the turbulence model, scale effects on the trim moment range from 15% to 27%, and differences in pressure coefficient on the hull can be observed between the different Reynolds numbers, especially around the aft of the ship of between 23.6% and 32.5%.
Phase difference effects on synthetic jet array flow: A proper orthogonal decomposition study
Authors: Pasa Jangyadatta , Arumuru Venugopal
Published: January 2025

In the present work, a proper orthogonal decomposition (POD) analysis is conducted for a synthetic jet array (SJ array) to qualitatively and quantitatively investigate the influence of jet vectoring resulting from the phase difference (∅) between the actuators on the distribution of kinetic energy (KE) among the vortices and their oscillating behavior across various modes. Here, the POD analysis is conducted for the SJ array operated at Strouhal number St=0.086 with different phase differences for a fixed Reynolds number Re=300. The simulated cases were run in OpenFOAM software, utilizing a two-dimensional, incompressible solver, and k-omega shear stress transport turbulence model. It has been observed that increased jet vectoring enhances vortex interactions, leading to the formation of smaller secondary vortical structures and a redistribution of KE toward higher modes. Furthermore, we observed that at phase differences of 60° and 90° (where maximum vectoring occurs), the energy within the synthetic jet array disperses evenly across various modes, indicating enhanced vortex interactions and leading to more complex flow dynamics. In contrast, at a phase difference of 180°, the jets exhibit continued interactive behavior, reflecting intricate flow patterns despite being completely out of phase with one another. The study also reveals that larger phase differences result in more complex flow behavior, requiring 324 modes to capture the actual flow at ∅=180°, compared to 295 modes at ∅=0°. This study highlights the critical role of jet vectoring in controlling the distribution of kinetic energy and the oscillation patterns of vortices, which are essential for optimizing the synthetic jet array and enhancing practical applications, such as targeted cooling efficiency and improved mixing processes in aerodynamics and thermal management systems.
Path integral Monte Carlo in a discrete variable representation with Gibbs sampling: Dipolar planar rotor chain
Authors: Zhang Wenxue , Moeed Muhammad Shaeer , Bright Andrew , Serwatka Tobias , De Oliveira Estevao , Roy Pierre-Nicholas
Published: January 2025

In this work, we propose a path integral Monte Carlo approach based on discretized continuous degrees of freedom and rejection-free Gibbs sampling. The ground state properties of a chain of planar rotors with dipole–dipole interactions are used to illustrate the approach. Energetic and structural properties are computed and compared to exact diagonalization and numerical matrix multiplication for N ≤ 3 to assess the systematic Trotter factorization error convergence. For larger chains with up to N = 100 rotors, Density Matrix Renormalization Group calculations are used as a benchmark. We show that using Gibbs sampling is advantageous compared to traditional Metropolis–Hastings rejection importance sampling. Indeed, Gibbs sampling leads to lower variance and correlation in the computed observables.
Crosswind-induced aero-performance deterioration of a vehicle passing by a hill with different windproof measures
Authors: He Hong , Li Guo-Zhi , Yang Wei-Chao , Liu Yi-Kang , Deng E
Published: January 2025

In crosswind conditions, the vehicle's aerodynamic performance significantly deteriorates when passing by a hill, impacting driving stability. Roadside windproof measures are effective in mitigating this performance deterioration. This study aims to explore the changes in aerodynamic performance of vehicles as they pass by a hill under three distinct scenarios: without wind barrier, solid wind barrier, and ventilation wind barrier. A three-dimensional computational fluid dynamics (CFD) model of the hill–embankment–wind barrier–vehicle–air, integrating the improved delayed detached eddy simulation (IDDES) turbulence model and a porous medium model, is established. The correctness of the numerical simulation is verified through field tests and wind tunnel experiments. The main conclusions are as follows: (1) When the vehicle passes by a hill under the crosswind, its aerodynamic loads undergo complex and significantly increased variations. ΔCx, ΔCy, ΔCz, ΔCmx, ΔCmy, and ΔCmz in the hill section without wind barrier are 2.79, 4.42, 5.18, 3.73, 4.45, and 2.73 times higher than those in the flat section. (2) The fluctuation amplitude of the aerodynamic loads and the maximum value of power spectral density (PSD) are the greatest under the solid wind barrier. Under the solid wind barrier, ΔCx, ΔCy, ΔCz, ΔCmx, ΔCmy, and ΔCmz are 3.63, 2.16, 4.34, 2.93, 2.00, and 3.21 times that with ventilation wind barrier. (3) Crosswinds cause flow separation on the leeward side and alter wind speed due to the hill's shelter without wind barrier. Ventilated barriers lessen these effects, while solid wind barrier reverses the crosswind direction, increases turbulence, and results in more erratic wind patterns and pressure changes on the vehicle's surface. (4) Without wind barrier, more vortex structures form on the leeward side and rear of the vehicle, which are smaller and less numerous with ventilation wind barrier. Solid wind barrier causes continuous changes in vortex structure position and size, resulting in the most significant aerodynamic load variations. This study provides valuable insights for selecting wind protection measures in hill sections of expressways.
In situ determination of the optical axis orientation in a single grain using time-domain Brillouin microscopy
Authors: Lejman M. , Vaudel G. , Juvé V. , Weber M. C. , Infante I. C. , Dkhil B. , Gusev V. , Ruello P.
Published: January 2025

In this paper, we develop a method that combines optical birefringence properties and time-domain Brillouin scattering microscopy to determine in situ the optical axis orientation of each single micrometer size grain in a polycrystalline sample. We illustrate the method by investigating the room temperature multiferroic material BiFeO3 where the optical axis coincides with the ferroelectric polarization direction. We are able to find the grain orientation and also provide the sound velocity (longitudinal and transverse) since the method is based on the Brillouin scattering process. These advances open interesting perspectives for probing the anisotropy of a micrometer size grain with an extension to the evaluation of the ferroelastic domain orientation in a non-contact and non-destructive manner.
Spin-transfer switching dynamics in a two-macrospin-coupled model system
Authors: Sun J. Z.
Published: January 2025

A quantitative understanding of spin-torque switching of nanomagnets beyond a macrospin limit and at finite temperature is important for applications, such as spin-torque magnetic random access memory (STT-MRAM). Thermally activated switching of a nanomagnet under a sub-threshold spin-transfer-torque (STT) bias has long been used to measure the thermal-activation reversal energy barrier related to memory bit’s data retention lifetime. Finite temperature write-error-rate (WER) statistics in non-macrospin systems are critically important for STT-MRAM write operations. For both thermally activated reversal and for write-error, descriptions beyond macrospin are necessary, as the macrospin-based asymptotic expressions are inaccurate beyond ∼2X for realistic experiments—doing so could cause unreliable interpretation for measurements of thermal-activation probability and WER characteristics. This is because most practical spin-transfer-torque switched MTJs are not macrospins. Here, using a two-macrospin coupled model as the next simplest case-study beyond a single macrospin, we demonstrate some key features of STT-biased non-macrospin dynamics, both in a thermal-activation region and for super-threshold fast-switching WER, and illustrate some behavioral differences of a system with more than a single macrospin’s internal degrees of freedom. These exercises provide an understanding to the correlation of quantitative trending of device behavior with material parameters and help to guide further optimization of materials and device designs for switching and data retention for nanomagnets in memory related applications.
Mechanism of matrix–fracture equilibrium time lag property inducing coal sub-matrix mass transfer behavior and its effect on the coal seepage characteristics in CO2 sequestration
Authors: Lin Xiaosong , Liu Zhengdong , Zhu Wancheng , Si Leilei , Qu Bao , Liu Shuyuan , Zhang Yihuai
Published: January 2025

Diffusion and seepage collectively govern the mass transfer behavior of gases in the CO2 enhancing coalbed methane recovery (CO2-ECBM) process, significantly influencing both coalbed methane extraction efficiency and CO2 sequestration capacity. Conventional theoretical models typically assume a uniform gas distribution within the coal matrix during injection. However, extensive field studies have revealed inconsistent conclusions. This paper delves into the gas equilibrium time lag property during the CO2-ECBM process, introducing the concept of sub-matrix mass transfer behavior to describe the non-uniform distribution of pressure, and construct the modified binary gas flow control equations and the permeability evolution model that takes this behavior into account. This model is used to investigate how sub-matrix mass transfer influences gas seepage characteristics. Findings show that the equilibrium time lag property intensify with coalbed extension but diminish over time. Despite an increased sub-matrix proportion enhancing CO2 adsorption capacity, the difference fades away due to the decay of the gas equilibrium time lag property. Furthermore, fixed-point monitoring reveals that a higher sub-matrix proportion aggravates permeability evolution, constraining fluid flow capacity. Based on these observations, a hypothesis of multi-level diffusion behavior within the coalbed is proposed, alongside an exploration of optimized CO2 injection strategies, providing new theoretical insights for CO2 sequestration in deep coalbeds.
Endohedral vs exohedral boron in C60: Bonding nature and impact on hot-electron relaxation dynamics
Authors: Xu Jianzhi , Guo Zhi-Xin , Hou Gao-Lei
Published: January 2025

Endohedral and exohedral fullerenes have both been employed as electron acceptors in polymer solar cells (PSCs). However, their differences in hot-electron relaxation dynamics remain unclear. Previous studies have shown that the location of a single atom, whether inside or outside the fullerene cage, results in significant differences in charge distribution. In this work, the hot-electron relaxations of endohedral B@C60+ and exohedral C60B+ are investigated using nonadiabatic molecular dynamics simulations. Our results reveal that the location of the boron atom—inside or outside the fullerene—significantly impacts the bonding interactions between boron and C60. Compared to C60B+, the weaker interactions in B@C60+ reduce the orbital overlap between LUMO+3 and LUMO+2 and increase the energy gap between them. This, in turn, slows hot-electron relaxation by weak nonadiabatic coupling, making B@C60+ more suitable for PSC applications. This study provides valuable insights into how atomic positioning affects the electronic properties in fullerene-based materials, contributing to the design of more efficient electron acceptors for photovoltaic devices.
Turbulence burst events in the bottom boundary layer of a tidal river
Authors: Liu Huan , Chen Xifen , Gu Junjie , Ye Leiping , Yang Desheng , Zhou Xuanyan , Wu Jiaxue
Published: January 2025

Understanding flow turbulence dynamics in tidal river systems is critical for nutrient transport, sediment dynamics, and ecosystem health in nature. This study investigates the characteristics of turbulent burst events within the bottom boundary layer of a tidal river, utilizing on site observational data and applying variational mode decomposition (VMD) and local intermittency detection (LIM). The results reveal that the VMD–LIM method is effective in examining multi-scale turbulent processes. Key findings indicate a positive correlation between turbulent eddy structures and flow velocity, with fully developed turbulence and frequent burst events observed during strong currents, contrasting with weak current periods. Distinct burst event types emerge across different frequencies, categorized as “turtle type” (lower intensity, longer duration) at low frequencies and “rabbit type” [higher intensity, shorter duration, on the order of O(100) Hz] at high frequencies [on the order of O(101) Hz]. Energy transfer predominantly occurs between adjacent intrinsic mode functions (IMFs), with more transfers during strong currents, highlighting a more active energy cascade process in tidal rivers compared to estuarine environments. The study emphasizes the need for further exploration of the effects of turbulent events across varying scales on Reynolds stress and sediment dynamics. By elucidating the relationship between turbulent burst events and flow conditions, we aim to provide valuable insight for predicting the impacts of turbulence on aquatic environments, furtherly improving models of sediment transport and enhancing the ecological health of tidal river ecosystems.
Impact of length ratio on vibration frequencies and localized stress in flexible cylindrical shells: A comprehensive fluid structure interaction analysis
Authors: Derakhshandeh Javad Farrokhi
Published: January 2025

The external flow around deformable or flexible thin-walled square and circular rings is investigated. Although numerous studies have focused on analyzing the characteristics of the flow over solid cylinders, investigations into the flow passing over a deformable ring are limited. This study comprehensively investigates the dynamic responses of very thin elastic cylindrical shells with square and circular cross sections in a laminar flow at Re = 200. An identical hydraulic diameter (Dh = 2 Ro= 10 mm) and an equal thickness (tc = 0.1 mm) were set for both shells. The cylinder height varies from LZ = 5 to 20 (mm). The relative fluidic and structural deformation equations are presented, and then the deformations or vibrations of the rings due to hydrodynamic forces are studied. A comprehensive modal analysis is performed. Furthermore, the lift and drag coefficients of the rings are analyzed and the vibration of the shells in x- and y-directions are investigated. The results show that as the height of the ring increases, a phase lag occurs between the drag and x-direction vibration of the shell; however, the phase lag between lift and y-direction vibration is almost negligible. It is demonstrated that the alignment or misalignment of vibrational responses with applied forces causes localized stress concentrations on the ring's surface in which the location of these stresses is influenced by the geometry and length of the cylinders.
Advanced fracability assessment in deep tight sandstone gas reservoirs: Methodologies and application to the Changling block, Songliao Basin
Authors: Wu Hua , Wang Xiaoqiong , Bai Jie , Ge Hongkui , Hao Chuncheng , Sheng Mao , Zhang Yanlong
Published: January 2025

Fracability is the ability of the reservoir to form a complex fracture network under hydraulic fracturing. In order to effectively evaluate the fracability of the deep tight sandstone gas reservoir in Changling Block, Songliao Basin of China, the velocities change with stresses, the stress–strain characteristics under uniaxial compression, combined with acoustic emission (AE) measurement experiments of the reservoir samples were conducted. Then, the experimental results of elastic parameters and the stress were used to calibrate the well logging data, and the in situ stress profiles and natural fractures development of the reservoir were systematically obtained. The research results indicate that the main controlling factors affecting the fracability of the deep tight sandstone gas reservoirs include matrix brittleness, natural fractures, compressive strength, the horizontal stress difference, and the minimum principal stress. The b-value of AE is derived from the Gutenberg formula, which can characterize the complexity of fractures. The larger the b-value, the higher the complexity of fractures. Then, a quantitative method for fracability evaluation of deep tight sandstone gas reservoirs was obtained based on the main controlling factors. The weights of each influencing factor were acquired by the correlation analysis of each influencing factor with the AE b-value. The quantitative method for fracability evaluation was then used for a vertical well and verified by the fracture-controlled production data indicating the reliability of the method. Finally, the suggestion for fracturing is put forward. It is recommended that during hydraulic fracturing, make the main fracture fully extend and communicate with as many natural fractures as possible. The natural fractures could be treated as the branching fracture of the hydraulic fracture. Then, a complex fracture network will be formed by increasing the net pressure inside the fracture.
The role of hemodynamics in the formation of atherosclerotic plaques
Authors: Quan Jianxun , Jiao Shuping , Ma Zheng , Chen Hongxun , Qu Lefeng , Wu Jianjin , Dai Chin
Published: January 2025

Carotid artery plaques pose a significant threat to human life and health, with the hemodynamics playing a crucial role in their formation and progression. In this study, we reconstructed geometric models of pre-pathological carotid arteries from the computed tomography angiography images. Using computational methods of fluid–structure interaction, key hemodynamic parameters that influence the plaques formation are investigated in the carotid arteries, such as time-averaged wall shear stress and oscillatory shear index (OSI). Additionally, a correlation between the shape index of endothelial cells and the hemodynamic parameters is established. Then, combining the pathology of atherosclerosis, a set of mathematical models is constructed to describe the transendothelial transport and evolution of key substances involved in plaque formation within the carotid arterial wall, thereby predicting high-risk areas for plaque formation. The results indicate a higher risk area around the carotid bifurcation, consistent with recirculation zones of blood flow and characterized by low WSS and high OSI. The risk areas predicted by our mathematical models are well validated by clinical images, suggesting the accuracy of models established in the study. This method predicts high-risk areas of plaque formation and provides valuable guidance for the clinical diagnosis and treatment.
Generalized Navier-slip approach for steady flows in common ducts and unsteady capillary slip-flow
Authors: Yap Emile Jean , Eny Geremino Ella , Hona Jacques , Azese Martin Ndi
Published: January 2025

This work presents a comprehensive analysis of slip phenomena by revisiting the Navier slip in common conduit geometries under dynamic equilibrium conditions. Focusing on slit-pore and cylindrical configurations, the study examines the Navier slip for linear flows in laminar slip-flows. The case studies are considered driven by constant wall velocities and pressure gradients, emphasizing equilibrium velocity profiles. By slip-flow, we mean flows influenced by slip. Key parameters—characteristic slip length (λ) and wall velocity (U0)—are isolated to highlight their influence within the flow. Two distinct analytical approaches are employed based on the dimensionless mean velocity (u¯m): one with a fixed u¯m=1, conducive to similarity studies, and another where u¯m varies with flow parameters, enabling broader velocity profile distributions. The fixed approach clusters data around u¯m=1, while the parameter-dependent approach yields profiles centered on parameter-specific mean velocities. Furthermore, through unsteady capillary flow analysis, the effects of slip on time-dependent velocity profiles and encroachment velocities are also examined, showing that increased slip results in higher imbibition velocities. These findings offer valuable insights into slip behavior in both simple and complex flows, aiding in the identification of slip effects via velocity profile analysis. They also provide a basis for aligning experimental and numerical data for validation purposes, enhancing the understanding of slip dynamics across varied flow conditions.
Defect-engineered electrical and optoelectronic properties of WS2 irradiated with 10 MeV protons
Authors: Lee Donggyu , Kwak Seung Jae , Bae Joonyup , Lee Won Bo , Kim Jihyun
Published: January 2025

Transition metal dichalcogenides (TMDs), particularly tungsten disulfide (WS2), have gained considerable attention due to their versatile electrical and optoelectronic properties, making them promising candidates for next-generation nano(opto)electronic devices. This study investigates the impact of 10 MeV proton irradiation on the electrical and optoelectronic properties of WS2, focusing on the controlled introduction of defects, primarily sulfur vacancies, which are crucial for tailoring material properties and enhancing their capabilities. By varying proton fluences from 1 × 1013 to 5 × 1014 cm−2 at an energy of 10 MeV, the defect density was precisely modulated. The effects of this defect-engineering strategy were characterized using micro-Raman spectroscopy, low-temperature photoluminescence, and density functional theory calculations. Both electronic (field-effect transistor) and optoelectronic (photodetector) devices fabricated with defect-engineered WS2 exhibited a 24-fold decrease in contact resistance and a fivefold improvement in photogain. These results demonstrate the potential of proton irradiation as a powerful tool for defect engineering in TMDs. The findings underscore the promise of this approach for optimizing TMD-based devices for advanced electronic and optoelectronic applications, paving the way for tailored material properties in next-generation technologies.
A radial micro-vibration system for reducing friction of passive interventional guidewire
Authors: Zhang Chaonan , Pan Liping , Wang Xiajing , Guo Ru , Zhao Yan , Liang Shuzhang
Published: January 2025

Endovascular guidewire interventional surgery is an effective treatment for vascular diseases. However, due to factors, such as blood viscosity and complex vascular morphology, the guidewire is interfered by strong varying resistance when moving in the lesion’s vasculature. This greatly affects the efficiency and safety of the clinical operation. Here, we develop a novel system that applies ultrasonic micro-amplitude vibration to the conventional passive guidewire for studying a drag reduction effect under multiple factors. The system is mainly composed of a sandwich-type ultrasonic transducer and a step-type horn for concentrating the unidirectional energy for micro-vibration. Subsequently, comparative experiments are designed to verify the effectiveness of this system for drag reduction. Through the multifactorial interactions, we study the friction reduction law of the microvibration-assisted method on the guidewire and the optimal drag reduction parameter combinations. The results show that the drag reduction effect varies with the amplitude–frequency response curve. An ultrasound vibration amplitude and a simulated vessel bending angle were the most significant factors. Only vibration frequency and amplitude interacted with a simulated vessel shape. Finally, using the resonance frequency and the maximum vibration amplitude to drive the guidewire vibration, the maximum friction reduction rate can be obtained, up to 85.2%. This system is expected to have important applications in clinical vascular interventional procedures.
450 nm light-induced upconversion ultraviolet-C photons for optical information encryption and sterilization
Authors: Zi Lingzhu , Yang Yanmin , Feng Shiji , Yang Furong , Wang Chunzheng , Li Leipeng
Published: January 2025

Ultraviolet-C (UVC) photons play a key role in many fields such as covert communication, bacterial inactivation, information storage, and encryption. Because the UVC component of solar spectrum is almost absorbed by the ozone layer around our earth, there is little natural UVC light on the earth. Therefore, developing artificial UVC light source is of great significance. The visible-to-UVC upconversion mechanism has been demonstrated to be a useful strategy. Here, we introduce a visible-to-UVC upconversion system, that is, CaSrSiO4:Pr3+. Under excitation of both commonly used laser and light-emitting diode at 450 nm, CaSrSiO4:Pr3+ emits UVC photons. The presence of UVC light of CaSrSiO4:Pr3+ has also been confirmed by a solar blind camera, in addition to an optical spectrometer. Moreover, experimental results show that the UVC emission of CaSrSiO4:Pr3+ is assigned to a two-photon assisted upconversion mechanism. In the end, we demonstrate the potential applications of CaSrSiO4:Pr3+ for information encryption and sterilization.
Challenging behaviour, activity, and participation following acquired brain injury: a scoping review of interventions delivered by allied health professionals
Authors: Sloan Sue , Bould Em , Callaway Libby
Published: January 2025

Background This scoping review aimed to identify literature describing allied health interventions used to address challenging behaviour for adults with an acquired brain injury (ABI) living in community settings and identify the impact of these interventions on outcomes across the domains of behaviour, activity, and participation. Methods The Polyglot Search Translator for scoping reviews guided the search of six databases: (1) Ovid Medline®, (2) EmCARE (Ovid), (3) CINAHL Complete, (4) Embase (Ovid), (5) Scopus, and (6) Cochrane Library to identify literature published between 1990 and 2023. Results Of the 1748 records screened, 16 articles met the inclusion criteria. Studies commonly described therapeutic, least restrictive approaches to challenging behaviour founded on a positive behaviour support framework. Interventions were individualised, combining multiple elements to effect change in the environment, behaviour of the people providing support, and/or skills and behaviour of the person with ABI. Although most studies reported clinical gains from intervention, study designs used a range of methods and either single cases or mixed populations. Conclusions The findings of this review suggest that allied health interventions have the potential to reduce challenging behaviour experienced by people with ABI. However, further research addressing the impact of interventions on activity and participation is required to inform clinical practice and improve long-term outcomes.
Magnetic topological Weyl fermions in half-metallic In2CoSe4
Authors: Bai Xiaosong , Wang Yan , Yang Wenwen , Xu Qiunan , Liu Wenjian
Published: January 2025

Magnetic Weyl semimetals (WSMs) have recently attracted much attention due to their potential in realizing strong anomalous Hall effects. Yet, how to design such systems remains unclear. Based on first-principles calculations, we show here that the ferromagnetic half-metallic compound In2CoSe4 has several pairs of Weyl points and is hence a good candidate for magnetic WSM. These Weyl points would approach the Fermi level gradually as the Hubbard U increases, and finally disappear after a critical value

U
c

. The range of the Hubbard U that can realize the magnetic WSM state can be expanded by pressure, manifesting the practical utility of the present prediction. Moreover, by generating two surface terminations at Co or In atom after cleaving the compound at the Co–Se bonds, the nontrivial Fermi arcs connecting one pair of Weyl points with opposite chirality are discovered in surface states. Furthermore, it is possible to observe the nontrivial surface state experimentally, e.g. angle-resolved photoemission spectroscopy measurements. As such, the present findings imply strongly a new magnetic WSM which may host a large anomalous Hall conductivity.
Methodology for determination of the emissivity of metal powders and uncertainty quantification using an infrared camera and thermocouples
Authors: Cullinan Michael , Vasilevskyi Oleksandr , Allison Jared
Published: January 2025

Experimental studies were carried out to determine the temperature and emissivity of 316L powder steel. It was found that the emissivity of powder steel varied from 0.33 to 0.58 in the temperature range from 59 °C to 900 °C. Based on the proposed methodology for quantitative assessment of temperature measurement uncertainty, it was established that the maximum value of the relative combined uncertainty in temperature measurement does not exceed 5.5%. Using the measure of agreement (normalized deviation), it was confirmed that the obtained results demonstrated the laboratory’s sufficient technical competence.
SS-DETR: a strong sensing DETR road obstacle detection model based on camera sensors for autonomous driving
Authors: Li Xiaomei , Deng Xiong , Wu Xiaoyong , Xie Zhijiang
Published: January 2025

As a key step in obstacle avoidance and path planning, obstacle detection via camera sensors is crucial for autonomous driving. The real traffic road environment is complex and variable, and the existing obstacle detection algorithms still have the problem of insufficient sensing ability. Therefore, this work suggests a camera sensors-based Strong Sensing DEtection TRansformer (SS-DETR) obstacle detection model for autonomous driving. Firstly, receptive-field attention ResNet is designed to improve feature analysis and extraction performance by considering the importance of receptive field spatial features and channels. Then, an intra-scale feature interaction module based on multiple information fusion attention is created to strengthen the representation of advanced feature maps. Furthermore, the cross-scale feature-fusion module is optimized to extract more detailed information from multi-scale feature maps. Finally, a localization loss function based on L1 and Powerful Intersection over Union v2 is implemented to further boost the detection performance. To verify the efficacy of the suggested model, the KITTI dataset containing camera sensors-based road obstacle images is adopted. The experimental results reveal that compared to real-time DETR, SS-DETR improves mean average precision (mAP)@50:95 and mAP@50 by 2.4% and 1.9%, respectively, and has a real-time inference speed of 33.7 frames per second. To further confirm the generalization ability of the approach, experiments are conducted on the camera sensors-based Cityscapes dataset. The results divulge that the suggested strategy can effectively raise the detection accuracy of obstacles, and offer a fresh perspective on obstacle identification.
Regional real-time GNSS satellite clock error estimation and real-time PPP service application
Authors: Li Xiaoming , Li Haojun , Hu Guo , Li Zhicheng
Published: January 2025

The regional global navigation satellite system (GNSS) real-time high-precision satellite clock error estimation is crucial for delivering accurate regional precise point positioning (PPP) services. To address challenges such as estimation accuracy, time consumption, uneven distribution of stations, and network latency in regional networks, which compromise the timeliness and accuracy of real-time satellite clock error services, an improved method for real-time clock error estimation and service is proposed. This method employs a satellite clock error model that utilizes polynomial and harmonic-based functions. It directly estimates the model coefficients using phase and pseudorange observation data from a regional GNSS network. PPP users can use these coefficients to derive satellite clock errors at any given time. The proposed method streamlines the process of real-time clock error estimation and service, potentially increasing service availability for GPS and BDS-3 by up to 16.1% and 21.3%, respectively. The clock error accuracy estimated by the proposed method is comparable to that of the single-epoch estimation method, while enabling PPP users to access 1–3 additional satellites clock error service. Experimental results demonstrate that the proposed clock error estimation method enhances the accuracy of both static and kinematic PPP, with a maximum improvement of approximately 33.3%. Additionally, it reduces positioning convergence time to varying degrees, with the most significant reduction being about 4.9 min. Overall, the proposed method not only improves the timeliness of real-time clock error services but also extends their availability. It proves to be both feasible and effective in enhancing positioning accuracy and accelerating convergence.
Effect of FLASH dose-rate and oxygen concentration in the production of H2O2 in cellular-like media versus water: a Monte Carlo track-structure study
Authors: D-Kondo J Naoki , Borys Damian , Ruciński Antoni , Brzozowska Beata , Masilela Thongchai A M , Grochowska-Tatarczak Magdalena , Węgrzyn Magdalena , Ramos-Mendez José
Published: January 2025

Objective. To study the effect of dose-rate in the time evolution of chemical yields produced in pure water versus a cellular-like environment for FLASH radiotherapy research. Approach. A version of TOPAS-nBio with Tau–Leaping algorithm was used to simulate the homogenous chemistry stage of water radiolysis using three chemical models: (1) liquid water model that considered scavenging of e
aq
−, H• by dissolved oxygen; (2) Michaels & Hunt model that considered scavenging of •OH, e
aq
‒, and H• by biomolecules existing in cellular environment; (3) Wardman model that considered model 2) and the non-enzymatic antioxidant glutathione (GSH). H2O2 concentrations at conventional and FLASH dose-rates were compared with published measurements. Model 3) was used to estimate DNA single-strand break (SSB) yields and compared with published data. SSBs were estimated from simulated yields of DNA hydrogen abstraction and attenuation factors to account for the scavenging capacity of the medium. The simulation setup consisted of monoenergetic protons (100 MeV) delivered in pulses at conventional (0.2857

Gy s

−1) and FLASH (500

Gy s

−1) dose rates. Dose varied from 5–20 Gy, and oxygen concentration from 10 µM–1 mM. Main Results. At the steady state, for model (1), H2O2 concentration differed by 81.5%± 4.0% between FLASH and conventional dose-rates. For models (2) and (3) the differences were within 8.0%± 4.8%, and calculated SSB yields agreed with published data within 3.8%± 1.2%. A maximum oxygen concentration difference of 60% and 50% for models (2) and (3) between conventional and FLASH dose-rates was found between 2 × 106 and 9 × 1013 ps for 20 Gy of absorbed dose. Significance. The findings highlight the importance of developing more advanced cellular models to account for both the chemical and biological factors that comprise the FLASH effect. It was found that differences between pure water and cellular environment models were significant and extrapolating results between the two should be avoided. Observed differences call for further experimental investigation.
Monte Carlo in the mechanistic modelling of the FLASH effect: a review
Authors: Pikes Gavin , Dass Joshua , Gill Suki , Ebert Martin , Reynolds Mark , Rowshanfarzad Pejman
Published: January 2025

FLASH radiotherapy employs ultra-high dose rates of

>

40

Gy s−1, which may reduce normal tissue complication as compared to conventional dose rate treatments, while still ensuring the same level of tumour control. The potential benefit this can offer to patients has been the cause of great interest within the radiation oncology community, but this has not translated to a direct understanding of the FLASH effect. The oxygen depletion and inter-track interaction hypotheses are currently the leading explanations as to the mechanisms behind FLASH, but these are still not well understood, with many questions remaining about the exact underpinnings of FLASH and the treatment parameters required to optimally induce it. Monte Carlo simulations may hold the key to unlocking the mystery behind FLASH, allowing for analysis of the underpinning mechanisms at a fundamental level, where the interactions between individual radiation particles, DNA strands and chemical species can be studied. Currently, however, there is still a great deal of disagreement in simulation findings and the importance of the different mechanisms they support. This review discusses current studies into the mechanisms of FLASH using the Monte Carlo method. The simulation parameters and results for all major investigations are provided. Discussion primarily revolves around the oxygen depletion and inter-track interactions hypotheses, though other, more novel, theories are also mentioned. A general list of recommendations for future simulations is provided, informed by the articles discussed. This review highlights some of the useful parameters and simulation methodologies that may be required to finally understand the FLASH effect.
A stick-slip piezoelectric actuator designed via the asymmetric friction
Authors: Li Honglong , Sun Fengmin , Lv Jing
Published: January 2025

This paper proposes an asymmetric friction driving method to address the backward motion issue of stick-slip piezoelectric actuators. The optimization of the driving foot is conducted using the flexibility matrix and finite element simulation method. A general dynamic model of the asymmetric frictional stick-slip piezoelectric actuator is developed to validate the feasibility of the proposed method. Additionally, the dynamics model is utilized to analyze the smooth motion mechanism. A prototype is manufactured and tested, with experimental results demonstrating that the new piezoelectric actuator achieves smooth motion. Compared to traditional stick-slip piezoelectric actuators, which typically exhibit a backward motion rate of more than 5%, the displacement of the proposed actuator shows no backward motion when the driving voltage is increased from 25 V to 125 V. This result verifies the effectiveness of the proposed method. Furthermore, this actuator features a compact structure and offers high motion stability, operating smoothly at low driving voltages and frequencies. These findings lay a theoretical and experimental foundation for future research and expand the potential applications of stick-slip piezoelectric actuators.
Multi-pulse Fourier codes for bit transmission at the quantum limit
Authors: Rosati Matteo
Published: January 2025

Bit-transmission can be enhanced by the use of quantum detection techniques, realizing a joint-detection receiver (JDR) that is able to decode transmitted signals via a collective operation and achieve the Holevo channel capacity. Explicit JDR designs proposed so far employ the Hadamard or Fourier transform to perform a phase-to-intensity translation of the information encoding, effectively falling in the class of on-off-keying (OOK) modulation techniques; they improve over classical decoders but fall short of the Holevo capacity, particularly at large signal mean photon number

n
≳
1

. Here we introduce new families of decoders based on multi-pulse and multi-level codes. We compute the rate of these codes exactly, and provide a comprehensive study of their performance. We show that multi-pulse codes can approach the rate of OOK closely, providing a simplified design for quantum-enhanced communication in the photon-starved regime; furthermore, multi-level codes can approach generalized-OOK strategies with multiple pulse types, thus they can be employed in the larger photon-number regime.
Shared entanglement for three-party causal order guessing game
Authors: Kukulski Ryszard , Lewandowska Paulina , Życzkowski Karol
Published: January 2025

In a variant of communication tasks, players cooperate in choosing their local strategies to compute a given task later, working separately. Utilizing quantum bits for communication and sharing entanglement between parties is a recognized method to enhance performance in these situations. In this work, we introduce the game for which three parties, Alice, Bob and Charlie, would like to discover the hidden order in which they make the moves. We show the advantage of quantum strategies that use shared entanglement and local operations over classical setups for discriminating operations’ composition order. The role of quantum resources improving the probability of successful discrimination is also investigated. Our research provides a basis for examining computational model featuring a specific gate set while examining the diverse operations achievable through permutations of its elements.
Design and analysis of novel field plate-trench composite anode terminal in high-voltage Ga2O3 Schottky Barrier diode
Authors: Wang Ying , Zhang Xiao-bei , Guan He , Gan Xue-tao
Published: January 2025

To improve the breakdown voltage of Ga2O3 vertical Schottky Barrier diode (SBD), this article innovatively proposes a novel field plate-trench composite structure. Different from the traditional field plate structures and trench structures, the proposed composite structure innovatively adds a shallow trench under the field plate structure, greatly reducing the depth of the trench and relieving the etching difficulty. At the same time, simulation results show that the field plate-shallow trench composite structure can increase the breakdown voltage of the device from 543 V to 952 V, which is nearly 1.76 times higher than that of traditional devices. The new field plate-trench composite structure greatly improves the breakdown voltage of Ga2O3 vertical SBD, while also increasing the forward characteristics and the reliability of the device, having superiority in size, and alleviating the difficulty of the process. Our research work also has guiding significance for the research of other wide bandgap power devices.
On Lie symmetries, soliton interaction nature and conservation laws of Broer-Kaup-Kupershmidt system in shallow water of uniform depth
Authors: Tanwar Dig Vijay
Published: January 2025

The exact solutions of nonlinear partial differential equations are significant to analyze the soliton nature of physical phenomena. Therefore, the Lie symmetry method is introduced to obtain exact solutions of the Broer-Kaup-Kupershmidt system. It represents two-dimensional propagation of nonlinear and dispersive long gravity waves in shallow water with uniform depth. The present work is devoted to derive symmetry reductions, soliton solutions, and conserved vectors under one-parameter Lie group transformations. Meanwhile, the invariance property of Lie groups validates the reducibility of the system. Therefore, a continual process of reductions transmutes the test system into a system of ordinary differential equations. Thus, this integrability property leads to generalized exact solutions with parametric constraints. These solutions entail all three arbitrary functions, f
1(y), f
2(t), f
3(t) existing in infinitesimals and various free parameters. On account of existing functions and free parameters, the obtained solutions are more admirable than those of preceding works (Kassem and Rasheed 2019 Chinese J. Phys. 57 90–104, Kumar et al 2022 Math. Comput. Simulat. 196 319–35, Tanwar and Kumar 2024 J. Ocean Eng. Sci. 9 199–206) and helpful to describe significant physical nature under wide parametric ranges. The deductions of previous results on imposing the particular values to arbitrary functions and constants ensure the generalness and novelty of derived results. Moreover, adjoint equations and conserved quantities associated with Lagrangian formulation have been evolved via Lie symmetries. We numerically simulate these solutions to analyze their physical nature. Consequently, soliton fusion and fission, line solitons, doubly solitons, multisolitons, and bright and dark soliton nature are discussed, which validate the physical relevance of the solutions.
Simulation of terahertz spectrum of historical paintings for pigment identification
Authors: Pakarzadeh Hassan , Yahyazadeh Zahra
Published: January 2025

Cultural heritage is an important socio-economic resource, something that is the evidence of the historical ages. Recognizing and analysing the materials used in historical works are very complicated and difficult in the sense that there should be no change or damage in the structure. In this paper, we present a theoretical study to simulate experimental terahertz (THz) transmission spectra of historical paintings for pigment identification. For this purpose, we determine the dielectric function of the historical pigments using Drude–Lorentz model where by fitting the simulated results to the experimental data, the THz transmission spectra of the pigments are predicted. The results show a very good agreement for historical pigments like Cobalt blue, Aureolin, Cinnabar and Verdigris.
Effects of stretching and bending on the performance of a PDMS-based polarization-sensitive terahertz metamaterial absorber
Authors: Shakiba Leila , Salehi Mohammad Reza
Published: January 2025

A perfect stretchable and flexible metamaterial absorber has been proposed for the terahertz region. The structure exhibits single-band absorption in TE polarization and double-band absorption in TM polarization, with absorption values exceeding 99%. The absorption spectrum has been analyzed for various polarization angles. The absorption mechanism has been investigated using interference theory, demonstrating excellent agreement between simulation and calculation results. The proposed structure has been evaluated under bending radii of 6 μm, 10 μm, 16 μm, and 20 μm, and the frequency shift of 5.25 THz, 4.53 THz, 4.2 THz, and 4 THz has been obtained for the mentioned bending radii. Furthermore, the metamaterial absorber has been studied under different stretch values (5%, 10%, 15%, 20%, and 25%) in both X and Y directions. The frequency shift at the highest stretching limit compared to the non-stretched state in the X and Y direction has been determined as 1.51 THz and 0.42 THz, respectively. Overall, the proposed structure offers versatility for single-band or double-band measurement operations in two different polarizations, making it a promising candidate for various applications in the terahertz region.