bluuebunny/crossref_metadata_2025 huggingface dataset:
A slip length analysis of microchannel flow with smooth and structured surfaces
Authors: Gluzdov Dmitry S. , Gatapova Elizaveta Ya.
Published: December 2024

One of the most significant challenges in microchannel design is the reduction of pressure drops within miniature fluidic pathways. A promising approach involves the manipulation of boundary conditions, mainly through the integration of structured hydrophobic surfaces. The mathematical characterization of these hydrophobic surfaces is achieved through the application of the Navier boundary condition, with the slip length identified as the critical parameter of interest. This paper delves into an in-depth exploration of how varying slip lengths impact the liquid flow dynamics within microchannels with a rectangular cross section. We consider a diverse range of microchannel hydraulic diameters 5–200 μm and aspect ratios from 1:1 to 1:20 for Reynolds numbers in the laminar range 10–1000. Three-dimensional calculations are performed on both conventional smooth microchannels and those equipped with air-filled groove-structured surfaces. The results are then compared with the analytical solution and experimental results. The application of a hydrophobic structure to a single microchannel surface is resulted in the friction factor reduction by over 30%, while the application of the hydrophobic structure to two opposing walls led to a reduction by over 60%. The maximum throughput is shown to be achieved for a bubble protrusion angle of approximately 0° for a microchannel with a single hydrophobic wall. The greatest reduction in the friction factor was achieved when the bubbles were positioned in a staggered configuration at bubble protrusion angles of approximately –25° for microchannel with two opposing hydrofobic walls.
Integrated optimization of turbomachinery via discrete adjoint and hierarchical free form deformation parameterization method
Authors: Zhang Jianshe , Zhang Yanfeng , Zhang Ziqing , Dong Xu , Yuan Hang , Lu Xingen
Published: December 2024

Aerodynamic optimization is an effective technology to improve the performance of turbomachinery. Traditional aerodynamic optimizations often focus on blade profiles and neglect the interactions between the blade and end wall, which may lead to suboptimal optimization result. To address this challenge, this study introduces an integrated optimization framework to simultaneously optimize both the blade and hub end wall aerodynamic shape. A hierarchical free form deformation (FFD) technique is employed to achieve integrated parameterization of the blade and hub, with a total of 580 design variables. To ensure efficient optimization with such a high-dimensional problem, the discrete adjoint method is used, which makes the optimization cycle less than one day. Under the framework, the blade optimization and integrated optimization of a typical compressor fan, rotor37, are conducted. With strict constraints on flow rate and total pressure ratio, the integrated optimization achieves a 2.85% improvement in isentropic efficiency—about 0.6% higher than blade optimization. The flow control mechanisms of two optimization approaches are compared, revealing that both blade optimization and integrated optimization effectively modify the blade profile to weaken the shock wave. Furthermore, by modifying the hub aerodynamic shape to improves the flow structure near the end wall, integrated optimization it is more efficient in turbomachinery aerodynamic optimization.
Roadway portal and self-moving hydraulic support for rockburst prevention in coal mine and its application
Authors: Li Xuelong , Chen Deyou , Li Zhen , Liu Shumin , Zhai Minghua , Li Yunzhe , Gong Bin , Sun Zhongguang , Wang Yong , Wang Dengke
Published: December 2024

As coal mining depths increase, rockbursts pose a significant threat to the safety of coal mine operations. Addressing the challenge of safely and steadily advancing excavation faces amid rockburst hazards, this study assesses the current state of reinforcement support technology for rockburst-prone roadways. It scrutinizes the concept of roadway anti-rockburst hydraulic support, support design, and the integration with the surrounding rock mass. The research delineates key directions for enhancing support systems, including the mechanical mechanisms of anti-rockburst hydraulic support, integrated roadway and support design, the synergistic pressure-equalizing effect of primary supports and bolts(cables), and the development of robotic systems for roadway anti-rockburst hydraulic support reinforcement. We propose an integrated design approach that holistically addresses both primary and reinforcement support in rockburst-prone roadways. To tackle the challenge of handling hydraulic supports in confined spaces, we developed a gantry hydraulic support system capable of self-movement with mechanical arm assistance for anti-rockburst hydraulic support. Field trials demonstrate that this system enables cyclical support advancement and retraction, automating and intelligently managing the underground advanced support sector. This innovation significantly reduces worker numbers and labor intensity, enhancing operational safety and efficiency. Furthermore, the system facilitates permanent support via bolt drilling under hydraulic protection, effectively mitigating the risks associated with unstable temporary roadway support and unsafe working conditions without proper roof coverage, thereby ensuring the secure and efficient operation of mining face.
Experimental study on dissipative characteristics of cathode plasma of coaxial magnetically insulated transmission lines based on microwave interferometry
Authors: Yang Yaorong , Wei Hao , Wu Hanyu , Li Mo , Wang Liangping , Hong Yaping , Shan Weihong , Sun Tieping
Published: December 2024

Flash x-ray radiography is an important diagnostic in hydrodynamic experiments to provide fluoroscopic imaging of fast-moving dense targets. In order to obtain multiple images of an object at different times in an experiment, a flash x-ray accelerator is required to output multiple pulses. For the induction voltage adder (IVA) multi-pulse accelerator, it is important to study the effect of the cathode plasma generated by the front pulse in magnetically insulated transmission lines (MITLs) on the transmission of the subsequent pulses. In this paper, a coaxial MITL experimental platform based on the “QiangGuang-I” accelerator is established to study the dissipation characteristics of the cathode plasma, and its working condition is similar to that of MITLs in typical IVA accelerators. In the experiment, a stable magnetic insulation is formed in the coaxial MITL, and the current loss along the line can be ignored. The microwave interferometer is used to measure the evolution of cathode plasma density over time for hundreds of microseconds after the pulse disappears. The measurement results of microwave interference show that the line-averaged density of the plasma in the anode–cathode gap is above 1 × 1018 m−3, and the time for the plasma density to decrease to 1 × 1016 m−3 is about 600 μs. The expansion velocity of the plasma after a pulse is much lower than that during the pulse. In addition, the dissipation characteristics of the cathode plasma with different electrical parameters of the pulses are compared and analyzed.
The fusion method based on small-sample aerodynamic thermal and force data
Authors: Sun Yahui , Li Yubo , Wu Anping , Wang Qingfeng , Huang Jun , Liu Feng
Published: December 2024

At present, high-fidelity data are expensive to acquire. When fusing limited high-fidelity data, the small-sample size introduces problems such as missing information and sample bias, which leads to overfitting of the results and accuracy degradation. In this paper, we propose a small-sample aerodynamic data fusion method based on deep neural networks. The method applies semi-supervised learning for model construction using multi-fidelity aerodynamic thermal and force data. The initial model is trained with both labeled and unlabeled data by an improved flexible loss function. Using unlabeled data as a soft constraint combined with semi-supervised learning enables the model to perform better with small-sample data. This article investigates the ONERA (National Office for Aerospace Studies and Research) M6 wing surface pressure distributions at different airfoil spread coordinates and verifies the applicability of the proposed method by reducing the proportion of high-fidelity data in the training and test datasets. The proposed method is then applied to the prediction of aerothermal data on the surface of a blunt bicone. The results show that, using a small-sample high-fidelity dataset, the proposed method can predict the surface pressure distribution and surface aerodynamic heat distribution of the aircraft relatively well. As the volume of high-fidelity data decreases, the proposed method outperforms other methods.
The influence of canard wing parameters on the vertical water entry of a vehicle
Authors: Li Wenpeng , Wang Cong , Wei Yingjie , Ding Yanyi , Bao Jian
Published: December 2024

Flow control techniques are beneficial for changing the flow and motion characteristics of a vehicle during water entry. Combined with high-speed photography and inertial measurement unit, this paper investigated the cavity evolution and vehicle kinematics during water entry by varying the length, height, and width of a single canard wing. Research indicates that changing the wing length minimally affects the shape and size of fore-end cavity. For the attached cavity on the wing, increasing wing length promotes the formation of the cloudy flow characterized by violent air–water mixing, destroying the integrity of it. As wing height increases, the fore-end cavity profile approaches a rectangle, while the attached cavity on the wing evolves from an ellipse to a triangle. Increasing the wing width shifts the fore-end cavity profile from a rectangle to a trapezoid. There is an impact on the vehicle when the fore-end cavity occurs pinch-off. The impact peak rises with the increase in wing height and width, while the impact duration decreases. Changing wing length has little effect on peak value of pinch-off. Increasing the wing length and height reduces deflection of the vehicle, while increasing the wing width promotes the deflection of the trajectory and attitude.
Instability of bubbly jets subjected to unrelaxed axial elastic tension
Authors: Sun Hu , Cui Xiao , Zhang Dingwei , Liu Qiyou , Yang Lijun , Ji Bingqiang , Fu Qingfei
Published: December 2024

Injection of bubbly jets is a critical process in various fields, such as fuel atomization and petrochemicals. However, existing instability models for bubbly jets have predominantly focused on density variations due to bubble compressibility, largely neglecting the impact of bubbles on the macroscopic rheological properties of the mixture. In this study, we have integrated compressibility with non-Newtonian properties induced by bubbles to explore the evaluation of jet perturbations. Additionally, considering bubble pre-deformation before injection, we particularly examine the role of unrelaxed axial elastic tension in the bubbly jets. Both linear stability analysis and energy budget methods are used to illustrate the contributions of viscosity, elasticity, and compressibility. The results indicate that the viscoelastic effects induced by bubbles can significantly outweigh the effects of compressibility during the jet destabilization process. Notably, a slight unrelaxed tension can markedly increase both the perturbation growth rate and the cutoff wavenumber, potentially making it a more dominant driver of jet instability than the classical surface tension.
Pore-scale T2-based numerical investigation on dynamics and wettability in mixed-wet shale oil reservoirs
Authors: Liu Jilong , Xie Ranhong , Guo Jiangfeng
Published: December 2024

Oil recovery in shale reservoirs is low due to the dynamics and wettability characteristics in mixed-wet shale oil reservoirs. Nuclear magnetic resonance (NMR) logging, a nondestructive and noninvasive technique, effectively evaluates the continuous dynamics and wettability in these reservoirs. The NMR numerical investigation can characterize the effects of dynamics and wettability, including varying wet regions and wet angles, on NMR responses, providing new insights into the frequency-dependent of T2-based petrophysical parameters. The NMR relaxation theory for mixed-wet shale oil reservoirs was proposed, and the relevant parameters were determined. The dynamics and wettability were characterized using the Shan Chen Lattice Boltzmann method, with constraints based on digital core technology. For the first time, the random walk method was employed to simulate the effects of water-wet regions with varying proportions, echo spacings, and wet angles on NMR responses in mixed-wet shale oil reservoirs at different frequencies. The proportions of water-wet regions, magnetic field frequencies, and echo spacings significantly influence porosity and T2LM, indicating that pore structure governs the dynamics and wettability and that petrophysical parameters can be characterized by their frequency dependence in mixed-wet shale oil reservoirs.
Managing south-east Asia’s savannas: challenges and holistic approaches through community-based fire management
Authors: Tornorsam Marina , Nguyen Thi Thuy , Poortinga Ate , Machuca Vanessa , Bihari Enikoe , Tenneson Karis , Nguyen Hanh Quyen , Buchholz Thomas , Saah David , Cutter Peter , Ganz David
Published: December 2024

Savannas, characterised by a continuous grass layer and discontinuous tree layer, are widespread globally and highly flammable during dry seasons, contributing to 90% of annual global burned areas and significant emissions. Asian savannas, often mismanaged owing to structural variability and misclassification as ‘poor forests’, face excessive or insufficient fire regimes. Addressing trans-boundary haze and climate mitigation requires improved understanding and sustainable management. This paper addresses savanna management challenges, particularly misclassified dry dipterocarp forests in the Lower Mekong, by synthesising knowledge on their distribution and the role of fire use by local communities, and recommends holistic, community-based fire management, integrated planning and incentives.
GSK3β phosphorylation catalyzes the aggregation of tau into Alzheimer's disease-like filaments
Authors: Chakraborty Pijush , Ibáñez de Opakua Alain , Purslow Jeffrey A. , Fromm Simon A. , Chatterjee Debdeep , Zachrdla Milan , Zhuang Shannon , Puri Sambhavi , Wolozin Benjamin , Zweckstetter Markus
Published: December 2024

The pathological deposition of proteins is a hallmark of several devastating neurodegenerative diseases. These pathological deposits comprise aggregates of proteins that adopt distinct structures named strains. However, the molecular factors responsible for the formation of distinct aggregate strains are unknown. Here, we show that the serine/threonine kinase GSK3β catalyzes the aggregation of the protein tau into Alzheimer’s disease (AD)-like filaments. We demonstrate that phosphorylation by GSK3β, but not by several other kinases, promotes the aggregation of full-length tau as well as enhances phase separation into gel-like condensate structures. Cryoelectron microscopy further reveals that the fibrils formed by GSK3β-phosphorylated tau adopt a fold comparable to that of paired helical filaments isolated from the brains of AD patients. Our results elucidate the intricate relationship between posttranslational modification and the formation of tau strains in neurodegenerative diseases.
Exploring the potential of textually‑enhanced captioned video to
direct learners’ attention to challenging sound contrasts
Authors: Fouz-González Jonás , Mora Joan C.
Published: December 2024

This study investigates the potential of textually-enhanced
captioned video to direct EFL learners’ attention to a difficult L2 vowel
contrast (English /æ/-/ʌ/) while watching a 30-minute episode of
Ted Lasso. Spanish EFL learners (N = 89) were randomly assigned
to five different viewing conditions: unenhanced captions (1); enhanced captions
with /æ/ and /ʌ/ in two different colours with the target words either in
phonetic symbols (2) or orthography (3); or with /æ/ and /ʌ/ in the same colour,
either in phonetic symbols (4) or orthography (5). The participants’ eye
movements were recorded with a Tobii TX-1200 eye-tracker. The textual
enhancement implemented was effective in directing learners’ attention to the
target words and attention was generally maintained during the episode. The
enhanced conditions promoted higher fixation rates and durations than the
unenhanced one. Additionally, the participants’ answers to a post-viewing
questionnaire revealed that they considered these types of enhancement useful to
help them spot instances of the target sounds and that the captions were not
overwhelming.
Trap density estimation for TDDB testing in SiC power MOSFETs
Authors: Luo Houcai , Lu Kang , Zheng Kai , Chen Xianping
Published: December 2024

The trap density estimation of SiC power MOSFETs in time-dependent dielectric breakdown (TDDB) was investigated using experiments and TCAD simulations. The gate leakage current (I
GSS) under negative voltage was measured and a current spike was found which was linearly shifted with TDDB stress. Based on a four-state nonradiative multi-phonon defect capture model, the mechanism and modeling of the I
GSS current spike was studied. Based on TCAD simulations, the characteristics of the gate oxygen donor traps, including trap energy level, trap density, and position distribution, were estimated, and the trap density model for the TDDB experiment was proposed and verified. This study may contribute to the estimation of trap density in SiC MOSFETs.
Prediction of quaternary SnGeS2As4 monolayer as a promising photocatalyst for water splitting: a DFT study
Authors: Trung Pham D , Tong Hien D
Published: December 2024

The SnGeS2As4 monolayer was studied by first-principles calculations to estimate its potential for use as a photocatalyst in the water splitting process. The stability of this structure is confirmed based on the analysis of its phonon dispersion and AIDM simulations. The electronic features including density of states (DOS), band structure, and Bader charge were calculated. These data show the role of each constituent element in the formation of covalent

π
−

and

σ
−

bonds, which play an important role in stabilizing the buckled honeycomb structure. In addition, the DOS and band structure also provide information regarding the high light absorption rate

α
(
ω
)

of 105–106 cm−1. The positions of valence band maximum and conduction band minimum are suitable for generation of hydrogen and oxygen gases. The SnGeS2As4 monolayer also has an optimal work function of 5.16 eV for the water splitting process and a rather high solar-to-hydrogen efficiency

η

STH

′

= 13.11%. It is worth noting that SnGeS2As4 monolayers with strains ranging from −2% to 6% are still capable of triggering redox reactions in the water splitting process. Moreover, the tensile strains slightly increase the light absorption rates. Such characteristics not only make the SnGeS2As4 monolayer a suitable photocatalyst for water splitting but also ensures its performance in a wider range of applications.
Large scale Raman spectrum calculations in defective 2D materials using deep learning
Authors: Malenfant-Thuot Olivier , Shaaban Kabakibo Dounia , Blackburn Simon , Rousseau Bruno , Côté Michel
Published: December 2024

We introduce a machine learning prediction workflow to study the impact of defects on the Raman response of 2D materials. By combining the use of machine-learned interatomic potentials, the Raman-active Γ-weighted density of states method and splitting configurations in independant patches, we are able to reach simulation sizes in the tens of thousands of atoms, with diagonalization now being the main bottleneck of the simulation. We apply the method to two systems, isotopic graphene and defective hexagonal boron nitride, and compare our predicted Raman response to experimental results, with good agreement. Our method opens up many possibilities for future studies of Raman response in solid-state physics.
The interplay of energy and motion of coupled pendulums: a high school student exploration
Authors: Soin Sahej , Batra Somya , Maurya Vishal K , Pulikkotil Jiji , Kumar Ajeet
Published: December 2024

The experiment of string-coupled pendulums offers high school students a hands-on opportunity to explore fundamental principles of physics while developing critical skills. In this experiment, students investigate how an oscillating pendulum transfers kinetic energy to a stationary one, resulting in a cyclical exchange marked by role reversals. The motion of the coupled pendulum is studied using a simple smartphone equipped with free software. Pendulums of equal length and point-mass are arranged in three different configurations: pendulum on a fixed rod, pendulum on a string, and string-coupled pendulum. These configurations not only exhibit varying time periods but also significantly different amplitude decay patterns. Despite inevitable energy dissipation due to frictional losses and air resistance, the oscillations exhibited by the coupled pendulums clearly demonstrate the interplay between synchronization and energy transfer. This initial hands-on investigation serves as a springboard for a more comprehensive exploration of the captivating energy transfer mechanisms and dynamical characteristics inherent to string-coupled pendulums.
Computationally efficient collimator-detector response compensation in high energy SPECT using 1D convolutions and rotations
Authors: Polson Lucas A , Esquinas Pedro , Kurkowska Sara , Li Chenguang , Sheikhzadeh Peyman , Abbassi Mehrshad , Farzanehfar Saeed , Mirabedian Seyyede , Uribe Carlos , Rahmim Arman
Published: December 2024

Objective. Modeling of the collimator-detector response (CDR) in single photon emission computed tomography (SPECT) reconstruction enables improved resolution and accuracy, and is thus important for quantitative imaging applications such as dosimetry. The implementation of CDR modeling, however, can become a computational bottleneck when there are substantial components of septal penetration and scatter in the acquired data, since a direct convolution-based approach requires large 2D kernels. This work proposes a 1D convolution and rotation-based CDR model that reduces reconstruction times but maintains consistency with models that employ 2D convolutions. To enable open-source development and use of these models in image reconstruction, we release a SPECTPSFToolbox repository for the PyTomography project on GitHub. Approach. A 1D/rotation-based CDR model was formulated and subsequently fit to Monte Carlo (MC) point source data representative of 177Lu, 131I, and 225Ac imaging. Computation times of (i) the proposed 1D/rotation-based model and (ii) a traditional model that uses 2D convolutions were compared for typical SPECT matrix sizes. Both CDR models were then used in the reconstruction of MC, physical phantom, and patient data; the models were compared by quantifying total counts in hot regions of interest (ROIs) and activity contrast between hot ROIs and background regions. Results. For typical matrix sizes in SPECT reconstruction, application of the 1D/rotation-based model provides a two-fold computational speed-up over the 2D model when running on GPU. Only small differences between the 1D/rotation-based and 2D models (order of 1%) were obtained for count and contrast quantification in select ROIs. Significance. A technique for CDR modeling in SPECT was proposed that (i) significantly speeds up reconstruction times, and (ii) yields nearly identical reconstructions to traditional 2D convolution based CDR techniques. The released toolbox will permit open-source development of similar models for different isotopes and collimators.
Proteinoid-polyaniline neuromorphic composites for audio recognition
Authors: Mougkogiannis Panagiotis , Adamatzky Andrew
Published: December 2024

We present an innovative neuromorphic system using a proteinoid-polyaniline (PANI) composite for recognition of audio inputs of the English alphabet. Neuromorphic devices, which draw inspiration from the neural networks of the brain, have emerged as very promising potential solutions for efficient signal processing. The proteinoid-PANI composite was synthesized through a template-free method, resulting in a unique nanostructure consisting of both nanorods and nanospheres. Principal component analysis, spectrogram analysis, and temporal spiking response analysis were among the signal processing methods used to examine the composite’s audio response to English alphabet stimuli. The system showed a moderate positive correlation between input and output signals, unique time–frequency response patterns, and convoluted spiking behaviour. In addition, the output amplitude showed less variation compared to the input, while maintaining the same temporal characteristics. Microscopic analysis provided detailed information about the morphology of the composite. The nanorods displayed an optimal aspect ratio and had diameters of around 100 nm, while the nanospheres varied in size, ranging from 200 to 500 nm in diameter. The nanostructure, morphological characteristics, and signal processing properties of the proteinoid-PANI composite demonstrate its potential for advanced applications in neuromorphic computing and signal processing, particularly in speech recognition and human–machine interaction.
Design, experiment and modeling of a damper based on magnetic gradient pinch mode MR valve
Authors: Lin Dezhao , Yang Fan , Li Ruihong , Zhang Weiqiang
Published: December 2024

In this study, a novel magnetorheological (MR) damper designed based on the magnetic gradient pinch mode MR (MGPMR) valve, is investigated analytically and experimentally. The prototype and experimental platform are designed and established to characterize the dynamic force–displacement/velocity properties under board ranges of excitation and current conditions with the consideration of the effect of design parameters, which mainly includes the number of the non-magnetic rings and the diameter of the flow channel. The experimental data shows that the tunable damping range is positive correlation with the number of non-magnetic rings and negative correlation with the diameter of flow channel. Therefore, an analytical model, which considers the hysteresis damping model of the MGPMR valve, ideal gas model, and the hysteresis friction of seals, is established to describes the dynamic force–displacement/velocity properties of the MGPMR damper with 4 non-magnetic rings and 7 mm diameter of the MGPMR valve. The proposed hysteresis damping model of the MGPMR valve consists of the tangential hyperbolic hysteresis model, tunable viscous damping, and fluid inertial together with the identified model parameters. The validity of the proposed model of MGPMR damper is demonstrated through a comparison between the simulation and experiment results showing good agreement of the hysteresis loops and output force-displacement/velocity characteristics under wide range of excitation and currents conditions.
Interference of longitudinal and transversal fragmentations in the Josephson tunneling dynamics of Bose–Einstein condensates
Authors: Bhowmik Anal , Alon Ofir E
Published: December 2024

The dynamics of bosons in Josephson junctions have drawn much attention where the bosons are initially condensed. When interacting bosons tunnel back and forth along the junction, depletion and, eventually, fragmentation develop. Here, we pose the question how do fragmented bosons tunnel in a bosonic Josephson junction? To this end, we exploit the transverse degree-of-freedom of the junction to encode initial fragmentation to the bosonic cloud. We find rich many-body dynamics, which includes the speed up of the collapse of density oscillations and slow down of the revival process, by analyzing the survival probability along the junction, fluctuations of particle positions across the junction, and the occupancy of the lowest single-particle states. It is found that a fully fragmented state significantly accelerates the revival process compared to the conventional Bose–Einstein condensate. To explain the underlying many-body mechanism, we show that the initial fragmentation in the transverse direction interferes with the development of fragmentation in time along the junction. The magnitude of this interference is quantified by the transition from a decrease of occupation to build up of occupation in the first excited single-particle state. The interference mechanism is a purely many-body effect that does not occur in the mean-field dynamics. All in all, we show that the interference of longitudinal and transversal fragmentations leads to new rules for macroscopic tunneling phenomena of interacting bosons in traps.
3D simulation of polar bear fur’s thermal insulation
Authors: Rchida Lamiaâ , Bihi Abdelilah Nait , Rattal Mourad , Bahou Younouss , Mouhsen Azeddine , Harmouchi Mohammed , Oualim El Mostafa
Published: December 2024

Biomimicry, emulating nature’s time-tested strategies, has emerged as a powerful tool for solving complex engineering challenges. Over millions of years of evolution, organisms have developed highly efficient systems for survival in extreme environments, offering solutions that often surpass human-made technologies. Scientists can create materials that mimic nature’s exceptional efficiency in regulating heat transfer by studying natural systems, such as polar bear’s fur or other organism’s structures adapted to harsh climates. With its specialised multi-layered structure and optical properties, the polar bear’s fur is an excellent model for managing heat retention. This study examines its insulating qualities using a comprehensive 3D simulation to understand how the structure regulates body heat. We use MATLAB to simulate radiative heat transfer between individual hair fibers while considering optical characteristics, such as transmittance, absorption, and reflectivity. The results reveal that even in freezing temperatures (−40 °C), the unique structure of polar bear hair considerably reduces radiative heat loss, keeping interior temperatures over 37 °C. Additionally, according to our simulations, multi-layer hair arrangements increase thermal efficiency by up to 16 °C, indicating conceivable uses for bio-inspired insulation materials. These results have consequences for ecological sustainability, the development of thermal insulation technology, and the design of energy-efficient materials and structures.
Reflective linear polarization converter with multimode, dual band and high efficiency
Authors: Ahmad Ijaz , Ali Wajid , Zhou Rongjiang , Jamali Sain Bux , Deng Lianwen
Published: December 2024

A thin, dual-band, highly efficient linear polarization converter based on a multi-mode metasurface was proposed. The high-efficiency manipulation of polarization states of electromagnetic waves in dual-band frequencies was achieved by utilizing a diagonally etched metasurface as a square joined by a ring. The metasurface transforms incident linearly polarized (LP) waves into cross-polarized LP waves at various frequencies. Numerical simulations reveal that the metasurface operates efficiently in the bands from 7.724 GHz to 8.192 GHz and 13.142 GHz to 15.95 GHz, with a polarization conversion ratio (PCR) of about 95% in both bands. To validate the theoretical analysis and simulation results, a model is fabricated and measured. The experimental results confirm that the proposed metasurface successfully achieves dual-band and dual-mode polarization conversion, showing reasonable consistency of theoretical and simulated findings. This converter can optimize the signal performance by clarifying polarized radio waves.
Ground state manipulation of atomic waveguide by a giant atom
Authors: Sun Ruijin , Wang Zhihai
Published: December 2024

In this paper, we study the ground state of a Rydberg atomic waveguide, which is coupled to a giant atom nonlocally via two or multiple sites. This many body system undergoes the degeneracy broken or energy level anti-crossing, depending on the parity of the size of the giant atom and the detuning between the atomic transition frequency and that of the driving field. Together with manipulation of the energy gap, we further show the interesting alternative atomic magnetization in the waveguide and the simultaneous suppression of the atomic magnetization and enhancement of atomic correlation.
Thermodynamic properties of condensates with spin-

f

atoms (

f
≥
1

) in the neighborhood of zero temperature
Authors: He Y Z , Liu Y M , Bao C G , Li Z B
Published: December 2024

When the Hamiltonian of a condensate containing spin-

f

bosons is dominated by attractive singlet pairing interaction with the strength  − ∣G
0∣ and when the temperature T is in the neighborhood of zero, the many-body Schrödinger equation can be exactly solved. Based on the complete and exact spectra the thermodynamic properties of these systems different in particle number N and

f

have been studied. The variation of the function

∂
C

∂
x

against x is firstly studied, where C is the capacity, x ≡ lg(k
B
T/∣G
0∣), and k
B is the Boltzmann constant. It was found that the variation can be divided into four stages. In the very narrow first stage,

∂
C

∂
x

appears as a sharp peak. The second stage is broad where

∂
C

∂
x

=
0

. The third stage is also very narrow where

∂
C

∂
x

appears as a sharp anti-peak. In the fourth stage,

∂
C

∂
x

becomes zero again. All the thermodynamic functions: the internal energy, the capacity, and the entropy vary accordingly. How these functions are affected by N,

f

, and ∣G
0∣ in each stage has been clarified. The spin-thermodynamics would replace the traditional thermodynamics in the neighborhood of zero temperature, where the spin degrees of freedom play an essential role.
Probing heavy charged Higgs bosons at gamma-gamma colliders using a multivariate technique*
Authors: Ahmed Ijaz , Quddus Abdul , Muhammad Jamil , Shoaib Muhammad , Shafaq Saba
Published: December 2024

This study explores the production of charged Higgs particles through photon-photon collisions within the context of the Two Higgs Doublet Model, including one-loop-level scattering amplitudes of electroweak and QED radiation. The cross-section has been scanned for the plane (

) to investigate the process of

. Three particular numerical scenarios, i.e., low-

, non-alignment, and short-cascade are employed. The decay channels for charged Higgs particles are examined using

for low-

and

for non-alignment and short-cascade scenarios incorporating the new experimental and theoretical constraints along with the analysis for cross-sections. We find that, at a low energy, the cross-section is consistently higher for all scenarios. However, as

increases, it reaches a peak value at 1

TeV for all benchmark scenarios. The branching ratio of the decay channels indicates that for non-alignment, the mode of decay

takes control, and for a short cascade, the prominent decay mode remains

, whereas in the low-

scenario, the dominant decay channel is of

. In our research, we employ contemporary machine-learning methodologies to investigate the production of high-energy Higgs bosons within a 3.0 TeV

collider. We have used multivariate approaches such as Boosted Decision Trees (BDT), LikelihoodD, and Multilayer Perceptron (MLP) to show the observability of heavy-charged Higgs Bosons versus the most significant Standard Model backgrounds. The purity of the signal efficiency and background rejection are measured for each cut value.
Tactile sensitivity to softness in virtual reality can increase when visual expectation and tactile feedback contradict each other
Authors: Frediani Gabriele , Carpi Federico
Published: December 2024

Objective. The perception of softness plays a key role in interactions with various objects, both in the real world and in virtual/augmented reality (VR/AR) systems. The latter can be enriched with haptic feedback on virtual objects’ softness to improve immersivity and realism. In such systems, visual expectation can influence tactile sensitivity to softness, as multisensory integration attempts to create a coherent perceptual experience. Nevertheless, expectation is sometimes reported to attenuate, and other times to enhance, perception. Elucidating how the perception of softness is affected by visual expectation in VR/AR is relevant not only to the neuropsychology and neuroscience of perception, but also to practical applications, such as VR/AR-based training or rehabilitation. Approach. Here, by using novel wearable tactile displays of softness previously described by us, we investigated how the sensitivity to softness in a visuo–tactile VR platform can be influenced by expectation. Twelve subjects were engaged in comparing the softness of pairs of virtual objects, familiar or not, with tactile feedback of softness and visual expectation either conflicting or not. The objects’ Young’s moduli were initially randomly selected from a large set, spanning two orders of magnitude (0.5, 2, 20, 50 and 100 MPa), and then their difference was iteratively reduced, to reach the just noticeable difference in softness. Main results. For the intermediate modulus, a conflict between tactile feedback and visual expectation caused a statistically significant increase in sensitivity. Significance. This finding supports the theory that there can be conditions in which contradictory stimuli strengthen attention (to resolve conflicting sensory information), which in turn can reverse the sensory silencing effect that expectation may otherwise have on perception.
Air pollution modelling of accidents involving hazardous substances
Authors: Ostromsky Tzvetan , Alexiev Kiril , Parvanov Stefan
Published: December 2024

Air pollution modeling for accidents involving hazardous substances is a critical aspect of emergency response and environmental protection. This modeling aims to predict the dispersion and impact of toxic substances released into the atmosphere during accidents, such as industrial spills, transport accidents, chemical plant incidents or acts of terrorism. Such dangers are among the challenges which the modern society is facing and has to overcome. In this study we propose a systematic approach for organizing monitoring, collecting data from mobile sensors, creating situation development scenarios, modelling the spread of potential toxic-element pollution in dependence with the current meteorological conditions. The UNI-DEM model for simulation of the pollutants’ dispersion and transport in the air, as well as models for spread of leaking gas and liquid vapors are involved in this study. Finally, depending on the comprehensive analysis of the modeling results, an adequate response to such severe situations can be proposed. Assessment of safety, healthcare and environmental impacts should be the final result and the most socially important application of our work. The calculated pollutant concentrations can be compared with regulatory standards or health-based guidelines to assess potential health risks to exposed populations and environmental impacts on ecosystems. The importance of this information for emergency response planning, public health interventions, and environmental management strategies is beyond dispute.
Analytical Solution for Transverse Velocity of Turbulent Flow in Channel
Authors: Fedoseyev Alex
Published: December 2024

The analytical solution for the streamwise mean velocity of turbulent flow of incompressible fluid in a channel was presented in Fedoseyev (2023) paper. In this work, we present both the stationary and transient solutions for the transverse velocity component. The obtained transient solution is a product of a series of periodic functions in space and time, multiplied by a growing exponential function of time. This analytical solution reveals the instability and imminence of oscillations in the turbulent flow. The obtained solutions are compared with numerical simulation results and experimental data, demonstrating a close agreement or strong similarity.
Exploring SO2 air pollution in Plovdiv through multivariate adaptive regression splines: A case study
Authors: Ivanov Atanas , Gocheva-Ilieva Snezhana , Stoimenova-Minova Maya
Published: December 2024

This case study delves into the assessment of Sulfur dioxide (SO2) air pollution in Plovdiv by employing Multivariate Adaptive Regression Splines (MARS) to model and understand the factors influencing daily SO2 levels. By analyzing a dataset characterized by an average SO2 pollution level of 0.43ppm, this study highlights the potency of MARS in capturing the non-linear relationships and complex interactions between SO2 concentrations and measured meteorological and atmospheric time series in the form of quantitative and categorical variables. In particular, an increase in model performance is demonstrated by performing a modified Yeo-Johnson transformation on pollutant data and constructing additional predictors such as lag variables, date variable and dummies. A significant achievement of this investigation is the attainment of a coefficient of determination (R2) exceeding 0.91. This high level of accuracy highlights the efficiency of MARS as a flexible and reliable machine learning tool thus emphasizing its potential in contributing to the urban air quality management toolbox.
Preconditioned IDR solution method in scientific and industrial applications
Authors: Fedoseyev Alex
Published: December 2024

A review of preconditioned solver for large-scale applications in science and industry is presented. The analysis, parallelization, and optimization approach for large unstructured sparse matrices using IDR methods are considered for modern multicore microprocessors.

Performance criteria and methods have been revisited, along with consideration of parallelization involving the solver and preconditioner using the OpenMP environment. Results of the successful implementation for efficient parallelization are presented.
Mitigating Drying Shrinkage in High-Strength Concrete Using Glass and Polypropylene Fibers with Diatomaceous Earth as Cement Substitute
Authors: Zaki Hilma Nuraisyah , Hasan Muttaqin , Saidi Taufiq
Published: December 2024

In recent decades, the demand for high-strength concrete has surged due to its enhanced workability and durability. However, the high cement content in such concrete impacts its hardening properties, particularly causing drying shrinkage strain, which affects structural performance and durability. Adding fibers like glass and polypropylene can mitigate this drying shrinkage by improving tensile and flexural strength, ductility, and crack control. High cement content also raises environmental concerns, including increased CO2 emissions. Diatomaceous earth, an eco-friendly and cost-effective cement substitute, can address these issues. This study explores the effects of glass and polypropylene fibers on concrete drying shrinkage and the impact of diatomaceous earth. Concrete specimens (100 mm × 100 mm × 400 mm) with 0% and 10% diatomaceous earth and varying fiber contents (0%, 0.2%, 0.4%, 0.8%, 1%) were tested. Drying shrinkage data over 60 days were recorded using dial gauges. Results indicate that both types of fibers effectively reduce drying shrinkage, with glass fibers being more effective. Additionally, the usage of 10% diatomaceous earth also reduces drying shrinkage. A modified B4-Bazant model incorporating coefficients for diatomaceous earth (Kd), fiber type (Kf), and fiber volume (Kvf) was developed. Further research with different fiber proportions is recommended for more accurate modeling.
Experimental study of mechanical properties of conventional concrete and geopolymer concrete with and without white soil
Authors: Priastiwi Yulita Arni , Wibowo Hardi , Wijayaningsih Emy Shinta
Published: December 2024

Concrete is an important material in the construction of buildings, but the use of cement produces CO2 gas emissions, so it is not considered environmentally friendly. One of the efforts to replace cement without reducing the quality of concrete involves utilising fly ash and a certain percentage of white soil as a substitute for fly ash. This study compares the compressive strength, elastic modulus, and Poisson’s ratio of conventional and geopolymer concrete with or without white soil substitution with 150 x 300 mm cylindrical specimens. The fly ash was F-grade from the Tanjung Jati B Jepara power plant, and the white soil was from Kupang, NTT. A conventional concrete mix composition used a ratio of cement to fine aggregate to coarse aggregate of 1: 1.831 : 2.434 with a cement water factor of 0.5. The geopolymer concrete maintains the same proportions, substituting cement with fly ash or white soil and incorporating an alkali activator composed of NaOH (12M) and Na2SiO3 Be52 in a 1:2.5 ratio. The concrete treatment is dry curing (room temperature). The results showed that conventional concrete has a higher compressive strength and elastic modulus but a lower Poisson’s ratio compared to geopolymer concrete.
Stress-strain ratio on stabilization work in the saturated zone causes rapid road failure
Authors: Munirwansyah Munirwansyah
Published: December 2024

Road construction frequently encounters difficulties with soil with low bearing capacity, such as soil subsidence, which results in the deformation or waves of the surface road. The investigation was conducted at the Paya Tumpi quarry and quarry in Krueng Raya-Laweung, which are the providers of soil material used in road construction. These two quarries, due to their extensive clay soil criteria, are unsuitable for use as road subgrade material. Hence, to utilize this soil, it is necessary to stabilize it by incorporating volcanic ash. This will be accomplished by evaluating the shear strength of mixed soil, the optimum water content for compaction, and the stress-strain ratio’s behaviour as a result of the stabilization effect. To determine the cohesion and shear angles at a defined shear stress and the response of each test object to strain and stress, a series of experiments were carried out. The research findings indicated that the cohesion and shear angles of the soil samples were enhanced by the addition of volcanic ash in comparison to natural soil. The cohesion (c) of sample-1, sample-2, and sample-3 increased from 0.034-0.223 kg/cm2, 0.093-0.118 kg/cm2, and 0.008–0.037 kg/cm2, respectively. Similarly, the shear angles (ϕ) increase from 32.30o to 40.30o, 27.20o to 30.10o, and 27.90o to 36.20o, respectively. The stress-strain ratio is intermediate between local failure and punching.
Calibration of base saturation flow rate at pretimed signal intersection utilizing Bayesian linear regression considering morning and evening peak hour observations
Authors: Lulusi L. , Sugiarto S , Saleh S M , Isya M
Published: December 2024

Base saturation flow is a critical constraint used for evaluating the capacity of signalized intersections. The Indonesian Highway Capacity Manual (IHCM, 2023) is frequently used for signalized intersection planning in Indonesia. In heterogeneous traffic environments, the driver characteristics and behaviors exhibit significant variations. However, the base saturation flow was also influenced by traffic volume during the observation period. This study modeled the base saturation flow by analyzing differences in morning and afternoon peak hour data. The objective was to examine the base saturation flow at pretimed signal in Banda Aceh, with a focus on traffic volume fluctuations during peak hours. Four intersections were investigated in this study. Unmanned aerial vehicles were employed to record discharge flow pattern within targeted signalized intersection. Manual timing was conducted using stopwatches and geometric road data were collected through direct field measurements. Bayesian linear regression with a Gibbs sampling approach was utilized to recalibrate the saturation flow rate coefficients. The base saturation flow during the morning peak is 284 We, while in the afternoon peak, it is 285 We, with We representing the effective intersection approach.