bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixing small proteins with lipids and cholesterol
Authors: Basu Subhadip , Farago Oded
Published: December 2024

Many ternary mixtures composed of saturated and unsaturated lipids with cholesterol (Chol) exhibit a region of coexistence between liquid-disordered (Ld) and liquid-ordered (Lo) domains, bearing some similarities to lipid rafts in biological membranes. However, biological rafts also contain many proteins that interact with the lipids and modify the distribution of lipids. Here, we extend a previously published lattice model of ternary DPPC/DOPC/Chol mixtures by introducing a small amount of small proteins (peptides). We use Monte Carlo simulations to explore the mixing phase behavior of the components as a function of the interaction parameter representing the affinity between the proteins and the saturated DPPC chains and for different mixture compositions. At moderate fractions of DPPC, the system is in a two-phase Ld + Lo coexistence, and the proteins exhibit a simple partition behavior between the phases that depends on the protein–lipid affinity parameter. At low DPPC compositions, the mixture is in Ld phase with local nanoscopic ordered domains. The addition of proteins with sufficiently strong attraction to the saturated lipids can induce the separation of a distinct Lo large domain with tightly packed gel-like clusters of proteins and saturated lipids. Consistent with the theory of phase transitions, we observe that the domain sizes grow when the mixture composition is in the vicinity of the critical point. Our simulations show that the addition of a small amount of proteins to such mixtures can cause their size to grow even further and lead to the formation of metastable dynamic Lo domains with sizes comparable to biological rafts.
Integrating path sampling with enhanced sampling for rare-event kinetics
Authors: Ray Dhiman
Published: December 2024

Studying the kinetics of long-timescale rare events is a fundamental challenge in molecular simulation. To address this problem, we propose an integration of two different rare-event sampling philosophies: biased enhanced sampling and unbiased path sampling. Enhanced sampling methods, e.g., metadynamics, can facilitate the crossing of free energy barriers by applying an external bias potential. On the contrary, path sampling methods like weighted ensemble do not apply any biasing force but accelerate the exploration of rugged free energy surfaces through trajectory resampling. We show that a judicious combination of the weighted ensemble with a metadynamics-like algorithm can synergize the strengths and mitigate the deficiencies of path sampling and enhanced sampling approaches. The resulting integrated sampling (IS) algorithm improves the computational efficiency of calculating the kinetics of peptide conformational transitions, protein unfolding, and the dissociation of a ligand–receptor complex. Furthermore, the IS approach can direct sampling along the minimum free energy pathway even when the collective variable used for biasing is suboptimal. These advantages make the IS algorithm suitable for studying the kinetics of complex molecular systems of biological and pharmaceutical relevance.
Zonal flow instability induced by nonlinear inertial waves in a librating cylinder with sloping ends
Authors: Subbotin Stanislav , Shiryaeva Mariya , Shmakova Natalia , Ermanyuk Evgeny
Published: December 2024

This paper compares the nonlinear dynamics of two key types of motion observed in a rotating liquid-filled cavity subject to external forcing: an inertial wave attractor and resonant inertial oscillations (inertial modes). Experiments are performed with a cavity having a specific shape of a truncated circular cylinder delimited by plane-parallel end walls inclined with respect to the cylinder base. The cavity rotation axis coincides with the axis of the cylindrical surface. Libration-type forcing is introduced by harmonic modulation of the background rotation frequency. The sloping end walls break the axial symmetry of the liquid domain: the shape of the axial-radial cross sections varies from parallelogram to rectangle depending on the azimuthal angle. It is found that, regardless of the liquid response type (wave attractor or inertial modes), the transition from linear to nonlinear dynamics follows the scenario of triadic resonance instability. However, the time-averaged zonal flow responds differently to the primary wave instability. Inertial-mode instability generates a system of azimuthally periodic averaged vortices, whose frequency coincides with the subharmonic frequency of the triadic resonance. At high libration amplitudes, a low-frequency component appears in the azimuthal velocity spectrum, being associated with excitation of the retrograde system of vortices. The development of the weakly nonlinear regime of the wave attractor is accompanied by the instability of the viscous boundary layers—fine-scale pattern formation occurs close to the reflection zones of the attractor branches at the cylindrical sidewall. In the strongly nonlinear wave regime, coherent vortex structures are excited, performing azimuthal and radial drifts.
Dissociative triple ionization of argon dimers in elliptically polarized two-color laser fields
Authors: Ma Junyang , Wang Pengzhao , Li Shuqi , Yang Yan , Sun Zhenrong
Published: December 2024

Using ion–ion coincidence measurements, we experimentally investigate the dissociative triple ionization of argon dimers in relative phase controlled elliptically polarized two-color femtosecond laser fields. By examining the kinetic energy release-dependent momentum angular distribution of the ejected ionic fragments, two distinct pathways, each associated with different intermediates, are identified. Control over the emission directions of the ionic fragments is achieved by varying the relative phase of the elliptical two-color laser fields. Notably, the two pathways exhibit nearly opposite asymmetries in their dependence on the relative phase. Our findings demonstrate the critical role of intermediates in the dissociative triple ionization of dimers and provide a method to distinguish the intermediates involved in this process.
A pair of entrapping or coalescing bubbles affected by convection during downward solidification
Authors: Luo Chao-Wei , Wei Peng-Sheng
Published: December 2024

In this study, the development of solute concentration and velocity fields of a pair of entrapping or coalescing bubbles during downward solidification is provided. The gas-induced pores in the metal not only deteriorates the properties of the processed workpiece by causing stress concentration and defects within the material, but pore formation in sea ice also plays an important role in global warming. Using COMSOL Multiphysics version 5.2, the unsteady, two-dimensional transport equations of mass, momentum, energy, and concentration are solved. The results show that bubble coalescence is facilitated by decreasing solid thermal conductivity and interpore spacing. Unlike the symmetric distribution of concentration observed with a low Henry's law constant and liquid solute diffusivity, an asymmetric distribution occurs, with high and low concentration gradients near the leading and rear edges of each bubble, respectively, due to the liquid velocity from the upstream direction. An outward flow in the opposite direction occurs near the triple-phase line, resulting in an inflection region in the iso-concentration field. The thickness of the concentration boundary layer surrounding the pores also decreases with decreasing Henry's law constant and liquid solute diffusivity, as well as with increasing ambient pressure, gravitational acceleration, solid thermal conductivity, and surface tension. The predicted contact angle during solidification aligns well with Abel's equation. Solute segregation associated with the formation of multiple pores can be controlled.
Flame acceleration and detonation initiation in a non-uniform hydrogen–air mixture with a combination of fluid and solid obstacles
Authors: Zhu Yuejin , Zhao Xinyu , Fan Liangyi
Published: December 2024

Flame acceleration and the deflagration-to-detonation transition (DDT) process in premixed combustible gases are complex phenomena involving both fluid dynamics and chemical reactions. However in practical scenarios, premixed combustible gases are often non-uniform. Based on the OpenFOAM platform, this numerical study examines the impact of combined fluid and solid obstacles on flame acceleration and DDT within various non-uniform concentration fields. The results indicate that in the initial stage of flame development, the absence of blockages on one side of the pipe and the presence of a higher concentration of hydrogen contribute to faster flame acceleration. Additionally, the narrow channel formed between obstacles and the wall, enhanced by the pressure gradient, produces a stronger suction effect, causing the flame to experience multiple zones of velocity enhancement. Furthermore, the detonation initiation can be categorized into two types: a) detonation initiated by the interaction between the flame surface and the reflected shock wave; b) detonation triggered by the coupling of the flame front with high-pressure regions. During the detonation wave's propagation, hydrogen levels below 12.7% cause detonation wave decoupling, affecting its shape based on hydrogen concentration distribution. From the perspective of flame evolution, fluid obstacles introduce more disturbances and vortices, promoting the formation of pressure gradients, which accelerates flame development and facilitates detonation initiation. The combination of fluid and solid obstacles can effectively reduce the initiation distance and time required for DDT. Also, a more uniform distribution of hydrogen concentration leads to faster changes in the flame state, enabling quicker detonation initiation.
Origin of the contrasting magnetic stability of antiferromagnetic CuMnAs and CuMnSb
Authors: Teng Gaofeng , Chen Zehua , Wei Su-Huai
Published: December 2024

Antiferromagnetic (AFM) materials exhibit great potential for next-generation spintronic applications because they have some unique characteristics compared to ferromagnetic (FM) materials. For example, the successful electrical manipulation and detection of the Néel vector at room temperature was recently realized for AFM CuMnAs in its tetragonal phase. The Néel temperature (TN) for tetragonal CuMnAs is about 480 K. In contrast, cubic half-Heusler CuMnSb, despite it is isovalent to CuMnAs, exhibits a notably lower TN of about 50 K, limiting its applicability in spintronic devices. The physical origin behind the stark difference in TN between the two compounds remains unclear. In this study, we investigate both CuMnAs and CuMnSb in both tetragonal and cubic phases. We find that the band crossing between the valence band and conduction band is more pronounced in CuMnSb compared to CuMnAs. This disparity arises from the higher energy level of the Sb 5p orbital relative to the As 4p orbital, resulting in a greater abundance of carriers in CuMnSb than in CuMnAs. Utilizing the effective band coupling model, we establish a relationship between carrier concentration and magnetic stability and confirm that the elevated carrier concentration is the origin of the weakened antiferromagnetism observed in both phases of CuMnSb.
Visualization and characterization of capillary-to-viscous transition in fluid-induced granular deformation
Authors: Ke Feihu , Dai Quanwei , Kwok Chung-Yee , Duan Kang
Published: December 2024

Comprehending pattern transitions during immiscible two-phase flow through granular materials is of paramount scientific and practical importance, as flow conditions are susceptible to variability along transport pathways in natural and engineering systems. The localized fluid displacement frequently mobilizes the hosting grains and triggers diverse morphological deformation. The interplay between such hydrodynamic and mechanical forces renders the deformation transitions inherently complex and hard to predict. Here, we integrate laboratory experiments with numerical simulations to probe the morphodynamics of fluid-driven granular deformation at the fundamental pore scale. Upon systematically varying capillary–viscous flows, we unveil three deformation patterns and propose a new dimensionless number incorporating the overlooked inertial and size effects to capture their transitions from slender channels to circular cavities to ramified fingers. We consistently observe lower residual saturation in the cavity regime attributed to the balanced capillary–viscous forces in this transition zone. Notably, our numerical model accurately mirrors the experimental observations and sheds light on the physics underlying the nucleation of characteristic crossover cavitation based on the microscale quantities of trivial energy leftover and uniform flow resistance.
Research and application of flying-wing aircraft bow wave modeling method based on convolutional neural network
Authors: Yin Shilong , Song Yanping , Chen Fu , Yu Jianyang , Ma Jiaping
Published: December 2024

With the development of aviation technology, aircraft voyage improvement has become an urgent problem to be addressed. Aerial refueling technology has been widely used as an important method for improving endurance. In probe-and-drogue refueling (PDR), the tanker's hose-drogue system is offset by the bow wave generated by the receiver's head. By probe-and-drogue refueling, we mean soft aerial refueling, which is a method that transfers fuel by connecting the drogue of tanker with the probe near the oil receiver's head to transfer fuel. The ability to accurately calculate flow field changes caused by the bow wave and the hose-drogue system offset position have become key factors for successful docking during PDR. However, existing bow wave models based on the potential flow method cannot accurately calculate the bow wave flow field of a flying-wing aircraft. Therefore, this paper proposes a variety of bow wave models based on a convolutional neural network (CNN), which aims to accurately solve the bow wave flow field of a flying-wing unmanned aerial vehicle in the process of autonomous aerial refueling. In addition, a method to calculate the hose-drogue system position based on the dynamics of a multi-body system is proposed, which calculates the final position of the hose-drogue system after docking from the coupled flow field of the tanker and receiver. Finally, by applying the bow wave model to the position calculation of the hose-drogue system, it was verified that the CNN model can be accurately applied to research related to aerial refueling.
Performance study on a new solar air heater for space heating: A numerical and experimental study
Authors: Amari Malika , Ali Amjad , Pallathadka Harikumar , AL-Zoubi Omar H. , Kaur Harpreet , Kaur Jatinder , Kumar Abhinav , Alzubaidi Laith H. , Foladi Ali
Published: December 2024

The need to address energy challenges and environmental pollution has led researchers to focus on utilizing solar energy. In this study, a new solar air heater collector system was developed that incorporates arc-shaped wire roughness and external airflow recycling. The system performance was evaluated under various conditions using energy conservation equations and a semi-analytical method for modeling. The results were validated, confirming the method’s accuracy. The findings revealed that the hybrid system significantly improved energy and exergy efficiencies at lower mass flow rates. Increasing the airflow recycle ratio up to 3 in conditions of constant roughness and low mass flow rates enhanced collector performance. However, at high flow rates and recycle ratios, exergy efficiency decreased due to increased pressure drop, despite a rise in energy efficiency, making it less effective than a simple collector system. The results show that the temperature increase is not so much from a mass flow rate of more than 0.05 kg/s. The existence of considered artificial roughness has caused an increase in temperature, especially in mass flow rates of less than 0.035 kg/s.
Impact of reservoir pressure fluctuations on fracture shear slip behavior in shale gas hydraulic fracturing
Authors: Lu Zhaohui , Du Liwei , Jia Yunzhong , Lu Yiyu , Zhou Lei , Zhou Junping
Published: December 2024

To elucidate the effect of fluid pressurization rate on the shear slip behavior of shale fractures during reservoir hydraulic pressure fluctuations, shale slip experiments with constant axial stress were conducted at 0.5, 2, 8, and 30 MPa/min pressurization rates based on the pressure fluctuation characteristics of hydraulically fractured reservoirs of deep shale gas in the Sichuan Basin. The results indicated that quasi-static slip exhibited higher average velocities than creep slip by 2–3 orders of magnitude at equivalent pressurization rates. Additionally, at 30 MPa/min pressurization rates, the slip type transitioned directly from creep to dynamic slip. The slip velocity increases with increasing pressurization rate, and the average velocities of quasi-static slip are 7.10 × 10−4, 2.20 × 10−3, and 5.40 × 10−3 mm/s, respectively. Dynamic slip exhibited the highest critical slip pressure of 7.14 MPa and the largest friction coefficient increased by 55% at a pressurization rate of 2 MPa/min. Friction strength primarily increased by 42% during creep slip at a pressurization rate of 0.5 MPa/min, while the friction coefficient minimally decreased by 0.03% during dynamic slip. Notably, dynamic slip exhibited a significant increasing trend in the percentage of friction coefficient increment. The critical dynamic slip pressure and energy released during slip exhibited an initially increasing and then decreasing pattern over the range of pressurization rates in this experiment, which is a result of the degree of inhomogeneity of the fluid increasing and then decreasing with the pressurization rate. Consequently, this led to maximum accumulation and energy release at the fracture surface, resulting in minimal quasi-static slip displacement, and is not conducive to improved reservoir permeability characteristics and safe shale gas recovery.
Langmuir solitons in plasma with κ-deformed Kaniadakis distributed electrons in the kinetic regime
Authors: Zhou Suyun , Chen Hui
Published: December 2024

The dynamics of Langmuir solitons in plasma with κ-deformed Kaniadakis distributed electrons is studied. First, a Zakharov-type equation describing the evolution of the fields of Langmuir and ion-acoustic wave is derived in a kinetic regime. Then, in the one-dimensional case, the Zakharov-type equation is reduced to the well-known nonlinear Schrödinger equation that is applied to investigate the characteristics of modulated Langmuir wave packets. It is shown that there are two types of solitons, one is bright soliton in the subsonic regime and the other is dark soliton in the supersonic regime. It also found that when the amplitudes of both types of solitons are fixed, the width of bright soliton increases, while the width of dark soliton decreases, with increased distribution index κ. The present work may serve as a preliminary investigation into the nonlinearity of the κ-deformed Kaniadakis distributed plasma system.
Hydrogen ejection from hydrocarbons: Characterization and relevance in soot formation and interstellar chemistry
Authors: Hendrix Josie , Hait Diptarka , Michelsen Hope A. , Head-Gordon Martin
Published: December 2024

Polycyclic aromatic hydrocarbons (PAHs) play a major role in the chemistry of combustion, pyrolysis, and the interstellar medium. Production (or activation) of radical PAHs and propagation of their resulting reactions require efficient dehydrogenation, but the preferred method of hydrogen loss is not well understood. Unimolecular hydrogen ejection (i.e., direct C─H bond fission) and bimolecular radical abstraction are two main candidate pathways. We performed a computational study to characterize the role of H ejection, particularly as a driver for radical-centric hydrocarbon-growth mechanisms and particle formation. Electronic structure calculations establish that C─H bond strengths span a broad range of energies, which can be weaker than 30 kcal/mol in some C
9
and C
13
PAH radicals. At
T
> 1200 K, calculated thermal rates for hydrogen ejection from weak C─H bonds at zigzag sites on PAH radicals are significantly larger than typical H-abstraction rates. These results are highly relevant in the context of chain reactions of radical species and soot inception under fuel-rich combustion conditions. Furthermore, calculated microcanonical rates that include the additional internal energy released by bond formation (e.g., ring closure to yield C
9
H
9
) yield significantly higher rates than those associated with full thermalization. These microcanonical considerations are relevant to the astrochemical processes associated with hydrocarbon growth and processing in the low-density interstellar environment.
Identification of 10,000-year-old rice beer at Shangshan in the Lower Yangzi River valley of China
Authors: Liu Li , Zhang Jianping , Li Jingbo , He Yahui , Gao Zhongzhe , Jiang Leping
Published: December 2024

The origins of rice domestication and the beginnings of alcoholic fermentation in China are intriguing research topics, with the Shangshan culture in the Lower Yangzi River region being a focal point of archaeological investigations. This study employs a multiproxy approach (phytolith, starch, and fungi) to analyze microfossil remains associated with pottery vessels from the earliest phase of the Shangshan site (ca. 10,000 to 9,000 cal. BP). The results indicate that rice was consumed as a dietary staple and used for brewing fermented beverages with a
qu
starter containing
Monascus
mold and yeast as fermentation agents. The fermentation ingredients included rice, supplemented with other cereals (Job’s tears, Panicoideae, and Triticeae), acorn, and lily. This rice-fungi-based multiplant brewing method marked the earliest-known alcoholic fermentation technique in East Asia. The emergence of this fermentation technology is attributable to the early development of rice domestication and the arrival of the wet-warm Holocene climate, which was favorable for fungal growth. These alcoholic beverages likely played a pivotal role in ceremonial feasting, highlighting their ritual function as a driving factor that may have stimulated the intensive utilization and widespread cultivation of rice in Neolithic China.
A physically modelled selection function for compact binary mergers in the LIGO-Virgo O3 run and beyond
Authors: Lorenzo-Medina Ana , Dent Thomas
Published: December 2024

Despite the observation of nearly 100 compact binary coalescence (CBC) events up to the end of the Advanced gravitational-wave (GW) detectors’ third observing run (O3), there remain fundamental open questions regarding their astrophysical formation mechanisms and environments. Population analysis should yield insights into these questions, but requires careful control of uncertainties and biases. GW observations have a strong selection bias: this is due first to the dependence of the signal amplitude on the source’s (intrinsic and extrinsic) parameters, and second to the complicated nature of detector noise and of current detection methods. In this work, we introduce a new physically-motivated model of the sensitivity of GW searches for CBC events, aimed at enhancing the accuracy and efficiency of population reconstructions. In contrast to current methods which rely on re-weighting simulated signals (injections) via importance sampling, we model the probability of detection of binary black hole (BBH) mergers as a smooth, analytic function of source masses, orbit-aligned spins, and distance, fitted to accurately match injection results. The estimate can thus be used for population models whose signal distribution over parameter space differs significantly from the injection distribution. Our method has already been used in population studies such as reconstructing the BBH merger rate dependence on redshift.
Properties of interacting quark star in light of Rastall gravity
Authors: Banerjee Ayan , Pradhan Anirudh , Sakallı İzzet , Dixit Archana
Published: December 2024

This study explores the properties of quark stars (QSs) formulated with an interacting quark matter equation of state within the framework of Rastall gravity, a modified theory of gravity. We derive the mass-radius relationships and calculate the maximum gravitational masses and their corresponding radii, comparing these results under both Rastall gravity and general relativity. Our analysis incorporates recent observational data, including the GW190425 event, to constrain the model parameters (

λ
¯

,
η
,

B
eff

). We also assess the stability of these QSs by evaluating their static stability, adiabatic index, and sound velocity profiles, thus confirming their viability within the modified gravitational framework.
Non-local quantum field theory from doubly special relativity
Authors: Relancio J J , Santamaría-Sanz L
Published: December 2024

Doubly special relativity (DSR) is usually regarded as a low-energy limit of a quantum gravity theory with testable predictions. On the other hand, non-local quantum field theories have been presented as a solution to the inconsistencies arising when quantizing gravity. Here, we present a new formulation of quantum field theories in DSR with non-local behavior. Our construction restricts the models to those showing linear Lorentz invariance. We derive the deformed Klein–Gordon, Dirac, and electromagnetic Lagrangians, as well as the deformed Maxwell equations. We also discuss the electric potential of a point charge. Finally, we analyze the connection between the nonlocality of field theories and DSR.
Tailoring the performance of the multidimensional electrostatically formed nanowire gas sensor
Authors: Mukherjee Anwesha , ShemTov Idan , Sharma Bhavya , Rosenwaks Yossi
Published: December 2024

Multi-gate field effect transistors (FETs) based on silicon-on-insulator have been popular for several decades due to their improved electrostatic control of the channel current between the source and the drain. Chemical sensors based on such multi-gate FET platform can leverage this improved electrostatic control to detect gases at very low concentration with ultrahigh sensitivity. Electrostatically formed nanowire (EFN) is a multiple-gate FET device which has proven to be an excellent platform for detecting volatile organic compounds and gases. In case of such multi-gate FET sensors, it is imperative to rigorously understand the influence of each gate in controlling the sensing performances. Using palladium nanoparticles decorated EFN (Pd-EFN) as an example, the current work presents a detailed methodology for determining the operating parameters for maximal sensing performances of the Pd-EFN sensor towards hydrogen sensing. We observed that a single operating point does not yield best results with regard to sensor response, dynamic range, and power efficiency. By optimizing the operating points (by varying the different gate biases), a sensor response of 107% was reached even at low concentrations of hydrogen (500 ppm) which is significantly lower than the lower explosive limit of 4% and a tunable dynamic range over three decades (4–8000 ppm) was obtained. Also, the sensor response was not compromised at low driving voltages (100 mV) thus contributing to low power consumption of the sensor. Such a correlation between the working point of the transistor and the various sensor performance metrics (maximum sensor response, dynamic range etc) has not been studied before to the best of our knowledge and this study can be extended to EFN for other gases and any other multi-gate FET sensors (not limited to Si based sensors). This study can pave the way for effective design of future multi-gate transistors for gas sensing.
Tunable directional radiation and reception based on magneto-optical photonic crystal waveguides
Authors: Huang Yuhao , Zheng Yidong , Li Zhi-Yuan , Liang Wenyao
Published: December 2024

We have proposed a magneto-optical photonic crystal (MOPC) waveguide that can not only realize highly directional radiation but also work as an electromagnetic (EM) wave receiver. This waveguide consists of a square MOPC and a covering layer of Al2O3 PC tilted at 45° that allows for the penetration of EM waves. Due to the broken time-reversal symmetry caused by an external magnetic field, there exists a unidirectional leaky topological edge state within the photonic bandgap. Such the leaky edge state transmits unidirectional and radiates into the air simultaneously, leading to a broadside radiation beam with a low half-power beam width of less than 4°. More importantly, the radiation direction of the beam can be tuned over a wide angular range by adjusting the operation frequency or the magnetic field strength. Besides, this designed waveguide can also act as a tunable receiver for capturing incident EM waves effectively. These results have potential for various practical applications, such as antennas and sensors.
Intrinsic defects in α-

Al

2

O

3

: structural and electronic properties
Authors: Xiang Bo , Feng Muti , Zheng Ruogu , Wang Hai , Guo Long , Wang Qingbo , Jin Lei , Zhong Hongxia
Published: December 2024

Due to their high dielectric constants and wide band gaps,

Al

2

O

3

has become popular in semiconductor applications, but with high-density interface defect structures. Understanding the structural distortions of intrinsic defects and their impact on electronic properties, is of particular importance for the applications. Herein, we study the impacts of four intrinsic defects on the structural and electronic properties of α-

Al

2

O

3

using first-principles calculations. The four intrinsic defects cause structural distortions at their respective defect sites and defect states within the band gap, with

O

i

inducing the most significant distortions and exhibiting the most complex defect states accordingly. When the Fermi level is 3.05 eV under O-poor conditions, VO
is the most favorable defects based on the formation energy calculations. Additionally, the intrinsic defects in α-

Al

2

O

3

can effectively modulate band edges, and thus modify the leakage currents. In summary, our results provide significant theoretical insights for α-

Al

2

O

3

-based semiconductor applications.
Reflectionless filtering power divider with wide passband using LTCC technology
Authors: Feng Wenyuan , Yuan Xue , Wang Dongxu , Chen Jianzhong , Xu Kai-Da
Published: December 2024

This paper presents a reflectionless filtering power divider (FPD) in low-temperature co-fired ceramic (LTCC) technology. The proposed FPD consists of a pair of parallel-coupled lines (PCLs), an absorptive bandstop filtering (ABSF) section and a Wilkinson power divider section, which are distributed in different LTCC layers. A controllable wide passband is realized by quarter-wavelength PCLs and reflectionless performance at the out-of-band is achieved by employing a lossy resistor loaded in the ABSF section. For demonstration, a prototype of the proposed FPD operating at 6.5 GHz with a 3 dB fractional bandwidth of 60% is designed and fabricated using LTCC. The measured results are in good agreement with the simulated ones, which validates the theoretical prediction and design idea.
A single layer 1-bit ultra-wideband conformal metasurface for RCS-reduction with polarization conversion
Authors: Liu Youya , Jiang Dapeng , Fu Yang , Zhou Xiaofeng , Ding Fan , Yang Helin
Published: December 2024

This paper proposes a single layer 1-bit linear polarization converter for reducing the ultra-wideband radar cross section (RCS) of both planar and conformal surfaces. The layout of the supercells was optimized using the simulated annealing algorithm, achieving an average RCS reduction of over 10 dB in the range of 6.39–18.1 GHz in the planar case. By conforming the metasurface with cylinders of different radius of curvature, the result still meets the requirement of a 10 dB reduction within the bandwidth, which solves the expansion of the RCS reduction from planar to curved surfaces. Sample was prepared and experiments were conducted. The test results were consistent with the simulation results, indicating that the designed metasurface has potential applications in electromagnetic stealth for large targets.
A sound insulation cooling fin for broadband noise control and ventilation
Authors: Liao Weiwei , Hao Jia , Luo Xiaobing
Published: December 2024

The noise generated by the ultrathin centrifugal fan in a laptop can significantly impact user comfort. While optimizing the fan itself for noise control is important, addressing noise propagation is also crucial. Due to space limitations inside a laptop, adding an extra component for noise control is nearly impossible. Therefore, modifying the cooling fin outside of the fan outlet for sound insulation can be an effective solution. A sound insulation cooling fin is proposed to provide broadband noise insulation while maintaining proper ventilation. Through the introduction of a coupled area change passage, noise at specific frequencies at the passage outlet can be managed to be insulated due to the destructive interference. The effectiveness of the unit’s sound insulation is verified through an impedance tube measurement. Moreover, combining different units can create a multi-peak sound insulation effect which is suitable for various noise conditions. To meet the demand of real situations, a reversal design flow combining neural network and nonlinear constrained optimization algorithm is developed. As a result, a sound cooling fin combing 2 sound insulation units featuring 4013 Hz and 6000 Hz is fabricated and the actual insulation performance is measured in an anechoic chamber. The sound transmission loss at the designed frequency range reaches 5 dB, aligning well with the simulation results. The sound insulation cooling fin has the potential to be widely used for noise control in small-scale electronic devices.
Nickelocene SPM tip as a molecular spin sensor
Authors: Pinar Solé Andrés , Kumar Manish , Soler-Polo Diego , Stetsovych Oleksandr , Jelínek Pavel
Published: December 2024

Functionalization of a scanning microscopy probe with a single nickelocene allows reproducible spin-sensitive measurements of magnetic systems on surfaces. The triplet ground state of the nickelocene tip gives rise to a characteristic inelastic electron spin-flip excitation, which can change upon interaction with spin systems on the surface. These changes, together with theoretical simulations, enable us to determine the local spin moment on the surface. In this paper, we discuss the experimental and theoretical aspects of nickelocene-tip measurements. We rationalize the interactions between the nickelocene spin and the magnetic centers using a spin Heisenberg and dipole model, complemented by cotunneling theory, and compare the simulated dI/dV with selected experimental results. We developed a Python script to simulate this magnetic interaction, which is available on GitHub.
A remarkable match of optical response in the amorphous-crystalline and zinc blende-rock salt phase pairs of GeTe
Authors: Plekhanov E A , Tchougréeff A L , Kolobov A V
Published: December 2024

Despite a large amount of theoretical and experimental work performed so far, the search of phase change materials (PCMs) is done with use of numerical modeling. However, it is not fully clear how and why the phase change translates into the optical contrast. In this work, we argue that a key prerequisite for a material to have a pronounced difference in optical properties between crystalline and glassy phases of PCM is the similar contrast between the observed crystalline and (may be experimentally inaccessible) parent crystalline polymorph of the glassy phase. To illustrate this claim, we report a comparison of dynamic dielectric function of zinc-blende (α-ZnS), CsCl, and rock-salt (NaCl) phases of the binary

A

IV

B

VI

PCM exemplified by the well known GeTe prototype compound with experimental data and supply a theoretical explanation to the observed behavior based on topological properties of the Fermi surfaces appearing in the protoptypic ‘degenerate’ crystals with A = B having the same local structure as the parent polymorphs and derived from simple analytical model. By this, we arrive to a qualitative rather than purely numeric guidance for possible search of the novel phase-change materials.
RBNN with cycle-based parameter updates and its application to RUL prediction
Authors: Guo Runxia , Wang Siying , Luo Xianfeng
Published: December 2024

Bayesian neural networks (BNNs) combine Bayesian theory with deep learning, providing a probabilistic interpretation of deep learning models. Traditional BNNs typically assume that model prior follows a standard Gaussian distribution, which may not accurately reflect the actual situation. To address this issue, this paper proposes a recurrent BNN (RBNN) that employs two trainable Gaussian distributions as priors. Furthermore, an alternating cycle model parameter update algorithm is designed accordingly, which not only prevents overfitting to specific data during training but also enhances the robustness of model parameters in error approximation. Additionally, this RBNN module can be integrated with classical neural network architecture conveniently. By integrating the RBNN with a temporal convolutional network, the effectiveness of the proposed approach was validated using a dataset for remaining useful life (RUL) prediction of gear and bearing components in civil aircraft. Comparative studies show that the integrated model outperforms traditional methods in terms of RUL prediction and uncertainty quantification, offering superior accuracy and robustness, and the RMSE of the RBNN prediction results is reduced by 17.7% and score is increased by 27.5% compared to BNN.
Enhanced RUL predictions of rolling bearings using a nonlinear Wiener model with an extended incremental Kalman filter
Authors: Li Junxing , Fan Jiahui , Wang Zhihua , Zhang Zhiwen , Pang Xiaoxu , Qiu Ming
Published: December 2024

To predict the remaining useful life (RUL) of rolling bearings, a novel two-stage degradation model is constructed, taking into account the two-phase characteristics of bearing performance degradation, which includes stable (stage 1) and degrading (stage 2) phases. The model employs an autoregressive model and a nonlinear Wiener process to describe the performance degradation at each stage. Subsequently, a residual cumulative sum control chart is proposed to identify the first change-point from stage 1 to stage 2. In response to the limitations of existing extended Kalman filter methods that overlook the dynamic characteristics of state increments for state updates, an adaptive extended increment Kalman filter is introduced to update the degradation state and achieve accurate RUL predictions of rolling bearings. Finally, the effectiveness and applicability of this method are validated using a self-constructed dataset from 16 004 bearing test data and XJTU-SY bearing data. The results demonstrate that this approach can accurately identify the first change-point and enhance the accuracy of RUL predictions.
Fine-grained fault diagnosis of photovoltaic systems based on DMAD-GAN and IFD-FGIF
Authors: Qiao Juanjuan , Qi Yongsheng , Liu Liqiang , Li Yongting , Luo Zhihong
Published: December 2024

In the field of photovoltaic (PV) system monitoring, fault detection faces two critical challenges: data imbalance and fault diversity, as well as incomplete complex fault information. To tackle these issues, this paper proposes a dual-mechanism anomaly detection with generative adversarial network (DMAD-GAN) and an integrated fault diagnosis with fine-grained information fusion (IFD-FGIF). DMAD-GAN utilizes GAN to integrate dual mechanisms for anomaly detection in PV datasets, with coordinate-space attention enhancing the perception of subtle features and differences in PV panels. The anomaly scoring mechanism utilizes an improved loss function to compute anomaly scores, assessing the degree of anomaly for each sample. In the IFD-FGIF method, t-SNE is used to visualize features for fault pre-classification to determine the presence of new faults. A fine-grained information fusion module is designed, leveraging ResNet50 to extract features from fault key areas and original images. This module integrates fine-grained features, original features, and fine-grained attributes. Fault attributes and categories are determined using an attribute classifier and Euclidean distance. If a new fault is identified during pre-classification, the network undergoes transfer learning to recognize and adapt to the new fault. The experimental results demonstrate that the proposed method outperforms other networks, achieving an anomaly detection accuracy of 95.86%. The fault fine-grained recognition accuracy is 95.62%. The accuracy of fine-grained information fusion has improved by 4%, and unsupervised learning of new faults has been successfully achieved. The proposed method can enhance the intelligent operation and maintenance capability of PV power plants, reduce false alarm rates in fault detection, and minimize operational risks caused by potential faults, thus effectively shortening downtime and lowering maintenance costs.
MLDM: a multi learning domain model for fault identification of centrifugal fan
Authors: Wang Ruijun , Fan Zhixia , Liu Yuan
Published: December 2024

In centrifugal fan fault diagnosis, the influence of multiple noise sources causes the collected fault signals to contain interference of different modes. Therefore, the difficulty of capturing fault characteristics greatly increases in this situation. In this article, a multi learning domain model scheme is proposed based on signal processing technology and artificial intelligence methods. The Haar wavelet convolution extraction module in the scheme is used to synchronously map features at different frequency scales, while the lightweight multi-scale feature enhancement module enhances feature extraction at different time scales. Meanwhile, upsampling is employed to enhance the expression of fault features. In addition, applying information rectification learning to feature maps extracted at each level allows for spatial representation and selection of extracted fault features, providing a basis for final decision-making. This scheme performs multi-level and multi-scale analysis on fault signals, jointly extracting time, frequency, and spatial information to improve the robustness and generalization ability of the model. Conduct experimental verification using data from the same type of centrifugal fan and rotor. The experimental results show that the recognition accuracy of the proposed model is about 93% for fan data at SNR = −4 dB, which has certain competitiveness compared to other excellent models.
Research on deterioration state evaluation of hydropower units based on successive variational mode decomposition and Mahalanobis distance
Authors: Wei Jiafu , Cao Chaofan , Yu Qing , Lu Na , Guo Jiang
Published: December 2024

In order to better acquire the real-time operating status of hydropower units and realize early fault warning, a deterioration state evaluation method for hydropower units based on successive variational mode decomposition (SVMD) and Mahalanobis distance (MD) is proposed. In the offline stage, SVMD is optimized with dispersion entropy as the fitness function, and historical health data is used to obtain a health baseline. In the online stage, the real-time monitoring signal is input into the optimized SVMD model first. The features of the intrinsic mode functions are then extracted. Subsequently, synthetic detection index and detection index are utilized for feature parameter selection. Finally, a degradation indicator is constructed based on Gaussian mixture model and MD, and the degradation curve is drown to evaluate the real-time deterioration state of the unit. Experimental results demonstrate that the proposed method can effectively characterize the real-time operating status of hydropower units, identify abnormal changes of the unit 4 d in advance, and issue timely warning.
Parameterized ZNCC image correlation for rotary-angle measurement
Authors: Wei Wang , Yang Wenyi , Li Chujun , Yuan Guixin , Xia Yang
Published: December 2024

High-accuracy rotary-angle measurement is critical for precise positioning and control of robots, machine arms, and machine tools in industry. Image-based measurement is a very promising technology for angle positioning owing to its simple system, low cost, and good robustness to environments. Image correlation, such as the zero-mean normalized cross correlation (ZNCC) method, can obtain high accuracy image-positioning results, but their efficiency is too low to directly use in industries. This paper proposes to measure the absolute rotary angle using a parameterized ZNCC (PZNCC) image correlation method. The PZNCC expresses the ZNCC coefficient by the image-shift parameters explicitly, so that the precise match point corresponding to the global ZNCC maximum can be efficiently obtained and no image-resampling process is required. As a result, PZNCC is approximately 5 times faster than the classic inverse compositional Gauss–Newton algorithm. Experiments show that rotary angle measurement based on PZNCC can obtain absolute angle positions with an accuracy of 1.16 arcsec (RMSE).
Exploring hydrogen adsorption and release in 2D M2C-MXenes: structural and functional insights
Authors: Xu Wenzhen , Sun Liang , Zhai Wenyan , Yang Jia , Jiang Tao , Peng Jianhong
Published: December 2024

Two-dimensional M2C-MXenes, characterized by their lightweight nature, tunable surface structures, and strong affinity for hydrogen, hold significant promise for addressing various challenges in hydrogen energy utilization. This study focuses on investigating the hydrogen adsorption and desorption properties, as well as the stability of hydrogenated compounds in 19 pure M2C-MXenes nanosheets. The results indicate that hydrogen adsorption on M2C primarily occurs through weak physisorption, with Mn2C and Fe2C from the fourth period, and Ag2C and Cd2C from the fifth period exhibiting the lowest adsorption energies. In contrast, hydrogen atoms are adsorbed on M2C primarily through chemisorption, leading to the potential dissociation of H2 molecules into two hydrogen atoms. Among the M2C-MXenes, Ti2C, and Zr2C in the d4
and d5
, respectively, demonstrate the most stable hydrogen atom binding. Hydrogen evolution is most facile on Cu2C and Ag2C surfaces. Two types of stacking configurations, face-centered cubic and hexagonal close-packed, are observed for hydrogenated M2C surfaces (e.g. Co2C and Zr2C), showing excellent thermodynamic stability. This work elucidates the hydrogen utilization performance of pure M2C-MXenes nanosheets and guides future research aimed at achieving high hydrogen storage capacities through the functional tuning of MXenes.