bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic wave propagation in depth-evolving sound-speed field using the lattice Boltzmann method
Authors: Chu Xuesen , Zhao Feng , Wang Zhengdao , Qian Yuehong , Yang Guangwen
Published: September 2024

This study investigates the propagation of sound waves within deep-sea low-sound-speed channels using the lattice Boltzmann method, with a key focus on the influence of depth-dependent sound speed on wave propagation. The depth-variable sound speed condition is realized through the incorporation of an external force proportional to the density gradient. After the model verification, investigations into the two-dimensional spreading of sound sources reveal that the depth-dependent sound speed curves the wave propagation. When source depths differing from the low-sound-speed channel, wave paths deviate due to contrasting speeds above and below. When the sound source is situated within the low-sound-speed channel, waves exhibit converging patterns. The simulations also detail the total reflection behavior of sound waves. When the incident angle falls exceeds the critical angle, the waves remain intact within the low-sound-speed channel, thereby enabling the preservation of high amplitude acoustic signals even at remote locations. The subsequent simulations of sound wave propagation around obstacles demonstrate that the low-sound-speed channel also exhibits better signal transmission capabilities in the presence of obstacles. In a uniform sound speed environment, acoustic wave propagation around a submarine exhibits a symmetric pattern. By contrast, under depth-evolving speed conditions, submarines operating at various depths manifest distinct propagation characteristics, such as asymmetric wave propagation during shallow diving, as well as wave attenuation or even silencing when cruising within low-sound-speed channels. These findings underscore the profound implications of depth-evolving sound speed on underwater acoustic signal detection and transmission.
Influence of local structure and metal-oxygen hybridization on the electrical and magnetic properties of alkaline earth metal (Mg2+, Ca2+, Sr2+) substituted LaFeO3 ceramics
Authors: Nandy Subhajit , Theingi Mya , Ghosh Sayan , Chae Keun Hwa , Sudakar C.
Published: September 2024

Pristine and alkaline-earth metal-substituted LaFeO3 (La1−xAxFeO3−δ; x = 0 and 0.2; A = Mg2+, Ca2+, and Sr2+) sintered ceramics are prepared from nanoparticles synthesized via a low-temperature citrate sol–gel technique. X-ray diffraction studies confirm the formation of a phase-pure LaFeO3 structure without any secondary phases for all the La1−xAxFeO3−δ compositions. LaFeO3 and La0.8Mg0.2FeO3−δ ceramics show Raman active modes related to La vibration, oxygen octahedral tilting, bending, and stretching. The optical bandgap is estimated to be 2.34 eV for pure LaFeO3 and reduces to 2.23 eV for La0.8Mg0.2FeO3−δ ceramics. On the contrary, La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics show no features in Raman spectra, consistent with the observation of metallic nature and diffuse band edge without any indication of sharp band edge noted. X-ray absorption spectroscopy (XAS) studies on La-L3 and Fe-K-edges confirm the oxidation states of La3+ and Fe3+ in all these ceramics. Local structural distortions and formation of oxygen vacancies in La0.8A0.2FeO3−δ (A = Mg2+, Ca2+, and Sr2+) ceramics are discerned from XAS structure analysis compared to the pristine LaFeO3 ceramics. Magnetic measurements of La1−xAxFeO3−δ reveal weak ferromagnetic nature except for La0.8Mg0.2FeO3−δ, which shows a large magnetization of 4.6 (6.7) emu/g at 300 (5) K. The ferromagnetic behavior of La0.8Mg0.2FeO3−δ ceramics seems to originate from the modification of hybridization between Fe(3d)–O(2p), La(5d)–O(2p), and Fe(4sp)–O(2p) orbitals. An anomalous magnetic transition observed only in zero-field-cooled curves at 88 K in La0.8Ca0.2FeO3−δ and La0.8Sr0.2FeO3−δ ceramics is correlated to the formation of new electronic states containing O 2p character as discerned from pre-peak O-K-edge.
Numerical pore-scale investigation of two-phase displacement with non-Newtonian defending fluid
Authors: Wang Wenyuan , Liu Pengfei , Zhou Chen , Bate Bate , Chen Yunmin
Published: September 2024

In the petroleum engineering and chemical industries, fluids engaging in displacement often have non-Newtonian properties, even though many former studies assume constant viscosities in the defending fluid. In this study, the computational fluid dynamics approach was performed in a two-dimensional model with uniformly distributed disks. This arrangement helps reveal the phenomenon and mechanics of how non-Newtonian characteristics of defending fluid affect two-phase displacement in porous media. Both global (in the whole medium) and regional (in the pore throat) studies revealed that shear-thinning makes capillary force and the pressure in the invading fluid decisive and leads to a uniform pattern. Meanwhile, the shear-thickening causes fingering due to the pressure drop in the defending fluid that becomes decisive. Cases of increasing injection rates were investigated to verify their ability to improve efficiency. The results verified that increased injection rates are effective in shear-thinning cases but energy-intensive when it comes to costs in shear-thickening cases. Finally, the viscosity ratio and capillary number (M-Ca) diagram were extended by plotting non-Newtonian cases as lines to consider viscosity variation. An estimation method was presented, which calculates the characteristic viscosity and locates non-Newtonian cases on an M-Ca diagram. This work can serve as a reference for enhanced oil recovery method development and microfluidic manipulation.
Automobile aerodynamic drag reduction based on the bionic dorsal fin
Authors: Zhao Jian , Su Chuqi , Liu Xun , Yuan Xiaohong , Li Wenjie , Wang Yiping
Published: September 2024

Airflow separation at the rear area of the automobile is the main source of automobile aerodynamic drag. To suppress the airflow separation, minimize the aerodynamic drag of the automobile, realize energy saving and emission reduction, a bionic drag reduction device was designed based on the dorsal fin of the orca with low drag characteristics. A numerical computation method was established to maximize the drag reduction performance of the bionic device, and the parametric modeling of the bionic drag reduction device was carried out. The design of experiments, the Kriging surrogate model, and an optimization algorithm were used to optimize the bionic drag reduction device. The validity of the optimization design was validated by the wind tunnel test. Finally, the mechanism and effectiveness of the bionic device in reducing aerodynamic drag were investigated through the comparison of flow field. The results show that the optimized bionic drag reduction device can delay the airflow separation and effectively reduce turbulence intensity of the automobile. According to the wind tunnel test, the aerodynamic drag coefficient of the optimized model is reduced by 6.16% compared with the original model.
Theoretical prediction of chalcogen-based Janus monolayers for self-powered optoelectronic devices
Authors: Sun Yuxuan , Sun Naizhang , Zhou Wenlin , Ye Han
Published: September 2024

Exploring potential two-dimensional monolayers with large photogalvanic effect (PGE) has been of great importance for developing self-powered optoelectronic devices. In this paper, we systematically investigate the generation of PGE photocurrent in chalcogen-based Janus XYZ monolayers (X/Y/Z = S, Se, Te; X ≠ Y ≠ Z) based on non-equilibrium Green's function formalism with density functional theory. The optimized Janus SSeTe, SeSTe, and TeSeS monolayers in the rectangular phase are shown stable and, respectively, possess 1.54, 1.49, and 1.74 eV indirect bandgaps. Illuminated by linearly polarized light, the PGE photocurrent without bias voltage can be collected in both armchair and zigzag directions. Unlike common Janus 2D materials with C3v symmetry, the photocurrent peak values of Janus XYZ monolayers do not come up with certain polarization angles, while the relations can be fitted by Iph = α sin(2θ) + β cos(2θ) + γ at each photon energy. Meanwhile, the maximum photoresponses of Janus SSeTe, SeSTe, and TeSeS monolayers are 2.02, 3.33, and 4.42 a20/photon, respectively. The relatively large PGE photocurrents and complicated polarization relations result from the lower symmetry of Janus XYZ monolayers. Moreover, the specific polarization angles for maximum photoresponses at each photon energy and the ratio between two transport directions are demonstrated, reflecting the anisotropy. Our results theoretically predict a potential Janus monolayer family for self-powered optoelectronic applications.
Low detection limit of uric acid based on Prussian blue-enhanced photothermal effect with microfiber knot resonator
Authors: Zhang Yangyuan , Bai Yangbo , Miao Yinping , Chen Xuanyi , Han Zhuoyang , Yao Jianquan
Published: September 2024

The human serum uric acid (UA) level is a crucial indicator for diagnosing dementia in middle-aged and elderly individuals, with decreased levels being expressed in patients. Therefore, developing a high-performance sensor for online uric acid detection is of significant research interest. Herein, a microfiber knot resonator (MKR) sensor for quantitative detection of UA levels is reported. Combining polydimethylsiloxane (PDMS) with an adiabatic MKR, the specificity of UA detection in serum is improved using the photothermal effect of Prussian blue-enhanced uricase reaction. During the sensor operation, UA generates the photothermal effect under 650 nm laser irradiation, causing the PDMS film to expand with heat absorption, thereby shifting the resonance spectrum of the PDMS-MKR sensor. Experimental results demonstrate a sensitivity of 0.0559 nm/(μmol/L) within a UA concentration range of 40–120 μmol/L and a detection limit as low as 0.3578 μmol/L. The proposed sensor shows potential applications in clinical point-of-care early diagnosis and prognosis of dementia due to its specificity, fast detection speed, robustness, and high integration.
Colloid thermophoresis in surfactant solutions: Probing colloid–solvent interactions through microscale experiments
Authors: Pu Di , Panahi Amirreza , Natale Giovanniantonio , Benneker Anne M.
Published: September 2024

Thermophoresis has emerged as a powerful tool for characterizing and manipulating colloids at the nano- and micro-scales due to its sensitivity to colloid–solvent interactions. The use of surfactants enables the tailoring of surface chemistry on colloidal particles and the tuning of interfacial interactions. However, the microscopic mechanisms underlying thermophoresis in surfactant solutions remain poorly understood due to the complexity of multiscale interaction coupling. To achieve a more fundamental understanding of the roles of surfactants, we investigated the thermophoretic behavior of silica beads in both ionic and nonionic surfactant solutions at various background temperatures. We provide a complete mechanistic picture of the effects of surfactants on interfacial interactions through mode-coupling analysis of both electrophoretic and thermophoretic experiments. Our results demonstrate that silica thermophoresis is predominantly governed by the dissociation of silanol functional groups at silica–water interfaces in nonionic surfactant solutions, while in ionic surfactant solutions, the primary mechanism driving silica thermophoresis is the adsorption of ionic surfactants onto the silica surface.
Structural and electrical properties of grafted Si/GaAsSb heterojunction
Authors: Abbasi Haris Naeem , Lee Seunghyun , Jung Hyemin , Gajowski Nathan , Lu Yi , Wang Yifan , Kim Donghyeok , Zhou Jie , Gong Jiarui , Chae Chris , Hwang Jinwoo , Muduli Manisha , Nookala Subramanya , Ma Zhenqiang , Krishna Sanjay
Published: September 2024

The short-wave infrared (SWIR) wavelength, especially 1.55 μm, has attracted significant attention in various areas such as high-speed optical communication and LiDAR systems. Avalanche photodiodes (APDs) are a critical component as a receiver in these systems due to their internal gain, which enhances the system performance. Silicon-based APDs are promising since they are CMOS compatible, but they are limited in detecting 1.55 μm light detection. This study proposes a p-type Si on n-type GaAs0.51Sb0.49 (GaAsSb) lattice matched to InP substrates heterojunction formed using a grafting technique for future GaAsSb/Si APD technology. A p+Si nanomembrane is transferred onto the GaAsSb/AlInAs/InP substrate, with an ultrathin ALD-Al2O3 oxide at the interface, which behaves as both double-side passivation and quantum tunneling layers. The devices exhibit excellent surface morphology and interface quality, confirmed by atomic force microscope and transmission electron microscope. Also, the current–voltage (I–V) of the p+Si/n−GaAsSb heterojunction shows the rectifying characteristics with an ideality factor of 1.8. The I–V tests across multiple devices confirm high consistency and yield. Furthermore, the x-ray photoelectron spectroscopy measurement reveals that GaAsSb and Si are found to have type-II band alignment with a conduction band offset of 50 meV, which is favorable for the high-bandwidth APD application. The demonstration of the GaAsSb/Si heterojunction highlights the potential to advance current SWIR PD technologies.
Unraveling abnormal collective effects via the non-monotonic number dependence of electron transfer in confined electromagnetic fields
Authors: Sharma Shravan Kumar , Chen Hsing-Ta
Published: September 2024

Strong light–matter coupling within an optical cavity leverages the collective interactions of molecules and confined electromagnetic fields, giving rise to the possibilities of modifying chemical reactivity and molecular properties. While collective optical responses, such as enhanced Rabi splitting, are often observed, the overall effect of the cavity on molecular systems remains ambiguous for a large number of molecules. In this paper, we investigate the non-adiabatic electron transfer process in electron donor–acceptor pairs influenced by collective excitation and local molecular dynamics. Using the timescale difference between reorganization and thermal fluctuations, we derive analytical formulas for the electron transfer rate constant and the polariton relaxation rate. These formulas apply to any number of molecules (N) and account for the collective effect as induced by cavity photon coupling. Our findings reveal a non-monotonic dependence of the rate constant on N, which can be understood by the interplay between electron transfer and polariton relaxation. As a result, the cavity-induced quantum yield increases linearly with N for small N (as predicted by a simple Dicke model) but shows a turnover and suppression for large N. We also interrelate the thermal bath frequency and the number of molecules, suggesting the optimal number for maximizing enhancement. The analysis provides an analytical insight for understanding the collective excitation of light and electron transfer, helping to predict the optimal condition for effective cavity-controlled chemical reactivity.
Non-simultaneous impact of droplet pairs on solid surfaces
Authors: Goswami Anjan , Hardalupas Yannis
Published: September 2024

This study delves into the dynamics of non-simultaneous droplet impacts on solid substrates, focusing on interactions between identical impacting droplets. Comparisons between non-simultaneous and simultaneous impacts are presented to understand the phenomena comprehensively. An in-house-built microcontroller-based droplet generator releases two equal-sized droplets on demand, allowing for simultaneous or non-simultaneous impacts. The interaction between impacting droplets generates an uprising sheet, whose characteristics vary with time lag between impacts, impact Weber number, and inter-droplet spacing. The evolution of central sheet characteristics, lamellae spreading dynamics, splashing mechanism, and secondary atomization is evaluated. Findings reveal that central sheet morphology varies with the time lag between impacts, transitioning from a two-dimensional (2D) “semilunar” sheet (vertical or inclined) with a linear base to a three-dimensional (3D) sheet with a curved base, increasing the probability of secondary atomization. The temporal evolution of the central sheet position, height, and inclination angle is governed by the momentum of spreading lamellae. A novel scaling law for maximum sheet extension and a theoretical expression for surface liquid spread are proposed, consistent with the measurements. The characteristics of secondary droplets generated during non-simultaneous impacts are similar to those from simultaneous impacts, with the size of the secondary droplets being one order of magnitude larger than those expected from isolated single-droplet impacts.
Design and application of pneumatic rehabilitation glove system based on brain–computer interface
Authors: Chen Cheng , Song Yize , Chen Duoyou , Zhu Jiahua , Ning Huansheng , Xiao Ruoxiu
Published: September 2024

Stroke has been the second leading cause of death and disability worldwide. With the innovation of therapeutic schedules, its death rate has decreased significantly but still guides chronic movement disorders. Due to the lack of independent activities and minimum exercise standards, the traditional rehabilitation means of occupational therapy and constraint-induced movement therapy pose challenges in stroke patients with severe impairments. Therefore, specific and effective rehabilitation methods seek innovation. To address the overlooked limitation, we design a pneumatic rehabilitation glove system. Specially, we developed a pneumatic glove, which utilizes ElectroEncephaloGram (EEG) acquisition to gain the EEG signals. A proposed EEGTran model is inserted into the system to distinguish the specific motor imagination behavior, thus, the glove can perform specific activities according to the patient's imagination, facilitating the patients with severe movement disorders and promoting the rehabilitation technology. The experimental results show that the proposed EEGTrans reached an accuracy of 87.3% and outperformed that of competitors. It demonstrates that our pneumatic rehabilitation glove system contributes to the rehabilitation training of stroke patients.
Fabrication of graphene field effect transistors on complex non-planar surfaces
Authors: Holicky M. , Fenech-Salerno B. , Cass A. E. G. , Torrisi F.
Published: September 2024

Graphene field effect transistors (GFETs) are promising devices for biochemical sensing. Integrating GFETs onto complex non-planar surfaces could uncap their potential in emerging areas of wearable electronics, such as smart contact lenses and microneedle sensing. However, the fabrication of GFETs on non-planar surfaces is challenging using conventional lithography approaches. Here, we develop a combined spray-coating and photolithography setup for the scalable fabrication of GFETs on non-planar surfaces and demonstrate their application as integrated GFETs on microneedles. We optimize the setup to pattern ∼ 67 μm long GFET channels across the microneedle tips. Graphene is deposited between photo-patterned electrodes by spray-coating a liquid-phase exfoliated graphene ink while monitoring the channel resistance to achieve the required conductivity. The formation of the GFET channels is confirmed by SEM and EDX mapping, and the GFETs are shown to modulate in solution. This demonstrates an approach for manufacturing graphene electronic devices on complex non-planar surfaces like microneedles and opens possibilities for wearable GFET microneedle sensors for real-time monitoring of biomarkers.
Two-dimensional BC12 as an ultra-high performance anode material for lithium-ion batteries
Authors: Ye Xiao-Juan , Cao Hong-Bao , Shen Rui , Liu Chun-Sheng
Published: September 2024

With the gradual development of renewable energy, search for high-performance energy storage materials as anodes for lithium-ion batteries (LIBs) has become urgent. Two-dimensional (2D) materials are considered as candidates for anode materials due to their unique structure and physicochemical properties. Based on first-principles calculations, we propose a 2D material, BC12 monolayer, as an excellent anode for LIBs. BC12 exhibits outstanding dynamic, mechanical, and thermal stability. In addition, BC12 monolayers show not only remarkably high storage capacity (2767.57 mA h g−1) but also low diffusion barrier energy (0.175 eV) and appropriate open circuit voltage (0.3 V). A small volume expansion (0.38%) is also observed during the lithiation process. Furthermore, we undertake a comprehensive analysis on the impact of carbon vacancy in BC12. The presence of carbon vacancy makes the adsorption and diffusion of Li relatively weak, which should be carefully handled in the experimental synthesis process. The above-mentioned investigation offers valuable insights and guidance for the future development and application of 2D anode materials in metal-ion batteries.
Electromagnetic modulating action in a microstrip cavity with embedded two detuned resonators
Authors: Jiang Rui , Gao Lei , Yang Lei , He Wenzhe , Wang Jun , Wu Qian , Sun Yong , Wu Quanying , Chen Yongqiang
Published: September 2024

We present a novel approach for actively controlling electromagnetically induced transparency (EIT) analogs in a single-mode microstrip cavity. This cavity is side-coupled with a pair of varactor-loaded split-ring resonators (SRRs). The EIT-like effect is achieved through resonance hybridization between the paired SRRs with frequency detuning. The microstrip cavity is utilized to enhance the EIT-like transmission properties, including Q-factor and group delay. Varactor diodes, soldered at the gap of the SRRs, are biased electrically through a DC voltage source. This dynamic modulation setup allows for the tuning of the enhanced EIT analog. Experimental results demonstrate that the enhanced EIT-like transmission spectrum can be tuned reversibly by 378 MHz with respect to the transmission dip frequency of 2.464 GHz under the bias voltage ranging from 0 to 5 V. Simultaneously, the controlled transmission spectrum enables a remarkable change in group delay of 10.9 ns. Moreover, the modulation amplitude of the composite SRRs-cavity structure reaches a peak value of up to 34.5 dB, significantly higher than the 6.4 dB of the individual SRRs pair. These results hold promise for inspiring innovation in actively controlled photonic devices for practical applications.
Research on lubrication mechanism of plunger pair considering viscosity temperature and pressure effect
Authors: Du Yuanying , Zhao Hairong , Ji Hong , Wang Wenshan , Wang Hongbo , Xu Feiqin
Published: September 2024

Aiming at the key problems such as serious friction and wear and large leakage of aviation piston pumps operating under high-speed and high-pressure harsh conditions, the lubrication characteristics of aviation plunger pumps are studied in this paper. In order to improve the lubrication performance of the plunger pump, as well as its working efficiency and service life, the equations of pressure, the thickness, and the leakage of the plunger pair oil film under the combined actions of viscosity temperature and pressure under pressure flow, shear flow, and cylinder elastic deformation are established. The finite difference method is used to analyze the lubrication characteristics and the leakage of the plunger pair under these four different conditions: considering, respectively, the effect of viscosity temperature and pressure, only considering the effect of viscosity temperature or viscosity pressure, without considering the effect of viscosity temperature and viscosity pressure. As a result, coupled by the effects of viscosity temperature and viscosity pressure, when the temperature increases from 20 to 60 °C, the oil film pressure increases, and the thickness decreases faster. When the temperature increases from 60 to 120 °C, the oil film pressure increases and the thickness decreases slower When the contact length of the plunger pair increases from 17 to 37 mm, the leakage ratio decreases more rapidly, and when it is greater than 37 mm, it decreases more slowly. The following conclusions were obtained: the viscosity of lubricating fluid is greatly affected by temperature and pressure. The viscosity decreases and increases hyperbolically with the increase in temperature and pressure, the maximum oil film pressure when considering the effect of viscosity temperature and pressure was significantly greater than that without considering the viscosity temperature and pressure, and the minimum oil film thickness was much smaller than that without considering the viscosity temperature and pressure. The leakage curve when considering the viscosity temperature and pressure effect was obviously different from when only considering a single factor or not considering the viscosity temperature and pressure effect. The magnitude of leakage in the four cases is: considering the viscosity temperature effect, considering the viscosity temperature and pressure effect, not considering the viscosity temperature and pressure effect, and considering the viscosity pressure effect. This study can provide a reference for the accurate theoretical design and safe and stable operation of the plunger pair in the plunger pump.
Near room-temperature large negative electrocaloric effect accompanied by giant thermal switching ratio in Zr-rich lead zirconate titanate
Authors: Guo Jian , Yu Haoran , Yuan Mingqian , Yan Xue-Jun , Zhang Shan-Tao
Published: September 2024

Materials with electrocaloric effect (ECE) and/or thermal switching ratio λ are desirable for developing various heat management devices, but developing high-performance candidates, especially those that simultaneously possess large near room-temperature ECE and λ is actually absent. The Zr-rich PbZr1−xTixO3 (PZT) displays a composition-induced antiferroelectric-ferroelectric (AFE-FE) phase boundary, where an unusual negative ECE is expected. Meanwhile, the electric field-sensitive dipole orientation during the AFE-FE phase transition can be employed to modulate λ. In this work, the Zr-rich PZT with coexisting AFE and FE phases was developed and the AFE-FE phase transition temperature is tuned toward room temperature by changing the Ti content to achieve large negative ECE and λ. A large adiabatic temperature change ΔT of −3.3 K accompanied by a giant λ of 1.84 near 60 °C is captured in optimal PbZr0.95Ti0.05O3 ceramics, demonstrating a prominent application prospect in solid-state refrigeration.
Evolution of large-scale flow structures in an axial-flow pump during performance breakdown
Authors: Wang Lei , Kang Shaoxuan , Li Yaojun , Chen Weisheng
Published: September 2024

This paper presents a very large eddy simulation analysis of the unsteady flow in the pre-stall to stall transition process of an axial-flow pump, with the aim to elucidate the spatiotemporal evolution of large-scale flow structures during the performance breakdown of the pump. The transient flow is investigated utilizing a time-dependent flow rate computation scheme. The results demonstrate that, as the flow rate is dynamically reduced, the reduction in pump head is found lags behind the reduction in flow rate by approximately 15 impeller revolutions. The leading edge separation on the blade suction side (SS) evolves into a leading edge separation vortex (LSV) in conjunction with the dynamic reduction in flow rate. The attached flow on the SS in the vicinity of the hub and blade trailing edge squeezes the mainstream outwards, resulting in the formation of a cross passage vortex (CPV) on the tip side of the passage. The combined effect of the LSV, CPV, and tip-clearance flow induces a penetrating upstream flow in the tip region of the impeller, which gives rise to a swirling backflow within the inlet pipe. At stall, the CPV is stably attached to the SS and extends upstream of the leading edge of the neighboring blade. Furthermore, a trailing edge backflow is observed near the junction of the blade trailing edge and the hub, and it collides with the inflow near the hub, resulting in the formation of a hub-attached vortex.
Study on the electrical performance degradation mechanism of
β
-Ga2O3 p-n diode under heavy ion radiation
Authors: Yue Shaozhong , Zheng Xuefeng , Zhang Fang , Lin Danmei , Bu Sijie , Wang Yingzhe , Hu Peipei , Liu Jie , Zhang Weidong , Zhang Jianfu , Ma Xiaohua , Hao Yue
Published: September 2024

The impact of heavy ion irradiation on the β-Ga2O3 p-n diode and its physical mechanism have been studied in this Letter. After the irradiation fluence of 1 × 108 cm−2, it is observed that the electrical performance of the device is significantly degraded. The forward current density (JF) is reduced by 49.4%, the reverse current density (JR) is increased by more than two orders of magnitude, and the breakdown voltage (VBR) is decreased by 30%. Based on the results of the deep-level transient spectroscopy measurement, it is concluded that acceptor-like traps generated with an energy level of EC-0.75 eV in the β-Ga2O3 drift layer dominate the JF degradation of the device, which are most likely related to Ga vacancies. These acceptor-like traps result in the reduction of change carrier concentration, which in turn leads to a decrease in JF. In addition, according to the conductive atomic force microscope measurements and theoretical calculation, it is clearly observed that the latent tracks induced by heavy ion irradiation can act as leakage paths, leading to a significant degradation of JR and VBR.
Temporal-spatial and energy dissipation characteristics of vortex evolutions in Francis turbine during load reduction
Authors: Sun Longgang , Liu Lei , Wang Zhaoning , Guo Pengcheng , Xu Zhuofei
Published: September 2024

This study numerically investigates the load reduction effects, on a model Francis turbine, combining cavitation model and structured dynamic grid technique. The results indicate that the vapor volume in the draft tube undergoes two rapid increases and decreases until cavitation ceases. The precessing vortex rope transitions from a strong helical structure to axial contraction as ellipticity increases, ultimately forming a discrete band before disappearing. Initially, vapor volume in the runner increases gradually and linearly, followed by continued growth with a consistent pulsation amplitude. The inter-blade vortex (IBV) first appears at the blade trailing edge and then develops into a complete structure extending from the runner crown to the blade trailing edge, driven by pulsating vapor volume growth. Axial force extracted by the runner changes significantly and correlates closely with variations in the vapor volume in the runner. Flow separation in the runner occurs near the runner crown, forming dual separation lines that enhance IBV formation, which highlights the significant influence of crown-proximal flow separation on IBV development. Regarding energy loss, initial decreases followed by increases are observed in both the draft tube and runner, with draft tube losses consistently exceeding 57.4% and runner losses exceeding 27.1%. Turbulent kinetic energy generation and Reynolds stress are the primary forms of energy dissipation, with high-value regions corresponding to vortex locations, underscoring the substantial role of vortices in energy dissipation. This study provides new insights into the evolution of vortices and energy dissipation characteristics during load reduction in Francis turbines.
Sterol–lipids enable large-scale, liquid–liquid phase separation in bilayer membranes of only two components
Authors: Wilson Kent J. , Nguyen Huy Q. , Gervay-Hague Jacquelyn , Keller Sarah L.
Published: September 2024

Despite longstanding excitement and progress toward understanding liquid–liquid phase separation in natural and artificial membranes, fundamental questions have persisted about which molecules are required for this phenomenon. Except in extraordinary circumstances, the smallest number of components that has produced large-scale, liquid–liquid phase separation in bilayers has stubbornly remained at three: a sterol, a phospholipid with ordered chains, and a phospholipid with disordered chains. This requirement of three components is puzzling because only two components are required for liquid–liquid phase separation in lipid monolayers, which resemble half of a bilayer. Inspired by reports that sterols interact closely with lipids with ordered chains, we tested whether phase separation would occur in bilayers in which a sterol and lipid were replaced by a single, joined sterol–lipid. By evaluating a panel of sterol–lipids, some of which are present in bacteria, we found a minimal bilayer of only two components (PChemsPC and diPhyPC) that robustly demixes into micron-scale, liquid phases. It suggests an additional role for sterol–lipids in nature, and it reveals a membrane in which tie-lines (and, therefore, the lipid composition of each phase) are straightforward to determine and will be consistent across multiple laboratories.
Effects of system-sanctioned framing on climate awareness and environmental action in the United States and beyond
Authors: Mason Katherine A. , Vlasceanu Madalina , Jost John T.
Published: September 2024

Despite growing scientific alarm about anthropogenic climate change, the world is not on track to solve the crisis. Inaction may be partially explained by skepticism about climate change and resistance to proenvironmental policies from people who are motivated to maintain the status quo (i.e., conservative-rightists). Therefore, practical interventions are needed. In the present research program, we tested an experimental manipulation derived from system justification theory in which proenvironmental initiatives were framed as patriotic and necessary to maintain the American “way of life.” In a large, nationally representative U.S. sample, we found that the system-sanctioned change intervention successfully increased liberal-leftists’ as well as conservative-rightists’ belief in climate change; support for proenvironmental policies; and willingness to share climate information on social media. Similar messages were effective in an aggregated analysis involving 63 countries, although the overall effect sizes were small. More granular exploratory analyses at the country level revealed that while the intervention was moderately successful in some countries (e.g., Brazil, France, Israel), it backfired in others (Germany, Belgium, Russia). Across the three outcome variables, the effects of the intervention were consistent and pronounced in the United States, in support of the hypothesis that system justification motivation can be harnessed on behalf of social change. Potential explanations for divergent country-level effects are discussed. The system-sanctioned change intervention holds considerable promise for policymakers and communicators seeking to increase climate awareness and action.
“Biden’s Saigon”
Authors: Pjesivac Ivanka , Imre Iveta , Klein Leslie , Petrov Ana
Published: September 2024

This study examined the Russian state-sponsored outlet “Sputnik’s” metaphorical use in covering American
withdrawal from Afghanistan to explain rhetorical devices used to disseminate discourse about Russia’s geo-political rival, the
United States. Using the Metaphor Identification Procedure (MIP), the study analyzed 28 main metaphors and metaphorical
expressions in “Sputnik’s” coverage during the week of the American pullout. Metaphors such as Biden’s Saigon, puppet
government, or Night of the Long Knives suggest the existence of a discourse criticizing the rival
and historicizing the event. The results are interpreted in light of using metaphors in the media’s conflict coverage.
Distribution of angular momenta ML and MS in non-relativistic configurations: statistical analysis using cumulants and Gram–Charlier series
Authors: Pain Jean-Christophe , Poirier Michel
Published: September 2024

The distributions

P
(

M
L

,

M
S

)

of the total magnetic quantum numbers ML
and MS
for N electrons of angular momentum

ℓ

, as well as the enumeration of LS spectroscopic terms and spectral lines, are crucial for the calculation of atomic structure and spectra, in particular for the modeling of emission or absorption properties of hot plasmas. However, no explicit formula for

P
(

M
L

,

M
S

)

is known yet. In the present work, we show that the generating function for the cumulants, which characterize the distribution, obeys a recurrence relation, similar to the Newton–Girard identities relating elementary symmetric polynomials to power sums. This enables us to provide an explicit formula for the generating function. We also analyze the possibility of representing the

P
(

M
L

,

M
S

)

distribution by a bi-variate Gram–Charlier series, which coefficients are obtained from the knowledge of the exact moments of

P
(

M
L

,

M
S

)

. It is shown that a simple approximation is obtained by truncating this series to the first few terms, though it is not convergent.
Intrinsic exchange bias from interfacial reconstruction in an epitaxial NixCoyFe3−x−yO4(111)/α-Al2O3(0001) thin film family
Authors: Yang Detian , Liu Yaohua , Xu Xiaoshan
Published: September 2024

Intrinsic exchange bias is known as the unidirectional exchange anisotropy that emerges in a nominally single-component ferro-(ferri-)magnetic system. In this work, with magnetic and structural characterizations, we demonstrate that intrinsic exchange bias is a general phenomenon in (Ni, Co, Fe)-based spinel oxide films deposited onα-Al2O3(0001) substrates, due to the emergence of a rock-salt interfacial layer consisting of antiferromagnetic CoO from interfacial reconstruction. We show that in NixCoyFe3−x−yO4(111)/α-Al2O3(0001) films, intrinsic exchange bias and interfacial reconstruction have consistent dependences on Co concentrationy, while the Ni and Fe concentration appears to be less important. This work establishes a family of intrinsic exchange bias materials with great tunability by stoichiometry and highlights the strategy of interface engineering in controlling material functionalities.
Reconstruction method of high-precision longwall mining floor curved surface model driven by data points fitting of equipment
Authors: Zheng Ziying , Xie Jiacheng , Fang Shukai , Wang Yichen , Wang Yirong , Wang Xuewen
Published: September 2024

High-precision coal seam model is the basis of intelligent mining. The longwall mining face floor model, which can provide data sources for the correction of the dynamic coal seam model, is difficult to measurement directly. To address this issue, this paper proposes a high-precision coal seam surface model reconstruction and correction method based on a large number of operating data points. Firstly, the coupling model of equipment and floor is obtained based on the coupling model of plane and surface. Subsequently, the plane data points of the equipment are corrected based on the coupling model of equipment and floor to obtain the floor reconstruction points. The Catmull–Clark surface subdivision method is then used to subdivide the plane formed by the equipment data points to obtain surface subdivision points. The floor model reconstructed using surface data points is validated and corrected using the physics engine in the Unity 3d platform. Finally, the verification of the reconstruction point selection method, the coupling principle between the equipment and the floor model, the reconstruction accuracy of the base plate and the correction principle were carried out based on the equipment and floor model in the laboratory. The experimental results show the feasibility of the floor reconstruction, verification and correction method, which can provide a new idea for the reconstruction of the floor of the longwall mining face and the correction of the dynamic coal seam.
SPRout-DBN: a cross domain bearing fault diagnosis method based on spatial pyramid pooling residual network-DBN
Authors: Lin Daxuan , Jiao Weidong , Dong Zhilin , Rehman Attiq Ur , Wang Wenjie , Jiang Yonghua , Sun Jianfeng
Published: September 2024

Effectively leveraging the spatial features of time series signals to improve the accuracy of bearing fault classification in neural networks presents a significant challenge. To address this issue of different operating conditions, a novel model termed spatial pyramid pooling residual network-deep belief network (SPRout-DBN) is proposed. First and foremost, the Gramian angular difference fields (GADF) are utilized to encode original vibration signals of bearings. Secondly, two-dimensional images transformed by GADF from original signals are input to a novel designed residual network with spatial pyramid pooling to extract fixed-size temporal fusion feature vectors. Finally, a deep belief network is employed for classification and cross-domain learning, enabling the identification of fault samples under varying operating conditions. The proposed method is validated by two sets of datasets from Case Western Reserve University and Jiangnan University, achieving accuracies of 99.81% and 99.0% under identical operating conditions, and 99.41% and 98.43% under different operating conditions with 40 samples. Comparative analysis indicates that the proposed SPRout-DBN remains more robust and effective compared with other methods such as K-nearest neighbors, support vector machines, LeNet-5, ResNet-18, domain adaptation networks, and domain-adversarial neural networks in diverse operating environments.
GSMS: a goaf scanning and modeling system for underground mines based on a quadruped robot
Authors: Xi Mengnan , Peng Pingan , Wang Liguan , Wang Jiaheng , Pan Jin
Published: September 2024

Underground mining creates goafs, impacting resource extraction and safety. To address the issues of low efficiency and high reliance on manual operations in traditional techniques, this paper proposes a goaf scanning and modeling system (GSMS) for underground mine based on a quadruped robot. This system performs three-dimensional modeling of goafs through two main modules: frontend mapping and backend optimization, and evaluates the modeling accuracy using a multi-dimensional precision evaluation module. To validate the effectiveness of this system, both simulation and field experiments were conducted. The experimental results indicate that the goaf models established using GSMS achieved a level of accuracy comparable to traditional methods: the volume error of the constructed goaf models compared to the reference models was less than 3%, and the average profile contour similarity exceeded 98%.
Role of growth temperature on microstructural and electronic properties of rapid thermally grown MoTe2 thin film for infrared detection
Authors: Gartia Anurag , Pradhan Diana , Sahoo Kiran K , Biswal Sameer R , Sabat Somesh , Kar Jyoti P
Published: September 2024

In the field of electronic and optoelectronic applications, two-dimensional materials are found to be promising candidates for futuristic devices. For the detection of infrared (IR) light, MoTe2 possesses an appropriate bandgap for which p-MoTe2/n-Si heterojunctions are well suited for photodetectors. In this study, a rapid thermal technique is used to grow MoTe2 thin films on silicon (Si) substrates. Molybdenum (Mo) thin films are deposited using a sputtering system on the Si substrate and tellurium (Te) film is deposited on the Mo film by a thermal evaporation technique. The substrates with Mo/Te thin films are kept in a face-to-face manner inside the rapid thermal-processing furnace. The growth is carried out at a base pressure of 2 torr with a flow of 160 sccm of argon gas at different temperatures ranging from 400 °C to 700 °C. The x-ray diffraction peaks appear around 2θ = 12.8°, 25.5°, 39.2°, and 53.2° corresponding to (002), (004), (006), and (008) orientation of a hexagonal 2H-MoTe2 structure. The characteristic Raman peaks of MoTe2, observed at ∼119 cm−1 and ∼172 cm−1, correspond to the in-plane E1g and out-of-plane A1g modes of MoTe2, whereas the prominent peaks of the in-plane E1
2g mode at ∼234 cm−1 and the out-of-plane B1
2g mode at ∼289 cm−1 are also observed. Root mean square (RMS) roughness is found to increase with increasing growth temperature. The bandgap of MoTe2 is calculated using a Tauc plot and is found to be 0.90 eV. Electrical characterizations are carried out using current–voltage and current–time measurement, where the maximum responsivity and detectivity are found to be 127.37 mA W−1 and 85.21 × 107 Jones for a growth temperature of 600 °C and an IR wavelength illumination of 1060 nm.
Reduced order modeling for real-time monitoring of structural displacements due to electromagnetic forces in large scale tokamaks
Authors: Lucchini F , Frescura A , Torchio R , Alotto P , Bettini P
Published: September 2024

The real-time monitoring of the structural displacement of the vacuum vessel of thermonuclear fusion devices caused by electromagnetic loads is of great interest. In this paper, model order reduction is applied to the integral equation methods and the finite elements method to develop electromagnetic and structural reduced order models (ROMs) compatible with real-time execution which allows for the real-time monitoring of strain and displacement in critical positions of Tokamaks machines. Low-rank compression techniques based on hierarchical matrices are applied to reduce the computational cost during the offline stage when the ROMs are constructed. Numerical results show the accuracy of the approach and demonstrate the compatibility with real-time execution in standard hardware.
A comprehensive study of gate-induced drain leakage current and electrical characteristics in nanosheet field-effect transistors due to variation in structural parameters and ambient temperature
Authors: Shubham  , Bhosle Shruti , Pandey Rajan Kumar
Published: September 2024

In this paper, two substrate optimization approaches for triple stacked nanosheet field-effect transistors (SNSHFETs), namely the optimization of buried oxide and the selective deposition of punch-through-stopper (PTS) substrate, have been examined, and simulations have been carried out using technology computer-aided software. A comprehensive study of the leakage current and key electrical characteristics (I
ON, V
T, subthreshold swing, drain-induced barrier lowering) has also been performed based on variations in temperature from 298 K to 450 K, sheet width, fin pitch, substrate width, and source/drain doping, as well as different substrates. When the ambient temperature of the SNSHFET is varied from 298 K to 450 K, the gate-induced drain leakage (GIDL) current increases and degrades the V
T and I
ON/I
OFF ratio. The GIDL current also increases with increased doping of the source and drain. The impact of ultra-thin body substrate in the SNSHFET is also studied for the reduction in GIDL current and optimization in the performance. It is observed that a reduction in the substrate width and the nanosheet width decreases the GIDL current, while variation in the inter-fin pitch has no significant impact on the GIDL current and other electrical characteristics. The band-to-band tunneling rate and electric field profiles are observed in the channel–drain and gate–substrate overlap regions to understand the physical insights of leakage current in the SNSHFET. This work also clarifies the dependency of the GIDL current on the gate and drain voltage supply, respectively. In addition, how the GIDL current responds to the variation in the source–drain doping and with different PTS doping has been explained. A 3 nm SNSHFET is designed and its electrical and GIDL characteristics are compared with those of novel devices such as the forksheet FET and complementary FET.