bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of freestream turbulence on boundary layer transition over a controlled-diffusion compressor blade
Authors: Katiyar S. , Sarkar S.
Published: June 2024

The influence of inlet freestream turbulence (FST) on the boundary layer transition over the suction surface of a controlled-diffusion compressor blade is demonstrated here by employing a well-resolved large-eddy simulation. Inherent to low Reynolds number conditions, a laminar separation bubble (LSB) forms on the suction surface, attributing to substantial flow diffusion. Inlet FST levels ranging from 1.5% to 7.6% are systematically varied, while maintaining a constant Reynolds number based on axial chord and inlet velocity at 2.1 × 105. Transition of the shear layer is initiated via Kelvin–Helmholtz instability with the amplification of selective frequencies until an inlet FST of 2.3%. Secondary instability emerges in the second half of the LSB, attributed to the amplification of perturbations in the braid region, ultimately leading to breakdown near the reattachment. At a moderate FST level of 4.2%, longitudinal streaks in the first half of the blade elongate downstream, causing the LSB to disappear, while the flow becomes inflectional at the mid-chord. Thus, the boundary layer transition in the second half of the blade is attributed to the high receptivity of the inflectional layer and breakdown of streaks, leading to an exponential growth of disturbances. Finally, at an inlet FST of 7.6%, the boundary layer appears pre-transitional in the first half of the blade, exhibiting significant turbulence levels. In the latter half, excitation occurs primarily through the breakdown of streaks, reflecting an algebraic growth of disturbances. Flow features and oscillations in the Nusselt number in this case suggest the outer mode of streak-induced instability.
Dimensionless dynamics: Multipeak and envelope solitons in perturbed nonlinear Schrödinger equation with Kerr law nonlinearity
Authors: Afsar H. , Peiwei G. , Alshamrani A. , Aldandani M. , Alam M. M. , Aljohani A. F.
Published: June 2024

In this work, the dimensionless form of the improved perturbed nonlinear Schrödinger equation with Kerr law of fiber nonlinearity is solved for distinct exact soliton solutions. We examined the multi-wave solitons and rational solitons of the governing equation using the logarithmic transformation and symbolic computation using an ansatz functions approach. Multi-wave solitons in fluid dynamics describe the situation in which a fluid flow shows several different regions (or peaks) of high concentration or intensity of a particular variable (e.g., velocity, pressure, or vorticity). Multi-wave solitons in turbulent flows might indicate the existence of several coherent structures, like eddies or vortices. These formations are areas of concentrated energy or vorticity in the turbulent flow. Understanding how these peaks interact and change is essential to comprehending the energy cascade and dissipation in turbulent systems. Furthermore, a sub-ordinary differential equation approach is used to create solutions for the Weierstrass elliptic function, periodic function, hyperbolic function, Chirped free, dark-bright (envelope solitons), and rational solitons, as well as the Jacobian elliptic function, periodic function, and rational solitons. Also, as the Jacobian elliptic function's' modulus m approaches values of 1 and 0, we find trigonometric function solutions, solitons-like solutions, and computed chirp free-solitons. Envelope solitons can arise in stratified fluids and spread over the interface between layers, such as layers in the ocean with varying densities. Their research aids in the management and prediction of wave events in artificial and natural fluid settings. In fluids, periodic solitons are persistent, confined wave structures that repeat on a regular basis, retaining their form and velocity over extended distances. These structures occur in a variety of settings, including internal waves in stratified fluids, shallow water waves, and even plasma physics.
The South American genus Cnemalobus (Coleoptera: Carabidae: Cnemalobini): phylogeny and biogeographic analysis with the description of four new species from extra-Andean Patagonian mountains
Authors: Griotti Mariana , Olave Melisa , Cornejo Paula , Miras Diego , Roig-Juñent Sergio
Published: June 2024

The carabid beetle Cnemalobus Guérin-Ménéville, 1838 inhabits high- and lowland grasslands of southern South America. The highest diversity is found in the Patagonian Steppe, where distribution patterns are associated with latitude and elevation. Northern Patagonia, a large volcanic region with a complex geoclimatic history, exhibits elevated grades of endemism. However, a great deal remains unknown regarding diversification and biogeographical patterns for most of the endemic groups. We describe new Cnemalobus species restricted to isolated volcanoes from these extra-Andean mountain systems. We assess the phylogenetic relationships by updating the phylogeny of the genus and conduct a Bayesian binary Markov chain-Monte Carlo (MCMC) analysis on the resulting phylogenetic tree to discuss the biogeographical distribution patterns. We also provide a taxonomic key to all currently known species of Cnemalobus from the Patagonian Steppe. Our phylogenetic analysis supports the monophyly of the new species Cnemalobus tromen sp. nov., Cnemalobus silviae sp. nov., Cnemalobus aucamahuida sp. nov. and Cnemalobus domuyo sp. nov. grouped with C. diamante and C. nevado, referred to as the ‘Extra-Andean’ mountain lineage. Biogeographical analysis recognises vicariant events as the most plausible explanation for the allopatric distributions of the new species. We hypothesise that these vicariant events could be related to climatic barriers that likely promoted speciation processes by generating geographical isolation in ancestral populations. Our findings contribute significantly to the biogeographical understanding of the Patagonian volcanic region, prompting new inquiries to unravel the speciation processes of the endemic biota in extra-Andean mountain systems. ZooBank: urn:lsid:zoobank.org:pub:6A7585E8-5006-45BC-A1A3-F874F18A6049
MDGAs perform activity-dependent synapse type-specific suppression via distinct extracellular mechanisms
Authors: Kim Seungjoon , Jang Gyubin , Kim Hyeonho , Lim Dongseok , Han Kyung Ah , Um Ji Won , Ko Jaewon
Published: June 2024

MDGA (MAM domain containing glycosylphosphatidylinositol anchor) family proteins were previously identified as synaptic suppressive factors. However, various genetic manipulations have yielded often irreconcilable results, precluding precise evaluation of MDGA functions. Here, we found that, in cultured hippocampal neurons, conditional deletion of MDGA1 and MDGA2 causes specific alterations in synapse numbers, basal synaptic transmission, and synaptic strength at GABAergic and glutamatergic synapses, respectively. Moreover, MDGA2 deletion enhanced both N-methyl-D-aspartate (NMDA) receptor- and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor-mediated postsynaptic responses. Strikingly, ablation of both MDGA1 and MDGA2 abolished the effect of deleting individual MDGAs that is abrogated by chronic blockade of synaptic activity. Molecular replacement experiments further showed that MDGA1 requires the meprin/A5 protein/PTPmu (MAM) domain, whereas MDGA2 acts via neuroligin-dependent and/or MAM domain-dependent pathways to regulate distinct postsynaptic properties. Together, our data demonstrate that MDGA paralogs act as unique negative regulators of activity-dependent postsynaptic organization at distinct synapse types, and cooperatively contribute to adjustment of excitation–inhibition balance.
Nonlinear design, analysis, and testing of a single-stage compliant orthogonal displacement amplifier with a single input force for microgrippers
Authors: Chen Weilin , Fan Zuyang , Lu Qinghua , Xu Yujie , Li Zhihang , Wei Huiling , Zhang Qinghua , Luo Lufeng
Published: June 2024

To achieve dexterous and stable micro/nanomanipulation, a large grasping stroke, compact design, and parallel grasping are required for microgrippers; thus, a single-stage compliant orthogonal displacement amplifier (CODA) with a single input force would be an ideal transmission mechanism. However, the existing small-deflection-based design schemes cannot adapt to large deflections or shearing effect, thereby affecting the orthogonal movement transformation accuracy. This study proposed, analyzed, and experimentally investigated a nonlinear design scheme for a single-stage CODA with a single input force. First, the nonlinear design principle is described qualitatively. By combining closed-form analytical modelling, finite element analysis, and numerical fitting, the nonlinear extent of a pre-set variable cross-sectional beam in the CODA is formulated. By utilizing the beam constraint model and small-deflection-based modelling, the nonlinear extent of the undetermined uniform straight beam in the CODA is derived. Based on the design principle and nonlinear models, a nonlinear design scheme is proposed quantitatively. Finite element simulations and experimental tests are conducted to verify the proposed scheme, and the limitations of our previous study are revealed.
MBE growth of Ge1−x
Sn
x
devices with intrinsic disorder
Authors: Holmes S N , Gul Y , Pullen I , Gough J , Thomas K J , Jia H , Tang M , Liu H , Pepper M
Published: June 2024

We discuss the electrical properties of molecular beam epitaxy (MBE) grown, modulation doped, Ge1−x
Sn
x
quantum well devices. A consequence of the epitaxial growth process is that electronic disorder is introduced even in modulation doped quantum well structures and electrical transport properties that are characteristic of a high level of disorder are apparent. MBE growth of this material also results in the surface segregation of elemental β-Sn in the way that has been observed utilizing other epitaxial growth methods. A thermally activated, p-type mobility is a clear feature of the electrical properties with generally temperature independent hole densities ∼1012 cm−2 from the measured Hall effect and coming from the modulation doping. We present a discussion of Hall effect measurements in this disordered regime. The percolation carrier density in MBE modulation doped GeSn is in the region of ∼1 × 1012 cm−2 although Hall measurements in this regime are difficult to quantify when the resistivity >(h/e
2). In this notation h is Planck’s constant and e is the unit of charge. Conductivities (σ) as low as ∼0.028 × (e
2/h) × square can be measured in the four-contact ac configuration and the temperature dependence indicates a mobility edge in these p-type devices below ∼2 × 1012 cm−2. At lower temperatures (<∼1 K) the presence of a Coulomb gap can be determined using dc transport, constant voltage measurements where small ac current excitation is not available experimentally. This two-contact configuration can determine σ down to ∼10−6 × (e
2/h), deep into the localization regime, revealing a hopping conductivity dominated system. We discuss the relevance of these electrical properties for MBE grown GeSn devices.
Molecular beam epitaxy and other large-scale methods for producing monolayer transition metal dichalcogenides
Authors: Maurtua Collin , Zide Joshua , Chakraborty Chitraleema
Published: June 2024

Transition metal dichalcogenide (TMD/TMDC) monolayers have gained considerable attention in recent years for their unique properties. Some of these properties include direct bandgap emission and strong mechanical and electronic properties. For these reasons, monolayer TMDs have been considered a promising material for next-generation quantum technologies and optoelectronic devices. However, for the field to make more gainful advancements and be implemented in devices, high-quality TMD monolayers need to be produced at a larger scale with high quality. In this article, some of the current means to produce larger-scale semiconducting monolayer TMDs will be reviewed. An emphasis will be given to the technique of molecular beam epitaxy (MBE) for two main reasons: (1) there is a growing body of research using this technique to grow TMD monolayers and (2) there is yet to be a body of work that has summarized the current research for MBE monolayer growth of TMDs.
Development and evaluation of an on-site calibration technique for energy meter reference standards
Authors: Haiba Ahmed S , Halawa Mamdouh
Published: June 2024

To address the challenges and time-consuming nature of the calibration process for electric energy meters, this paper proposes a method that involves calibrating energy reference devices directly at the customer’s site. This on-site calibration approach uses a traceable portable high accuracy reference standard. A software program is developed to simplify the process of taking readings and allow for efficient management of calibration data using a personal computer. In addition to the calibration itself, uncertainty budgets are estimated for both active and reactive electrical energy measurements. This provides a comprehensive understanding of the measurement uncertainties associated with the calibration process. Furthermore, the obtained results are validated using a conventional procedure and a normalized error tool to ensure the accuracy and validity of the proposed technique. Validation results indicate that the suggested method produces outcomes that are deemed satisfactory. Overall, this work offers a practical and reliable approach to on-site calibration, benefiting customers by saving time and effort while maintaining accurate measurement results.
A comprehensive study on temple clamping force for eyeglasses design: from measuring to modelling
Authors: Zhang Jie , Chen Junjian , Luximon Yan
Published: June 2024

A key factor in determining the comfort level of eyeglasses is the clamping force at the temple. However, how to accurately measure and estimate the clamping force remains under-explored. Hence, to address this gap, we proposed a novel temple clamping force measurement method with a digital tension meter and developed a mathematical model to calculate the clamping force of the temples based on eyeglasses parameters (including length, one-side displacement, and flexural rigidity of the temples). To validate our method, we collected the simulated and physical datasets of different eyeglasses and conducted a multiple regression analysis to calculate the model parameters. The experimental results demonstrated the accuracy and reliability of the proposed method. This model can guide us in customizing the parameters of the eyeglasses to produce comfortable clamping forces for the users. Our codes and data will be publicly available at: https://github.com/Easy-Shu/Eyeglasses_Force_Modelling.
Rolling bearing fault diagnosis based on correlated channel attention-optimized convolutional neural networks
Authors: Jing Zhu , Ou Li , Minghui Chen , Lili Xing
Published: June 2024

In the field of intelligent fault diagnosis, traditional convolutional neural network (CNN)-based models for rolling bearing fault diagnosis are effective in extracting signal features but fall short in identifying subtle fault features in noisy environments. To address this challenge, this paper introduces a correlated channel attention-optimized deep convolutional neural network (CAOCNN) for fault diagnosis. The main innovations of this study include: firstly, the expansion of the convolutional kernel width through dilated convolution and optimized network parameter settings, which broadens the receptive field for feature extraction and effectively suppresses high-frequency noise; secondly, the relevant channel attention mechanism was constructed., which not only considers the channel weights post-global average pooling but also analyzes the correlations between channel features and the global feature center, dynamically adjusting channel weights to enhance model focus on critical features; additionally, the use of the Nesterov momentum optimization algorithm to optimize network parameters, reducing oscillations and increasing efficiency during training. Experimental results demonstrate that the CAOCNN achieved accuracies of 99.71% and 100% on the Case Western Reserve University and Xi’an Jiaotong University rolling bearing datasets, respectively, improving by 2.91% and 7.6% over traditional CNN models. In noisy conditions, T-SNE visual analysis further confirmed the excellent robustness and feature classification capability of the CAOCNN. These achievements validate the effectiveness of the CAOCNN in diagnosing rolling bearing faults in complex noise environments, contributing valuable advancements to the technology of intelligent fault diagnosis.
Simulation of taper heating and variable pressing rate to improve extrusion performance for high-strength aluminum alloys
Authors: Danilin Vladimir N , Aleshchenko Alexander S , Danilin Andrei V , Koshmin Alexander N
Published: June 2024

The main process parameters of direct and indirect extrusion of aluminum alloys were studied using FE-modeling in this article. The subject of the study was the use of billets taper heating and variable pressing rate as compared to the standard extrusion conditions. Extrusion of AA2024 grade alloy and experimental Al-2%Cu-1.5%Mn-1%Mg-1%Zn alloy was considered. The flow stress-on-strain dependences within the 350 °C–450 °C range at strain rates of 0.1–10 s−1 were determined for the experimental alloy. Considering the time of billet transportation to the extrusion equipment, its optimum temperature gradient was determined to be 500 °C at the front end and 140 °C at the tail end. Direct extrusion of taper heated billets at the variable rate and elongation of 7 allowed increasing the process performance by 5.6 times (from 1.8 mm s−1 to an average of 10 mm s−1, in case uniformly heated billets are extruded at the constant rate). In case of pressing at high elongations (15 and 25), the performance increase was about 2 times. It was found that the use of taper heating, both in case of grade alloy and model alloy extrusion, in all the considered conditions, allows achieving a significant increase in performance. However, these results are considered to be most effective in case of direct extrusion at small elongation ratios.
Molecular dynamics insights on the self-interstitial diffusion in α-Beryllium
Authors: Wang Huiming , Jin Jianfeng , Wang Dongxin , Xu Demei , Guo Kaiqi , Yang Peijun , Qin Gaowu
Published: June 2024

Beryllium has some unique properties and plays a key role in many special applications. However, Beryllium (α-Be) is of close-packed hexagonal (HCP) crystal structure, which has a strong anisotropic feature and limits its applications. In this work, diffusion behaviors of the self-interstitial atom (SIA) in α-Be at the temperature of 300–1100 K are studied using molecular dynamics simulations. It is observed that the diffusion mechanisms are not only dominated by the SIA jumps among the BO and BS sites on the basal plane, but also by the jumps among the C and O sites along the c-axis, which strongly depend on temperature. Diffusion behaviors of SIA can be divided into two stages with the temperature of 300–800 K and 800–1100 K, respectively, in which diffusion coefficient component of the c-axis (D
c) is higher than that of the basal plane (D
b) at first and then becomes closer to the D
b after 800 K, in consistent with diffusion mechanisms. When the temperature rises from 300 K to 1100 K, the total diffusion coefficient of SIA (D
t) increases gradually from 0.34 × 10−4 cm2 s−1 to 1.13 × 10−4 cm2 s−1. With the temperature increasing from 300 K to 1100 K, the anisotropy factor (η = D
c
/D
b) of SIA diffusion drastically decreases from 1.76 to 1.01 in α-Be, while the η increases from 0.21 to 0.70 in α-Zr with the temperature from 500 K to 1100 K.
Symmetry-preserving quadratic Lindbladian and dissipation driven topological transitions in Gaussian states
Authors: Mao Liang , Yang Fan , Zhai Hui
Published: June 2024

The dynamical evolution of an open quantum system can be governed by the Lindblad equation of the density matrix. In this paper, we propose to characterize the density matrix topology by the topological invariant of its modular Hamiltonian. Since the topological classification of such Hamiltonians depends on their symmetry classes, a primary issue we address is determining the requirement for the Lindbladian operators, under which the modular Hamiltonian can preserve its symmetry class during the dynamical evolution. We solve this problem for the fermionic Gaussian state and for the modular Hamiltonian being a quadratic operator of a set of fermionic operators. When these conditions are satisfied, along with a nontrivial topological classification of the symmetry class of the modular Hamiltonian, a topological transition can occur as time evolves. We present two examples of dissipation-driven topological transitions where the modular Hamiltonian lies in the AIII class with U(1) symmetry and the DIII class without U(1) symmetry. By a finite size scaling, we show that this density matrix topology transition occurs at a finite time. We also present the physical signature of this transition.
Quantitative characterization of fatigue damage in plate structures based on FSOM
Authors: Zhang Chunbing , Liu Xiaofeng , Wei Daiping , Bo Lin
Published: June 2024

For the problem of fatigue damage detection and damage degree assessment of plate structures, a quantitative damage assessment method based on the fast self-organizing feature mapping (FSOM) algorithm is proposed in this paper. The damage detection problem is transformed into a binary classification problem by extracting multidimensional damage features of the Lamb wave signal in plate to be detected and selecting damage sensitive features. Then, the FSOM network is used to identify the health state of the plate to be inspected, and the damage index is obtained by fusing the damage sensitive features using FSOM to quantitatively evaluate the damage level of the plate to be inspected. Simulation and experimental results show this method has a good dynamic tracking capability for the fatigue damage evolution of aluminum and composite plates, and can achieve quantitative assessment of fatigue damage of plate structures.
Fast stiffness variation gripper with efficient adhesion control
Authors: Chen Wenqing , Sun Tianhui , Li Jingyang , Li Xiaosong , Li Lvzhou , Meng Yonggang , Tian Yu
Published: June 2024

The mushroom-shape gecko-inspired adhesive has been extensively studied and applied in a wide range of fields. However, current research primarily focuses on enhancing its adhesion properties, necessitating further exploration in strategies of detachment and adaptation, which significantly constrain its practical applications. In this study, a stiffness variable gripper with controllable adhesion and fast response is developed by integrating mushroom-shape adhesive with granular jamming technology. A theoretical model for the detachment of the gripper is established, indicating the effect of backing stiffness on adhesion performance, which is verified through contact area observations and adhesion experiments. The proposed modulation method demonstrates an impressive adhesion-to-detachment ratio of 92.8, with adhesion capacity of up to 41.023 N and detachment force of only 0.442 N. The switch time is remarkably fast at just 0.5 s. Additionally, the designed gripper, under pressure difference of 60 kPa, is able to stably grasp smooth objects with various shapes weighing over 2 kg, with a load-to-weight ratio of approximately 8, and a minimal power consumption of only 4.404 W. The work here presents a comprehensive understanding of adhesion modulation of fibrillar adhesive through granular jamming, and provides new insights into robust reversible adhesion design for related technologies.
Soft robotic fingers with sensorized pre-charged finger pulp
Authors: Zhu Zihui , Yang Yang , Yan Shaoyang , Wang Songyan , Xie Yuan , Fu Yili , Li Yunquan , Jiang Pei
Published: June 2024

Pneumatically driven soft actuators with sensors have been developing rapidly these years. They can perceive external stimulus and be applied to different scenarios. In this study, we present a novel soft robotic finger with sensorized finger pulp based on sealing a flexible fabric piezoresistive film called Velostat into a pre-charged air bag, which can perceive the contact force with an object based on changes in resistance value of the sensor. The soft sensor mimics human finger pulp and deforms passively according to the shape of objects during grasping, so that it can firmly contact with objects and as such improves the gripper’s grasping stability. Moreover, based on force feedback, the actuator can reduce or increase the input pressure to hold the object and control the contact force precisely. The sensor exhibits a sensitivity of up to 0.328 kPa−1 and can measure pressures ranging from 0 to over 10 kPa. The sensor’s measurement range and sensitivity can be pre-adjusted by regulating the pre-charged pressure during fabrication for different grasping tasks. The response/recovery time of the sensor is 80/60 ms on average. Experiments show that the finger with sensorized pulp can be applied for object softness and size detection, object transport minitoring as well as force control grasping. The proposed soft robotic finger has potential for applications in scenarios that require safe contact and closed-loop control.
Higher-order topological Dirac phase in Y3InC: a first-principles study
Authors: Sreeparvathy P C , Villaos Rovi Angelo B , Huang Zhi-Quan , Chuang Feng-Chuan
Published: June 2024

Higher-order topological insulators hosting intriguing topologically protected hinge or corner states are of significant research interest. However, materials that possess higher-order topological hinge states associated with gapless bulk Dirac phases still need to be explored. Using first-principles calculations with hybrid exchange functional, we explore the electronic structure and topological properties of Y3InC and a few of its sister compounds, totaling 16 bulk materials. A symmetry-protected triple point phase, with dominated d-t
2g
character, is observed in Y3InC without spin–orbit coupling (SOC). Interestingly, the SOC induces a twin Dirac node phase in the bulk Y3InC. Furthermore, the computed Z
4 topological invariant reveals the higher-order topological nature of investigated materials. To demonstrate the gapless hinge states, we conduct edge state calculations using a rod-shaped geometry of Y3InC. Remarkably, Y3InC is identified to host multi-Dirac nodes in the bulk and surface phases together with the higher-order hinge states. These results lay the groundwork for further experimental and theoretical investigations into cubic antiperovskite materials for higher-order topological phases.
Chirality-enabled topological phase transitions in parity-time symmetric systems
Authors: Cao Yong , Sheng Lijuan , Zhou Qiang , Wang Rong , Chen Zhenkuan , Ling Xiaohui
Published: June 2024

Photonic spin Hall effect (PSHE) in chiral PT-symmetric systems exhibits many exotic features, but the underlying physical mechanism has not been well elucidated. Here, through rigorous calculations based on full-wave theory, we reveal the physical mechanism of the exotic PSHE and identify a chirality-enabled topological phase transition. When circularly polarized light is incident on a chiral PT-symmetric system, the transmitted beam contains two components: a spin-flipped abnormal mode that acquires a geometric phase (exhibiting a vortex or a spin-Hall shift), and a spin-maintained normal mode that does not exhibit such a phase. If the phase difference between the cross-polarized Fresnel coefficients cannot be ignored, it results in a chirality-enabled phase and intensity distribution in the abnormal mode, which induces an exotic PSHE. Consequently, as the incident angle increases, a chirality-induced topological phase transition occurs, namely the transition from the vortex generation to the exotic PSHE. Finally, we confirm that the asymmetric and periodic PSHE in the chiral slab is also related to the phase difference between the cross-polarized Fresnel coefficients. These concepts and findings also provide an opportunity for unifying the phenomena of topological phase transitions in various spin-orbit photonic systems.
Forward bias annealing of proton radiation damage in NiO/Ga2O3rectifiers
Authors: Li Jian-Sian , Chiang Chao-Ching , Wan Hsiao-Hsuan , Rasel Md Abu Jafar , Haque Aman , Kim Jihyun , Ren Fan , Chernyak Leonid , Pearton S J
Published: June 2024

17 MeV proton irradiation at fluences from 3–7 × 1013cm−2of vertical geometry NiO/β-Ga2O3heterojunction rectifiers produced carrier removal rates in the range 120–150 cm−1in the drift region. The forward current density decreased by up to 2 orders of magnitude for the highest fluence, while the reverse leakage current increased by a factor of ∼20. Low-temperature annealing methods are of interest for mitigating radiation damage in such devices where thermal annealing is not feasible at the temperatures needed to remove defects. While thermal annealing has previously been shown to produce a limited recovery of the damage under these conditions, athermal annealing by minority carrier injection from NiO into the Ga2O3has not previously been attempted. Forward bias annealing produced an increase in forward current and a partial recovery of the proton-induced damage. Since the minority carrier diffusion length is 150–200 nm in proton irradiated Ga2O3, recombination-enhanced annealing of point defects cannot be the mechanism for this recovery, and we suggest that electron wind force annealing occurs.
High-efficiency ultra-thin GaAs solar cells based on ITO/Ag/ITO transparent electrodes and photonic crystals
Authors: Zhu Jun , Lin Sunlong , Tang Jian
Published: June 2024

Ultrathin photovoltaic technology has great potential to improve efficiency and reduce costs. However, achieving optical thickness requires an effective light capture strategy. In this study, for GaAs thin film solar cells with an active layer thickness of 500 nm, we adopt a combination strategy of front-end ITO/Ag/ITO transparent electrodes and back-end photonic crystals (PC). By employing the finite difference time domain (FDTD) simulation, we verify that ITO/Ag/ITO transparent electrodes and AlGaAs PC can effectively enhance the light-harvesting capacity of cells. The proposed cell structure has a spectral absorption rate (SAR) of 0.9781 in the visible wavelength range. To further optimize the photovoltaic performance parameters, we optimize the doping concentration of the pn junction in the cell. Finally, the short circuit current density

J

s
c

,

open circuit voltage

V

o
c

,

fill factor (FF) and photoelectric conversion efficiency (PCE) of GaAs thin film solar cells are successfully increased to

31.10

mA

cm

−
2

,

1.28

V
,

88.18% and 35.12%, respectively. This provides crucial experimental validation and theoretical guidance for advancing ultra-thin photovoltaic technology.
Interfacial charge and temperature analysis of gate-all-around line tunneling TFET for improved device reliability
Authors: Karthik Kadava R N , Pandey Chandan Kumar
Published: June 2024

In this article, the impact of interface-trap charges (ITCs) on the DC and analog/RF parameters of gate-all-around vertical TFET (GAA-VTFET) are considered to evaluate the reliability of the device. ITCs are included at oxide/semiconductor interface of GAA-VTFET where the probability of occurrence of traps are high owing to faults in the manufacturing process. A detailed investigation is carried out by tuning the temperature, polarities and density of ITCs. It is clearly observed from TCAD based simulation results that the presence of traps alters the flat-band voltage, thereby affecting the overall performance of the device. Transfer characteristics of the device depicts that impact of traps shows more variation in the OFF-state current than the ON-current. However, presence of donor traps improves the analog/RF parameter, such as parasitic capacitances (Cgg), Transconductance (gm), cut-off frequency (fT), output resistance (Rout) etc. Furthermore, the simulation results proclaim that GAA-VTFET shows more resilient to acceptor traps than the positive traps. Moreover, by examining the influence of ambient temperature on device performance, it is revealed that the drain current in the subthreshold region (at low gate bias) is more susceptible to the degradation than the super-threshold region at elevated temperature. This is mainly due to the superiority of the trap-assisted tunneling (TAT) and Shockley-Read-Hall (SRH) recombination mechanisms over the band-to-band tunneling (BTBT). When the raise in ambient temperature is tuned between minimum of 200 K to maximum of 400 K, it is observed that OFF-current increases by ∼7 times. Lastly, voltage-transfer characteristics (VTC) analysis of the resistive-load inverter clearly demonstrates that the influence of traps on the noise margin is within acceptable limits.
Development of a low-frequency broadband sound absorber based on a micro-perforated panel coupled with the Helmholtz resonator system
Authors: Li Qi , Wu Jinwu , Mao Qibo , Jv Xin , Chen Minghao
Published: June 2024

In the field of vibration and noise reduction, micro-perforated panel (MPP) structures and Helmholtz resonators (HR) play crucial roles as common sound-absorbing elements. However, independently applied MPP and HR structures cannot provide sufficiently wide absorption bandwidths at low frequencies. To achieve low-frequency broadband sound absorption, this study proposes a novel low-frequency broadband sound absorption structure (EMH) based on MPP and HR with a thickness of 40 mm to achieve a subwavelength, efficient, and compact design. We establish theoretical models of MPP and HR coupled systems, systematically analyze the sound absorption performance of same-element and different-element coupled structures, and employ the particle swarm optimization (PSO) algorithm to obtain structural parameters for efficient coupled sound absorption. Furthermore, we compare the sound absorption performance of three optimized coupled structures (MPP-coupled (SM), HR-coupled (SH), and MPP and HR-coupled) from the perspective of the theoretical calculation of the sound absorption coefficient and finite element analysis of the sound absorption mechanism. Finally, samples fabricated using 3D printing technology are tested in an impedance tube. The results demonstrate that efficient coupled sound absorption of MPP and HR can be achieved through parameter optimization. SH and SM exhibit nearly perfect sound absorption in the frequency ranges of 323–495 Hz and 615–1600 Hz, respectively, whereas the effective absorption bandwidth of EMH can reach 1225 Hz in the range of 200–1600 Hz. EMH shows superior low-frequency broadband sound absorption performance with a lightweight and simple structure, which holds the potential for application in low-frequency noise control.
Design and fabrication of a multi-purpose four arm electrothermal microgripper; a novel approach to control maximum gripping force limit
Authors: Barati Hamed , Barazandeh Farshad , Jabari Alireza , Akbari Mohammad , Golshani Vahid , Asgari Mohammad
Published: June 2024

The development of microgrippers requires accurate control of force and position for the grasping mechanisms in micromanipulation. This controllability ensures the safe transfer of sensitive micro-objects, such as living cells. The design of microgrippers is often limited by the dimensions and adaptability of the micro-objects being manipulated. Therefore, microgrippers should be customized for each micro-object. Additionally, complex sensor mechanisms are required to control the gripping force. This study introduces a novel design of a four-arm MEMS electrothermal microgripper intended for versatile micromanipulation purposes. The microgripper design procedure is compatible with a list of constraints, including biological and microfabrication constraints. The jaw form is designed to manipulate micro-objects with a wide range of dimensions (1 to 360 μm). Furthermore, a novel approach is presented here to control the force threshold of gripping without a sensor during manipulation. The proposed solution involves using structure stiffening to control the force and prevent damage to micro-objects. GA and analytical models (transient behaviour of structure) are used to satisfy the long list of constraints. The device is fabricated through UV-LIGA, utilizing nickel and copper as the structural and sacrificial layer. The experimental and simulation results demonstrate that the microgripper can achieve a 60 μm jaw displacement at a voltage of 0.329V. The gripping arms can provide a force of 15 to 450 μN for the handling of micro-objects. The maximum gripper temperature of 98 °C makes it suitable for biological applications. The innovative form and systematic design of the microgripper enable its adaptability for various applications.
Large valley splitting induced by spin-orbit coupling effects in monolayer Hf3N2O2
Authors: Qiao Shiqian , Zhang Yang , Lan Mengxian , Ji Zhiqiang , Song Shuhua , Qu Weichun , Wu Hong , Pu Yong , Li Feng
Published: June 2024

Valleytronics is an emerging field of electronics that aims to utilize valley degrees of freedom in materials for information processing and storage. Nowadays, the valley splitting of 2D materials is not particularly large, therefore, the search for large valley splitting materials is very important for the development of valleytronics. This work theoretically predicts that MXene Hf3N2O2 is a 2D material with large valley splitting. It is an indirect bandgap semiconductor with a bandgap of 0.32 eV at the PBE level and increases to 0.55 eV at the HSE06 level. Since Hf3N2O2 breaks the symmetry of spatial inversion, when we consider spin–orbit coupling (SOC), there is a valley splitting at K/K′ of the valence band with a valley splitting value of 98.76 meV. The valley splitting value slightly decreases to 88.96 meV at the HSE06 level. In addition, The phonon spectrum and elastic constants indicate that it is both dynamically and mechanically stable. According to the maximum localization of the Wannier function, it is obtained that the Berry curvature is not zero at K/K′. When a biaxial strain is applied, Hf3N2O2 transitions from metal to semiconductor. With increasing biaxial strain, the valley splitting value increased from 70.13 meV to 109.11 meV. Our research shows that Hf3N2O2 is a promising material for valleytronics.
Metasurface loaded dual port circularly polarized dielectric resonator antenna with reduced RADAR cross section and mutual coupling features
Authors: Tripathi Meenakshi , Sharma Anand , Kumar Vinay
Published: June 2024

The design of dual port radiator with a polarization diversity technique and reduced radar cross section (RCS) is described in this study. Cross slot is used to stimulate cylindrical ceramic for generating circular polarization features. Mirror orientation of aperture between port-1 and port-2 improves the isolation level by 25 dB. To suppress the antenna’s monostatic RCS, split ring resonator (SRR) based frequency selective surface is positioned between and around the dual ports. Experimental outcomes confirm the designed radiator operates from 4.11–5.24 GHz along with 3-dB axial ratio in between 4.15–4.92 GHz. The value of monostatic RCS is reduced by 15 dBsm in between the operating band. Broadsided radiation characteristics and good value of diversity parameter makes the designed radiator applicable for C-band Radar applications.
Deconfinement of runaway electrons by local vertical magnetic field perturbation
Authors: Dutta Someswar , Sharma Deepti , Tanna R.L. , Ghosh J. , Raju D.
Published: June 2024

Runaway electron (RE) deconfinement and subsequent suppression is of prime importance for successful long-term operation of any tokamak. In this work, to deconfine and mitigate REs, the efficacy of local vertical field (LVF) perturbation has been explored numerically. LVF perturbation-assisted RE loss studies are carried out by simulating the drift orbits of the REs in magnetostatic perturbed fields and estimating the resulting orbit losses for different initial energies and magnitudes of LVF perturbation. To this end, the pre-existing PARTICLE code has been extended to the relativistic full-orbit-following code PARTICLE-3D (P3D) integrated with the magnetic field calculation code EFFI and plasma equilibrium field calculation code IPREQ to include the required fields for studying particle dynamics in general; this is then used to numerically model LVF perturbation-assisted RE deconfinement experiments conducted in the ADITYA tokamak. Simulation results show a significant (∼90%) deconfinement of REs with the application of LVF perturbation of a suitable amplitude (∼0.1% of the total magnetic field) in a preferred direction. The existence of a threshold magnitude of the applied field is also established, which is observed to be dependent on the energy of the REs. The simulation results reproduce all the experimental observations and reveal other interesting features of RE mitigation using LVF perturbation. The temporal map of orbiting time of REs shows that REs originating from the inboard side edge region (

ψ

N > 0.5) of the plasma are relatively more prone to be lost with the application of suitable LVF perturbation than those originating from the plasma core. Interestingly, the simulation results demonstrate the existence of strong correlation between the safety factor (q) profile in the plasma edge region (

ψ

N > 0.7) and the level of RE deconfinement using LVF perturbation.
Combinatorial patchworking: Back from tropical geometry
Authors: Brugallé Erwan , López de Medrano Lucía , Rau Johannes
Published: June 2024

We show that, once translated to the dual setting of convex triangulations of lattice polytopes, results and methods from Arnal, Renaudineau, and Shaw [Ann. H. Lebesgue 4 (2021), pp. 1347–1387], Renaudineau and Shaw [Ann. Sci. Éc. Norm. Supér. (4) 56 (2023), pp. 945–980], Jell, Rau, and Shaw [Épijournal Géom. Algébrique 2 (2018), p. 27] and Reanaudineau, Rau, and Shaw [Real phase structures on tropical manifolds and patchworks in higher codimension, in preparation] extend to non-convex triangulations. So, while the translation of Viro’s patchworking method to the setting of tropical hypersurfaces has inspired several tremendous developments over the last two decades, we return to the original polytope setting in order to generalize and simplify some results regarding the topology of

T
T

-submanifolds of real toric varieties.
Higher integrability for measures satisfying a PDE constraint
Authors: Arroyo-Rabasa Adolfo , De Philippis Guido , Hirsch Jonas , Rindler Filip , Skorobogatova Anna
Published: June 2024

We establish higher integrability estimates for constant-coefficient systems of linear PDEs
\[

A

μ
=
σ
,

\mathcal {A} \mu = \sigma ,

\]
where

μ
∈

M

(
Ω
;
V
)

\mu \in \mathcal {M}(\Omega ;V)

and

σ
∈

M

(
Ω
;
W
)

\sigma \in \mathcal {M}(\Omega ;W)

are vector measures and the polar

d

μ

d

|

μ

|

\frac {\mathrm {d}\mu }{\mathrm {d}|\mu |}

is uniformly close to a convex cone of

V
V

intersecting the wave cone of

A

\mathcal {A}

only at the origin. More precisely, we prove local compensated compactness estimates of the form
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="double-vertical-bar mu double-vertical-bar Subscript normal upper L Sub Superscript p Subscript left-parenthesis normal upper Omega Sub Superscript prime Subscript right-parenthesis Baseline less-than-or-equivalent-to StartAbsoluteValue mu EndAbsoluteValue left-parenthesis normal upper Omega right-parenthesis plus StartAbsoluteValue sigma EndAbsoluteValue left-parenthesis normal upper Omega right-parenthesis comma normal upper Omega prime double-subset normal upper Omega period">

‖
μ

‖

L

p

(

Ω
′

)

≲

|

μ

|

(
Ω
)
+

|

σ

|

(
Ω
)
,

Ω
′

⋐
Ω
.

\|\mu \|_{\mathrm {L}^p(\Omega ’)} \lesssim |\mu |(\Omega ) + |\sigma |(\Omega ), \qquad \Omega ’ \Subset \Omega .

\]
Here, the exponent

p
p

belongs to the (optimal) range

1
≤
p
>
d

/

(
d
−
k
)

1 \leq p > d/(d-k)

,

d
d

is the dimension of

Ω
\Omega

, and

k
k

is the order of

A

\mathcal {A}

. We also obtain the limiting case

p
=
d

/

(
d
−
k
)

p = d/(d-k)

for canceling constant-rank operators. We consider applications to compensated compactness and applications to the theory of functions of bounded variation and bounded deformation.
Multidimensional backward stochastic differential equations with rough drifts
Authors: Liang Jiahao , Tang Shanjian
Published: June 2024

In this paper, we study a multidimensional backward stochastic differential equation (BSDE) with an additional rough drift (rough BSDE), and give the existence and uniqueness of the adapted solution, either when the terminal value and the geometric rough path are small, or when each component of the rough drift only depends on the corresponding component of the first unknown variable (but we drop the one-dimensional assumption of Diehl and Friz [Ann. Probab. 40 (2012), pp. 1715–1758]). We also introduce a new notion of the

p
p

-rough stochastic integral for

p
∈

[
2
,
3
)

p \in \left [2, 3\right )

, and then succeed in giving—through a fixed-point argument—a general existence and uniqueness result on a multidimensional rough BSDE with a general square-integrable terminal value, allowing the rough drift to be random and time-varying but having to be linear; furthermore, we connect it to a system of rough partial differential equations.
Non-periodic not everywhere dense trajectories in triangular billiards
Authors: Slipantschuk Julia , Bandtlow Oscar F. , Just Wolfram
Published: June 2024

Building on tools that have been successfully used in the study of rational billiards, such as induced maps and interval exchange transformations, we provide a construction of a one-parameter family of isosceles triangles exhibiting non-periodic trajectories that are not everywhere dense. This provides, by elementary means, a definitive negative answer to a long-standing open question on the density of non-periodic trajectories in triangular billiards.
Interaction of liquid crystals with a rigid body
Authors: Binz Tim , Brandt Felix , Hieber Matthias , Roy Arnab
Published: June 2024

This article investigates the interaction of nematic liquid crystals modeled by a simplified Ericksen-Leslie model with a rigid body. It is shown that this problem is locally strongly well-posed, and that it also admits a unique, global strong solution for initial data close to constant equilibria. The proof of the global strong solution relies on a new splitting method for the director in a mean value zero and average part.