bluuebunny/crossref_metadata_2025 huggingface dataset:
Microparticle sorting in microfluidic Taylor–Couette flows
Authors: Brockmann Philipp , Symanczyk Christoph , Dong Xulan , Kagathara Yashkumar , Corluka Lukas , Hussong Jeanette
Published: November 2024

In this experimental study, we demonstrate that settling polymethyl methacrylate (PMMA) microparticles with diameters ranging from 6 to 60 µm segregate into distinct bands according to their size when subjected to a rotating laminar annular gap flow with a diverging gap width in the axial direction. Different gap widths ranging from 130 to 1200 µm have been investigated in the fully laminar flow regime. Distinct, spatially separated particle bands of different particle sizes have been observed for nine different geometric configurations, including non-conical, conical, double conical, and variously inclined conical inner cylinder shapes. The study considers different rotation rates, geometric combinations, particle volume fractions, and particle size combinations. Particle size separation was achieved at volume fractions ranging from 2.2% to 11% for rotating inner cylinders. In contrast, no separation occurs during the experimental run when both the outer and inner cylinders are perfectly cylindrical, with no significant variation in the annular gap height. Our experiments also show that rotation of the inner cylinder results in more pronounced particle separation than rotation of the outer cylinder. Microscopic particle image velocimetry (µPIV) measurements show that the presence of particles induces an axial velocity component, which acts as a key transport mechanism. In addition, a significant variation in shear rate is observed across particle bands, which may explain size segregation by shear-induced migration. Furthermore, single particle simulations show that particle trajectories and velocities vary significantly with particle size.
Reproducing hydrodynamics and elastic objects: A hybrid mesh-free model framework for dynamic multi-phase flows
Authors: Palermo Eric T. , Wolf Ki T. , Clemmer Joel T. , O'Connor Thomas C.
Published: November 2024

Reproducing Hydrodynamics and Elastic Objects (RHEO) is a new meshfree modeling framework for simulating complex multi-phase flows of fluids and solids. RHEO is implemented within the open-source Large-Scale Atomic/Molecular Massively Parallel Simulator particle dynamics code and couples a reproducing kernel smoothed particle hydrodynamics scheme for modeling fluid flow and heat transfer with a bonded particle model for modeling breakable elastic bodies. The resulting scheme provides a robust framework for simulating multi-phase material systems with complex and evolving boundaries and interfaces. RHEO collects many advanced mesh-free modeling features into a centralized, modular, and easily extensible package, including heat transport, reversible melting and solidification, particle distribution regularization, and user adjustable kernel accuracy. We report comprehensive tests of RHEO's accuracy and convergence for common benchmark flows of bulk fluids, boundary driven flows, and complex fluid/solid systems. A series of multi-phase systems are highlighted, including a bouncing water balloon, the fracture and flow of a brittle egg, melting of a free-standing solid beam, and conductive cooling and solidification of an extruded polymer during 3D printing.
Reduced density matrix dynamics in multistate harmonic models via time-convolution and time-convolutionless quantum master equations with quantum-mechanical and semiclassical kernels
Authors: Sun Xiang , Liu Zengkui
Published: November 2024

In this work, we explore the electronic reduced density matrix (RDM) dynamics using time-convolution (TC) and time-convolutionless (TCL) quantum master equations (QMEs) that are based on perturbative electronic couplings within the framework of multistate harmonic (MSH) models. The MSH model Hamiltonian consistently incorporates the electronic–vibrational correlations between all pairs of states by satisfying the pairwise reorganization energies directly obtained from all-atom simulations, representing the globally heterogeneous environments that couple to the multiple states differently. We derive the exact quantum-mechanical and a hierarchy of semiclassical approximate expressions for the kernels in TC and TCL QMEs that project the full RDM for general shifted harmonic systems, including the MSH model. These QMEs are applied to simulate RDM dynamics of photoinduced charge transfer (PICT) in organic photovoltaic carotenoid–porphyrin–fullerene triad solvated in tetrahydrofuran solution and the excitation energy transfer (EET) dynamics in photosynthetic Fenna–Matthews–Olson complexes from C. tepidum and P. aestuarii. Our results show that while both TC and TCL QMEs capture similar phenomena in PICT and EET processes, TC QME generally provides more accurate results than TCL QME, particularly in the initial oscillation of EET population dynamics. This study highlights the effectiveness of the TC and TCL QMEs in modeling RDM dynamics of nonadiabatic processes, offering insights for realistic condensed phase systems.
Numerical investigation on hydraulic fracture propagation mechanism in fault-karst carbonate reservoir
Authors: Li Yue , Yan Xiaolun , Zheng Honglin , Pu Hongyuan , Xiao Cong , Zhang Shicheng , Mou Jianye
Published: November 2024

The fault-karst reservoir takes the fault-controlled fracture-cavity system as storage space, which is surrounded by a large number of high permeability zones. The distribution of reservoir seepage field has an important influence on fracture propagation behavior during the hydraulic fracturing process. Based on statistical damage mechanics theory and finite element method, this paper established a seepage-stress coupling numerical model of fracture propagation under the complex medium condition of matrix-cave-natural fracture in fault-karst carbonate reservoir. This new model innovatively considers the effects of matrix seepage, which is generally ignored by the traditional numerical models, for simulating the fluid–solid coupled fracture propagation behavior. The communication mechanism between fracture and cave is first revealed. The influence of geologic and engineering factors, e.g., permeability in high permeability zone around cave and injection rate etc., on hydraulic fracture propagation in fault-karst reservoir is studied. The results show that the high permeability zone around cave can provide sufficient infiltration capacity to communicate fracture with cave in the form of fluid pressure through fluid flow and fluid pressure conduction, even if hydraulic fracture does not directly communicate the cave. Hydraulic fracture is deflected to the direction of cave under the influence of seepage field, but the deflection angle is mostly within 10°. The high permeability of high permeability zone around cave and the short cave offset distance are conducive to the virtual communication between fracture and cave. Communicating fracture with cave in the non-principal stress direction can be accomplished by fluid flow and fluid pressure conduction, optimizing hydraulic fracturing treatment parameters should be performed by choosing lower injection rates and lower fracturing fluid viscosities. This study can provide key technical support and theoretical guidance for oil and gas development in fault-karst reservoir.
Non-stoichimometric square sheets in RSe2−x (x ∼ 1/6) (R = Gd and Tb)
Authors: Boswell Matt , Yang Yongqi , Mandal Manasi , Li Mingda , Xie Weiwei
Published: November 2024

The application of optimal electron count has proven effective in predicting the existence of complex structural topologies containing electron-rich polyanionic networks, including linear and zig-zag chains, square planar structures, and simple cubic lattices of main group elements. In this study, we report the successful synthesis of a new family of magnetic compounds, RSe2−x (x ∼ 1/6) (R = Gd and Tb), using KCl flux. The resulting crystal structure of RSe2−x is tetragonal, exhibiting PbFCl-type symmetry with space group P4/nmm. Chemical composition analysis consistently reveals x ∼ 1/6, indicating chalcogen-deficient square sheets. This observation suggests that RSe2−x adheres to the 14-electron rule, as the total valence electrons per RSe2−x (x ∼ 1/6) is 14 e−. In GdSe2−x (x ∼ 1/6), the magnetic susceptibility measurement displays a lambda-shaped peak around 8 K, indicating an antiferromagnetic-type transition. However, the positive Curie–Weiss temperature (θCW) suggests the presence of an additional ferromagnetic interaction, which may result from the large magnetic moment of the Gd atoms. In contrast, TbSe2−x (x ∼ 1/6) exhibits antiferromagnetic ordering. Chemical bonding analysis also indicates that the strong Se–Se antibonding in the square net may be related to Se deficiency. Our work shed light on ellucidating the interplay between chemical rule, defects, and magnetism.
Electronic properties of corundum-like Ir2O3 and Ir2O3-Ga2O3 alloys
Authors: Khalid Shoaib , Janotti Anderson
Published: November 2024

In the hexagonal, corundum-like structure, α-Ga2O3 has a bandgap of ∼ 5.1 eV, which, combined with its relatively small electron effective mass, high Baliga's figure of merit, and high breakdown field, makes it a promising candidate for power electronics. Ga2O3 is easy to dope n-type, but impossible to dope p-type, impeding the realization of some electronic device designs. Developing a lattice-matched p-type material that forms a high-quality heterojunction with n-type Ga2O3 would open new opportunities in electronics and perhaps optoelectronic devices. In this work, we studied Ir2O3 as a candidate for that purpose. Using hybrid density functional theory calculations we predict the electronic band structure of α-Ir2O3 and compare that to α-Ga2O3, and study the stability and electronic properties of α-(IrxGa1−x)2O3 alloys. We discuss the band offset between the two materials and compare it with recently available experimental data. We find that the Ir d bands that compose the top of the valence band in α-Ir2O3 are much higher in energy than O p bands in α-Ga2O3, possibly enabling effective p-type doping. Our results provide an insight into using the Ir2O3 or Ir2O3-Ga2O3 alloys as p-type material lattice-matched to α-Ga2O3 for the realization of p–n heterojunctions.
Toward aerodynamic surrogate modeling based on β-variational autoencoders
Authors: Francés-Belda Víctor , Solera-Rico Alberto , Nieto-Centenero Javier , Andrés Esther , Sanmiguel Vila Carlos , Castellanos Rodrigo
Published: November 2024

Surrogate models that combine dimensionality reduction and regression techniques are essential to reduce the need for costly high-fidelity computational fluid dynamics data. New approaches using β-variational autoencoder (β-VAE) architectures have shown promise in obtaining high-quality low-dimensional representations of high-dimensional flow data while enabling physical interpretation of their latent spaces. We propose a surrogate model based on latent space regression to predict pressure distributions on a transonic wing given the flight conditions: Mach number and angle of attack. The β-VAE model, enhanced with principal component analysis (PCA), maps high-dimensional data to a low-dimensional latent space, showing a direct correlation with flight conditions. Regularization through β requires careful tuning to improve overall performance, while PCA preprocessing helps to construct an effective latent space, improving autoencoder training and performance. Gaussian process regression is used to predict latent space variables from flight conditions, showing robust behavior independent of β, and the decoder reconstructs the high-dimensional pressure field data. This pipeline provides insight into unexplored flight conditions. Furthermore, a fine-tuning process of the decoder further refines the model, reducing the dependence on β and enhancing accuracy. Structured latent space, robust regression performance, and significant improvements in fine-tuning collectively create a highly accurate and efficient surrogate model. Our methodology demonstrates the effectiveness of β-VAEs for aerodynamic surrogate modeling, offering a rapid, cost-effective, and reliable alternative for aerodynamic data prediction.
Piezoelectric polymer generators: The large bending regime
Authors: Sarrey E. , Sigallon M. C. , Clochard M.-C. , Wegrowe J.-E. , Hamon A.-L.
Published: November 2024

There is an important difference between piezoelectric polymer films and solid crystals for the application of piezoelectric generators. In the case of polymers, the optimal piezoelectric response imposes a large bending regime. Starting from the linear Curie’s constitutive equations, we develop an analytical model under the assumption of the large bending regime resulting from bulge testing configuration. This model shows a specific non-linear piezoelectric response, which follows a power of 2/3 of the mechanical excitation. The piezoelectric voltage and the corresponding power are then studied experimentally as a function of the angular frequency ω of the mechanical excitation, the load resistance R, and the thickness of the film ℓ. The experimental results carried out on piezoelectric polyvinylidene fluoride (PVDF) films validate the model.
DC characteristics of a dynamic vision sensor's photoreceptor circuit evaluated for event-based sensing in the mid-wave infrared
Authors: Alsaad Z. M. , Logan J. V. , Morath C. P. , McMahon-Crabtree P. N. , Kulesza L. N. , Theis Z. , Maestas D. , Graca R. , McReynolds B. J. , Zarkesh-Ha P. , Webster P. T.
Published: November 2024

Forthcoming infrared event-based sensors will have utility in the space-based surveillance domain where they could potentially perform traditional sensing and tracking functions with significantly enhanced temporal resolution and reduced downstream datalink demands and power consumption. As a first step toward extending event-based sensing technology into the mid-wave infrared, a DC simulation of the conventional event-based sensor unit cell's photoreceptor circuit is performed, and the results are compared with measurements of a printed circuit board implementation of the same circuit to assess what design freedom is available to interface the photoreceptor with a mid-wave infrared photodetector. Detailed analysis of the circuit and measurements provides insight into which fundamental properties of the transistors drive the photoreceptor's dynamic range and demonstrates several characteristics that are relevant to mid-wave infrared sensing. These characteristics include the capability to produce a stable, low voltage bias on the infrared photodetector to maximize sensitivity, and that operating the circuit below room temperature increases the photoreceptor's dynamic range. Measurements show that even the simplest implementation of the photoreceptor circuit exhibits a dynamic range of logarithmic compression of 150 dB at room temperature. However, the dynamic range is ultimately limited by the mid-wave infrared photodetector's dark current activation energy, which is significantly lower than the threshold voltage (energy) of the photoreceptor's feedback transistor and, thus, there is an incentive for the photodetector's dark current to be diffusion-limited.
An ultralow-frequency high-efficiency rotational energy harvester with bistability principle and magnetic plucking mechanism
Authors: Rui Xiaobo , Li Hang , Zhang Yu , Sha Zhou , Feng Hao , Zeng Zhoumo
Published: November 2024

In this paper, we propose an energy harvester that overcomes the bottleneck problem under ultralow-frequency rotational motion. The harvester consists of bistable dual piezoelectric energy harvesters (BD-PEH) with the magnetic plucking mechanism. The driving magnet is introduced to provide the magnetic plucking to BD-PEH. Therefore, the BD-PEH can operate at high-frequency vibrations across the potential well under ultralow-frequency rotation, which enhances energy harvesting efficiency. A numerical model of the harvester is developed, and the model results are in agreement with the experimental results. The effect of the depth of the potential well on the performance of the harvester is analyzed. The deeper the potential well, the higher the energy output, but it will reduce the bandwidth of the harvester. The experimental results show that the highest average power output is 0.81 mW at 1.2 Hz. In conclusion, the energy harvester proposed in this paper can generate enough energy to drive low-power electronic devices under ultralow-frequency rotational motion.
Energy relaxation of N2O in gaseous, supercritical, and liquid xenon and SF6
Authors: Töpfer Kai , Erramilli Shyamsunder , Ziegler Lawrence D. , Meuwly Markus
Published: November 2024

Rotational and vibrational energy relaxation (RER and VER) of N2O embedded in xenon and SF6 environments ranging from the gas phase to the liquid, including the supercritical regime, is studied at a molecular level. Calibrated intermolecular interactions from high-level electronic structure calculations, validated against experiments for the pure solvents, were used to carry out classical molecular dynamics simulations corresponding to experimental state points for near-critical isotherms. The computed RER rates in low-density solvents of krotXe=(3.67±0.25)×1010 s−1 M−1 and krotSF6=(1.25±0.12)×1011 s−1 M−1 compare well with the rates determined by the analysis of two-dimensional infrared experiments. Simulations find that an isolated binary collision description is successful up to solvent concentrations of ∼4 M. For higher densities, including the supercritical regime, the simulations do not correctly describe RER, probably due to the neglect of solvent–solute coupling in the analysis of the rotational motion. For VER, the near-quantitative agreement between simulations and pump–probe experiments captures the solvent density-dependent trends.
Machine learning algorithms for optimization of magnetocaloric effect in all-d-metal Heusler alloys
Authors: Baigutlin D. R. , Sokolovskiy V. V. , Buchelnikov V. D. , Taskaev S. V.
Published: November 2024

This study examines the application of machine learning algorithms, specifically the Random Forest regression model, to optimize the magnetocaloric effect in all-d-metal Heusler alloys. The model was trained using descriptors related to the mean properties of individual atoms, the properties of simple compounds in their ground state, and measures of chemical disorder. It demonstrated high accuracy in predicting structural properties, while exhibiting moderate accuracy in predicting magnetic properties. To identify optimal alloy compositions, a genetic algorithm was used to find those with the greatest differences in magnetization during martensitic transitions. Using this combined approach, the Ni–Co–Mn–Ti alloy system was thoroughly explored, resulting in the discovery of an alloy with a maximum magnetization difference. These results are consistent with previous research based on density functional theory and highlight the effectiveness of integrating machine learning with genetic algorithms for the discovery of new materials with outstanding magnetocaloric properties. The study emphasizes the need for further refinement of models capable of accurately predicting complex magnetic interactions, which is essential for fully leveraging the potential of all-d-metal Heusler alloys in practical applications.
Ultrafast dynamics of two-dimensional electron gas at Al2O3/SrTiO3 interface studied by surface terahertz spectroscopy
Authors: Ma Junying , Wang Yuhan , Su Yudan , Tian Chuanshan
Published: November 2024

Two-dimensional electron gas (2DEG) confined at the interface of SrTiO3-based heterostructure exhibits intriguing electronic and optoelectronic properties. In this work, we study the ultrafast dynamics of 2DEG at the Al2O3/SrTiO3 interface using surface-specific terahertz difference-frequency spectroscopy. Through proper polarization selection, we have resolved simultaneously the evolution of 2DEG confined in the quantum well and the surface potential after optical pump with different photon energies. The hot electrons excited from 2DEG with pump photon energy below the band gap relax to the ground state through two processes, a fast interfacial process associated with electron–electron and electron–phonon scattering on the order of tens of picoseconds and a slow surface-to-bulk transport on the order of hundreds of picoseconds. When the pump photon energy exceeds the bandgap, electrons are directly injected from the valence band to 2DEG at the interface and relax via electron–hole recombination in 3 ps. The recorded dynamic change of interfacial potential provides the key information to identify the drift and diffusion of photocarriers at the interface. Our results broaden the horizon of investigation on the comprehension of complex oxide interfaces and their photonics capabilities.
The unappreciated centrality of ethnoracially mixed Americans to the nation’s demographic future
Authors: Alba Richard
Published: November 2024

The ethnoracial future of the United States has been framed as a demographic binary: Whites vs. people of color. The argument here is that this binary distorts by failing to take into adequate account the rapidly growing group of Americans who have been raised in mixed minority and White families, the great majority of the total mixed population. The members of this group generally have distinctive social characteristics: socioeconomic advantages compared to minorities and social integration into milieus with many Whites, as revealed by relatively high rates of marriage to them. However, their identities often encompass their minority heritage. Accordingly, they straddle the society’s major ethnoracial fracture line, creating an in-between social space and connecting, through kinship and other close social relations, both of its sides. However, their numbers are distorted in public national population data, such as census data and population projections; and they are typically counted as part of the non-White population. The recently announced revision of the race/ethnic data standards for the census offers an opportunity to refashion public data in a way that illuminates the important role this mixed group is likely to play in the nation’s demographic future.
Clubroot Disease (
Plasmodiophora brassicae
) as a Threat to Worldwide Rapeseed or Canola
(Brassica napus)
Authors: Ludwig-Müller Jutta
Published: November 2024

The clubroot disease is a devastating threat to Brassica crops throughout many parts of the world. Recently, it has become more prevalent in several European countries, particularly in rapeseed (canola,
Brassica napus
). The disease is difficult to control and only a few chemical treatments are available. The majority of control approaches focus on hygiene, crop rotation and in particular resistant cultivars. However, such resistance often relies on single genes and is rarely employed in Europe. Other possibilities include the exploitation of biocontrol agents, which have not yet proven effective in combating this disease. Rapeseed is not the only crop susceptible to the soilborne protist
Plasmodiophora brassicae
(Kingdom Chromista), but it may account for a large proportion of the commercial cash crops. Since the protist cannot be cultivated outside of its host, research relies on either investigating interactions with the host or using heterologous expression systems, which will not be discussed here. In this case study, a worldwide perspective on infested rapeseed plants that pose a threat to clubroot dissemination is presented. The complex life cycle is discussed, as well as possible control strategies such as breeding or interactions with beneficial microbes.

Information

© The Author 2024
Novelty detection for long-term diagnostic data with Gaussian and non-Gaussian disturbances using a support vector machine
Authors: Moosavi Forough , Shiri Hamid , Vashishtha Govind , Chauhan Sumika , Wylomanska Agnieszka , Zimroz Radoslaw
Published: November 2024

In condition monitoring lack of properly balanced data sets with faulty and healthy cases makes proper condition recognition very challenging. In many cases, one may have good condition data only as the machine is unique and there is no other example. This issue is addressed by proposing a support vector machine for novelty detection applied to health index data. In this scheme, the moving window approach has been utilized in which the simple statistical parameterization of the data is carried out. Then the model in the multidimensional (mD) space is constructed whose shape is defined by an estimated hypersphere border. If the data lies inside the border then it can be used to re-train the model. Whereas if it is outside the border then it cannot be recognized as a healthy case. The size of the mD hypersphere (for m = 2) describes the location of the good-condition data cloud as a potential feature. If the size of the data cloud is growing, it means more dispersion of the data. The efficiency of the method is tested on simulated and well-known real data sets having Gaussian and non-Gaussian disturbances.
Scale-adaptive salience supervision and dynamic token filtering for small object detection in remote sensing images
Authors: Zhang Qian , Yi Shimeng , Shao Mingwen , Liang Hong
Published: November 2024

Recently, DETR-like detectors, which have shown remarkable performance in general object detection, face limitations when dealing with remote sensing images primarily containing small objects. Mainstream two-stage DETR-like models employ a pipeline that selects and processes a small portion of informative tokens, which enhances performance but also shows a high dependency on token selection. The current static token selection strategies lead to inconsistencies between the static selection criteria and dynamic token updates. Additionally, in remote sensing images, the limited information available for small objects and their inherent sensitivity to pixel shifts further degrade detection performance. To address this, we propose Scale-Adaptive Salience DETR (SAS DETR), a two-stage DETR-like method. SAS DETR incorporates dynamic token filtering, which uses a global threshold predictor to determine the token filtering ratio for each layer of the encoder. This approach selects an appropriate filtering ratio for different network layers while maintaining consistency between the foreground confidence map and token updates. Furthermore, we introduce a novel scale-adaptive salience supervision mechanism that adaptively scales the salience computation area based on object size, ensuring the model more effectively supervises small objects and utilizes the information within tokens without compromising the detection performance for objects of other sizes. Finally, we employ Scale-adaptive Intersection over Union to reduce the impact of pixel shifts on small objects. With these improvements, our proposed SAS DETR achieves 25.2% AP on the AI-TOD-V2 dataset with 24 training epochs and 50.4% AP on the COCO 2017 dataset with 12 training epochs.
Design and analysis of terrestrial laser scanner based on a 3-SPR parallel mechanism for improved anti-occlusion scanning
Authors: Chang Yizhe , Xu He , Zhou Jiaqiang , Ma Zhen , Nie Peng , Aziz Zohaib
Published: November 2024

Laser scanner technology swiftly captures point cloud data of objects and their surrounding environments, proving extensive applications across various sectors. However, it often encounters challenges related to incomplete point clouds due to occlusion from stationary objects. This paper presents a terrestrial laser scanning system based on a 3-SPR (3-Spherical Joint-Active Prismatic Joint-Rotating Joint) parallel mechanism (TLS-PM), specifically designed to enhance scanning coverage during single-station measurements, reduce positioning and workload during multi-station measurements, and mitigate point cloud gaps caused by occlusions. Initially, a simulation model of the TLS-PM was developed, and both forward and inverse kinematic analysis were performed. Subsequently, the workspace was computed for different spherical joints using this model. An introduction to the TLS-PM’s error and the registration algorithm employed was then provided. Finally, through comparative analysis of simulations and experimental results, the device’s measurement accuracy and its capability to resist occlusions were validated. Additionally, the TLS-PM’s anti-occlusion performance was evaluated under various scenarios in a simulated setting. The experimental results demonstrate that, when employing the same conventional point cloud processing algorithms, the TLS-PM significantly improves the background scanning coverage.
Application of the AVMD-AIMCKD method to the enhancement of rolling bearing fault features
Authors: Wang Chenxu , Bao Huaiqian , Zhang Zongzhen , Han Baokun , Wang Jinrui
Published: November 2024

Rolling bearings are prone to failure due to harsh working environments, which can affect production efficiency. Given the background environmental noise interference, it is difficult to extract the fault characteristics of rolling bearings in the early stages of weak fault signals. Based on adaptive VMD combined with adaptive IMCKD (AVMD-AIMCKD), a rolling bearing fault diagnosis method is proposed in this paper. The vibration signal from the rolling element bearing is processed by adaptive variational modal decomposition (AVMD) to extract and select the time-frequency domain signal characteristics. The adaptive improved maximum correlated kurtosis deconvolution (AIMCKD) algorithm is used for noise reduction optimization to obtain the best extraction results. Because the traditional method requires input parameter values for variable mode decomposition (VMD) and improved maximum correlated kurtosis deconvolution (IMCKD), it is not adaptive. The particle swarm optimization algorithm is utilized in this study to optimize two variables: the penalty factor and decomposition mode number of VMD. The filter length and shift order of the IMCKD are optimized to make it adaptive. The viability of the method is substantiated through simulations, and the efficacy and precision are validated by comparative studies. The experimental results show that the AVMD-AIMCKD method has high accuracy and robustness in rolling bearing fault diagnosis and provides an accurate reference for rolling bearing health monitoring in engineering practice. The AVMD-AIMCKD method effectively extracts the early fault features through adaptive optimization, overcomes the restrictions of traditional methods, and provides a more accurate and reliable tool for bearing fault signal diagnosis.
DESENet: a bilateral network with detail-enhanced semantic encoder for real-time semantic segmentation
Authors: Tang Qingsong , Min Shitong , Shi Xiaomeng , Zhang Qi , Liu Yang
Published: November 2024

Real-time semantic segmentation is widely used in various domains such as autonomous driving and medical imaging. Most real-time semantic segmentation networks adopt an encoder–decoder structure. During encoding, feature maps undergo multiple downsampling stages to enhance computational efficiency and enlarge the receptive field. However, this process may lead to the loss of detailed information, which may not be fully recovered during upsampling. Moreover, upsampling semantic features may cause blurring and deviations due to the lack of spatial detail information. To mitigate these issues, we use spatially guided cross-resolution self-attention to improve the upsampling of the semantic features by supplementing detailed information from the spatial branch. Furthermore, we incorporate an inductive bias into the cross-resolution attention mechanism to enhance its ability to learn generalized features. Additionally, we design a semantic feature extraction block, and a spatial feature extraction branch to construct a lightweight backbone. The results on Cityscapes and CamVid show that the proposed model achieves a good balance between accuracy and parameter size. Specifically, it obtains 74.2% and 71.5% mIoU on the two test datasets with 1.31 M parameters, respectively. Code is available on https://github.com/clearwater753/DECENet.
An explicitly magnetic modified embedded atom method formalism for coupled spin dynamics and molecular dynamics
Authors: Dickel D , Baskes M I
Published: November 2024

In this paper, we augment the modified embedded atom method formalism to include magnetic spin–spin interactions for elements with a persistent magnetic moment. While previous spin coupling methods have been based on pair potentials, our Magnetic MEAM formalism, which we term MagMEAM, incorporates the many-body and angular effects of MEAM allowing for the strength of the magnetic interaction to vary with atomic environment. In particular, this allows potentials using this formalism to differentiate the magnetic interaction of different stable phases of magnetic elements such as the ferritic and austenitic phases of iron. This, in turn, allows for a more robust and realistic description of magnetism in polymorphic materials than was previously possible. The motivation for MagMEAM, including the insufficiency of magnetic pair potentials, is presented and the structure of the formalism is developed. A sample iron potential is developed using this formalism and shown to exceed the capabilities of existing magnetic pair potentials by simultaneously reproducing the magnetic energy of both martensite and austenite as well as the dynamic mechanical and magnetic properties of martensite. This newly designed formalism will allow for deeper explorations in the the complex interaction between different phases of polymorphic magnetic materials at the molecular dynamics scale.
Feedback switching control of a walking piezoelectric actuator for trajectory tracking
Authors: Ruan Zhiwei , Li Qin , Guo Liang , Ding Chenyang
Published: November 2024

This paper proposes a feedback switching control (FSC) scheme for a walking piezoelectric actuator (WPA) to track a time-varying trajectory. A WPA has two feet with each foot integrated with a clamp and shear piezoelectric stack actuators (PSAs). The first foot pushes the stage translator a step forward when clamped while the second foot is reset and retracted; subsequently, ‘foot switching’ occurs; as a result, the second foot is clamped to push the translator to make a next step forward and the first foot is reset and retracted. To make sure that the translator is always controlled in closed-loop no matter which foot is clamped, the FSC scheme is proposed. It consists of a clamping waveform generator which converts the trajectory into control signals for the clamp PSAs of the two feet and a feedback controller which provides control signals for the two shear PSAs of the feet. Experimental results show that the proposed control scheme achieves a tracking error of 0.028 µm for a constant velocity trajectory, which is a 75% reduction compared to the 0.113 µm of waveform-based control with iterative learning control compensation in literature.
New analytical wave structures for generalized B-type Kadomtsev–Petviashvili equation by improved modified extended tanh function method
Authors: Ghayad Mohammed S , Ahmed Hamdy M , Badra Niveen M , Rezazadeh Hadi , Hosseinzadeh Mohammad Ali , Rabie Wafaa B
Published: November 2024

Recently, solving the complicated nonlinear partial differential equations has become very important demand in order to simulate their physical phenomena. This manuscript focuses on extracting the wave solutions of (3 + 1)-dimensional generalized B-type Kadomtsev-Petviashvili equation (GBKPE), which demonstrates the behavior of nonlinear waves in fluid mechanics. The improved modified extended Tanh function (IMETF) method is the suggested method to do this task as it gives different types of solutions. This method enables us to obtain many solutions, such as Jacobi elliptic, dark soliton, and singular soliton, exponential, and singular periodic wave solutions. Additionally, for more illustrations graphical visual representations of some solutions are provided.
Numerical investigation on the polarization-dependent light extraction of 275-nm AlGaN based nanowire with bowtie antenna array or passivation layer
Authors: Nie Kui-Ying , Fang Ming , Hu Zonghua , Ren Fang-Fang
Published: November 2024

The low light extraction efficiency (LEE) is one of the major factors hindering the application of AlGaN based deep ultraviolet (DUV) light-emitting diodes (LEDs). Here we investigate the LEE of AlGaN based nanowire (NW) DUV LEDs emitting at 275 nm for bare NW, NW integrated with aluminum (Al) bowtie antenna array, and NW with passivation layer under transverse-electric (TE) and transverse-magnetic (TM) polarization. It is observed that by integrating plasmonic Al bowtie antenna array with AlGaN based NW, the LEE up to 83% and 74% can be achieved under TE and TM polarization. In addition, the effect of the three different passivation layer SiO2, SiNx and AlN on the LEE of AlGaN based NW is also analysed, the results suggests that SiO2, which has smaller refractive index than NW core, could extract more photons from the NW and lead to large enhancement of LEE. For SiNx and AlN passivation layer, which has refractive index similar to the NW core, have strong coupling with the NW core, when the thickness of passivation layer satisfy resonance coupling conditions, the LEE could be achieved more than 80% for both TE and TM polarization. These integrated NW/antenna array and NW with passivation layer system can provide guidelines for designing other nano-photonic devices.
Styrene-Butadiene-Styrene polymer modified bitumen: A review on compatibility and physico-chemical properties
Authors: Bansal Shubham , Gupta Vivek , Chopra Tanuj , Mehta Rajeev
Published: November 2024

The triblock elastomeric copolymer Styrene-Butadiene-Styrene (SBS) improves the engineering properties of bitumen and the performance parameters of flexible pavements. Although research investigations have been conducted worldwide, the literature lacks a comprehensive review to provide the up-to-date research status in this field. The current review summarizes the research findings on the compatibility, stability, physical properties, microscopic characterization, and chemical characterization of SBS modified bitumen. Quantitative analysis of physical test results concerning major pavement distresses shows improvement, particularly in high-temperature zones. The interlocked state of phase transition can be achieved at SBS content between 5%–6% and the optimum SBS content has been reported to lie within this range. The blending temperature of SBS modified bitumen varies between 140 °C–210 °C out of which 180 °C is the most frequently used by researchers. In addition, physical and chemical characteristics of aged binder have been reviewed. Aging indices (residual penetration ratio, change in softening point, viscosity aging ratio, residual ductility ratio) didn’t show any consistent trend, which establishes the need of exploring the co-additives to substantially improve the aging deterioration. Preliminary research on nano-additives showed the improved storage stability at high temperature and the performance of aged modified bitumen. This review has drawn essential conclusions and highlights existing research gaps for peer researchers and field engineers.
Silver antimony sulfide thin films and its selenization on stainless steel substrates by chemical bath deposition
Authors: Capistrán-Martínez Jesús , Romano-Trujillo R , Gracia-Jiménez J M , Coyopol A , Silva-González N R , García G , Galeazzi R , Nieto-Caballero F G , Rosendo E , Morales C
Published: November 2024

In this study, 304 stainless steel (SS304) substrates were used for the first time for the deposition of cubic silver antimony sulfide selenide (AgSb(S, Se)2) films. The AgSbS2 films were deposited using chemical bath deposition (CBD) followed by a one-step selenization process. Amorphous AgSbS2 films were produced through two sequential chemical depositions carried out over 4 h at 2 °C. The transformation from the amorphous state to cubic AgSb(S, Se)2 was achieved via selenization under ambient air conditions. Grazing incidence x-ray diffraction (GIXRD) confirmed the formation of cubic AgSbS1.7Se0.3 and AgSbS1.5Se0.5 solid solutions, with a calculated crystal size of approximately 9 nm. Raman spectroscopy revealed the amorphous nature of the as-deposited AgSbS2 films, with an asymmetric band observed at 331 cm−1, while polycrystalline AgSb(S, Se)2 films exhibited vibrational modes at 147, 190, 205, 253, 270, 324, and 493 cm−1. Scanning electron microscopy (SEM) analysis indicated a transformation of the granular morphology of AgSbS2 films into a smoother surface upon selenization. Energy dispersive spectroscopy (EDS) detected selenium incorporation up to 11.4 atomic percent (at%) in the AgSbS1.5Se0.5 film. The optical band gap (E

g
) was modulated from 1.71 eV to 1.47 eV, depending on the selenium content introduced through selenization. The C/SS304/AgSb(S, Se)2/C structure fabricated on stainless steel substrates exhibited ohmic contact, suggesting its potential for application in flexible solar cells.
Initial-offset and amplitude control of multi-scroll attractor in a chaotic jerk system
Authors: Jin Zihan , Wang Ning , Zhang Guoshan
Published: November 2024

With the gradual deepening of research on chaos, in order to flexibly apply chaos, offset boosting and amplitude control have become a hot topic. However, few people have studied chaotic systems with multi-scroll attractor under initial conditions. This paper constructs and analyzes a simple four-dimensional chaotic system. Unlike other extension methods that modify the original seed system, this method does not make any changes to the original seed system, only adds a new variable in the extension dimension. It is found that the proposed system can achieve offset boosting and amplitude control by changing the initial values, and the system has characteristics such as multi-scroll attractors, infinite equilibrium points, symmetry, and so on. Finally, FPGA hardware implementation was carried out to verify the numerical results.
Normalization of hot deformation parameters for activation energy analysis in metallic alloys
Authors: Ahmedabadi Parag M
Published: November 2024

Depending on the melting point of a given alloy, the temperature range for hot deformation of alloys varies widely. Consequently, the apparent activation energy of hot deformation, Q, is greatly influenced by the temperature range as well as the strain rate applied during hot deformation. The purpose of this investigation is to normalize hot deformation parameters—temperature and strain rate—to study their effects on activation energy. Seventy published hot-deformation datasets were used to investigate the effects of normalized hot-deformation variables on Arrhenius-type constitutive model parameters. Flow stress, strain rate, and temperature from sample datasets were normalized to the range [0, 1] and fitted with an Arrhenius-type model. The results showed that, for normalized parameters, the activation energy has exponential relationships with the partial derivative of flow stress with respect to strain rate and temperature.
Broadband polarization-insensitive terahertz absorber based on Ta2O5 snowflake-like structure
Authors: Ji Shijun , Qin Mingfei , Dai Handa , Li Jingjin
Published: November 2024

In this paper, an ultra-broadband tantalum pentoxide (Ta2O5) all-dielectric metamaterial absorber is proposed from the far-infrared to the terahertz range, which exhibits polarization-insensitive and wide-angle characteristics. The absorber consistently demonstrates an impressive absorption rate exceeding 90% within the frequency range from 1.1 THz to 20 THz. Such an absorber can have a bandwidth and relative bandwidth ratio of 18.9 THz and 179.15%. We employ an equivalent circuit model to simulate the performance of the absorber using transmission line theory, which facilitates near-perfect absorption by finely tuning the geometrical parameters of the structure to match the input impedance with that of free space. Detailed calculations and analyses of the electric and magnetic field distributions, as well as power loss density, are presented to clarifying the underlying mechanisms of absorption. The design of the proposed absorber inherently provides insensitivity to polarization angles and sustains superior absorption efficiency at substantial incidence angles. An exhaustive exploration of the influence of structural variations on the performance of the absorber has been conducted. Looking ahead, the proposed absorber can be potential application in enhanced terahertz imaging, terahertz communication systems, novel energy harvesting solutions and broad scientific research endeavours.
High-fidelity analysis of the electro-optical non-equivalence of planar electrical substitution radiometers*
Authors: Gieseler J , White M G , Harber D , Haun R , Tomlin N A , Lehman J H
Published: November 2024

We present the results of a finite element analysis of the electro-optical non-equivalence of planar electrical substitution radiometers with vertically aligned carbon nanotube absorbers, operating at either room or cryogenic temperature. These detectors are the basis of the new room temperature standards of the Laboratory for Atmospheric and Space Physics’ (LASP) Total solar irradiance Radiometer Facility and the Spectral solar irradiance Radiometer Facility, and the NIST Boulder open beam cryogenic radiometer facility. We show that the detector of our cryogenic electrical substitution radiometer has no significant electro-optical non-equivalence. Further, we also show that with careful detector design, the non-equivalence can be minimized at room temperature. It was found that in general the non-equivalence cannot be deduced from the temperature mismatch between the electrical and the optical states without considering the conductance mismatch and optical power input. The results are regarded as being precise rather than absolute to account for potentially unknown modeling errors. The numerical accuracy is typically less than 5 ppm.
Correlation of the L-mode density limit with edge collisionality
Authors: Maris A.D. , Rea C. , Pau A. , Hu W. , Xiao B. , Granetz R. , Marmar E. ,   the EUROfusion Tokamak Exploitation team,   the Alcator C-Mod team,   the ASDEX Upgrade team,   the DIII-D Team,   the EAST Team,   and the TCV team
Published: November 2024

The ‘density limit’ is one of the fundamental bounds on tokamak operating space, and is commonly estimated via the empirical Greenwald scaling. This limit has garnered renewed interest in recent years as it has become clear that ITER and many tokamak pilot plant concepts must operate near or above the Greenwald limit to achieve their objectives. Evidence has also grown that the Greenwald scaling—in its remarkable simplicity—may not capture the full complexity of the density limit. In this study, we assemble a multi-machine database to quantify the effectiveness of the Greenwald limit as a predictor of the L-mode density limit and compare it with data-driven approaches. We find that a boundary in the plasma edge involving dimensionless collisionality and pressure,

ν

∗
,

edge

limit

=
3.5

β

T
,
edge

−
0.40

, achieves significantly higher accuracy (false positive rate (FPR) of 2.3% at a true positive rate (TPR) of 95%) of predicting density limit disruptions than the Greenwald limit (FPR of 13.4% at a TPR of 95%) across a multi-machine dataset including metal- and carbon-wall tokamaks (AUG, C-Mod, DIII-D, and TCV). This two-parameter boundary succeeds at predicting L-mode density limits by robustly identifying the radiative state preceding the terminal MHD instability. This boundary can be applied for density limit avoidance in current devices and in ITER, where it can be measured and responded to in real time.