bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic characteristics of the train under the stationary thunderstorm downburst wind
Authors: Hu Peng , Zhang Fei , Han Yan , Cai C. S. , Wang Zhongbo , Long Jiahui
Published: August 2024

The aerodynamic characteristics of the train under the stationary thunderstorm downburst wind were studied. The thunderstorm downburst wind test device was employed to simulate the thunderstorm downburst wind field. Based on the rigid model pressure measurement tests, analyses were conducted on the influence of radial distance on the pressure coefficients on the train surface, the aerodynamic load coefficients of the train section, and the total force coefficients of the middle and head cars. On this basis, combined with the computational fluid dynamics model, further exploration was conducted on the characteristics of the mean pressure on the train surface and the flow field around the train at different radial distances under the stationary thunderstorm downburst wind. The research results show that the train's total aerodynamic coefficients fluctuate with the train's position. The non-uniform distribution of the lateral force coefficient for each train section is primarily caused by variations in the wind yaw angle along the train's longitudinal axis. Variations in the wind attack angle at different radial distances cause the total lateral force coefficient to change accordingly. When the radial distance r/Dj = 0.5, there is no significant vortex-shedding phenomenon in the flow field around the train. However, when radial distance r/Dj = 1 and 1.5, the leeward surface exhibits a regular vortex-shedding phenomenon. Vortex shedding starts at the junction of the leeward surface and the top surface, extending from the middle car along the train's longitudinal axis toward the front and rear.
The growth-adjusted impact factors of Physics of Fluids
Authors: Zatloukal M. , Giacomin A. J. , Phan-Thien N.
Published: August 2024

From Phan-Thien and Giacomin [“Growth-adjusted impact factor,” Phys. Fluids 36, 050402 (2024)], we learn that journal growth decreases impact factor (all else being held equal). In this Editorial, we apply the teachings of Phan-Thien and Giacomin [“Growth-adjusted impact factor,” Phys. Fluids 36, 050402 (2024)] to growth-adjust the impact factors of the journal Physics of Fluids. We do so for the years for which the data are available, 2001–2023. We find that, over the course of its history, the growth of Physics of Fluids often suppressed its impact factor.
Prediction of Shockley–Read–Hall lifetimes in strained layer superlattices for mid-wave and long-wave infrared photodetectors
Authors: Yu Zhi-Gang , Krishnamurthy S. , Ciani Anthony , Grein C.
Published: August 2024

We have calculated carrier nonradiative recombination lifetimes limited by Shockley–Read–Hall (SRH) centers in strained layer superlattices (SLSs) for mid-wave and long-wave infrared applications. The capture rate of an electron (hole) in the SLS's conduction (valence) band by the defect level is dominated by a multi-phonon process, which is orders-of-magnitude more efficient than the radiative process. Long-range polar coupling between electrons and optical phonons can account for the observed SRH lifetimes in a variety of SLSs reported in the literature. The capture rate depends on temperature rather weakly, consistent with experimental observations. The efficient capture is caused by the comparable electronic difference and lattice relaxation energy, Ect∼Sℏω, with S and ℏω being the Huang–Rhys factor and optical photon energy in the SLSs. A weaker polar coupling would give rise to a smaller capture cross section, which, for InAs/InAsSb SLSs, can be achieved by increasing Sb in the alloy region.
Electron transport through two interacting channels in Azurin-based solid-state junctions
Authors: Li Ping’an , Bera Sudipta , Kumar-Saxena Shailendra , Pecht Israel , Sheves Mordechai , Cahen David , Selzer Yoram
Published: August 2024

The fundamental question of “what is the transport path of electrons through proteins?” initially introduced while studying long-range electron transfer between localized redox centers in proteins in vivo is also highly relevant to the transport properties of solid-state, dry metal–protein–metal junctions. Here, we report conductance measurements of such junctions, Au-(
Azurin
monolayer ensemble)-Bismuth (Bi) ones, with well-defined nanopore geometry and ~10
3
proteins/pore. Our results can be understood as follows. (1) Transport is via two interacting conducting channels, characterized by different spatial and time scales. The slow and spatially localized channel is associated with the Cu center of
Azurin
and the fast delocalized one with the protein’s polypeptide matrix. Transport via the slow channel is by a sequential (noncoherent) process and in the second one by direct, off-resonant tunneling. (2) The two channels are capacitively coupled. Thus, with a change in charge occupation of the weakly coupled (metal center) channel, the broad energy level manifold, responsible for off-resonance tunneling, shifts, relative to the electrodes’ Fermi levels. In this process, the off-resonance (fast) channel dominates transport, and the slow (redox) channel, while contributing only negligibly directly, significantly affects transport by intramolecular gating.
Formation of human kinship structures depending on population size and cultural mutation rate
Authors: Itao Kenji , Kaneko Kunihiko
Published: August 2024

How does social complexity depend on population size and cultural transmission? Kinship structures in traditional societies provide a fundamental illustration, where cultural rules between clans determine people’s marriage possibilities. Here, we propose a simple model of kinship interactions that considers kin and in-law cooperation and sexual rivalry. In this model, multiple societies compete. Societies consist of multiple families with different cultural traits and mating preferences. These values determine interactions and hence the growth rate of families and are transmitted to offspring with mutations. Through a multilevel evolutionary simulation, family traits and preferences are grouped into multiple clans with interclan mating preferences. It illustrates the emergence of kinship structures as the spontaneous formation of interdependent cultural associations. Emergent kinship structures are characterized by the cycle length of marriage exchange and the number of cycles in society. We numerically and analytically clarify their parameter dependence. The relative importance of cooperation versus rivalry determines whether attraction or repulsion exists between families. Different structures evolve as locally stable attractors. The probabilities of formation and collapse of complex structures depend on the number of families and the mutation rate, showing characteristic scaling relationships. It is now possible to explore macroscopic kinship structures based on microscopic interactions, together with their environmental dependence and the historical causality of their evolution. We propose the basic causal mechanism of the formation of typical human social structures by referring to ethnographic observations and concepts from statistical physics and multilevel evolution. Such interdisciplinary collaboration will unveil universal features in human societies.
Land conflicts from overlapping claims in Brazil’s rural environmental registry
Authors: Furumo Paul R. , Yu Jevan , Hogan J. Aaron , Tavares de Carvalho Luis M. , Brito Brenda , Lambin Eric F.
Published: August 2024

Satellite-based land use monitoring and farm-level traceability offer opportunities for targeted zero-deforestation interventions on private lands. Brazil’s Rural Environmental Registry (Cadastro Ambiental Rural, or “CAR”), a land cadaster based on self-declaration of property boundaries, was created to monitor compliance with national forest laws. It has become an important enabling measure for sustainable supply chain initiatives like the Amazon Soy Moratorium. However, CAR enrollment is increasingly used to bolster illegal land claims, putting it at the heart of land grabbing dynamics. Self-declaration of properties in the CAR offers a unique situation to study land conflicts and their impact on land use decisions on a large scale. We quantified competing land claims among 846,420 registrations in the Brazilian Legal Amazon and applied a series of generalized linear mixed-effects models. We determined that CAR overlaps are more prevalent on larger registrations, in more densely settled areas, and in areas with less secure land tenure. We tested how landholders respond to land conflicts, finding significantly more deforestation and declared legal forest reserve on lands with multiple claims. CAR overlap results in an overestimation of forest reserves by up to 9.7 million hectares when considering double-counted and deforested areas of reserves, highlighting an overlooked form of Forest Code noncompliance. While the CAR continues to be used as evidence of land tenure, we conclude that the formalization of land claims through self-declarations is inadequate to decrease conflicts. CAR overlap information provides objective evidence of land conflict that authorities can leverage with field inspection to ensure peaceful occupation before issuing land titles.
Bioinspired iontronic synapse fibers for ultralow-power multiplexing neuromorphic sensorimotor textiles
Authors: Chen Long , Ren Ming , Zhou Jianxian , Zhou Xuhui , Liu Fan , Di Jiangtao , Xue Pan , Li Chunsheng , Li Qingwen , Li Yang , Wei Lei , Zhang Qichong
Published: August 2024

Artificial neuromorphic devices can emulate dendric integration, axonal parallel transmission, along with superior energy efficiency in facilitating efficient information processing, offering enormous potential for wearable electronics. However, integrating such circuits into textiles to achieve biomimetic information perception, processing, and control motion feedback remains a formidable challenge. Here, we engineer a quasi-solid-state iontronic synapse fiber (ISF) comprising photoresponsive TiO
2
, ion storage Co-MoS
2
, and an ion transport layer. The resulting ISF achieves inherent short-term synaptic plasticity, femtojoule-range energy consumption, and the ability to transduce chemical/optical signals. Multiple ISFs are interwoven into a synthetic neural fabric, allowing the simultaneous propagation of distinct optical signals for transmitting parallel information. Importantly, IFSs with multiple input electrodes exhibit spatiotemporal information integration. As a proof of concept, a textile-based multiplexing neuromorphic sensorimotor system is constructed to connect synaptic fibers with artificial fiber muscles, enabling preneuronal sensing information integration, parallel transmission, and postneuronal information output to control the coordinated motor of fiber muscles. The proposed fiber system holds enormous promise in wearable electronics, soft robotics, and biomedical engineering.
Gut bacteria are essential for development of an invasive bark beetle by regulating glucose transport
Authors: Liu Fanghua , Ye Fangyuan , Yang Yunwen , Kang Zhiwei , Liu Yang , Chen Wei , Wang Saige , Kou Hongru , Kang Le , Sun Jianghua
Published: August 2024

Insects and their gut bacteria form a tight and beneficial relationship, especially in utilization of host nutrients. The red turpentine beetle (RTB), a destructive and invasive pine pest, employs mutualistic microbes to facilitate its invasion success. However, the molecular mechanism underlying the utilization of nutrients remains unknown. In this study, we found that gut bacteria are crucial for the utilization of D-glucose, a main carbon source for RTB development. Downstream assays revealed that gut bacteria-induced gut hypoxia and the secretion of riboflavin are responsible for RTB development by regulating D-glucose transport via the activation of a hypoxia-induced transcription factor 1 (Hif-1α). Further functional investigations confirmed that Hif-1α mediates glucose transport by direct upregulation of two glucose transporters (ST10 and ST27), thereby promoting RTB development. Our findings reveal how gut bacteria regulate the development of RTB, and promote our understanding of the mutualistic relationship of animals and their gut bacteria.
Kv1.1 channels help set the pace
Authors: Short Ben
Published: August 2024

JGP study (Si et al. https://doi.org/10.1085/jgp.202413578) reveals that, although they are present at low levels and only generate small currents in the sinoatrial node, Kv1.1 channels have a significant impact on cardiac pacemaking.
Gravitational waves on Kerr black holes: I. Reconstruction of linearized metric perturbations
Authors: Berens Roman , Gravely Trevor , Lupsasca Alexandru
Published: August 2024

The gravitational perturbations of a rotating Kerr black hole are notoriously complicated, even at the linear level. In 1973, Teukolsky showed that their physical degrees of freedom are encoded in two gauge-invariant Weyl curvature scalars that obey a separable wave equation. Determining these scalars is sufficient for many purposes, such as the computation of energy fluxes. However, some applications—such as second-order perturbation theory—require the reconstruction of metric perturbations. In principle, this problem was solved long ago, but in practice, the solution has never been worked out explicitly. Here, we do so by writing down the metric perturbation (in either ingoing or outgoing radiation gauge) that corresponds to a given mode of either Weyl scalar. Our formulas make no reference to the Hertz potential (an intermediate quantity that plays no fundamental role) and involve only the radial and angular Kerr modes, but not their derivatives, which can be altogether eliminated using the Teukolsky–Starobinsky identities. We expect these analytic results to prove useful in numerical studies and for extending black hole perturbation theory beyond the linear regime.
Advanced undergraduate laboratory: exploring isotopic shifts in molecular spectroscopy
Authors: Fei Ye , Ye Yanpeng , Zhang Qihang , Liu Yuzhu
Published: August 2024

Current university physics curricula and pedagogical research lack the study of molecular spectrum and its isotopic effects. In light of this, and considering the simplistic architecture of CN molecules alongside the significance of carbon isotopes in atmospheric cycles and various other disciplines, we have developed an advanced molecular spectroscopy experiment tailored for upper-level undergraduate physics educational courses. Utilizing 12CO2 and 13CO2 as experimental mediums, this study delves into the exploration of molecular energy level transitions and isotopic effects within molecular spectra through the analysis of CN molecular emission spectra. Additionally, simulations of CN molecular energy level transitions were conducted using LIFBASE software, thereby deepening students’ grasp of molecular energy level quantization. This experiment uses molecular spectrum to realize the interpretation of energy level structure and isotope effects, which is groundbreaking and will add experimental reference and expansion to the teaching of atomic physics.
The process of constructing new knowledge: an undergraduate laboratory exercise facilitated by a vacuum capacitor-resistor circuit
Authors: Kowalski Frank V
Published: August 2024

The process of constructing knowledge is typically taught to students by having them reproduce established results (e.g. homework problems). An alternative pedagogical strategy is to illustrate this process using an open problem, such as voltage decay in an RC circuit as described below. Analyzing data from this circuit in an undergraduate physics laboratory course reveals a discrepancy between the data and the exponential decay model found in textbooks. As students attempt to reconcile this discrepancy, the instructor can provide guidance in the process of validating data, modeling, and experimental design. This undergraduate laboratory exercise also provides an engaging transition from classroom learning to real world experience.
Ground state properties and bubble structure of the isotopic chains of Z = 125 and 126 using the relativistic mean-field formalism
Authors: Priyanka S , Chauhan A , Mehta M S , Bhuyan M
Published: August 2024

The ground state properties of Z = 125 and 126 nuclei are investigated, taking the isotopic series from the proton to neutron drip-lines. This analysis uses the relativistic mean-field approach with NL3 and the Relativistic-Hartree–Bogoliubov model with DD-ME2 parameterization. The bulk properties under examination include the binding energy per nucleon, the neutron separation energies, the differential variation of the separation energy, the quadrupole deformation parameter β
2, and the single-particle energy. We observed the stability at N = 172 and 184 over the isotopic chain for both parameter sets. The quadrupole deformation parameter reveals a shape transition from prolate to spherical and back to prolate with mass number. No signature of a super- and/or hyper-deformed structure is found over the isotopic chain. Furthermore, the analysis is extended to examine the bubble structure, revealing a bubble/semi-bubble structure for a few neutron-rich isotopes.
Epitaxial growth in one dimension
Authors: Álvarez-Cuartas Juan David , González-Cabrera Diego Luis , Camargo Manuel
Published: August 2024

The final structure and properties of layers grown by epitaxy techniques are determined in the very early stage of the process. This review describes one-dimensional models for epitaxial growth, emphasizing the basic theoretical concepts employed to analyze nucleation and aggregation phenomena in the submonolayer regime. The main findings regarding the evolution of quantities that define the properties of the system, such as monomer and island densities, and the associated island size, gap length, and capture zone distributions are discussed, as well as the analytical tools used to evaluate them. This review provides a concise overview of the most widely used algorithms for simulating growth processes, discusses relevant experimental results, and establishes connections with existing theoretical studies.
Magnetization dynamics in single and trilayer nanowires
Authors: Kuchibhotla Mahathi , Haldar Arabinda , Adeyeye Adekunle Olusola
Published: August 2024

We have studied the magnetization dynamics of single Py(t) (t = 20 nm, 50 nm) and trilayer [Py(50)/Pd(t
Pd)/Py(20)] nanowire arrays fabricated over large areas using deep ultraviolet lithography technique. The dynamic properties are sensitive to the field orientation and magnetic film thicknesses. A single resonant mode corresponding to the excitations at the bulk part of the wire is detected in all the single-layer nanowire arrays. Furthermore, the spacer layer thickness influenced the dynamic properties in trilayer samples due to the different coupling mechanisms. A single resonant mode is observed in t
Pd = 2 nm trilayer nanowires with a sharp frequency jump from 13 GHz to 15 GHz across the reversal regime. This indicates the exchange coupling and the coherence in magnetization precession in the ferromagnetic layers. On the other hand, wires with 10 nm-spacer display two well-resolved modes separated by ∼3 GHz with a gradual change in frequency across the reversal regime from

−
26

mT to

−
46

mT, indicating the presence of long-range dipolar interactions instead of exchange coupling. The spacer layer of the proposed spin-valve-type structure can be tailored for desired microwave splitters or combiners.
Predicting the wear on the non-working side of the rail profile registration method and its validation
Authors: Nie Liangtao , Li Weimin , Qu Xiangyu , Jing Guoqing , Liu Xiubo , Feng Xiaomeng
Published: August 2024

Rail cross-section profile detection can assess the wear and tear of measured rails, providing crucial references for railway maintenance and upkeep. It is challenging to use the conventional method to register only the profile of rail head detection accurately. After the rail edge adjustment in some conventional railways, it becomes difficult to determine the base point of rail profile registration. Due to the wear of non-working edge of rail, a rail profile registration method is proposed. Firstly, a wear prediction model based on the generalized regression neural network is constructed by optimizing smoothing parameters through ten-fold cross-validation to achieve the optimal values. This model predicts the wear values on the non-working rail edge, providing reliable coordinates for two wear points as alignment reference points. Secondly, an initial alignment between the measured profile and the target profile is achieved using the nearest point iterative algorithm, which ensures that both profiles are in the same region and oriented similarly. Thirdly, the weight is assigned to the wear measurement points based on their respective wear values. The predicted positions of wear points are applied for calculating the translation and rotation parameters. These parameters could align the measured profile and facilitate the final profile alignment. Lastly, the experimental profiles under rail adjustment conditions were registered, verifying the accuracy of the proposed method. The research results indicate that under rail adjustment conditions, the mean squared error (MSE) between the calculated and actual values of lateral wear is 0.094 mm2, which is lower than the MSE from manual measurements. The calculated lateral wear value for experimental profiles achieved high alignment and calculation accuracy. This method can be applied in practical projects, providing an effective solution for rail head profile alignment and serving as a reference for profile alignment on the non-working rail edge with incomplete measurement data.
Damage-related imbalance identification for UAV composite propeller blades based on bidirectional temporal convolutional network and a flexible sensing system
Authors: Gu Ran , Zhang Shufeng , Zhu Jialing , Zhu Haibin , Li Yue
Published: August 2024

Damage to the composite propeller blades could lead to rotational imbalance, which seriously affects the operational safety of unmanned aerial vehicles (UAVs), therefore, a novel method combining the Teager energy operator (TEO) and bidirectional temporal convolutional network (BiTCN) is proposed for detecting, localizing, and quantifying the damage-related imbalance in the blades. A flexible sensing system that contains Micro electro mechanical sensor accelerometers, signal conditioning, and wireless transmission is integrated with the composite propeller for in-situ signal acquisition of the propeller blades. TEO is applied to demodulate and enhance the pulse compositions in vibration signals and singular value decomposition (SVD) is employed to suppress random noise, resulting in denoised Teager energy spectrums for model input. Temporal convolutional network (TCN) has been widely used in sequence signal modeling because the causal dilated convolution could learn the context information of sequence signals while maintaining the advantages of parallel computing. To fully extract the signal features, BiTCN models are established to learn both the forward and backward signal features. Experimental verification results show that the proposed method detects the existence of imbalance with 100% accuracy, and the accuracies of localization and quantization are 99.65% and 98.61%, respectively, which are much higher than those of the models with the original signal as input. In addition, compared with the other four different algorithms, BiTCN is superior in terms of convergence speed and prediction accuracy.
ICP registration with SHOT descriptor for arresters point clouds
Authors: Lu Senjian , Zhu Wen , Hou Beiping , Dong Jianwei , Zheng Yangbin , Qi Xiaoxin , Zhu Yuzhen , Yu Aihua
Published: August 2024

Arresters are one of the critical components of the power system. However, due to the arrester’s regular and uniform umbrella skirt, both traditional manual detection methods and existing computer vision approaches exhibit limitations in accuracy and efficiency. This paper proposes an automatic, robust, efficient arrester point cloud registration method to address this problem. First, a robotic arm maneuvers a depth camera to capture point cloud data from various perspectives. Then, the fast global registration point cloud coarse registration method based on the signature of histograms of orientations descriptor to produce preliminary registration results. This result is ultimately used as the initial value of the improved iterative closest point algorithm to refine the registration further. Experimental results on various data sets collected from arrester and public data sets show that the algorithm’s root mean square error is less than 0.1 mm, meeting the requirements of the engineering application of arrester detection.
Microporous tungsten oxide spheres coupled with Ti3C2Tx nanosheets for high-volumetric capacitance supercapacitors
Authors: Zhang Peigen , Li Yang , Zhang Hanning , Yang Li , Yin Xiaodan , Zheng Wei , Ding Jianxiang , Sun ZhengMing
Published: August 2024

In the contemporary landscape of technological advancements, the burgeoning demand for portable electronics and flexible wearable devices has necessitated the development of energy storage systems with superior volumetric performance. Tungsten oxide (WO3), known for its high density and theoretical capacitance, is a promising electrode material for supercapacitors. However, low conductivity and poor cycling stability are still the key bottlenecks for its application. Herein, a novel composite comprising hollow porous WO3 spheres (HPWS) derived by template method was electrostatic self-assembled on the surface of the Ti3C2T
x
nanosheets. The resulting electrodes exhibited ultra-high volumetric capacitance of 1930 F cm−3 at 1 A g−1 and rate capability of 46% at 50 A g−1, attributed to enhanced ion accessibility from microporous structure and electron transport from conductive network of Ti3C2T
x
even at a high packing density of 3.86 g cm−3. Utilizing HPWS/Ti3C2T
x
as the negative electrode and porous carbon as the positive electrode, the assembled asymmetric supercapacitor achieved an energy density of 31 Wh kg−1 at a power density of 650 W kg−1 with over 107% capacitance retention after 5000 cycles. This work provides a promising approach for developing next-generation supercapacitors with ultra-high volumetric capacitance.
Plasma-enhanced atomic layer deposition of Sn-doped indium oxide semiconductor nano-films for thin-film transistors
Authors: Luo Binbin , Zhang Conglin , Meng Wei , Xiong Wen , Yang Min , Yang Linlong , Zhu Bao , Wu Xiaohan , Ding Shi-Jin
Published: August 2024

Sn-doped indium oxide (ITO) semiconductor nano-films are fabricated by plasma-enhanced atomic layer deposition using trimethylindium (TMIn), tetrakis(dimethylamino)tin (TDMASn), and O2 plasma as the sources of In, Sn and O, respectively. A shared temperature window of 150 °C– 200 °C is observed for the deposition of ITO nano-films. The introduction of Sn into indium oxide is found to increase the concentration of oxygen into the ITO films and inhibit crystallization. Furthermore, two oxidation states are observed for In and Sn, respectively. With the increment of interfaces of In–O/Sn–O in the ITO films, the relative percentage of In3+ ions increases and that of Sn4+ decreases, which is generated by interfacial competing reactions. By optimizing the channel component, the In0.77Sn0.23O1.11 thin-film transistors (TFTs) demonstrate high performance, including μ
FE of 52.7 cm2 V−1 s−1, and a high I
ON/I
OFF of ∼5 × 109. Moreover, the devices show excellent positive bias temperature stress stability at 3 MV cm−1 and 85 °C, i.e. a minimal V
th shift of 0.017 V after 4 ks stress. This work highlights the successful application of ITO semiconductor nano-films by ALD for TFTs.
Remarks on the separation of Navier–Stokes flows
Authors: Bradshaw Zachary
Published: August 2024

Recently, strong evidence has accumulated that some solutions to the Navier–Stokes equations in physically meaningful classes are not unique. The primary purpose of this paper is to establish necessary properties for the error of hypothetical non-unique Navier–Stokes flows under conditions motivated by the scaling of the equations. Our first set of results show that some scales are necessarily active—comparable in norm to the full error—as solutions separate. ‘Scale’ is interpreted in several ways, namely via algebraic bounds, the Fourier transform and discrete volume elements. These results include a new type of uniqueness criteria which is stated in terms of the error. The second result is a conditional predictability criteria for the separation of small perturbations. An implication is that the error necessarily activates at larger scales as flows de-correlate. The last result says that the error of the hypothetical non-unique Leray–Hopf solutions of Jia and Šverák locally grows in a self-similar fashion. Consequently, within the Leray–Hopf class, energy can hypothetically de-correlate at a rate which is faster than linear. This contrasts numerical work on predictability which identifies a linear rate. Our results suggest that this discrepancy may be explained by the fact that non-uniqueness might arise from perturbation around a singular flow.
Scaling of the emission of low frequency radiation by transient surface currents in laser–solid interactions
Authors: Robinson A P L
Published: August 2024

It has been suggested that ‘transient surface currents’ caused by multi-MeV fast electrons can be responsible for the emission of low frequency radiation (e.g. in THz range) from ultra-intense laser–solid interactions. This mechanism has been analyzed, and analytic upper bounds on the intensity, electric field amplitude, and normalized vector potential have been developed and tested against 1D EM Particle-in-Cell simulations. The ‘transient surface current’ mechanism is effective and sufficiently efficient to fully account for all radiation that has been emitted in experiments so far.
Temperature- and gate voltage-dependent I–V modeling of GaN HEMTs based on ASM-HEMT
Authors: Zhou Ziwei , Liu Guipeng , Zhao Guijuan
Published: August 2024

In this paper, a temperature- and gate voltage-dependent current–voltage (I–V) model for gallium nitride (GaN) high electron mobility transistors (HEMTs) devices is studied. To help researchers and designers simulate devices in the absence of experimental data and improve the parameter extraction efficiency, the temperature and gate voltage dependence of mobility are discussed and incorporated into the proposed model, which is revised from the standard advanced SPICE model (ASM) for GaN HEMTs. The mobility variations with the gate voltage from −2 V to 6 V and the temperature from 10 K to 1000 K are analyzed. The simulation results of our model are compared with the standard ASM-HEMT model, and the output and transfer characteristics of the device from 270 K to 420 K are simulated. Therefore, our model may simulate various applications of GaN HEMTs at different gate voltages and temperatures in the early stages of design and research.
A comparative analysis of the tribological performance of coir, bamboo and wood filler reinforced polymer composites
Authors: Paul Rajdeep , Mahakur Vijay Kumar , Bhowmik Sumit
Published: August 2024

Researchers and academics are increasingly favoring natural fibres for incorporation into polymer composites on account of their ecological compatibility and longevity. The aim of this comparative study is to identify the optimal natural filler by AHP-TOPSIS approach by analyzing the tribological performance of three distinct natural fillers: coir, bamboo, and wood reinforced polymer composite. These filler materials are pre-treated by alkali treatment to increase the interlinking properties between filler and polymer. The outcome of these treatments on the composites’ physical and mechanical properties are investigated. Using a Pin-on-disk (POD) machine under dry, wet, and heated sliding contact conditions, different natural fillers’ effects on polymer wear and friction are examined. The wear rate and coefficient of friction (COF) were quantified as a function of the sliding distance (0–2000 m) under various normal loads (5–40 N). It was observed from the different experimental results that coir filler reinforced composite shows best wear resistance property whereas wood filler reinforced composite shows the least wear resistance composite. Results revealed that lower filler support and low load show better wear resistant property compared to the higher filler support and high load condition. When seen through a microscope, the worn surfaces of the composite material exhibit micro and macro fissures, as well as debonding and plastic deformation. The coir filler-based composite was found to be the best alternative using the AHP-TOPSIS method, with a closeness coefficient of 0.770023.
Design and analysis of discrete fractional-order chaotic map with offset-boosting behavior
Authors: Huang Lilian , Zheng Lei , Yang Yan , Yu Xihong , Li Chuang
Published: August 2024

Fractional calculus, as a more accurate tool for depicting the dynamics of complex systems, has been introduced into discrete chaotic maps. To further describe the offset-boosting behavior in discrete systems, a discrete fractional-order chaotic map (DFOCM) based on the Caputo difference operator is constructed. The mapping order of this fractional-order model controls the stability of the fixed point, thereby affecting the dynamic behavior of the map. The dynamics of DFOCM is studied using numerical simulation methods such as bifurcation diagrams and maximum Lyapunov exponents, revealing the presence of multistability. By comparing with integer-order map, it is found that DFOCM exhibit a larger chaotic region. Based on this, the difference between fractional order and integer order offset-boosting behavior is theoretically derived. Specifically, the offset-boosting behavior of fractional-order maps concerning mapping parameters is related to the initial state, which was further demonstrated through numerical simulations. SE complexity proves that the chaotic sequences generated by DFOCM have high unpredictability and pseudo-randomness. Finally, the proposed DFOCM is implemented on the DSP hardware platform, and the physical feasibility of numerical simulation is verified.
Optical soliton solutions of the nonlinear complex Ginzburg-Landau equation with the generalized quadratic-cubic law nonlinearity having the chromatic dispersion
Authors: Esen Handenur , Secer Aydin , Ozisik Muslum , Bayram Mustafa
Published: August 2024

In this study, we consider the complex Ginzburg-Landau equation with the generalized quadratic-cubic law of self-phase modulation. This model finds applications in various fields, such as the study of superconductivity, nonlinear optical phenomena, pattern formation, and designing photonic devices and systems. This manuscript successfully employs the new Kudryashov method to derive analytical solutions for complex Ginzburg-Landau equations with the generalized quadratic-cubic law of self-phase modulation. The 3D, contour, and 2D graphical representations of the acquired solutions are represented. Therefore, W-shaped, bright, and dark soliton structures are derived. Through rigorous analysis and interpretation, valuable insights into the influence of the parameters of the presented model on the soliton behavior are achieved.
Theoretical study of the MWCNT particle layer and size impact on sodium alginate heat transfer
Authors: Akinshilo A T , Folaranmi A , Ilegbusi A O
Published: August 2024

This paper theoretically studies the effects of the size of multiwalled carbon nanotube (MWCNT) nanoparticles and layers on the flow of sodium alginate (SA) base fluid in a vertical channel. The nanoparticles are used to improve the thermal characteristics of the base fluid. The nanolayer shows the relationship between the particles and the base fluid, justifying the rise in thermal conductivity, even at a low volume of the nanoparticle in the base fluid. The mechanics of the fluid through the channels are developed using nonlinear models of coupled higher order differentials analyzed using the adomian decomposition method, an analytical scheme. The nanolayer effect of MWCNT particles on pure sodium alginate enhances heat transfer by 31.83% upon a step increase of 0.4 from 0.2 nm. Additionally, the combined effects of the rheological parameters of particle size, radiation and shear stress lead to a high heat transfer rate. The results obtained from the analysis were verified with results obtained from the literature for simple conditions, which validated the analysis. The results of this study may provide meaningful insight into the physical application of the sodium alginate.
Multi-physics modeling of tungsten collector probe samples during the WEST C4 He campaign
Authors: Lasa A. , Blondel S. , Curreli D. , Drobny J. , Garcia W.A. , Gunn J. , Hayes A. , Lore J.D. , Renganathan A. , Tsitrone E. , Unterberg E. , Wirth B.D.
Published: August 2024

We describe the results of a multi-scale, multi-physics modeling assessment of SOLPS-ITER, hPIC2, RustBCA and Xolotl, in which five single-crystal tungsten (W) samples were placed in a reciprocating collector probe and exposed to helium (He) plasma in the WEST fusion device. In our models, we considered a pure (100 %) He plasma, as well as one with oxygen (O) present (95% He 5% O) corresponding to the impurity concentration estimated during the C4 He campaign in WEST. Our SOLPS simulations approximately match experimental reciprocating Langmuir probe plasma measurements of plasma density and temperature. Using these plasma parameters as input, hPIC2 and RustBCA predict that the presence of oxygen impurities lead to a 15%–20% decrease in ion and heat fluxes to the surface, and an order of magnitude higher sputtering yields (compared with a pure He plasma). Xolotl predictions for the response of tungsten to plasma surface interactions (PSIs) agree with experimental LAMS analysis, and indicate large near-surface He concentrations, which quickly decay with depth. Our model also shows an increasing role of erosion—in removing the near-surface He—with time. Overall, slightly higher retention is predicted for tungsten exposed to a pure He plasma, with the largest differences in the near-surface gas content caused by the large oxygen-induced erosion. This highlights the important role that impurities play in PSI. Therefore, future work will focus on providing a fully self-consistent description of oxygen (and oxides, etc.) in our models, through multi-species implementation in GITR and inclusion of oxygen and tungsten oxide formation in Xolotl.
Observation of tungsten emission spectra up to W46+ ions in the Large Helical Device and contribution to the study of high-Z impurity transport in fusion plasmas
Authors: Oishi Tetsutarou , Morita Shigeru , Kato Daiji , Murakami Izumi , Sakaue Hiroyuki A. , Goto Motoshi , Kawamoto Yasuko , Kawate Tomoko , Nishimura Ryota , Takahashi Hiroyuki , Tobita Kenji
Published: August 2024

Spectroscopic studies of emissions released from tungsten ions combined with a pellet injection technique have been conducted in Large Helical Device for contribution to the tungsten transport study in tungsten divertor fusion devices and for expansion of the experimental database of tungsten line emissions. The spectral intensities of W5+, W24+–W28+, W37+, W38+, W41+–W43+, W45+, and W46+ emission lines were measured simultaneously over a wide wavelength range from x-ray to visible. Time evolutions of the various tungsten line spectra indicate that the tungsten confinement time depends on the electron density of the plasma and is long in high density plasmas, on the order of seconds, and short in low density plasmas, on the order of sub-seconds. When the confinement time was long, the tungsten ions remained in the plasma until the end of the discharge, changing their dominant charge with the change in electron temperature. When the confinement time was short, the tungsten ions rapidly decreased in all charge states and disappeared. Space-resolved EUV and visible spectroscopy measurements have revealed that tungsten ions stayed in the core region of the plasma with changing their dominant charge state depending on the electron temperature in the discharges with the long confinement time. Detailed analysis of soft x-ray emission suggested that the confinement time increases with density and becomes saturated when the central electron density exceeds 2 × 1013 cm−3.
Formation of orientation-dependent surface morphologies on tungsten after low energy helium plasma exposure: multiscale characterization and new insights
Authors: Zhu Yi-Wen , Li Yu , Sun Yuhan , Liu Hao-Dong , Yang Xin , Cheng Long , Yuan Yue , Lu Guang-Hong , Luo Guang-Nan , Zhou Hai-Shan
Published: August 2024

In ITER, the helium (He) impurity produced by the deuterium-tritium reaction will bombard the tungsten (W) divertor armor at the strike points. Consequently, strong interaction occurs therein that both impact the performance of the plasmas and the lifetime of the divertor. Despite an ever-increasing understanding of this interaction, some experimental phenomena remain mysterious, especially the formation of orientation-dependent surface morphologies. Here, we combine multiscale experimental characterization and theoretical models to shed new light on this problem. After low-energy He plasma exposure in a linear plasma generator, the polycrystalline W surface developed various morphologies. Through electron backscatter diffraction analysis, we found that the {111} grains developed cube-corner structures, the {110} grains developed ripple structures, whereas the {100} grains remained smooth. Then, electron-transparent lamellae were extracted from such grains to observe the subsurface He bubbles by transmission electron microscopy. The volume density, size distribution, and depth range of the He bubbles weakly depend on the crystallographic orientation, suggesting that the migration of W atoms causes the morphology variety. Accordingly, we proposed a two-stage formation mechanism. First, W atoms generated by over-pressurized He bubbles glide on the slip plane and in the slip direction to reach the surface, forming characteristic patterns that are enclosed by the slip traces. Second, morphological instability drives the evolution of the surface patterns, in which the initial surface structure and surface self-diffusion kinetics mediate. The proposed mechanism has been incorporated into a topographical instability model to enable asemi-quantitative analysis. The obtained new insights are valuable to the impurity control of the core plasmas and the lifetime analysis of the divertor for ITER.
Fault diagnosis method for elevator carriages based on temporal generative federated distillation
Authors: Zhang Guowei , Li Cong , Sun Qi
Published: August 2024

Addressing the ‘data silo’ issue among different elevator operating units and the temporal correlations in elevator vibration signals, a novel small-sample fault diagnosis method for elevator carriages based on temporal generative federated distillation is proposed. This method incorporates a temporal generative adversarial network into Federated Distillation via Generative Learning (FedGen). FedGen combines federated learning, knowledge distillation, and generative models to enhance model aggregation efficiency while mitigating data heterogeneity. However, the original generative model struggles to maintain dynamic correlations between signals when extracting temporal features. Therefore, an improved Time Series Generative Adversarial Networks (TimeGAN) model is introduced, substituting the initial logarithmic loss function with a least squares error function, thereby enhancing training stability and data quality. This approach eliminates the need for proxy datasets in knowledge distillation, avoiding the loss of temporal information during central server feature extraction. Simulation results demonstrate that this method enables data sharing while protecting data privacy, and enhances model generalization capabilities.
Generic Stabilizers in Actions of Simple Algebraic Groups
Authors: Guralnick R. , Lawther R.
Published: August 2024

In this paper we treat faithful actions of simple algebraic groups on irreducible modules and on the associated Grassmannian varieties. By explicit calculation, we show that in each case, with essentially one exception, there is a dense open subset any point of which has stabilizer conjugate to a fixed subgroup, called the generic stabilizer. We provide tables listing generic stabilizers in the cases where they are non-trivial; in addition we decide whether or not there is a dense orbit, or a regular orbit for the action on the module.
Noncommutative Coordinates for Symplectic Representations
Authors: Alessandrini Daniele , Guichard Olivier , Rogozinnikov Eugen , Wienhard Anna
Published: August 2024

We introduce coordinates on the spaces of framed and decorated representations of the fundamental group of a surface with nonempty boundary into the symplectic group

S
p
(
2
n
,

R

)

Sp(2n,\mathbf R)

. These coordinates provide a noncommutative generalization of the parametrizations of the spaces of representations into

S
L
(
2
,

R

)

SL(2,\mathbf R)

or

P
S
L
(
2
,

R

)

PSL(2,\mathbf R)

given by Thurston, Penner, Kashaev and Fock–Goncharov. On the space of decorated symplectic representations the coordinates give a geometric realization of the noncommutative cluster-like structures introduced by Berenstein–Retakh. The locus of positive coordinates maps to the space of framed maximal representations. We use this to determine an explicit homeomorphism between the space of framed maximal representations and a quotient by the group 

O
(
n
)

O(n)

. This allows us to describe the homotopy type and, when

n
=
2

n=2

, to give an exact description of the singularities. Along the way, we establish a complete classification of pairs of nondegenerate quadratic forms.
Extreme Superposition: High-Order Fundamental Rogue Waves in the Far-Field Regime
Authors: Bilman Deniz , Miller Peter
Published: August 2024

This Memoir concerns fundamental rogue-wave solutions of the focusing nonlinear Schrödinger equation in the limit that the order of the rogue wave is large and the independent variables

(
x
,
t
)

(x,t)

are proportional to the order (the far-field limit). We first formulate a Riemann-Hilbert representation of these solutions that allows the order to vary continuously rather than by integer increments. The intermediate solutions in this continuous family include also soliton solutions for zero boundary conditions spectrally encoded by a single complex-conjugate pair of poles of arbitrary order, as well as other solutions having nonzero boundary conditions matching those of the rogue waves albeit with far slower decay as

x
→
±
∞

x\to \pm \infty

. The large-order far-field asymptotic behavior of the solution depends on which of three disjoint regions

C

\mathcal {C}

(the “channels”),

S

\mathcal {S}

(the “shelves”), and

E

\mathcal {E}

(the “exterior domain”) contains the rescaled variables. On the region

C

\mathcal {C}

, the amplitude is small and the solution is highly oscillatory, while on the region

S

\mathcal {S}

, the solution is approximated by a modulated plane wave with a highly oscillatory correction term. The asymptotic behavior on these two domains is the same for all continuous orders. Assuming that the order belongs to the discrete sequence characteristic of rogue-wave solutions, the asymptotic behavior of the solution on the region

E

\mathcal {E}

resembles that on

S

\mathcal {S}

but without the oscillatory correction term. Solutions of other continuous orders behave quite differently on

E

\mathcal {E}

.