bluuebunny/crossref_metadata_2025 huggingface dataset:
Fault diagnostic research on the MMC output current sensors
Authors: Kang Zhuang , Zhang Li
Published: October 2024

The modular multilevel converter (MMC) has been extensively studied, and sensors are an important part of the MMC control link. However, few diagnostic methods exist to study the diagnosis of sensor faults in MMCs. This paper proposes a fault diagnosis strategy for output sensors in MMCs, which can complete the detection and localization of the faulty output current sensor. According to the operating principle and mathematical model of MMC, the fault mechanism and fault feature are analyzed. Secondly, the fault diagnosis method is designed according to the fault characteristics. Finally, simulation results show that the strategy proposed in this paper can accurately diagnose faults.
Development of spectral radiation imaging diagnostic systems for HFRC Device
Authors: Han Cheng , Cheng Zhifeng , Lin Weijie , Tian Ye , Zhang Yuchen , Rao Bo , Jin Xinyi
Published: October 2024

Spectral radiation imaging diagnostic systems utilizing PDA (avalanche PhotoDiode Array) have been developed and deployed on the HFRC device (HUST Field Reversed Configuration Device). These systems are designed to measure Hα radiation imaging, plasma velocity, orientation, and shape. Their innovative features include higher spatial resolution, integrated system design, flexible measurement, and superior electronic performance. This paper discusses the selection of basic electronic circuits, circuit analysis, parameter design, and noise analysis in detail. The accuracy of the design is validated through simulation and practical testing. The final system parameters achieved a bandwidth of 610 kHz, low noise of 2.5 mV, approximately 3% system overshoot, and a rising time of 468.5 ns. Additionally, preliminary measurement results are provided.
Mechanical State Fault Diagnosis Method of High Voltage Circuit Breaker Based on ICEEMDAN-Hilbert Marginal Spectral Energy Entropy
Authors: Peng Bohao , Wang Zhijuan , Qi Runze , Wei Binbin , Cao Shi , Liu Qinzhe
Published: October 2024

The predominant faults in high-voltage circuit breakers often stem from mechanical malfunctions within the operating mechanism. Addressing the intricate nature of feature extraction arising from the transient, nonlinear, and non-stationary characteristics of mechanical vibration signals during the circuit breaker’s operation, we propose a method for vibration signal feature extraction and fault diagnosis. This method integrates an Intrinsic Computing Expressive Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) with Hilbert marginal spectrum analysis. ICEEMDAN is utilized to decompose vibration signals, while Hilbert marginal spectrum is employed to calculate effective Intrinsic Mode Function (IMF) components. The distribution of Hilbert marginal spectrum energy entropy is analyzed, and the feature vectors are fed into an SVM classifier to achieve intelligent diagnosis of mechanical faults in high-voltage circuit breakers. Experimental validation demonstrates the reliability and effectiveness of the proposed ICEEMDAN-Hilbert marginal spectrum energy entropy-based approach for diagnosing mechanical faults in high-voltage circuit breaker operating mechanisms, offering valuable insights for practical applications.
Research on multipath error detection model in forest based on Signal-to-noise ratio
Authors: Bian Xiaoyuan , Xu Zhijing
Published: October 2024

Vegetation obstruction in densely wooded regions induces multipath errors in receivers, challenging their positioning accuracy. This paper proposes a pseudorange multipath error detection model for single-frequency receivers in forests, leveraging signal-to-noise ratio (SNR) principles. By analyzing SNR and elevation in open areas, threshold ranges are established to detect multipath errors. Experiments in various forest settings show significant enhancements in single and combined system positioning accuracy, up to 29.4%, 21.9%, and 55.4% in eastward, northward, and upward directions respectively, underscoring the model’s effectiveness in mitigating multipath errors in forest environments.
Monitoring system for external force damage on power transmission lines integrated with millimeter-wave radar and visual surveillance
Authors: Li Mengxuan , Shi Jiangtao , Yang Zhi , Zhang Sihang , Tang Haitao , Zhang Guoqiang
Published: October 2024

This paper proposes a monitoring system for detecting external force damage on power transmission lines by integrating millimeter-wave radar and visual surveillance. The aim is to address key issues in current transmission line monitoring, such as high labor costs, low efficiency, and environmental susceptibility. By organically combining millimeter-wave radar and visual surveillance devices, the system achieves all-weather, real-time monitoring and early warning of potential threats such as large machinery around power transmission lines. The system employs an RK3399PRO microcontroller as the main control module, utilizes 24 GHz millimeter-wave radar for long-distance target detection, and employs a back-illuminated ultra-low-light camera for day and night all-weather monitoring. Moreover, the system software supports automatic target recognition, tracking, and warning, thereby improving monitoring efficiency and accuracy. Additionally, the system is powered by solar energy, demonstrating good environmental adaptability and cost-effectiveness. Through application in a 220 KV line in Daxing District, Beijing, it is demonstrated that this monitoring system effectively enhances the safety monitoring level of power transmission lines, providing robust assurance for the safe operation of transmission lines.
Sea surface target detection method based on spectrum split-peak and hurst exponent
Authors: Bi Xiaowen , Shu Qin , Xu Fangwei
Published: October 2024

The sea surface is complex and affected by numerous factors, including radar parameters and environmental circumstances. Therefore, target identification at sea poses a significant challenge for maritime radar detection. This paper proposes spectral peak segmentability by analyzing the characteristics of sea clutter and targets, which combines the spectral Hurst exponent as a feature for identifying targets under sea clutter. The spectral split-peak method, based on the scale-space representation, can effectively identify the number of peaks in the echo spectrum and provides a foundation for target detection under sea clutter. It also introduces a new feature for target identification and enhances the detection performance of sea surface targets by integrating spectral fractal features. Finally, the method is tested by using IPIX-measured data. The target range bins can be effectively detected, and the target signal can be accurately extracted, verifying the effectiveness of the method.
Research on improving the efficiency of wireless networking in the power system
Authors: Dai Hongguang , Chen Jinlei , Ni Yuanyuan , Chen Hui , Yu Yawei , Ji Xiaowei , Wu Lei
Published: October 2024

Considering the issue of slow station access speed leading to a subpar user experience in the current power wireless communication system, this paper proposes an initial networking scheme that enhances the speed of networking by broadcasting current networking frequency information on a designated public frequency point, avoiding sequential attempts at networking on multiple frequency points. Furthermore, the current wireless communication network utilized by the State Grid operates within the public frequency band, rendering it susceptible to co-channel interference, potentially resulting in network unavailability for some stations. Hence, this paper suggests a networking method in which the entered stations sequentially switch frequency points within the beacon/CSMA timeslots to search for potential stations and ultimately transition to a new frequency point suitable for all stations. The experimental results demonstrate that the network access time of the stations unaffected by co-channel interference is only 21.5% compared to the current sequentially detection network access scheme. The stations affected by co-channel interference can still achieve successful network access under the proposed solution, with a remarkable success rate of 100%, thereby effectively enhancing the networking success rate. In summary, the proposed scheme in this paper enhances networking efficiency by addressing both networking speed and success rate. In addition, through calculation and analysis, it is known that the complexity and power consumption associated with networking do not result in significant increments.
An optimized compression algorithm for distributed photovoltaic data
Authors: Shi Zhan , Liang Yutu
Published: October 2024

To realize the compression of data in distributed photovoltaic systems, this paper proposes a data compression algorithm that combines particle swarm optimization and multi-layer sparse autoencoder. Firstly, the particle swarm optimization algorithm was used to search the weights and thresholds globally to find the global optimal solution. Then, the weights and thresholds obtained in the previous step are used as inputs to the sparse autoencoder. Finally, the input data of the last hidden layer in the autoencoder is used as the compressed data, and the final compression result is obtained. Experiments show that the MSO algorithm is used to optimize the MSAE, and it has a good compression ratio for different types of photovoltaic data. And the compression ratio reaches up to 56%, which has a good data compression effect.
Effect of ultraviolet treatment on soft tissue healing and bacterial attachment to titania-coated zirconia
Authors: Tang Shuang , Zhang Jiebing , Ma Ping , Zhang Zutai
Published: October 2024

Zirconia is the most promising implant abutment material due to its excellent aesthetic effect, good biocompatibility and corrosion resistance. To obtain ideal soft tissue sealing, the implant abutment surface should facilitate cell adhesion and inhibit bacterial colonization. In this study, pre-sintered zirconia was placed in a suspension of titania (TiO2) and zirconium oxychloride (ZrOCl2) and heated in a water bath for dense sintering. A titania coating was prepared on the zirconia surface and subjected to UV irradiation. The surface morphology, elemental composition and chemical state of each group of samples were analyzed by scanning electron microscope, x-ray energy spectrometer, x-ray photoelectron spectroscopy and x-ray diffraction. The responses of human gingival fibroblasts (HGFs) and common oral pathogens Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) to modified zirconia were systematically assessed. Our findings demonstrated that the surface of titania-coated zirconia after UV irradiation produced a large number of hydroxyl groups, and its hydrophilicity was significantly improved. Meanwhile, the UV irradiation also greatly removed the hydrocarbon contaminants on the surface of the titania-coated zirconia. The UV-treated titania coating significantly promoted the proliferation, spreading, and up-regulation of adhesion-related genes and proteins of HGFs. Furthermore, the titania coating irradiated with UV could reduce the adhesion, colonization and metabolic activity of S. mutans and P. gingivalis. Therefore, UV irradiation of titania-coated zirconia can promote the biological behavior of HGFs and exert a significant antibacterial effect, which has broad clinical application prospects for improving soft tissue integration around zirconia abutments.
Biomimetic and soft lab-on-a-chip platform based on enzymatic-crosslinked silk fibroin hydrogel for 3D cell co-culture
Authors: Carvalho Mariana R , Caballero David , Kundu Subhas C , Reis Rui L , Oliveira Joaquim M
Published: October 2024

Integrating biological material within soft microfluidic systems made of hydrogels offers countless possibilities in biomedical research to overcome the intrinsic limitations of traditional microfluidics based on solid, non-biodegradable, and non-biocompatible materials. Hydrogel-based microfluidic technologies have the potential to transform in vitro cell/tissue culture and modeling. However, most hydrogel-based microfluidic platforms are associated with device deformation, poor structural definition, reduced stability/reproducibility due to swelling, and a limited range in rigidity, which threatens their applicability. Herein, we describe a new methodological approach for developing a soft cell-laden microfluidic device based on enzymatically-crosslinked silk fibroin (SF) hydrogels. Its unique mechano-chemical properties and high structural fidelity, make this platform especially suited for in vitro disease modelling, as demonstrated by reproducing the native dynamic 3D microenvironment of colorectal cancer and its response to chemotherapeutics in a simplistic way. Results show that from all the tested concentrations, 14 wt% enzymatically-crosslinked SF microfluidic platform has outstanding structural stability and the ability to perfuse fluid while displaying in vivo-like biological responses. Overall, this work shows a novel technique to obtain an enzymatically-crosslinked SF microfluidic platform that can be employed for developing soft lab-on-a-chip in vitro models.
Silk fibroin microspheres with photothermal nanocarrier encapsulation for anticancer drug delivery
Authors: Lu Changsheng , Shen Runqing , Wang Xiao
Published: October 2024

Controlled drug release systems are pivotal in optimizing therapeutic outcomes and mitigating side effects in treatment protocols. While traditional delivery vectors such as liposomes, micro/nanoparticles, and microspheres are effective, they often struggle with consistency in drug release rates. This study addresses these issues by integrating stimuli-responsive elements specifically magnetic, thermal, and pH-responsive components into drug delivery systems for precise control. Central to our approach is the use of silk fibroin (SF), chosen for its superior biocompatibility and tunable degradation kinetics. We developed uniform carrier microspheres (CMs) by embedding polydopamine nanoparticles (PDA NPs) into SF microspheres using a custom-designed microfluidic platform. The development process and the application of this platform are detailed, highlighting the precision in control achievable. These CMs showcased enhanced photothermal effects, with the thermal response finely adjustable by altering the PDA NPs concentration, achieving a notable temperature increase of 24.5 °C at 7.4 wt% concentration. High drug loading capacity (7.5%) and encapsulation efficiency (91.6%) were achieved, along with a pH-responsive release profile under near-infrared irradiation, paving the way for targeted anticancer drug delivery systems using the model drug doxorubicin hydrochloride. These findings underscore the potential of the developed CMs for external topical application, offering promising prospects for targeted cancer therapy utilizing drug-loaded microspheres.
Rising forest exposure and fire severity from climate warming amplify tree cover losses from wildfire in California
Authors: Wang Jonathan A , Goulden Michael L , Norlen Carl A , Bhoot Ved , Coffield Shane , Randerson James T
Published: October 2024

Warmer temperatures and severe drought are driving increases in wildfire activity in the western United States, threatening forest ecosystems. However, identifying the influence of fire severity on tree cover loss (TCL) is challenging using commonly used categorical metrics. In this study, we quantify regional trends in wildfire-driven TCL as the product of annual burned area, average forest exposure (pre-fire tree cover), and average fire severity (relative loss of tree cover). We quantified these trends with Landsat-based 30 m resolution fire and tree cover datasets for California wildfires from 1986–2021. Rates of TCL rose faster than trends in burned area, with the magnitude of tree cover area loss per unit of area burned increasing by 70% from 0.20 ± 0.05 during 1986–1996 to 0.34 ± 0.10 during 2011–2021. Forest exposure (pre-fire tree cover) within fires increased by 41% from a decadal mean of 23.4% ± 5.5% (1986–1996) to 33.1% ± 7.8% (2011–2021). Increasing forest exposure is associated with a recent expansion of fires in dense northern forests. Concurrently, fire severity (relative TCL) rose by 30% from a decadal mean of 50.4% ± 7.2% during 1986–1996 to 65.6% ± 6.5% during 2011–2021. We developed and applied a simple conceptual framework to quantify the combined effect of wildfires affecting denser forests and burning more severely. The combined effect of these two processes contributed to nearly half (47%) of the TCL since 1986, highlighting that recent changes in burned areas alone cannot explain observed tree cover trends. Linear regression analysis revealed that warmer summers and drier winters were significant drivers of increasing forest exposure, fire severity, and burned area (R
2 from 0.54 to 0.80, p ⩽ 0.001), particularly in the northern forests. Climate extremes had a disproportionate impact on dense forests that were once more resistant to wildfire but now face risks from a shifting wildfire regime.
A new Southwest Vortex objective identification algorithm based on precipitation perspective
Authors: Wang Qingyu , Cen Sixian , Huangfu Jingliang , Lai Xin , Yang Ruowen , Chen Wen , Wang Lin , Tang Yulian , Liu Kui
Published: October 2024

This study developed an objective identification algorithm for the Southwest Vortex (SWV), the dominant rainstorm system prevalent in Southwest China. Based on the TempestExt package, the newly developed SWV identification algorithm employed a 12 h minimum duration threshold, utilizing the high-resolution ERA5 dataset with 1 h intervals. The results reveal that the algorithm precisely identifies the SWV records documented in the SWV Yearbooks, achieving an optimal balance of high probability of detection and low false alarm rate. In addition, the algorithm can detect the SWVs in advance, offering a significant enhancement to SWV monitoring. Notably, the algorithm-detected SWVs exhibit a strong correlation with rainstorms, with a correlation coefficient of 0.70. From an on-site precipitation perspective, the algorithm-detected SWVs account for 87.6% of the observed rainstorm days. Collectively, this study introduces an updated tool for the SWV identification and underscores the algorithm’s promising potential in improving rainstorm forecasts in Southwest China.
Scarcity induces conflict in Puerto Rican fisheries
Authors: Gómez-Andújar Nicolás X , Woodill A John , Villegas Ciera , Watson James R
Published: October 2024

Small-scale fisheries provide vital food security for coastal communities worldwide, yet they face numerous challenges. In particular, fisheries conflicts arise when a marine resource is contested or disputed between a minimum of two actors. Despite the potentially large impacts of fisheries conflicts on marine-based economies, it is difficult to quantify the impact of conflict on fisheries production or on long-standing cooperative relationships that can be vital to the long-term sustainability of a given fishery. Previous work addressing fisheries conflicts has had a limited focus on quantitative measurements of how changes in fishing effort can influence how communities fall into conflict or make concerted efforts to cooperate. To address this knowledge gap, instances of conflict and cooperation amongst fishers in Puerto Rico were documented and categorized into different intensity levels. A linear probability model was then developed to estimate the probability of a conflict event occurring in a specific region, month, and year from 2012 to 2017. The model includes catch per unit effort as a predictor variable and controls for environmental factors. We found that an increase in catch per trip from the previous month has a negative and significant relationship with the probability of a conflict event. This result provides quantitative evidence for the supply-induced scarcity hypothesis, highlighting the importance of managing fisheries sustainably, to avoid future fisheries conflicts.
Impacts of potential energy oscillations on the friction of graphene and BN lubricants
Authors: Wang C Y , Li Z C , Wang L Y , Wang R J , Tang C
Published: October 2024

The frictional responses of graphene and boron nitride lubricants is studied from the perspective of the potential energy evolution. At a low normal load regime and high interface adhesion, friction can be effectively characterized by investigating the interfacial energy barrier formation process. By decomposing the energy evolution into strain and interfacial cohesive components, we find that the oscillation phase difference plays an essential role in the friction response and is controlled by the energy conversion between them. Analyses further reveal that the energy oscillations are excited by the vertical motion of the sliding asperity that induces periodic deformation and position changes in the lubrication systems. These new findings suggest the study of potential energy evolution is advantageous for understanding adhesive friction and infers the potential to leverage adhesion in 2D lubricant application through high conversion efficiency and out-of-phase oscillations between strain and cohesive energies.
Assessment, analysis and optimization for high temperature sliding wear process parameter with additive built nickel base superalloy
Authors: Jani S P , Arul Sujin Jose , Muthalagu R , Babu M Prakash , Perumalla Janaki Ramulu
Published: October 2024

Superalloys are highly demanding alloy for high temperature application. The conventional production process and metallurgical sustainability of the superalloy against the applications is the preamble of the existing research. Based on the review it is clear to say that the development of nickel base superalloy with advanced technique without compensating the quality is open for research. The nickel base superalloy is developed through additive manufacturing process following a metal laser sintering technique. The developed alloy is used to perform high temperature sliding wear analysis with the different input process conditions. Applied load, sliding duration and the working temperature are the defined process environment for the investigation. The process conditions are designed with twenty-seven set of experimental trials for statistical analysis and process assessment. The responses on surface roughness and the material loss with respect to the input process parameters are technically assessed and justifications made with the electron microscopic images. The surface topography has influenced due to applied load and the sliding duration. Applied load has influenced the contact area prone with severe wear and the ridges are notice from the microscopic analysis. The statistical analysis has proved that the influence of temperature is less and negotiable compared to the load and time factor. From the optimization process, the optimal parameter for the experimental design is 10 N, 100 °C and 30 min is the ultimate condition to produce best results from the high temperature sliding wear analysis.
Wear behaviour of T4 and T6 heat treated LM28 composite reinforced with ZrO2 particles by stir casting method
Authors: D Prabu , Palaniradja K
Published: October 2024

The current study was performed to investigate the metal alloy LM28’s wear characteristics, strengthened by fine and coarse ZrO2 were investigated after undergoing thermal treatment with T4 and T6 process. Aluminium degasification tablets were used during the stir casting liquid metallurgy process to produce the composites with less porosity. ZrO2 was employed as fine (10–30 μm) and coarse (80–120 μm) particles in a step size of 3% from 0 to 12 wt%. The traditional T4 and T6 HT process was applied to the composite materials (LM28 nZrO2). T4 heat treatment involved in elevating the composites to 450 °C for 120–180 min before quenching them into the oil and age them naturally for 8–42 days at ambient room temperature. T6 HT was performed in a routine fashion, but also underwent artificial aging at 190–240 °C for 3–7 h before normal cooling. When compared to T4 HT process and non-HT composites, the hardness of T6 HT composites gives better results against wear property. The ideal level of hardness and resistance to wear of the composite was found in T6 HT composites when tested with a pin on a disk throughout a range of sliding distances and loads. Scanning electron microscopy demonstrated that T4 HT and non-HT composites suffered more surface damage than T6 HT composites when subjected to the same load and sliding distance. Initially, material was removed by an abrasive wear process, but this shifted to an adhesive one as sliding distance increased. T6 thermal treated composites are ideal for usage in tough conditions as a result of their excellent hardness and resilience to wear.
Nonlinear saturation of reversed shear Alfvén eigenmode via high-frequency quasi-mode generation
Authors: CHENG 程 Zhiwen 志文 , WEI 魏 Guangyu 广宇 , YE 叶 Lei 磊 , QIU 仇 Zhiyong 志勇
Published: October 2024

A nonlinear saturation mechanism for reversed shear Alfvén eigenmode (RSAE) is proposed and analyzed, and is shown to be of relevance to typical reactor parameter region. The saturation is achieved through the generation of high-frequency quasi-mode due to nonlinear coupling of two RSAEs, which is then damped due to coupling with the shear Alfvén continuum, and leads to the nonlinear saturation of the primary RSAEs. An estimation of the nonlinear damping rate is also provided.
The role of metal-halide bond in the distortions and asymmetric non-covalent interactions in chiral hybrid perovskites
Authors: Fortino Mariagrazia , Mattoni Alessandro , Pietropaolo Adriana
Published: October 2024

Hybrid organic–inorganic perovskites have become interesting materials with a set of applications spanning from optoelectronics to energy conversion technologies. Recently, chiral hybrid perovskites encapsulating chiral organic ligands into the inorganic framework, have garnered significant attention for their promising potential in chiroptoelectronics. The generation of chirality and the corresponding chiroptical response are attributed to a chiral bias that arises from the chiral organic ligands extending into the inorganic framework. This was proposed to affect the inorganic geometry, propagating within the whole hybrid perovskite scaffold. Herein, we aim at clarifying the connection between coordination geometries and their distortions in chiral perovskites, by comparing tin and lead 2D perovskites encapsulating chiral methyl benzyl ammonium, S-(MBA+)2PbI4 and S-(MBA+)2SnI4. Ab-initio molecular dynamics simulations based on density functional theory methods were used and disclosed higher degrees of distortion for the tin-based chiral HOIP model, with prominent alteration of the equatorial coordination and evident bending of the equatorial angle. Such geometrical distortions stabilize non-covalent CH-π interaction observed in the tin-based chiral perovskite in which reduced ligand–ligand distances have been found during the dynamics. The substitution of lead with tin ions within the crystallographic coordinates of S-(MBA+)2PbI4 maintains the same degree of distortion observed in S-(MBA+)2SnI4. This result indicates that the central metal strongly influences the overall packing encapsulating the chiral ligands stabilized by non-covalent interactions. The more the central metal is a hard acid, the more the bond with the soft iodide base is weak or viceversa the more the central metal is a soft acid, the more the bond with a hard base is weak. The weakeness of the metal-halide bond increases the distortion and asymmetric non-covalent interactions within the chiral perovskite scaffold.
Heterogeneous interfaces of aluminum bronze/Inconel 718 dissimilar alloys under different wire arc directed energy deposition sequences
Authors: Chang Tianxing , Fang Xuewei , Zhou You , Zhang Hongkai , Xi Naiyuan , Ghafoor Shahid , Huang Ke
Published: October 2024

The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality, which has promising application potential in a large number of industrial areas. In this study, two components composed of ERCuAl-A2 aluminum bronze (CuAl9) and Inconel 718 nickel-based superalloy were fabricated with different deposition orders by wire-arc directed energy deposition. Subject to changes in heat input and thermophysical properties of the substrate, the transition region of the deposited Cu–Ni component with the bottom half of CuAl9 and the top half of Inconel 718 is narrow and serrated. This region features a laminated intermetallic compound layer due to the convection and rapid cooling in the molten pool. In contrast, the Ni–Cu component deposited in the opposite order exhibits a 2 mm gradient transition zone. Within this region, a large number of diverse precipitates were found as well as regional variations in grain size due to the multi-layer partial remelting. Both two components show strong bonds and their tensile specimens tested along the vertical direction always fracture at the softer CuAl9 side. Excellent tensile properties along the horizontal direction were obtained for Cu–Ni (Ultimate tensile strength: 573 MPa, yield stress: 302 MPa, elongation: 22%), while those of Ni–Cu are much lower due to the existence of the solidification cracks in the transition zone. The results from this study provide a reference for the additive manufacturing of Cu/Ni dissimilar alloy components, as well as their microstructure and mechanical properties control.
Focal volume optics for composite structuring in transparent solids
Authors: Zhang Bo , Wang Zhuo , Tan Dezhi , Gu Min , Yue Yuanzheng , Qiu Jianrong
Published: October 2024

Achieving high-level integration of composite micro-nano structures with different structural characteristics through a minimalist and universal process has long been the goal pursued by advanced manufacturing research but is rarely explored due to the absence of instructive mechanisms. Here, we revealed a controllable ultrafast laser-induced focal volume light field and experimentally succeeded in highly efficient one-step composite structuring in multiple transparent solids. A pair of spatially coupled twin periodic structures reflecting light distribution in the focal volume are simultaneously created and independently tuned by engineering ultrafast laser-matter interaction. We demonstrated that the generated composite micro-nano structures are applicable to multi-dimensional information integration, nonlinear diffractive elements, and multi-functional optical modulation. This work presents the experimental verification of highly universal all-optical fabrication of composite micro-nano structures with independent controllability in multiple degrees of freedom, expands the current cognition of ultrafast laser-based material modification in transparent solids, and establishes a new scientific aspect of strong-field optics, namely, focal volume optics for composite structuring transparent solids.
Self-adjusting voxelated electrochemical three-dimensional printing of metallic microstructures
Authors: Meng Xianghe , Wu Xiaomo , Shen Xingjian , Xu Yan , Zhang Hao , Chen Mingjun , Xie Hui
Published: October 2024

Microscale metallic structures enhanced by additive manufacturing technology have attracted extensive attention especially in microelectronics and electromechanical devices. Meniscus-confined electrodeposition (MCED) advances microscale 3D metal printing, enabling simpler fabrication of superior metallic microstructures in air without complex equipment or post-processing. However, accurately predicting growth rates with current MCED techniques remain challenging, which is essential for precise structure fabrication and preventing nozzle clogging. In this work, we present a novel approach to electrochemical 3D printing that utilizes a self-adjusting, voxelated method for fabricating metallic microstructures. Diverging from conventional voxelated printing which focuses on monitoring voxel thickness for structure control, this technique adopts a holistic strategy. It ensures each voxel’s position is in alignment with the final structure by synchronizing the micropipette’s trajectory during deposition with the intended design, thus facilitating self-regulation of voxel position and reducing errors associated with environmental fluctuations in deposition parameters. The method’s ability to print micropillars with various tilt angles, high density, and helical arrays demonstrates its refined control over the deposition process. Transmission electron microscopy analysis reveals that the deposited structures, which are fabricated through layer-by-layer (voxel) printing, contain nanotwins that are widely known to enhance the material’s mechanical and electrical properties. Correspondingly, in situ scanning electron microscopy (SEM) microcompression tests confirm this enhancement, showing these structures exhibit a compressive yield strength exceeding 1 GPa. The indentation tests provided an average hardness of 3.71 GPa, which is the highest value reported in previous work using MCED. The resistivity measured by the four-point probe method was (1.95 ± 0.01) × 10−7 Ω·m, nearly 11 times that of bulk copper. These findings demonstrate the considerable advantage of this technique in fabricating complex metallic microstructures with enhanced mechanical properties, making it suitable for advanced applications in microsensors, microelectronics, and micro-electromechanical systems.
Electrochemical cutting with flexible electrode of controlled online deformation
Authors: Liu Lin , Xu Zhengyang , Hao Yuheng , Teng Yunlong
Published: October 2024

Improvements in aero-engine performance have made the structures of the aero-engine components increasingly complex. To better adapt to the processing requirements of narrow twisted channels such as an integral shrouded blisk, this study proposes an innovative method of electrochemical cutting in which a flexible tube electrode is controlled by online deformation during processing. In this study, the processing principle of electrochemical cutting with a flexible electrode for controlled online deformation (FECC) was revealed for the first time. The online deformation process of flexible electrodes and the machining process of profiles were analysed in depth, and the corresponding theoretical models were established. Conventional electrochemical machining (ECM) is a multi-physical field-coupled process involving electric and flow fields. In FECC, classical mechanics are introduced into the tool cathode, which must be loaded at all times during the machining process. Therefore, in this study, before and after the deformation of the flexible electrode, a corresponding simulation study was conducted to understand the influence of the online deformation of the flexible electrode on the flow and electric fields. The feasibility of flexible electrodes for online deformation and the validity of the theoretical model were verified by deformation measurements and in situ observation experiments. Finally, the method was successfully applied to the machining of nickel-based high-temperature alloys, and different specifications of flexible electrodes were used to complete the machining of the corresponding complex profiles, thereby verifying the feasibility and versatility of the method. The method proposed in this study breaks the tradition of using a non-deformable cathode for ECM and adopts a flexible electrode that can be deformed during the machining process as the tool cathode, which improves machining flexibility and provides a valuable reference to promote the ECM of complex profiles.
Bending/force switching control of pneumatic soft actuator based on multi-sensor fusion
Authors: Fang Jiwen , Qin Shuangfa , Gao Renxiang , Li Chong , Lv Mingming
Published: October 2024

The soft actuator has unlimited freedom, and can realize the grasping of irregular or fragile objects. A pneumatic soft actuator is designed in this paper, which consists of a series of symmetrically distributed pneumatic chambers. The soft actuator consists of a top expansion layer composed of 20 chambers and a bottom restraint layer. The Yeoh model and the finite element method (FEM) were employed to analyze the bending of the soft actuator. To improve the tracking performance, a PID strategy of the endocrine system (ES-PID) based on the neuroendocrine thyroid hormone regulation mechanism was constructed to tune the bending deformation. To achieve steady and precise force control, a bending/force switching control algorithm based on multi-sensor fusion is designed to realize high control accuracy. The bending/force switching control strategy mainly consists of two feedback loops for bending control, a force control, and a switching control. In the experimental process, the bending control is the primary control, and the force control is the primary control when the switching condition is satisfied. In order to prevent the occurrence of a false switching action, a switching factor is constructed using the method of successive comparison of neighboring values. Finally, several experiments are carried out to verify the effectiveness and feasibility of the control algorithm.
A novel approach to iris recognition at-a-distance: leveraging BW-CNN framework
Authors: Shirke Swati , Midhunchakkaravarthy Divya , Deshpande Vivek
Published: October 2024

This paper introduces a novel iris recognition framework by integrating the Black Widow Optimization (BWO) algorithm with Convolutional Neural Networks (CNNs), forming the Black Widow-CNN (BW-CNN) framework. The necessity of this work stems from the increasing demand for secure and reliable biometric systems, particularly in iris recognition, which has become a critical tool in sectors such as national security, financial transactions, and contactless access controls. Traditional iris recognition systems face significant limitations under varying environmental conditions and subject distances, often compromising accuracy. The proposed BW-CNN framework is necessary as it addresses these challenges by offering a robust solution capable of precise iris detection even at a distance and in challenging real-world conditions. This approach enhances feature extraction and classification accuracy and streamlines the recognition process. The experimental results, evaluated across multiple datasets, demonstrate the superior performance of the BW-CNN framework over existing methods, showcasing its potential for deployment in high-security and real-time applications.
Mechanical performance of dissimilar Al6082 aluminum and AZ91 magnesium alloy joints produced by friction stir welding
Authors: K Raghu Ram Mohan Reddy , Muthadi Srinivas Reddy , K Venkata Rao , Dumpala Ravikumar , Ratna Sunil B
Published: October 2024

The current research work aims to produce a defect free joint of Al6082 aluminum and AZ91 magnesium alloy sheets by friction stir welding (FSW) at various tool rotational and travel speeds with an objective to obtain the best combination of welding parameters to produce quality joint. The weld joint that was produced at the combination of 1400 rpm tool rotational speed and 30 mm min−1 feed exhibited defect free stir zone. Microstructural studies carried out in the weld joint demonstrated mechanical mixing of base materials from both the alloys in the stir zone. The mixing of Al6082 and AZ91 alloys was clearly appeared in the weld zone. It can be observed that the x-ray diffraction studies clearly demonstrated the development of intermetallics in the weld region. Higher hardness was observed for the joints that can be ascertained to the presence of more mixed regions in the stir zone that contains hard and brittle intermetallics. From the tensile test data, lower strength (175.71 ± 4.24 MPa) was observed for the weld joint compared with Al6082 (242. 6 ± 11.4 MPa) and AZ91 (205.27 ± 6.39 MPa) base materials. Furthermore, the ductility of the weld joint was measured as marginally higher than the AZ91 Mg alloy and lower than the Al6082 alloy. It can be concluded that the defect free weld joints of Al6082-AZ91 alloys can be successfully produced by FSW for structural applications targeted for dry environment.
Graphene pixel based broadband polarization insensitive THz absorber
Authors: Sur Surajit , Bhattacharya Rajarshi
Published: October 2024

Suppressing undesired radiation and eliminating stray radiation in a high-frequency circuit might be challenging. Ultra-high frequency (UHF) electromagnetic wave absorbers are finding new applications in both the military and civilian domains. Obtaining an ultra-wide absorption band in a thin, single-layer Terahertz absorber becomes difficult. Also, achieving perfect absorption bandwidth on transverse electric (TE) and transverse magnetic (TM) mode is very sensitive. This paper presents a polarization-independent graphene-based absorbers with a near unity absorption band of 2.32 THz and 3.78 THz in a lower mid-infrared regime. The structure’s unit cell consists of cross-slot circular patches with Au as a ground separated by SiO2. To improve the absorption band another graphene layer was placed between the top and dielectric material. The absorber is polarization independent under normal incidence because of the deposited graphene structure’s fourfold symmetry. Both TE and TM polarizations were investigated, with wide-band absorption observed up to 60° incident angles in both cases. In terms of the lowest frequency of absorption, the prototype is deemed to be as thin as

∼
0.1

λ

max

for both absorbers. Similarly, the effective homogeneity criteria in the subwavelength region are supported by the unit cell’s period of

∼
0.1

λ

max

.

The proposed absorber-2 shows

10
%

higher FBW than existing work.
Heart rate variability series during physical activity analyzed with multifractal techniques
Authors: Aguilar-Molina Ana María , Zamora-Justo José Alberto , Angulo-Brown Fernando , Muñoz-Diosdado Alejandro
Published: October 2024

Our study uses multifractal techniques to analyze time series of heart rate variability series (RR time series) during rest and physical activity. Subsets of the RR time series data were extracted for each stage. The multifractal spectra of the RR time series data were constructed using the method developed by Chhabra and Jensen. Then, parameters such as width, symmetry, and curvature of the multifractal spectra were calculated. The multifractal spectra obtained at resting stage were broad, skewed to the right, and they had small curvatures around in the maximum. On the contrary, the subsets of the RR time series obtained during physical activity were narrow, skewed to the left, and showed an increased curvature value around the maximum. In addition, these multifractal spectrum parameters shown significant differences in series of subjects who perform physical activity regularly and sedentary. Furthermore, the results obtained from this study were compared with data from previous works involving patients with congestive heart failure and healthy subjects.
Understanding following patterns among high-performance athletes
Authors: Rodríguez Jorge P , Arola-Fernández Lluís
Published: October 2024

Professional sport enhances social interaction among athletes through meetings such as training groups, large-scale competitions and sponsored events. Among these, the Olympic Games represent the largest international competition, having a unique global impact. This event is assumed to promote international cooperation through the values of sport, becoming an opportunity for creating global connections between athletes. Here we want to understand the properties of the following activity, an indicator of the information flows, between highly successful Olympic athletes both at microscopic and macroscopic scales. To do so, we built a database including the Twitter usernames of Olympic medallists in Tokyo 2020, using it for creating the follower-followee network, a directed network representing who followed whom in this social network. From our database of 1052 athletes, we found 7326 connections among 964 athletes. The most popular athletes, those with highest number of followers, were Kevin Durant (basketball, USA), Allyson Felix (athletics, USA), Teddy Riner (judo, France), Alex Morgan (football, USA) and Simone Biles (gymnastics, USA). The macro-scale network structure displayed organized patterns related to microscopic—node—properties such as sex, country and sport, evidencing assortative connectivity patterns. These assortative patterns highlighted the need for a model quantifying the features’ importance in the followees choice, which we introduced through a gravity approach modelling the number of connections between homogeneous groups. Our research remarks the importance of datasets built from public exposure of professional athletes, serving as a proxy to investigate interesting aspects of many complex socio-cultural systems at different scales.
Infrastructure first principles for the Anthropocene
Authors: Chester Mikhail , Allenby Braden
Published: October 2024

There appears to be a growing decoupling between the conditions that infrastructures were designed for and today’s rapidly changing environments. Infrastructures today are largely predicated on the technologies, goals, and governance structures from a century ago. While infrastructures continue to deliver untold value, there is growing evidence that these critical, basic, and lifeline systems appear ill-equipped to confront the volatility, uncertainty, accelerating conditions, and complexity that define them and their changing environments. Innovative and disruptive first principles are needed to guide infrastructures in the Anthropocene. Drawing from emerging infrastructure research and disciplines that appear better able to confront disruption and change, a novel set of first principles are identified: (1) Plan for complex conditions and surprise; (2) Recouple with agility and flexibility; (3) Govern for exploration and instability; (4) Build consensus as control decentralizes; (5) Restructure to engage with porous boundaries; and, (6) Cyberthreat planning is now mission critical. These principles should guide infrastructure planning recognizing the changing nature and increasingly obsolete boundaries that have defined engineered systems in the modern era.
Semitoric Families
Authors: Le Floch Yohann , Palmer Joseph
Published: October 2024

Semitoric systems are a type of four-dimensional integrable system for which one of the integrals generates a global

S

1

\mathbb {S}^1

-action; these systems were classified by Pelayo and Vũ Ngọc in terms of five symplectic invariants. We introduce and study semitoric families, which are one-parameter families of integrable systems with a fixed

S

1

\mathbb {S}^1

-action that are semitoric for all but finitely many values of the parameter, with the goal of developing a strategy to find a semitoric system associated to a given partial list of semitoric invariants. We also enumerate the possible behaviors of such families at the parameter values for which they are not semitoric, providing examples illustrating nearly all possible behaviors, which describes the possible limits of semitoric systems with a fixed

S

1

\mathbb {S}^1

-action. Furthermore, we introduce natural notions of blowup and blowdown in this context, investigate how semitoric families behave under these operations, and use this to prove that each Hirzebruch surface admits a semitoric family with certain desirable invariants; these families are related to the semitoric minimal model program. Finally, we give several explicit semitoric families on the first and second Hirzebruch surfaces showcasing various possible behaviors of such families which include new semitoric systems.