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Enhanced piezoelectricity and lager strain in Bi0.5Li0.5HfO3 doped sodium potassium niobate-based ceramics with high Curie temperatures

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Ceramics International 2025年第15期51卷 20992-20998页

作者： Li, Yuxuan Peng, Zhanhui Chai, Qizhen Wang, Yuanhao Nie, Xinru Wei, Lingling Liang, Pengfei Wu, Di Chao, Xiaolian Yang, Zupei Key Laboratory for Macromolecular Science of Shaanxi Province Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Laboratory for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University Shaanxi Xi'an710062 China Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education School of Electronic Science and Engineering Faculty of Electronic and Information Engineering Xi'an Jiaotong University Xi'an710049 China School of Physics and Information Technology Shaanxi Normal University Shaanxi Xi'an710062 China School of Chemistry and Chemical Engineering Shaanxi Normal University Shaanxi Xi'an710062 China

High-temperature electronic ceramics are indispensable in applications such as the automotive sector, aerospace, oil exploration and other fields. Potassium sodium niobate-based (KNN-based) ceramics have emerged as critical materials for the development of environmentally friendly high-temperature sensors, filters, and other electronic devices. However, achieving a combination of superior piezoelectric properties and a high Curie temperature in KNN-based ceramics remains a significant challenge. In this study, we employed a strategy of constructing an orthorhombic-tetragonal (O-T) phase boundary with the objective of enhancing the piezoelectric properties of KNN-based ceramics and introduced Li+ to optimize the Curie temperature. In (1-x)K0.48Na0.52NbO3-xBi0.5Li0.5HfO3 ceramics, we realized high piezoelectric constant ∼ 340 pC/N, large strain (∼0.21 %) and elevated Curie temperature (Tc ∼ 354 °C) simultaneously. These findings not only identify a promising candidate for high-temperature sensors and filters but also provide valuable insights for advancing the design of high Curie temperature and lead-free piezoelectric ceramics based on KNN systems. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Piezoelectricity

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Decoupling the nonthermal effect of current by electrically assisted crystal plasticity modeling of Ni-based single crystal superalloys

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材料科学技术（英文版） 2025年第1期204卷 91-103页

作者： Jia Gao Hongwei Li Xin Zhang Guangda Shao Zhiyu Xiang Xinxin Sun State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of High-performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of High-performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi'an 710072China School of Mechanical and Electrical Engineering Northwestern Polytechnical UniversityXi'an 710072China Ministry of Industry and Information Technology Key Laboratory of Aeroengine Technology Northwestern Polytechnical UniversityXi'an 710072China

The electrically assisted(EA)deformation process has received considerable attention in recent years,ac-companied by research on current-induced deformation ***,there are still challenges in eliminating thermal effects,which have prevented a comprehensive understanding of the underlying current-induced *** for a single crystal(SC)in research provides advantages in decou-pling the nonthermal effect of electric current at smaller scales and eliminating the complex interactions that exist in polycrystalline ***,the innovation of this work lies in decoupling the non-thermal effect of electric current and conducting a comprehensive analysis of anisotropic deformation and mechanisms within a Ni-based SC with different crystallographic axes and various current directions dur-ing electrically assisted tensile simulation.A significant tension axis direction in the SC during EA tension was induced by the combination of a higher current direction factor(|cos θ|)and a dimensionless factor for the current density(Jα/Jα0|)along the[100]*** stress drop within the SC due to the nonthermal effect of electric current generally increased with increasing current *** was attributed to the increased dislocation density differences and decreased *** increased stress anisotropy of the SC at a current direction of 45° was attributed to fewer activated(111)slip systems and the pinning effect of more dislocations within these *** study advances our understanding of the thermal and nonthermal effects of electric current and offers valuable insights for the informed application of EA deformations in industrial and aerospace settings with SC superalloys.

关键词： Electrically assisted(EA)tension Single crystal superalloys Nonthermal effect Anisotropy Tension axis Current direction

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Effectiveness of Precursor Emission Reductions for the Control of Summertime Ozone and PM2.5 in the Beijing–Tianjin–Hebei Region under Different Meteorological Conditions

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Advances in Atmospheric sciences 2025年第4期42卷 653-669页

作者： Jing QIAN Hong LIAO Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044JiangsuChina

We used observed concentrations of air pollutants,reanalyzed meteorological parameters,and results from the Goddard Earth Observing System Chemical Transport Model to examine the relationships between concentrations of maximum daily 8-h average ozone(MDA8 O_(3)),PM_(2.5)(particulate matter with diameter of 2.5μm or less),and PM_(2.5)components and 2-m temperature(T2)or relative humidity(RH),as well as the effectiveness of precursor emission reductions on the control of O_(3) and PM_(2.5) in Beijing–Tianjin–Hebei(BTH)under different summertime temperature and humidity *** observed(simulated)MDA8 O_(3) and PM_(2.5) concentrations increased as T2 went up,with linear trends of 4.8(3.2)ppb℃^(−1) and 1.9(1.5)μg m^(−3)℃^(−1),*** results showed that the decreases in MDA8 O_(3) from precursor emission reductions were more sensitive to T2 than to *** a larger proportion of volatile organic compound(VOC)emissions at higher T2 was more effective for the control of summertime O_(3) in *** the control of summertime PM_(2.5) in BTH,reducing nitrogen oxides(NOx)combined with a small proportion of VOCs was the best *** magnitude of reduction in PM_(2.5) from reducing precursor emissions was more sensitive to RH than to T2,with the best efficiency at high *** from this study are helpful for formulating effective policies to tackle O_(3) and PM_(2.5) pollution in BTH.

关键词： ozone PM_(2.5) emission reductions meteorological conditions

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Circular Polarization Selective Metasurface for Folded Reflectarray Antenna at Ka-band

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IEEE Antennas and Wireless Propagation Letters 2025年第5期24卷 1278-1282页

作者： Huang, Heng Ye, Jingxin Xue, Chunhua Li, Teng Guangxi University of Science and Technology Guangxi Key Laboratory of Multidimensional Information Fusion for Intelligent Vehicles School of Electronic Engineering Liuzhou545006 China Southeast University State Key Laboratory of Millimeter Waves School of Information Science and Engineering Nanjing210096 China Purple Mountain Laboratories Nanjing211111 China

A circular polarization (CP) folded reflectarray antenna is proposed at the 30 GHz band. A five-layered circular polarization selective metasurface (CPSM) is introduced to realize the path folding for a CP source. The CPSM element consists of two back-to-back connected CP antennas with a slant I-shaped slot on the ground plane for electromagnetic wave coupling. A 2×2 patch array with a cross-shaped strip embedded in the center is designed for CP response. To enhance angular response stability, square patches are stacked on both the top and bottom sides. A metallic post through all layers is placed in the center to balance the transmission and axial ratio (AR) bandwidth. The proposed CPSM element exhibits superior AR and amplitude performance under larger-angle oblique incidence which promises the folded reflectarray antenna achieves excellent aperture efficiency along with substantial AR and gain bandwidth. To verify the proposed CPSM, a 40×40 folded reflectarray is presented. The measured results show a 3 dB AR bandwidth of 20.3% and a 3 dB gain bandwidth of 15.13%. The peak gain of 33.89 dBic is found at 30 GHz with an aperture efficiency of 60.9%. The remarkable results demonstrate the proposed CPSM for antenna engineering applications. © 2002-2011 IEEE.

关键词： Reflection

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Novel Sparse Codebook Design for MIMO-SCMA

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IEEE Transactions on Vehicular technology 2025年第5期74卷 8407-8412页

作者： Lei, Tuofeng Luo, Qu Ni, Shuyan Chen, Shimiao Yu, Lisu Xiao, Pei Space Engineering University Key Laboratory of Intelligent Space TTC&O Ministry of Education Beijing101416 China University of Electronic Science and Technology of China National Key Laboratory of Science and Technology on Communications Chengdu610054 China Nanchang University School of Information Engineering Nanchang330031 China Xidian University State Key Laboratory of ISN Xi'an710071 China

The combination of multiple-input multiple-output (MIMO) and sparse code multiple access (SCMA), referred to as MIMO-SCMA, can be leveraged to achieve high spectrum efficiency and provide massive connectivity for future machine -type communication networks. This paper aims to design enhanced sparse codebooks for MIMO-SCMA by jointly combining frequency and spatial diversity over Rayleigh fading channels. First, based on the pairwise error probability (PEP), novel codebook design criteria have been presented, namely the hybrid minimum product distance of the Euclidean distance (MPD-ED) and the minimum Euclidean distance of the superimposed constellation at each frequency element (MED-FE). Then, enhanced mother constellations (MC) are proposed by maximizing the MPD-ED of the MC based on the alternating optimization. Subsequently, the multi-dimensional codebooks are obtained by applying user-specific rotation of the proposed MC to maximize the MED-FE, where the unitary rotations are considered to fully leverage the Euclidean space of the transmit antennas while maintaining the MPD-ED value of the codebook. Finally, numerical results demonstrate that the proposed approach significantly outperforms the state-of-the-art codebooks. © 1967-2012 IEEE.

关键词： Fading channels

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Laser Scribed CNTs/PEEK/TPU Composites Film for High-Performance Stretchable Electrodes

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IEEE Sensors Journal 2025年第10期25卷 16666-16674页

作者： Jiang, Caiyun Tang, Lei Hou, Jian Ding, Guqiao Sheng, Bin University of Shanghai for Science and Technology College of Optical-Electrical and Computer Engineering Shanghai200093 China Shanghai Key Laboratory of Modern Optical Systems Engineering Research Center of Optical Instrument and System Shanghai200093 China Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences State Key Laboratory of Materials for Integrated Circuits Shanghai200050 China

In this article, an elastic composite material comprising carbon nanotubes (CNTs), polyether-ether-ketone (PEEK), and thermoplastic polyurethane (TPU) is presented, in which direct laser-induced graphitization was used to fabricate high-performance stretchable electrodes. The introduction of CNTs can enhance the conductivity and mechanical strength of the composites, thus improving the overall performance of the sensors. Flexible strain sensors with porous structures were prepared by appropriate encapsulation methods, which exhibited superior gauge factors (GFs) of 72, 367, and 972 in the 0%–30%, 30%–44%, and 44%–53% strain regions, respectively. Furthermore, it features a rapid response time (100 ms), excellent stability and durability, and is capable of detecting both large-scale human movement and monitoring of small physical signals. In addition, patterned laser-induced graphene interdigital electrodes (LIG-IDEs) were fabricated on composites using laser light. Highly sensitive humidity sensors were obtained using graphene oxide as the humidity-sensing material for respiratory monitoring and noncontact sensing. The thermoplastic properties of TPU allow the straight fiber to be thermoformed into highly stretchable helical electrode, which was of a helix index of 5 and with a high-quality factor (Q = 130) at 1250% strain. In conclusion, the preparation of LIG on stretchable composite films by direct laser scribing shows a promising approach for large-scale fabrication of wearable devices. © 2001-2012 IEEE.

关键词： Humidity sensors

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Plasma sprayed thermal barrier coatings with outstanding ultrahigh temperature thermal shock resistances through gradient porosity level optimizations

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Ceramics International 2025年第13期51卷 17484-17491页

作者： Liu, Liqiang Xu, Wenhu Shi, Junmiao Zhang, Xian-Cheng Tu, Shan-Tung Key Laboratory of Pressure Systems and Safety Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology Shanghai200237 China School of Mechanical and Electrical Engineering Changchun University of Science and Technology Changchun130022 China

In this study, the YSZ thermal barrier coatings (TBCs) with gradient porosity was developed through design the spraying parameters. The effect of the gradient porosity on the bond strength and thermal shock life was investigated, and the failure mechanism of the TBCs was explored. This article prepared three coatings with different porosities, tested the bonding strength of different porosities using the tensile method, and tested the thermal shock resistance of the coatings using water quenching after thermal shock. By simulating the residual stress inside the coatings after spraying, the failure mechanism of the coatings after thermal shock was analyzed. With the decrease of the porosity from TBC I to TBC III, the residual stress concentration after the spraying raised. Subsequently, the bond strength of the TBCs decreased form 37 MPa–31 MPa owing to the residual stress evolution. All of the three TBCs underwent three thermal shock test without macroscopic spalling. During the thermal shock test, tensile horizontal stress formed and promoted the formation of vertical cracks. Tensile vertical stress concentrated at the top - coat/bond - coat (TC/BC) interface significantly, inducing horizontal crack adjacent to the interface. Additionally, the TC layer surface zone sintered under the oxygen-acetylene flame heating. Then tensile vertical stress concentration was formed in the sintering zone region, and horizontal crack was detected in the TC layer. The connection of the vertical cracks and horizontal cracks was responsible for the spalling and failure of the TC layer. © 2025

关键词： Spalling

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Two efficient beamforming methods for hybrid IRS-aided AF relay wireless networks

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science China(information sciences) 2025年第4期68卷 363-379页

作者： Xuehui WANG Qingbo LI Wen ZHU Feng SHU Mengxing HUANG Fuhui ZHOU Riqing CHEN Cunhua PAN Yongpeng WU Jiangzhou WANG School of Mathematics and Statistics Hainan Normal University Key Laboratory of Data Science and Smart Education Ministry of Education Hainan Normal University School of Information and Communication Engineering Hainan University Collaborative Innovation Center of Information Technology Hainan University School of Electronic and Optical Engineering Nanjing University of Science and Technology College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Digital Fujian Institute of Big Data for Agriculture Fujian Agriculture and Forestry University National Mobile Communications Research Laboratory Southeast University Shanghai Key Laboratory of Navigation and Location Based Services Shanghai Jiao Tong University School of Engineering University of Kent

Owing to its ability to mitigate the double-fading effect by amplifying the reflected signal, the active intelligent reflecting surface(IRS) has garnered significant attention. In this paper, an amplify-and-forward(AF) relay network assisted by a hybrid IRS consisting of both passive and active units is developed. A signal-to-noise ratio(SNR) maximization problem is formulated, where the AF relay beamforming matrix and the hybrid IRS reflecting coefficient matrices for two-time slots need to be optimized. To address the SNR maximization problem, this paper proposes both a high-performance(HP) method and a low-complexity(LC) method. The HP method is based on the semidefinite relaxation and fractional programming(SDR-FP)algorithm, with rank-1 solutions obtained through Gaussian randomization. For the LC method, the amplification coefficient of each active IRS element is assumed to be equal. The SNR maximization problem is then addressed using the whitening filter,generalized power iteration, and generalized Rayleigh-Ritz(WF-GPI-GRR) approach. Simulation results show that compared with the benchmarks, such as the passive IRS-aided AF relay network, the proposed HP-SDR-FP and WF-GPI-GRR methods achieve significant rate improvements. In particular, the HP-SDR-FP and WF-GPI-GRR methods yield more than a 135.0%rate gain when the transmit power Ps of the source is 10 dBm. Furthermore, the proposed HP-SDR-FP method outperforms the WF-GPI-GRR method in terms of rate performance.

关键词： double-fading intelligent reflecting surface active elements passive elements hybrid IRS AF relay

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MATD3-Based End-Edge Collaborative Resource Optimization for NOMA-Assisted Industrial Wireless Networks

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Computers, Materials & Continua 2025年第2期82卷 3203-3222页

作者： Ru Hao Chi Xu Jing Liu College of Information Engineering Shenyang University of Chemical TechnologyShenyang110142China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016China Key Laboratory of Networked Control Systems Chinese Academy of SciencesShenyang110016China

Non-orthogonal multiple access (NOMA) technology has recently been widely integrated into multi-access edge computing (MEC) to support task offloading in industrial wireless networks (IWNs) with limited radio resources. This paper minimizes the system overhead regarding task processing delay and energy consumption for the IWN with hybrid NOMA and orthogonal multiple access (OMA) schemes. Specifically, we formulate the system overhead minimization (SOM) problem by considering the limited computation and communication resources and NOMA efficiency. To solve the complex mixed-integer nonconvex problem, we combine the multi-agent twin delayed deep deterministic policy gradient (MATD3) and convex optimization, namely MATD3-CO, for iterative optimization. Specifically, we first decouple SOM into two sub-problems, i.e., joint sub-channel allocation and task offloading sub-problem, and computation resource allocation sub-problem. Then, we propose MATD3 to optimize the sub-channel allocation and task offloading ratio, and employ the convex optimization to allocate the computation resource with a closed-form expression derived by the Karush-Kuhn-Tucker (KKT) conditions. The solution is obtained by iteratively solving these two sub-problems. The experimental results indicate that the MATD3-CO scheme, when compared to the benchmark schemes, significantly decreases system overhead with respect to both delay and energy consumption.

关键词： Industrial wireless networks(IWNs) multi-access edge computing(MEC) non-orthogonal multiple access(NOMA) task offloading resource allocation

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MLP-Mixer based Masked Auto encoders Are Effective, Explainable and Robust for Time Series Anomaly Detection 51st

MLP-Mixer based Masked Auto encoders Are Effective, Explaina...

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51st International Conference on Very Large Data Bases, VLDB 2025

作者： Tang, Qideng Dai, Chaofan Wu, Yahui Zhou, Haohao National Key Laboratory of Information Systems Engineering National University of Defense Technology China National University of Defense Technology China

Time series anomaly detection remains one of the most active research areas in data mining due to its wide range of real-world applications. In recent years, numerous deep learning-based methods have been proposed for this task. However, deep learning-based methods fail to detect subsequence anomalies with long durations, lack explain ability, and are vulnerable to training set contamination. This paper addresses these issues by proposing a novel deep learning framework for effective, explainable, and robust time series anomaly detection. Our framework, MMA, incorporates the MLP-Mixer backbone with a Masked Auto encoder-based anomaly detection approach to allow for a significantly larger input window size (10 to 20 times larger than the input window sizes of current models). This larger input window enables our model to detect challenging subsequence anomalies. Meanwhile, a contrast learning module is proposed to aid in detecting subtle anomalies that fail to be identified by residual errors. Furthermore, a dynamic anomaly filtering method is introduced to mitigate the impact of subsequence anomalies on the reconstruction of surrounding normal regions to reduce false alarms. Extensive experiments on univariate and multivariate time series datasets demonstrate that our proposed framework significantly outperforms state-of-the-art methods across rigorous evaluation metrics. Additionally, MMA has a strong ability to reconstruct potential normal patterns in anomalous regions, providing high levels of explain ability. Moreover, MMA demonstrates high robustness to various types of training set pollution. © 2025, VLDB Endowment, All rights reserved.

关键词： Mixers (machinery)

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