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Multifield tunable valley splitting in two-dimensional MXene Cr2COOH

Physical Review B 2023年第19期108卷 195424-195424页

作者： Ping Li Chao Wu Cheng Peng Mutian Yang Wei Xun State Key Laboratory for Mechanical Behavior of Materials Center for Spintronics and Quantum System School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 People's Republic of China State Key Laboratory for Surface Physics and Department of Physics Fudan University Shanghai 200433 People's Republic of China Faculty of Electronic Information Engineering Huaiyin Institute of Technology Huaian 223003 People's Republic of China

Manipulation of the valley degree of freedom provides a paradigm in quantum information technology. Here, through first-principles calculations and model analysis, we demonstrate that monolayer Cr2COOH MXene is a promising candidate material for valleytronics applications. We reveal that Cr2COOH is a ferromagnetic semiconductor and harbors valley features. Due to the simultaneous breaking inversion symmetry and time-reversal symmetry, the valleys are polarized spontaneously. Moreover, the valley polarization is sizable in both the valence and conduction bands, benefiting the observation of the anomalous valley Hall effect. More remarkably, the valley splitting can be effectively tuned by the magnetization direction, strain, and ferroelectric substrate. More interestingly, the ferroelectric substrate Sc2CO2 can not only regulate the MAE, but also tune valley polarization state. Our findings offer a practical way for realizing highly tunable valleys by multiferroic couplings.

关键词： First-principles calculations Magnetic anisotropy Spin-orbit coupling Valley degrees of freedom Valleytronics

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Composition-Dependent Optical, Dielectric and D-Orbital Electron Characteristic of High-Throughput Horizontal Composition Gradient Li1-Xmgxti2o4 Combinatorial Film

SSRN

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SSRN 2024年

作者： Wang, Yueming Li, Yongfu Wei, Mingyang Jin, Kui Li, Qian Zhang, Ding Zhou, Xiang'an Han, Yating Lian, Jie School of Information Science and Engineering Shandong Provincial Key Laboratory of Laser Technology and Application Shandong University Qingdao266237 China Center for Optics Research and Engineering Key Laboratory of Laser & Infrared System Ministry of Education Shandong University Qingdao266237 China National Lab for Superconductivity Institute of Physics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China

The unique physical properties of LiTi2O4 and MgTi2O4 have attracted extensive research interest in various fields, including new type batteries and high-temperature superconductors. However, the intricate mechanism governing the d-orbital electron within this system still awaits further excavation. Herein, we employed the combinatorial laser molecular beam epitaxy technique to fabricate a high-quality composition-spread Li1-xMgxTi2O4 film and evaluated its structure, composition, surface morphology and phonon modes by X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, and Raman scattering spectroscopy. The optical constants and dielectric properties of diverse microregions with varying Li/Mg content over a wide spectral range (189-1658 nm) were measured nondestructively using the ellipsometer, revealing the composition-dependent optical properties of Li1-xMgxTi2O4. By fitting the second derivative spectra (d2Ε/dE2) using the standard critical point model, five transitions within the detected spectral range were observed. Combining previous analyses and first-principles calculation, we attribute the critical points to crystal field (CF) transition 4A2 →4T1 originating from the spin state of tetrahedral Li/Mg ions, the binding of Ti-related pairs and electron transitions between O-2p to Ti-3d orbits. This exploration of the precise structure of the d-metal band provides a positive reference for the regulation and application of relevant devices. © 2024, The Authors. All rights reserved.

关键词： Lithium compounds

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Charge management system based on disturbance observer sliding mode control for space inertial sensors

arXiv

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arXiv 2024年

作者： Yang, Fangchao Hong, Wei Zhao, Yujie Zhejiang Lab Hangzhou311121 China MOE Key Laboratory of Fundamental Physical Quantities Measurement Hubei Key Laboratory of Gravitation and Quantum Physics PGMF School of Physics Huazhong University of Science and Technology Wuhan430074 China College of Information Science and Engineering Hunan Women’s University Hunan410004 China

Precision space inertial sensors are imperative for Earth geodesy missions, gravitational wave observations, and fundamental physics experiments in space. In these missions, free-falling test masses(TMs) are susceptible to parasitic electrostatic forces and torques, with significant contributions from the interaction between stray electric fields and TM charge. These effects can make up a sizable fraction of the noise budget. Thus, a charge management system(CMS) is essential in high-precise space-based missions. However, the operating environment for space charge control is full of uncertainties and disturbances. TM charge tracking precision is negatively affected by many physical parameters such as external charging rate, quantum yield, UV light power, etc. Those parameters are rarely measured and supposed to vary because of changes in solar activity, temperature, aging of electronic components and so on. The unpredictability and variability of these parameters affects the CMS performance in long-term space missions and must be evaluated or eliminated. This paper presents a simple physics-based model of the discharging process with high charging/discharging rate based on the geometry of inertial sensors. After that, a disturbance observer sliding mode control (DOSMC) is proposed for the CMS with parametric uncertainties and unknown disturbance to maintain the TM charge below a certain level and improve its robustness. The simulation results show that the DOSMC is able to force the system trajectory coincides with the sliding line, which depends neither on the parameters or disturbances. In this way, the DOSMC can effectively ignore the parameter perturbation and external disturbances. The control precision can reach 0.1 mV, which is superior to that of a classic proportional– integral–derivative controller and conventional sliding mode control. © 2024, CC BY.

关键词： Budget control

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Performance Analysis of Full-Duplex NOMA Assisted Satellite-Terrestrial systems with Hardware Impairments and Imperfect CSI

Performance Analysis of Full-Duplex NOMA Assisted Satellite-...

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International Conference on information, Communication and Networks (ICICN)

作者： Jinlong Zhao Mingming Huo Wanwei Tang Xinwei Yue School of Artificial Intelligence Gansu University of Political Science and Law Lanzhou China School of Electronic and Information Engineering Beihang university Beijing China Archives Center Lanzhou University of Technology Lanzhou China Key Lab of Intelligent Data Information Processing and Control of Hebei Province Tangshan University Tangshan China School of Information and Communication Engineering Beijing Information Science and Technology University Beijing China

ISBN: (纸本)9781665490832

In this paper, we investigate the satellite-terrestrial system employing non-orthogonal multiple access (NOMA) scheme, where a full-duplex (FD) decode-and-forward (DF) relaying assists the user in weak channel condition. The effects of hardware impairments, imperfect channel state information (CSI) and imperfect interference cancellation on system performance are considered. For this setting, we derive the closed-form expressions of the exact and asymptotic outage probabilities as well as delay-limited sum throughput for NOMA users. Numerical results are provided to demonstrate the correctness of theoretical analysis and the superiority of adopting FD NOMA scheme in the proposed system.

关键词： NOMA Interference cancellation Satellites system performance Full-duplex system Probability Throughput

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Dual-band cooperative backscatter communication system

Dual-band cooperative backscatter communication system

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Cong Ding Jun-Lin Zhan Hao Chen Zhen-Guo Liu Wei-Bing Lu Center for Flexible RF Technology State Key Lab of Millimeter Waves School of Information Science and Engineering Southeast University Nanjing China MOE Frontiers Science for Mobile Information Communication and Security Purple Mountain Laboratories Nanjing China

ISBN: (纸本)9781665482271

In this paper, we build a cooperative backscatter communication system in 2.4GHz and 3.5 GHz. A test platform including backscattering modulator, Microcontroller Unit (MCU) and receiver system based on Software Defined Radio (SDR) technology is described. In order to realize the communication in the above bands, an omnidirectional dual-band antenna is designed first. Then a backscattering modulation circuit is designed, and a diplexer with two PIN diodes are used to control the two frequency bands. The carrier transmitting and receiving demodulation system is designed at the receiving end. This paper explains the design strategy of realizing frequency- shift keying (FSK) and phase-shift keying (PSK) in the bands simultaneously, and receiving the two signals separately. It can not only meet the communication requirements for different nodes, but also realize rate superposition to improve transmission efficiency.

关键词： Microwave antennas Time-frequency analysis Protocols Modulation Dual band Frequency shift keying Binary phase shift keying

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Compact Triple-Passband Bandpass Filter Using Asymmetric Stepped Impedance Resonators

Compact Triple-Passband Bandpass Filter Using Asymmetric Ste...

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Asia-Pacific Conference on Microwave

作者： Shi-Peng Chen Hung-Wei Wu Yung-Wei Chen Chow-Yen-Desmond Sim Department of Electrical Engineering Feng Chia University Tainan Taiwan Micro Nano System Center School of Information Science and Technology Fudan University Shanghai China Department of Electrical Engineering National Cheng Kung University Tainan Taiwan

ISBN: (数字)9784902339567

ISBN: (纸本)9781665451086

This letter proposes the triple-passband bandpass filter based on stepped impedance resonators (SIRs) and asymmetric stepped impedance resonators (ASIRs). The filter has the advantages of compact circuit size, high passband selectivity, and low insertion loss. Furthermore, the asymmetric stepped impedance resonators are designed appropriately to make transmission zeros. This bandpass filter has three passbands at 2.4 GHz, 5.2 GHz, and 5.9 GHz. Therefore, the resonant frequencies and transmission zero can be easily controlled by controlling the impedance and length ratios of stepped impedance resonators (SIRs) and asymmetric stepped impedance resonators. As a result, the proposed filter has the advantages of low loss, compact size, and uncomplicated design rules for applying to multi-band and multi-service wireless communication systems.

关键词： Band-pass filters Wireless communication Resonator filters Resonant frequency Microwave theory and techniques Filtering theory Impedance

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Tunable mode-locked fiber laser using multifunctional long-period grating

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Chinese Optics Letters 2025年第4期 31-36页

作者：姜晨王治强万英云灵马跃辉陈思宇孙兵黄千千牟成博刘云启张祖兴 Advanced Photonic Technology Lab College of Electronic and Optical Engineering&College of Flexible Electronics Future TechnologyNanjing University of Posts and Telecommunications Information Materials and Intelligent Sensing Laboratory of Anhui Province Anhui University School of Physics and Optoelectronic Engineering Nanjing University of Information Science and Technology Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University

A laser has been demonstrated to achieve tunable mode-locked operation using a multifunctional long-period fiber grating(LPFG).By introducing an LPFG with a relatively high polarization-dependent loss of up to 21 dB into the laser cavity,a stable fundamental frequency mode-locked operation was achieved at 1546.26 *** also have achieved a wavelength-tunable40th-harmonic mode-locked laser with a tuning range of nearly 10 nm through simple thermal tuning,based on the tunable attenuation characteristics of the *** results indicate that the LPFG can simultaneously act as a polarizationselective and wavelength-selective element in mode-locked lasers.

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An adaptive weight based particle swarm optimization scheduling algorithm on cloud computing system 20

An adaptive weight based particle swarm optimization schedul...

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Proceedings of the 2020 3rd International Conference on E-Business, information Management and Computer science

作者： Fan Pei Dong Minggang Jing Chao College of Information Science and Engineering Guilin University of Technology Guilin Guangxi China College of Information Science and Engineering Guilin University of Technology Guangxi Key Laboratory of Embedded Technology and Intelligent System Guilin Guangxi China College of Information Science and Engineering Guilin University of Technology Guangxi Key Laboratory of Trusted Software Guilin University of Electronic and Technology Guilin China

ISBN: (纸本)9781450389099

The resource scheduling problem in cloud computing is one of the most concerned issues of researchers in related fields in recent years. With the aim of solving defects in particle swarm optimization algorithm (PSO) that it is easy to fall into local optimal solution and "premature", we propose a particle swarm optimization scheduling algorithm based on adaptive weights. By improving the inertia weight factor and using the number of iterations to control the size of the inertia weight, the algorithm convergence speed can be accelerated. Meanwhile, by updating the particle speed to update the weights of the cognitive and social coefficients in the number of iterations, the fitness function of the particles is improved to strengthen the adaptive ability of the particles and made the algorithm more in line with objective laws. A large number of simulation comparison experiments has been conducted on the Cloudsim platform. The experimental results show that the improved particle swarm optimization algorithm has better performance in adaptability, convergence speed, and capabilities of finding global optimums.

关键词： Adaptive

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Disentangled Noisy Correspondence Learning

arXiv

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arXiv 2024年

作者： Dang, Zhuohang Luo, Minnan Wang, Jihong Jia, Chengyou Han, Haochen Wan, Herun Dai, Guang Chang, Xiaojun Wang, Jingdong The School of Computer Science and Technology The Ministry of Education Key Laboratory of Intelligent Networks and Network Security The Shaanxi Province Key Laboratory of Big Data Knowledge Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China SGIT AI Lab State Grid Shaanxi Electric Power Company Limited State Grid Corporation of China Shaanxi China The School of Information Science and Technology University of Science and Technology China United Arab Emirates The Baidu Inc China

Cross-modal retrieval is crucial in understanding latent correspondences across modalities. However, existing methods implicitly assume well-matched training data, which is impractical as real-world data inevitably involves imperfect alignments, i.e., noisy correspondences. Although some works explore similarity-based strategies to address such noise, they suffer from sub-optimal similarity predictions influenced by modality-exclusive information (MEI), e.g., background noise in images and abstract definitions in texts. This issue arises as MEI is not shared across modalities, thus aligning it in training can markedly mislead similarity predictions. Moreover, although intuitive, directly applying previous cross-modal disentanglement methods suffers from limited noise tolerance and disentanglement efficacy. Inspired by the robustness of information bottlenecks against noise, we introduce DisNCL, a novel information-theoretic framework for feature Disentanglement in Noisy Correspondence Learning, to adaptively balance the extraction of MII and MEI with certifiable optimal cross-modal disentanglement efficacy. DisNCL then enhances similarity predictions in modality-invariant subspace, thereby greatly boosting similarity-based alleviation strategy for noisy correspondences. Furthermore, DisNCL introduces soft matching targets to model noisy many-to-many relationships inherent in multi-modal input for noise-robust and accurate cross-modal alignment. Extensive experiments confirm DisNCL's efficacy by 2% average recall improvement. Mutual information estimation and visualization results show that DisNCL learns meaningful MII/MEI subspaces, validating our theoretical analyses. Copyright © 2024, The Authors. All rights reserved.

关键词： Contrastive Learning

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Towards Fair Graph Representation Learning in Social Networks

arXiv

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arXiv 2024年

作者： Zhang, Guixian Yuan, Guan Cheng, Debo Liu, Lin Li, Jiuyong Zhang, Shichao School of Computer Science and Technology Mine Digitisation Engineering Research Center The Ministry of Education China University of Mining and Technology Jiangsu Xuzhou China UniSA STEM University of South Australia AdelaideSA Australia Guangxi Key Lab of Multisource Information Mining & Security Guangxi Normal University Guangxi Guilin China

With the widespread use of Graph Neural Networks (GNNs) for representation learning from network data, the fairness of GNN models has raised great attention lately. Fair GNNs aim to ensure that node representations can be accurately classified, but not easily associated with a specific group. Existing advanced approaches essentially enhance the generalisation of node representation in combination with data augmentation strategy, and do not directly impose constraints on the fairness of GNNs. In this work, we identify that a fundamental reason for the unfairness of GNNs in social network learning is the phenomenon of social homophily, i.e., users in the same group are more inclined to congregate. The message-passing mechanism of GNNs can cause users in the same group to have similar representations due to social homophily, leading model predictions to establish spurious correlations with sensitive attributes. Inspired by this reason, we propose a method called Equity-Aware GNN (EAGNN) towards fair graph representation learning. Specifically, to ensure that model predictions are independent of sensitive attributes while maintaining prediction performance, we introduce constraints for fair representation learning based on three principles: sufficiency, independence, and separation. We theoretically demonstrate that our EAGNN method can effectively achieve group fairness. Extensive experiments on three datasets with varying levels of social homophily illustrate that our EAGNN method achieves the state-of-the-art performance across two fairness metrics and offers competitive effectiveness. © 2024, CC BY-NC-ND.

关键词： Contrastive Learning

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