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Vehicle detection and monitoring using ultra-weak fiber Bragg grating distributed acoustic sensing

Optical engineering 2025年第3期64卷

作者： S., Wen Z., Luo X., Chen C., Ran Y., He China Three Gorges University College of Science Yichang China Hubei Engineering Research Center of Weak Magnetic-field Detection Yichang China Logging Technology Research Institute China National Logging Corporation Xi’an China

Intelligent transportation systems mainly use camera networks and radar systems for vehicle detection, but these methods are susceptible to light, occlusion, and inclement weather, with limited detection ranges and reliability that need improvement. To address these issues, a vehicle condition monitoring system based on ultra-weak fiber Bragg grating distributed acoustic sensing (uwDAS) technology is proposed to achieve real-time vehicle detection, classification, and traffic parameter estimation. Vehicle vibration signals captured by fiber-optic cables buried in actual roads are extracted using uwDAS equipment. Vehicles are then detected using an improved wavelet threshold denoising algorithm and a dual threshold algorithm to obtain traffic parameters such as the number of vehicles and vehicle speed. The vehicle signals are classified by the GoogLeNet v4 neural network. Finally, the preliminary construction of the vehicle condition monitoring system is completed. Experimental results show that the accuracy of vehicle detection is higher than 91%, the estimation error of speed is less than 3%, the estimation error of traffic flow is not more than 10%, and the accuracy of vehicle classification is higher than 92%. This provides a new idea and a reliable solution for road traffic monitoring. © 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： Street traffic control

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Critical behavior and magnetocaloric effect of Ba2-xAxFeMoO6 (A = Sm, Ag, x = 0.0, 0.025) simulated by Landau theory

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Applied Physics A 2025年第6期131卷 1-9页

作者： Ghorbani, Zahra Ehsani, Mohammad Hossein Hsini, Mohamed Ji, Pengyu Zhang, Yingde Piao, Hong-Guang Faculty of Physics Semnan University Semnan Iran Laboratory of Physical Chemistry of Materials Faculty of Science of Monastir Department of Physics University of Monastir Monastir Tunisia Department of Physics Yanbian University Yanji People’s Republic of China Hubei Engineering Research Center of Weak Magnetic-Field Detection China Three Gorges University Yichang People’s Republic of China Baotou Research Institute of Rare Earths Baotou People’s Republic of China

In this study, the magnetocaloric effect of Ba2-xAxFeMoO6 (A = Sm, Ag and x = 0.0, 0.025) has been modeled. The samples exhibit a second-order transition from ferromagnetic (FM) to paramagnetic (PM) states at transition temperatures (TC) of approximately 310 K, 322 K, and 304 K for the Ba2FeMoO6 (BFMO), Ba1.975Ag0.025FeMoO6 (BAFMO), and Ba1.975Sm0.025FeMoO6 (BSFMO) samples, respectively. Investigation the magnetocaloric effect (MCE) in these samples involved simulating the change in magnetic entropy (− ΔSM). The critical exponents, β, γ, and δ were obtained using a numerical method grounded in Landau free energy within the mean-field approximation; the simulated outcomes strongly correlate with the experimental data.

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Geometry engineering of tunneling transistors in transition metal dichalcogenide nanoribbon heterojunctions

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Communications Physics 2025年第1期8卷 1-9页

作者： Jiang, Ye Dan, Minjiang Fan, Shuaiwei Hu, Gongwei Huang, Fobao Wang, Wei-Yang Chen, Qiao School of Computational Science and Electronics The lnnovation Institute of Advanced Functional Materials Hunan Institute of Engineering Xiangtan China Joint Laboratory for Extreme Conditions Matter Properties School of Mathematics and Physics Southwest University of Science and Technology Mianyang China Hubei Engineering Research Center of Weak Magnetic-field Detection College of Science China Three Gorges University Yichang China School of Microelectronics Northwestern Polytechnical University Xi’an China Shangrao Open University Jiangxi Shangrao China

Graphene nanoribbon heterojunctions are promising one-dimensional materials for quantum electronics due to their tunable bandgap and sizable quantum confinement. However, their band alignment is significantly influenced by dimensional fluctuations, impeding the development of stable and reliable devices. Here, we engineer geometry edges of transition metal dichalcogenide (TMD) nanoribbons to design versatile nanoribbon heterojunctions by combining metallic zigzag and semiconducting armchair edges. T- and H-shaped nanoribbons exhibit robust edge-state transport for tunneling and resonant tunneling, respectively. The quantized subbands confined within H-shaped nanoribbon are modulated by zigzag edges. In contrast, T-shaped configuration shows different tunneling for electrons and holes, which are tunable via armchair edges. Moreover, the device characteristics suggest that tunneling transistors display moderate current dependence on the barrier width, while resonant tunneling transistors exhibit negative differential resistance with peak-valley ratio improved by lengthening armchair edge. This study proposes using geometry edge as a degree of freedom to engineer two-dimensional material nanoribbon heterojunctions, with broad potential for quantum electronic and optoelectronic applications. (Figure presented.) © The Author(s) 2025.

关键词： Quantum electronics

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Unconventional room-temperature negative magnetoresistance effect in Au/n-Ge:Sb/Au devices

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Chinese Physics B 2024年第3期33卷 602-608页

作者：何雄杨凡黎牛浩峪王立峰易立志许云丽刘敏潘礼庆夏正才 Hubei Engineering Research Center of Weak Magnetic-field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhan 430074China

Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room ***,how to obtain a large room-temperature negative MR effect in them remains to be *** this paper,by designing an Au/n-Ge:Sb/Au device with metal electrodes located on identical side,we observe an obvious room-temperature negative MR effect in a specific 50 T pulsed high magnetic field direction environment,but not in a static low magnetic field *** the analysis of the experimental measurement of the Hall effect results and bipolar transport theory,we propose that this unconventional negative MR effect is mainly related to the charge accumulation on the surface of the device under the modulation of the stronger Lorentz force provided by the pulsed high magnetic *** theoretical analytical model is further confirmed by regulating the geometry size of the *** work sheds light on the development of novel magnetic sensing,magnetic logic and other devices based on non-magnetic semiconductors operating in pulsed high magnetic field environment.

关键词： magnetoresistance germanium-based devices pulsed high magnetic fields

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engineering of topological tunneling transistors via quantum point contact

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Physical Review Applied 2025年第3期23卷 034074-034074页

作者： Gongwei Hu Jiaqi Yang Haozhen Chen Min Liu Shuaiwei Fan Fobao Huang Qiao Chen Minjiang Dan Hubei Engineering Research Center of Weak Magnetic-field Detection College of Science China Three Gorges University Yichang 443002 China College of Hydraulic & Environmental Engineering China Three Gorges University Yichang 443002 China School of Microelectronics Northwestern Polytechnical University Xi’an 710072 China Yangtze River Delta Research Institute of NPU Northwestern Polytechnical University Taicang 215400 China School of Computational Science and Electronics the lnnovation Institute of Advanced Functional Materials Hunan Institute of Engineering Xiangtan 411104 China Joint Laboratory for Extreme Conditions Matter Properties School of Mathematics and Physics Southwest University of Science and Technology Mianyang 621010 China

Owing to the versatile transport process, tunneling transistors (TTs) have become important building blocks for modern electronic, optoelectronic, and magnetic technologies. Although various TTs have been developed, their device operation still has challenges in terms of stability and reliability due to the tunneling process being susceptible to material size and interface scatterings. The robust edge channels in a topological insulator (TI) hold novel tunneling physics, but their TTs are still lacking. In this theoretical work, we propose topological tunneling and resonant TTs by using edge states (ESs) as transport channels in the quantum point contact (QPC) constriction. The finite size effect is the key to adjusting the band structure and tunneling barrier height of ESs by controlling the QPC width. By using the Bernevig-Hughes-Zhang (BHZ) model, we explore the single-QPC tunneling and double-QPC resonant tunneling transport, as well as their device characteristics via the quantum transport Kwant package. Topological TTs based on a single QPC possess excellent gate-modulated capability as well as a size-dependent current sensitivity of 0.1nm−1, several orders of magnitude lower than the conventional TTs. The transport results show that the tunneling probability is significantly influenced by the QPC width (barrier height) but is weakly dependent on the QPC length (barrier width). Moreover, topological resonant TTs are designed in a double-QPC structure and show a negative differential resistance with a large peak-valley current ratio (>104). The transmission spectrum exhibits multiple peaks due to the resonant tunneling driven by quantum well states. The distance between two QPCs can shift these resonant peaks by modulating the transverse confined effect. This study opens a window for designing stable, reliable, and high-performance tunneling devices via emerging quantum materials with great potential for low-power topological electronics applications.

关键词： Semiconductor quantum wells

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The structural, electronic and optical properties of cation-disordered (Li_xNa_1-x)₂Te alloys

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Materials Science and engineering: B 2025年 320卷

作者： Wei, Qiao Deng, Yuhang Kang, Sixin Yang, Liu Fan, Shuaiwei Department of Physics China Three Gorges University Yichang 443002 China Hubei Engineering Research Center of Weak Magnetic-field Detection China Three Gorges University Yichang 443002 China

The properties of (LixNa1-x)2Te alloys are studied by using the hybrid functionals method. Obtained results indicate (LixNa1-x)2Te alloys are direct gap semiconductors. As the alloy composition changes, the band gap o... 详细信息

The properties of (Li_xNa_1-x)₂Te alloys are studied by using the hybrid functionals method. Obtained results indicate (Li_xNa_1-x)₂Te alloys are direct gap semiconductors. As the alloy composition changes, the band gap of the alloys exhibits a nonlinear variation with the bowing parameter (−0.78 eV). When the Li composition reaches 0.50, the hole (electron) effective mass of (Li_0.5Na_0.5)₂Te alloy reduces to 0.314 (0.233) m₀, indicating approximate 80.0 % decrease in hole. Moreover, the optical properties show (Li_0.5Na_0.5)₂Te alloy possess low absorptivity and reflectivity, together with excellent transmittance in the visible light region. The mixing enthalpies and elastic constants verify that (Li_xNa_1-x)₂Te alloy can be synthesized experimentally and possess mechanical stability under ambient environments. These findings highlight the potential of the (Li_0.5Na_0.5)₂Te alloy as a promising transparent conducting material. © 2025 Elsevier B.V.

关键词： (LixNa1-x)2Te alloy Electronic structures Hybrid functional calculation Optical properties

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Polarity-controllable magnetic skyrmion filter

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Chinese Physics B 2024年第10期33卷 400-404页

作者： Xiao-Lin Ai Hui-Ting Li Xue-Feng Zhang Chang-Feng Li Je-Ho Shim Xiao-Ping Ma Hong-Guang Piao Hubei Engineering Research Center of Weak Magnetic-Field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Department of Physics College of ScienceYanbian UniversityYanji 133002China

The skyrmion generator is one of the indispensable components for the future functional skyrmion devices,but the process of generating skyrmion cannot avoid mixing with other magnetic textures,such as skyrmionium and nested skyrmion *** mixed magnetic textures will inevitably lead to the blockage of skyrmion transport and even the distortion of data ***,the design of an efficient skyrmion filter is of great significance for the development of skyrmion-based spintronic *** this work,a skyrmion filter scheme is proposed,and the high-efficiency filtering function is demonstrated by micromagnetic *** results show that the filtering effect of the scheme depends on the structure geometry and the spin current density that drives the *** on this scheme,the polarity of the filtered skyrmion can be controlled by switching the magnetization state at the output end,and the“cloning”of the skyrmion can be realized by geometric optimization of the *** believe that in the near future,the skyrmion filter will become one of the important components of skyrmion-based spintronic devices in the future.

关键词： spintronics skyrmions skyrmion filter skyrmion polarity skyrmion clone

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Nanocavity-Mediated Fast magnetic Vortex Core In-Situ Switching by Local magnetic field

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Chinese Physics Letters 2021年第12期38卷 76-79页

作者： Xiao-Ping Ma Hongguo Yang Changfeng Li Cheng Song Hong-Guang Piao Hubei Engineering Research Center of Weak Magnetic-Field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Key Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Fast in situ switching of magnetic vortex core in a ferromagnetic nanodisk assisted by a nanocavity,with diameter comparable to the dimension of a vortex core,is systematically investigated by changing the strength as well as the diameter of the effective circular region of the applied magnetic *** applying a local magnetic field within a small area at the nanodisk center,fast switching time of about 35 ps is achieved with relatively low field strength(70 mT)which is beneficial for fast data reading and *** reason for this phenomenon is that the magnetic spins around the nanocavity is aligned along the cavity wall due to the shape anisotropy when the perpendicular field is applied,which deepens the dip around the vortex core,and thus facilitates the vortex core switching.

关键词： strength cavity vortex

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Distributed strain sensing cable based on ultra-weak fiber grating

Distributed strain sensing cable based on ultra-weak fiber g...

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2023 Applied Optics and Photonics China: Optic Fiber Gyro, AOPC 2023

作者： Huang, Jianglou He, Yunrui Wang, Xiaolong Ran, Changyan He, Huiling Luo, Zhihui Hubei Engineering Research Center of Weak Magnetic-field Detection China Three Gorges University Hubei Yichang443002 China College of Science Chain Three Gorges University Hubei Yichang443002 China

ISBN: (纸本)9781510672420

Aiming at improving the performance of distributed sensing fiber, a distributed strain sensing optical cable based on ultra-weak fiber gratings is proposed. The optical cable is prepared by pretreating an ultra-weak fiber grating array with a pitch of 0.2 m, compounding it with glass fiber to make an FRP sensing fiber with a diameter of 1.0 mm, and then twisting with a steel cable and extruding the sheath. The multilayer structure strain transfer model of steel cable-FRP-optical fiber is established, and the temperature characteristics of the optical cable were tested by the water bath method, the tensile test of the optical cable was carried out by the tensile machine. The results show that the temperature sensitivity of the optical cable is 23.8 pm/°C, the strain sensitivity is 1.72 pm/N, there is no "strain dead zone"during strain tension, and the strain transfer effect is good, which provides a potential solution for high-resolution distributed strain sensing. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Tensile testing

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A switchable high-sensitivity strain sensor based on piezotronic resonant tunneling junctions

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Nano research 2024年第11期17卷 10242-10255页

作者： Gongwei Hu Li Zeng Fobao Huang Shuaiwei Fan Qiao Chen Wei Huang Hubei Engineering Research Center of Weak Magnetic-field Detection Department of Physics China Three Gorges University Yichang 443002 China School of Microelectronics Northwestern Polytechnical University Xi’an 710072 China Institute of Flexible Electronics Northwestern Polytechnical University Xi’an 710072 China School of Computational Science and Electronics Hunan Institute of Engineering Xiangtan 411104 China

Developing emerging technologies in Internet of Things and artificial intelligence requires high-speed, low-power, high-sensitivity, and switchable-functionality strain sensors capable of sensing subtle mechanical stimuli in complex ambience. Resonant tunneling diodes (RTDs) are the good candidate for such sensing applications due to the ultrafast transport process, lower tunneling current, and negative differential resistance. However, notably enhancing sensing sensitivity remains one of the greatest challenges for RTD-related strain sensors. Here, we use piezotronic effect to improve sensing performance of strain sensors in double-barrier ZnO nanowire RTDs. This strain sensor not only possesses an ultrahigh gauge factor (GF) 390 GPa^(−1), two orders of magnitude higher than these reported RTD-based strain sensors, but also can switch the sensitivity with a GF ratio of 160 by adjusting bias voltage in a small range of 0.2 V. By employing Landauer–Büttiker quantum transport theory, we uncover two primary factors governing piezotronic modulation of resonant tunneling transport, i.e., the strain-mediated polarization field for manipulation of quantized subband levels, and the interfacial polarization charges for adjustment of space charge region. These two mechanisms enable strain to induce the negative differential resistance, amplify the peak-valley current ratio, and diminish the resonant bias voltage. These performances can be engineered by the regulation of bias voltage, temperature, and device architectures. Moreover, a strain sensor capable of electrically switching sensing performance within sensitive and insensitive regimes is proposed. This study not only offers a deep insight into piezotronic modulation of resonant tunneling physics, but also advances the RTD towards highly sensitive and multifunctional sensor applications.

关键词： piezotronic effect resonant tunneling diode negative differential resistance highly sensitive strain sensor ZnO nanowire ratio of gauge factor

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