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Four ribbons of double-layer graphene suspending masses for NEMS applications

Microsystems & Nanoengineering 2024年第5期10卷 277-286页

作者： Xuge Fan Chang He Jie Ding Sayedeh Shirin Afyouni Akbari Wendong Zhang Advanced Research Institute of Multidisciplinary Sciences Bejing Institute of Technology100081 BeijingChina School of Integrated Circuits and Electronics Bejing Institute of Technology100081 BeijingChina Center for Interdisciplinary Science of Optical Quantum and NEMS Integration Beijing 100081China Advanced NEMS Group Ecole Polytechnique Federale de Lausanne(EPFL)1015 LausanneSwitzerland State Key Laboratory of Dynamic Measurement Technology North University of ChinaTaiyuan 030051China National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan 030051China

Graphene ribbons with a suspended proof mass for nanomechanical systems have been rarely ***,we report three types of nanomechanical devices consisting of graphene ribbons(two ribbons,four ribbons-cross and four ribbons-parallel)with suspended Si proof masses and studied their mechanical *** resonance frequencies and built-in stresses of three types of devices ranged from tens of kHz to hundreds of kHz,and from 82.61 MPa to 545.73 MPa,respectively,both of which decrease with the increase of the size of proof *** devices with four graphene ribbons featured higher resonance frequencies and spring constants,but lower built-in stresses than two ribbon devices under otherwise identical *** Young's modulus and fracture strain of double-layer graphene were measured to be 0.34 TPa and 1.13%respectively,by using the experimental data and finite element analysis(FEA)*** studies would lay the foundation for understanding of mechanical properties of graphene ribbons with a suspended proof mass and their potential applications in nanoelectromechanical systems.

关键词： proof layer double

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Turbulent drag reduction by sector-shaped counter-flow dielectric barrier discharge plasma actuator

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Chinese Physics B 2025年第2期34卷 362-370页

作者： Borui Zheng Shaojie Qi Minghao Yu Jianbo Zhang Linwu Wang Dongliang Bian School of Automation and Information Engineering Xi’an University of TechnologyXi’an 710048China School of Mechanical and Precision Instrument Engineering Xi’an University of TechnologyXi’an 710048China Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi’an 710038China Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xi’an 710048China Shaanxi University Key Laboratory of Photonic Power Devices and Discharge Regulation Xi’an 710048China

The primary objective in aircraft transportation is to minimize turbulent drag, thereby conserving energy and reducing emissions. We propose a sector-shaped counter-flow dielectric barrier discharge plasma actuator, which leverages jet synthesis for drag reduction. A drag control experiment was conducted in a low-speed wind tunnel with a controlled flow velocity of 9.6 m/s(Re = 1.445 × 10^(4)). This study investigated the effects of varying pulse frequencies and actuation voltages on the turbulent boundary layer. Using a hot-wire measurement system, we analyzed the pulsating and time-averaged velocity distributions within the boundary layer to evaluate the streamwise turbulent drag reduction. The results show that the local TDR decreases as the pulse frequency increases, reaching a maximum reduction of approximately 20.97% at a pulse frequency of 50 Hz. In addition, as the actuation voltage increases, the friction coefficient decreases, increasing the drag reduction rate. The maximum drag reduction of approximately 33.34% is achieved at an actuation voltage of 10 kV.

关键词： plasma flow control turbulent boundary layer turbulent drag reduction

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Quantum sensing with optically accessible spin defects in van der Waals layered materials

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Light(Science & Applications) 2024年第12期13卷 2983-3003页

作者： Hong-Hua Fang Xiao-Jie Wang Xavier Marie Hong-Bo Sun State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua University100084 BeijingChina Universitéde Toulouse INSA-CNRS-UPSLPCNO135 Avenue Rangueil31077 ToulouseFrance Institut Universitaire de France 75231ParisFrance

Quantum sensing has emerged as a powerful technique to detect and measure physical and chemical parameters with exceptional *** of the methods is to use optically active spin defects within solid-state *** defects act as sensors and have made significant progress in recent years,particularly in the realm of two-dimensional(2D)spin *** this article,we focus on the latest trends in quantum sensing that use spin defects in van der Waals(vdW)*** discuss the benefits of combining optically addressable spin defects with 2D vdW materials while highlighting the challenges and opportunities to use these *** make quantum sensing practical and applicable,the article identifies some areas worth further *** include identifying spin defects with properties suitable for quantum sensing,generating quantum defects on demand with control of their spatial localization,understanding the impact of layer thickness and interface on quantum sensing,and integrating spin defects with photonic structures for new functionalities and higher emission *** article explores the potential applications of quantum sensing in several fields,such as superconductivity,ferromagnetism,2D nanoelectronics,and *** instance,combining nanoscale microfluidic technology with nanopore and quantum sensing may lead to a new platform for DNA *** materials technology continues to evolve,and with the advancement of defect engineering techniques,2D spin defects are expected to play a vital role in quantum sensing.

关键词： materials. quantum layered

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A hierarchical image matching method for incremental SFM 10

A hierarchical image matching method for incremental SFM

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Optoelectronic Imaging and Multimedia technology X 2023

作者： Zhi, Cong Sun, Peng Dong, Mingli Yan, Bixi Wang, Jun Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument Beijing Information Science and Technology University Beijing100192 China

ISBN: (纸本)9781510667839

Since feature matching of image pairs brings a heavy computational burden, Structure-from-Motion faces great challenges in efficiency, especially for unordered large-scale image collections. To solve it, we propose a hierarchical image matching method in this paper. Our approach starts with an iterative image retrieval scheme, which can efficiently find potentially overlapping image pairs as candidates and avoid unnecessary computation. Then, feature extraction, feature matching and geometric verification are implemented in candidates to find the verified image pairs and inlier feature correspondences. Experiments on benchmark datasets and large-scale unordered datasets demonstrate that our method performs competitiveness in efficiency, without degrading the accuracy, compared with the state-of-the-art system. © 2023 SPIE. All rights reserved.

关键词： Image matching

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A motion characteristics modeled angular position sensor by nonlinear transfer of differential capacitance for miniaturized scanning mirrors

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Microsystems & Nanoengineering 2023年第6期9卷 129-147页

作者： Songtao Liu Gaofei Zhang Lingyun Zhang Junya Wang Minghao Gong Zheng You Department of Precision Instrument Tsinghua UniversityBejing 100084China Key Laboratory of Smart Microsystem(Tsinghua University) Ministry of EducationBeijing 100084China State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua UniversityBeijing 100084China School of Mechanical Science&Engineer Huazhong University of Science and TechnologyWuhan 430074China

In this paper,an angular position sensor(APS)designed for a resonant miniaturized scanning mirror(M-SM)is *** APS operates based on the principle of differential variable capacitance,significantly expanding the detectable bandwidth from a few hertz to several *** modeling the motion characteristics,the sampling rates of the biaxial scanning angles are 1473.6 times and 539.4 times higher than those of conventional ***,the motion characteristics model is presented as a simple harmonic motion,converting sampled capacitance into continuous ***,the nonparallel state of the M-SM and sensor is transformed into a parallel state through the space coordinate system ***,a 2D nonlinear angle transfer function is developed to convert the differential capacitance into an angle,thereby mitigating the nonlinear errors resulting from large *** an accuracy better than 0.014°,the measuring range expands from±0.5729°(±10 mrad)to±5.026°(±87 mrad).Additionally,the capturing mode and tracking mode are proposed to monitor real-time angular changes of the M-SM with an accuracy of 0.017°.High-precision APSs have enhanced beam pointing accuracy and resolution and can thereby be used to advance the development of laser components,including light detection and ranging(LiDAR).

关键词： capacitance angular nonlinear

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Terahertz shaping technology based on coherent beam combining

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Chinese Physics B 2023年第11期32卷 484-492页

作者：郑晓冉马丹妮蒋广通张存林张亮亮 Key Laboratory of Terahertz Optoelectronics Ministry of EducationBeijing Key Laboratory for Terahertz Spectroscopy and Imagingand Beijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Laser Industries Research Academy-Beijing Hubei Huazhong Changjiang Photoelectric Science and Technology LtdBeijing 102209China

The generation of terahertz(THz) waves by focusing a femtosecond pulsed laser beam at a distance is able to overcome the strong absorption properties of air and has rapidly attracted the attention of industry. However, the poor directionality of the THz wave radiation generated by this method is not conducive to THz wave applications. By controlling the morphology of the ultrafast laser-excited plasma filament and its electron density distribution through coherent beam combining technology, we achieve direct THz beam shaping and are able to obtain THz wave radiation of Gaussian or arbitrary transverse distribution. The novel experimental approach proposed in this paper opens up the research field of direct THz wave shaping using plasma. Moreover, it innovates multi-parameter convergence algorithms and, by doing so, has the potential to find beam patterns with higher energy conversion efficiency and break the energy limit of THz waves emitted by lasers at high power.

关键词： femtosecond pulsed laser coherent beam combining terahertz wave beam shaping plasma

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Advancements in heterojunction,cocatalyst,defect and morphology engineering of semiconductor oxide photocatalysts

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Journal of Materiomics 2024年第2期10卷 315-338页

作者： Guojing Wang Shasha Lv Yuanhua Shen Wei Li Linhan Lin Zhengcao Li State Key Laboratory of New Ceramics and Fine Processing Key Laboratory of Advanced Materials(MOE)School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Key Laboratory of Beam Technology and Material Modification Ministry of EducationCollege of Nuclear Science and TechnologyBeijing Normal UniversityBeijing100875China School of Physical Science and Technology Lanzhou UniversityLanzhou730000China Department of Engineering Physics Tsinghua UniversityBeijing100084China State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing100084China

Photocatalytic technology has emerged as a crucial avenue for harnessing solar energy,presenting itself as a viable solution to address the current energy crisis and environmental *** past 50 years have witnessed significant progress and breakthroughs in scientific research on photocatalytic *** paper provides a comprehensive review of the mechanism of photocatalytic technology and methods to improve the photocatalytic efficiency of semiconductor photocatalysts,such as TiO_(2) and *** this paper,common modification methods are divided into four categories:heterojunction con-struction,cocatalysts,defects,and morphological *** origin and development of photo-catalysts in each category are briefly summarized;moreover,the latest progress in each type of modification is discussed.S-scheme heterojunctions retain the high reduction and oxidation capacity of photogenerated electrons and holes by sacrificing half of the photogenerated carriers,showing excellent performance in photocatalysis and great application *** challenges associated with current modification schemes are *** is growing interest in quantitative and atomic-level modu-lation as attractive approaches to tackling these *** the electronic spin state and internal field is important for minimizing photogenerated carrier recombination in *** review will inspire researchers and promote the application of photocatalytic technology.

关键词： Photocatalytic activity Modification Heterostructure Thermal annealing Ion irradiation

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Influence of coil structure on the distribution of transmitting magnetic field in downhole electromagnetic detection 6

Influence of coil structure on the distribution of transmitt...

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6th International Conference on Intelligent control, measurement and Signal Processing, ICMSP 2024

作者： Liu, Changzan Li, Qinyang Liu, Jian Guo, An Xi'an Shiyou University Shaanxi Provincial Key Laboratory of Oil and Gas Well Measurement and Control Technology Xi'an China

ISBN: (纸本)9798331516550

The electromagnetic method is widely utilized for downhole detection, significantly enhancing the safety and efficiency of oil and gas production due to its sensitivity to resistivity and its capability for non-destructive testing. However, due to the narrow space within the downhole, the azimuthal resolution of downhole detection is not ideal. Based on the finite element method, this paper achieved the forward simulation of magnetic field distribution in three-dimensional wellbore electromagnetic detection. Various structures of the transmitting coil in electromagnetic detection tools were studied and compared, and the impact of the structure of the transmitting coils on their circumferential magnetic field distribution was analyzed. The simulation and analysis results offer valuable insights for accurately and effectively designing the transmitting coils to improve their azimuth resolution. © 2024 IEEE.

关键词： Oil well testing

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Noise suppression method for permanent downhole DC carrier communication system 8

Noise suppression method for permanent downhole DC carrier c...

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8th International Conference on Energy System, Electricity, and Power, ESEP 2023

作者： Tian, Shuaikang Fu, Jinpeng Shaanxi Key Laboratory of Measurement and Control Technology for Oil and Gas Wells Xi'an Shiyou University Xi'an710065 China

ISBN: (数字)9781510679801

ISBN: (纸本)9781510679795

The development of oil field needs to grasp the information of underground mining and water injection in real time, and the permanent underground communication system can solve this problem well. How to solve the impact of noise in the communication process. Because the filter can reduce noise, eliminate aliasing, reduce the ripple coefficient of output voltage and smooth the waveform, it has a good effect on noise suppression. By connecting the filter to the power module, this paper analyzes the characteristics and causes of the noise, studies the methods to suppress the noise, and improves and stabilizes the quality of realistic communication. The experimental results show that the noise attenuation is obvious when the filter is added to the system, and the noise generated in the communication of the permanent underground communication system is effectively suppressed. © 2024 SPIE.

关键词： Spurious signal noise

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Simulation Study on Low-speed Oil-Water Two-Phase Flow Based on Thermal Constant Power 8

Simulation Study on Low-speed Oil-Water Two-Phase Flow Based...

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8th International Conference on Energy System, Electricity, and Power, ESEP 2023

作者： Dongyao, Jiang Mengfan, Yang Yixin, Dang Shaanxi Key Laboratory of Measurement and Control Technology for Oil and Gas Wells Xi'an Shiyou University Xi'an710065 China

ISBN: (数字)9781510679801

ISBN: (纸本)9781510679795

Existing phase holdup measurement methods are mainly based on contact measurement, and long-term monitoring is easily affected by strong downhole interference environment. In order to solve this problem, a non-contact thermal oil-water two-phase flow phase holdup measurement method is proposed in this paper. The thermal conduction downhole oil-water two-phase flow holdup measurement model based on graphene electric heating belt is established using fluent, and the phase distribution characteristics of oil-water two-phase flow with different moisture contents at low flow rates are analyzed. The results show that the non-contact thermal flowmeter can realize the measurement of low flow rate fluid phase holdup, which lays a foundation for the measurement of two-phase flow holdup and production logging. © 2024 SPIE.

关键词： Moisture

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