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Computational spectropolarimetry with a tunable liquid crystal metasurface

eLight 2022年第1期2卷 291-300页

作者： Yibo Ni Chen Chen Shun Wen Xinyuan Xue Liqun Sun Yuanmu Yang State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to ***,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system ***,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal *** tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high *** concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.

关键词： Tunable metasurface Liquid crystal Computational spectropolarimetry

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DESIGN OF AN ELECTROMAGNETICALLY TUNED MASS DAMPER AND ITS EXPERIMENTAL STUDY ON VIBRATION REDUCTION FOR FLYWHEEL ROTOR SYSTEMS 10

DESIGN OF AN ELECTROMAGNETICALLY TUNED MASS DAMPER AND ITS E...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Nie, Haidu Tang, Changliang Mu, Mengliang Xu, Henglei Key Laboratory of Modern Measurement and Control Technology Ministry of Education Beijing Information Science and Technology University Beijing100192 China

ISBN: (纸本)9781837242672

The trend towards higher speeds in flywheel energy storage systems is highlighting the need for improved bearing support. To overcome the limitations of traditional oil dampers, such as narrow damping range and insufficient damping, this study introduces an Electromagnetic Tuned Mass Damper (ETMD) designed for high-speed, low-inertia flywheel systems. Using Comsol finite element software, a model was created to optimize the damper's parameters. A comparative experiment was conducted between the newly designed ETMD and a conventional oil damper on vibration damping single point flexible support. The experimental findings indicate that a uniform arrangement of permanent magnets within the eddy current damper yields greater damping forces, with the damping coefficient significantly increasing at amplitudes beyond 0.2 mm, and notably effective in controlling low-frequency vibrations within the 75 Hz to 25 Hz range. Although the magnetic yoke is crucial, variations in its thickness minimally affect performance, and the optimal damping effect is achieved with a back iron thickness of 4mm, highlighting the existence of an ideal thickness for the back iron. Rotor experiments have demonstrated that eddy current dampers demonstrate enhanced vibration control with amplitudes of 49 urn, outperforming hydrodynamic dampers at 75 μm during acceleration and 71 μm during deceleration. © The Institution of Engineering & technology 2024.

关键词： Permanent magnets

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STUDY OF THE SENSITIVITY MECHANISM OF A FLEXIBLE TEMPERATURE SENSOR 10

STUDY OF THE SENSITIVITY MECHANISM OF A FLEXIBLE TEMPERATURE...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Sun, Jiahao Piao, Linhua Zhang, Yonghao Beijing Key Laboratory of Sensors Beijing China Modern Measurement and Control Technology Ministry of Education Beijing China

ISBN: (纸本)9781837242672

In this paper, a structure of a flexible temperature sensor is proposed. And its sensitivity mechanism is investigated. A physical model is established based on the proposed structure. A mathematical model is established based on the actual situation. A 3D model of the structure is created by COMSOL software. In which the mathematical model is studied for this sensor. The temperature field within this sensitive structure was calculated using the finite element method. The corresponding material properties in the sensor structure were set. Setting up the physical fields required for operation. Mesh this 3D structure. Setting the external ambient temperature. Setup of the type of study according to the actual situation. The sensor detects the ambient temperature. Calculations are made based on the results of the finite element method, combined with the corresponding theoretical formulas. It is calculated that the temperature coefficient of resistance is 0.0316/° C in the temperature range of -18~80 °C, and the nonlinearity is 1.36%. There results conclude that the relationship between temperature and resistance is proportional. This lays a theoretical foundation for the optimisation of subsequent structural studies of flexible temperature sensors. It facilitates further performance enhancement in subsequent research. This promotes the research progress in related fields. © The Institution of Engineering & technology 2024.

关键词： Velocity measurement

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CALIBRATION EQUIPMENT FOR DEFIBRILLATOR ANALYZER DESIGNED WITH DIGITAL MULTIMETER AND OSCILLOSCOPE 10

CALIBRATION EQUIPMENT FOR DEFIBRILLATOR ANALYZER DESIGNED WI...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Wang, Yunling Zhan, Zhiqiang Yu, Lei Shanghai Institute of Measurement and Testing Technology Shanghai China Shanghai Key Laboratory of Online Test and Control Technology Shanghai China

ISBN: (纸本)9781837242672

Defibrillators use electrical pulses to the heart of patients to make hearts beating normally again. There are mainly 3 types of defibrillators, monophasic wave, biphasic wave, and multipulse biowave. Defibrillator analyzers are designed to calibrate defibrillators, and the pulse energy is an important parameter of defibrillator analyzers. In this manuscript, we use the voltage-resistance method for energy calibration. We need to design a high voltage divider, digitizing module, and data processing project. In the digitizing module, we use both the digital multimeter and the oscilloscope to sample. Making DC voltage measurements is one type of digitizing methods of keysight 3458A, which uses memory of the multimeter. The process project is developed by VB language with 10 Libraries Suite of keysight to implement the function of digitizing and energy calculation. We also choose NI PXI oscilloscope for digitizing, and the oscilloscope can be calibrated by NI Calibration Executive Software. The process project is developed by Lab View. The measurement results by 3458A and PXI-5122 are consistent. We evaluate the uncertainty at the end of this manuscript. © The Institution of Engineering & technology 2024.

关键词： Cathode ray oscilloscopes

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FAST DETECTION ALGORITHM BASED ON YOLOV8 WITH STRUCTURAL REPARAMETERISATION AND GROUPED CONVOLUTIONAL HEADS 10

FAST DETECTION ALGORITHM BASED ON YOLOV8 WITH STRUCTURAL REP...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Chen, Xuanyu Wu, Guoxin Zhang, Guolong Zhou, Linglong The Ministry of Education Key Laboratory of Modern Measurement and Control Technology Beijing Information Science & Technology University Beijing100192 China

ISBN: (纸本)9781837242672

As autonomous driving technology advances swiftly, the precise identification of road signs has become essential for enabling autonomous driving. This paper introduces an enhanced YOLOv8 model for road sign recognition. This model enhances the original C2f module by incorporating the RepViT Block, resulting in the C2f_RVB module. This alteration not only hastens the convergence rate of the model but also markedly boosts detection precision. Furthermore, we introduce a highly efficient architectural framework utilizing lightweight ViTs, which augments the model's detection speed while minimizing the parameter count. Lastly, we incorporate grouped convolution to enhance the detection head of YOLOv8. Tests were conducted utilizing the Street Sign Locator dataset, which was improved with information from the Roboflow stage. The exploratory comes about illustrate that the proposed RVB-YOLOv8 demonstrate accomplishes critical upgrades in discovery measurements like mAP and FLOPs when compared to the initial YOLOv8 demonstrate, whereas too diminishing the number of parameters by one-third. © The Institution of Engineering & technology 2024.

关键词： Convolution

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Multi-circular formation control with reinforced transient profiles for nonholonomic vehicles:A path-following framework

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Defence technology（防务技术） 2024年第1期31卷 278-287页

作者： Jintao Zhang Xingling Shao Wendong Zhang Zongyu Zuo School of Instrument and Electronics North University of ChinaTaiyuan 030051China State Key Laboratory of Dynamic Measurement Technology North University of ChinaTaiyuan 030051China Seventh Research Division School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100191China

This article investigates a multi-circular path-following formation control with reinforced transient profiles for nonholonomic vehicles connected by a digraph.A multi-circular formation controller endowed with the feature of spatial-temporal decoupling is devised for a group of vehicles guided by a virtual leader evolving along an implicit path,which allows for a circumnavigation on multiple circles with an anticipant angular *** addition,notice that it typically imposes a stringent time constraint on time-sensitive enclosing scenarios,hence an improved prescribed performance control(IPPC)using novel tighter behavior boundaries is presented to enhance transient capabilities with an ensured appointed-time convergence free from any *** significant merits are that coordinated circumnavigation along different circles can be realized via executing geometric and dynamic assignments independently with modified transient ***,all variables existing in the entire system are analyzed to be *** and experimental results are provided to validate the utility of suggested solution.

关键词： Multi-circular formation Reinforced transient profiles Nonholonomic vehicles Path following

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EXPERIMENTAL STUDY ON THE VIBRATION CHARACTERISTICS OF CONFLUENCE PLANETARY ROW IN HEALTH AND BROKEN TEETH FAILURE 10

EXPERIMENTAL STUDY ON THE VIBRATION CHARACTERISTICS OF CONFL...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Henglei, Xu Changliang, Tang Haoyan, Chen Shaodong, He Xuelian, Qu Key Laboratory of Modern Measurement and Control Technology Ministry of Education Beijing Information Science and Technology University Beijing100192 China

ISBN: (纸本)9781837242672

As one of the core components to realize dual-power convergence in the transmission device, the confluence planetary row is characterized by large force and high rotational speed in the actual operation process, and its failure is easy to lead to the failure of straight driving and steering function of the crawler vehicle. The design and construction of the converging planetary row vibration test bench, with the planetary wheel broken teeth fault as an example, respectively, to carry out healthy and broken teeth fault confluence planetary row dynamics characteristics of experimental research, through different loads and different degree of broken teeth faults and other groups of tests, for the groups of experimental results of the data analysis of the time-frequency domain response characteristics of the planetary wheel broken teeth faults to get the characteristics of the vibration of the planetary wheel broken teeth faults, as a confluence planetary row failure identification and diagnosis to provide the basis. The vibration characteristics of planetary wheel broken teeth are obtained to provide a basis for the identification and diagnosis of confluence planetary row fault. © The Institution of Engineering & technology 2024.

关键词： Semantic Segmentation

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RESEARCH STATUS AND DYNAMIC ANALYSIS OF DAMPING AND VIBRATION REDUCTION technology OF ROTATING MACHINERY ROTOR SYSTEM 10

RESEARCH STATUS AND DYNAMIC ANALYSIS OF DAMPING AND VIBRATIO...

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10th International Symposium on Test Automation and instrumentation, ISTAI 2024

作者： Xu, Jingwen Tang, Changliang He, Shaodong Key Laboratory of Modern Measurement and Control Technology Ministry of Education Beijing Information Science and Technology University Beijing100192 China

ISBN: (纸本)9781837242672

Large rotating machinery in nuclear, power, and petrochemical industries employ multi-span flexible connections. As the rotor length-to-diameter ratio rises, rigid rotors become flexible, exceeding critical speeds and inducing resonance. This challenges supercritical technologies like damping, vibration reduction, balancing, and driving. In view of the vibration problems of flexible rotor systems with wide-band, multi-mode, and multi-criticality, this paper examines damping and vibration reduction. It highlights modern industrial rotating machinery's evolution, analyzes gyro effects, and critiques traditional damping designs like squeeze film dampers for their limited application range. The paper then delves into rotor vibration control, categorizing technologies as active or passive, and outlining principles, advantages, and disadvantages. Active technology offers precision but high costs;passive technology is cost-effective yet limited in effect and scope. Finally, the research and application status of damping and vibration reduction technology in aerospace, civil engineering, machinery, transportation, and other fields are analyzed, which provides a theoretical reference for vibration reduction and noise reduction technology of rotating machinery. © The Institution of Engineering & technology 2024.

关键词： Rotating machinery

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Dual-atom-interferometric gyroscope with continuous cold atomic beams 9

Dual-atom-interferometric gyroscope with continuous cold ato...

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9th Symposium on Frequency Standards and Metrology, FSM 2023

作者： Wang, Shengzhe Meng, Zhixin Yan, Peiqiang Feng, Yanying State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Beijing China Department of Precision Instrument Tsinghua University Beijing China Beijing Institute of Aerospace Control Devices Beijing China

In closed-loop dual-atom interferometers, the initial phase shift is a non-inertial phase induced by Raman pulses. This initial optical phase affects the measurements of both acceleration and rotation rate. In this study, we present a method to modulate the initial optical phase of light pulse atom interferometers (LPAIs). Employing this modulation method, we investigated the influence of the initial optical phase on a closed-loop dual-atom interferometer. The results reveal a better short-term sensitivity in the rotation rate measurement at an initial optical phase of 0. Our closed-loop dual-atom interferometer allows for decoupled measurements of rotation rate and acceleration. With a short interrogation time of 2T = 1.73 ms, the short-term sensitivities of the rotation rate and acceleration measurements are 2.73×10-5(rad/s)/Hz and 272μg/Hz, respectively. © Published under licence by IOP Publishing Ltd.

关键词： Atoms

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FMCW Lidar combined frequency modulation and frequency shift 19

FMCW Lidar combined frequency modulation and frequency shift

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19th National Conference on Laser technology and Optoelectronics

作者： Duan, Pengcong Wang, Xin School of Optics and Photonics Beijing Institute of Technology Beijing100081 China Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology Beijing100081 China

ISBN: (纸本)9781510683228

The frequency-modulated continuous-wave (FMCW) lidar is widely applied due to its high sensitivity and strong anti-interference capabilities. However, when detecting high-speed moving targets, FMCW lidar encounters range-velocity coupling issue. This paper proposes a method to decouple the target distance and velocity by combining linear frequency modulation with a constant frequency shift. In this approach, the frequency of a single-frequency seed laser is modulated periodically. Each cycle of the frequency modulation signal consists of a sawtooth wave and a DC part. The chirped signal is split into two parts. one part serves as the local oscillator (LO), while the other part passes through a continuously operating frequency shifter and an amplifier, and finally emits to the target. The returned signal from the target beats with the LO to produce a radio frequency signal containing both target range and velocity information. The beat signal frequency of the chirped part comes from both the range induced frequency delay and the Doppler shift, while the target velocity only induces the Doppler frequency shift within the constant frequency duration. Therefore, using the known velocity the target range can be calculated from the beat chirped signal. Thereby, the velocity and the range of the target is decoupled. The simulation and experimental results validate the effectiveness of this method, demonstrating the high measurement resolution and low setup complexity. © 2024 SPIE.

关键词： Frequency modulation

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