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Non-intrusive Load Monitoring Using Gramian Angular Field Color Encoding in Edge Computing

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Chinese Journal of Electronics 2022年第4期31卷 595-603页

作者： CHEN Junfeng WANG Xue department of precision instrument State Key Laboratory of Precision Measurement Technology and Instrument Tsinghua University

Non-intrusive load monitoring(NILM)can infer the status of the appliances in operation and their energy consumption by analyzing the energy data collected from monitoring devices. With the rapid increase of electric loads in amount and type, the traditional way of uploading all energy data to cloud is facing enormous challenges. It becomes increasingly significant to construct distinguishable load signatures and build robust classification models for NILM. In this paper, we propose a load signature construction method for load recognition task in home scenarios. The load signature is based on the Gramian angular field encoding theory,which is convenient to construct and significantly reduces the data transmission volume of the network. Moreover,edge computing architecture can reasonably utilize computing resources and relieve the pressure of the *** experimental results on NILM datasets demonstrate that the proposed method obtains superior performance in the recognition of household appliances under insufficient resources.

关键词： Non-intrusive load monitoring (NILM) Appliance recognition Gramian angular field (GAF) Edge computing Load signature

A new method of continuous blood pressure monitoring using multichannel sensing signals on the wrist

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Microsystems & Nanoengineering 2023年第5期9卷 141-150页

作者： Liangqi Wang Shuo Tian Rong Zhu State Key Laboratory of precision Measurement Technology and instrument Department of Precision InstrumentTsinghua University100084 BeijingChina

Hypertension is a worldwide health problem and a primary risk factor for cardiovascular *** monitoring of blood pressure has important clinical value for the early diagnosis and prevention of cardiovascular ***,existing technologies for wearable continuous blood pressure monitoring are usually inaccurate,rely on subject-specific calibration and have poor generalization across individuals,which limit their practical ***,we report a new blood pressure measurement method and develop an associated wearable device to implement continuous blood pressure monitoring for new *** wearable device detects cardiac output and pulse waveform features through dual photoplethysmography(PPG)sensors worn on the palmar and dorsal sides of the wrist,incorporating custom-made interface sensors to detect the wearing contact pressure and skin *** detected multichannel signals are fused using a machine-learning algorithm to estimate continuous blood pressure in real *** dual PPG sensing method effectively eliminates the personal differences in PPG signals caused by different people and different wearing *** proposed wearable device enables continuous blood pressure monitoring with good generalizability across individuals and demonstrates promising potential in personal health care applications.

关键词： multichannel continuous method

Anisotropic stimulated emission cross-section measurement in Nd:YVO_4

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Chinese Physics B 2019年第4期28卷 202-206页

作者： Rui Guo Yijie Shen Yuan Meng Mali Gong department of precision instrument State Key Laboratory of precision Measurement and instruments Tsinghua University department of precision instrument State Key Laboratory of Tribology Tsinghua University

As a crucial parameter in the design and analysis of laser performances, stimulated emission(SE) cross-section is currently considered to be dependent on several factors, such as temperatures and eigen-polarizations for anisotropic crystals. In contrast with these factors, impact of propagating directions upon SE cross-section has garnered less *** this paper, to investigate the SE cross-section in arbitrary propagating directions, fluorescence spectra for the transition ~4F_(3/2)→~4I_(11/2) in Nd:YVO_4 are measured in different propagating directions. Based on Fuchtbauer–Ladenburg equation model, the propagating direction-dependent SE cross-section spectra in Nd:YVO_4 are obtained for the first time, to our best knowledge. A novel concept of anisotropic SE cross-section is proposed to interpret the propagating direction-dependent effect. The experiment results reveal that for an arbitrary propagating direction the SE cross-section of e light around 1064 nm can be expressed as a superposition from two principle axial propagating directions with a weight of plane projection.

关键词： solid-state lasers stimulated emission cross-section Nd:YVO4 laser spectroscopy

Effects of surface adsorbed oxygen, applied voltage, and temperature on UV photoresponse of ZnO nanorods

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Chinese Physics B 2015年第10期24卷 501-506页

作者：宗仙丽朱荣 State Key Laboratory of precision Measurement Technology and instruments Department of Precision InstrumentTsinghua University

The ultraviolet（UV） photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, including ambient environment, applied bias voltage, gate voltage and temperature. Experimental results indicate that the photoresponses of the ZnO nanorods can be modulated by surface oxygen adsorptions, applied voltages, as well as temperatures. A model taking into account both surface adsorbed oxygen and electron-hole activities inside ZnO nanorods is proposed. The enhancement effect of the bias voltage on photoresponse is also analyzed. Experimental results shows that the UV response time（to 63%） of ZnO nanorods in air and at 59°C could be shortened from 34.8 s to 0.24 s with a bias of 4 V applied between anode and cathode.

关键词： ZnO nanorods UV photoresponse surface effect applied voltage effect

Research on the resolution of micro stereo lithography

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Chinese Optics Letters 2009年第8期7卷 724-727页

作者：王翔何冀军裴香涛邵鹏褚家如黄文浩 department of precision machinery and precision instrumentation University of Science and Technology of China

Micro stereo lithography is a kind of technology utilizing the solidified effect that photo curable polymer will appear under ultraviolet （UV） laser exposure. It is widely used in three-dimensional （3D） micro fabrication. We get the experimental values of a pair of UV laser curing coefficients, absorption coefficient and critical curing energy, of curable resin by fitting the calculation results of the Gaussian beam theory and experimental curing results. The theoretical relation between the curing unit＇s shape and the exposure features of time and intensity of convergent Gaussian beam is presented. The calculation and experimental results of curing unit under different conditions agree well with each other. This research offers a steady base for further research about the improvement of resolution.

关键词： Curing Gaussian noise (electronic) Laser theory Research Resins Three dimensional

Improvements for Manipulating DNA with Optical Tweezers

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Chinese Physics Letters 2015年第10期32卷 170-173页

作者：朱春丽李静 department of precision machinery and precision instrumentation University of Science and Technology of China

Recently, numerous biological macromolecular experiments have been conducted with optical tweezers. For the single molecular stretching experiment with optical tweezers, three ways to determine the initial adhesion point of DNA on the coverslip are described in this work. In addition, a new method through analyzing the displacement variance of the trapped particle to obtain the trap height is introduced. Using our proposed methods, the obtained force-extension curve for the operated dsDNA agrees well with the worm-like chain model. These improved methods are also applicable to other related biological macromolecular experiments requiring high precision.

关键词： DNA Improvements for Manipulating DNA with Optical Tweezers

Spectral distortion of dual-comb spectrometry due to repetition rate fluctuation

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Chinese Physics B 2016年第4期25卷 161-165页

作者：杨宏雷尉昊赟李岩 State Key Laboratory of precision Measurement Technology & instruments Department of Precision InstrumentTsinghua University

Dual-comb spectrometry suffers the fluctuations of parameters in combs. We demonstrate that the repetition rate is more important than any other parameter, since the fluctuation of the repetition rate leads to a change of difference in the repetition rate between both combs, consequently causing the conversion factor variation and spectral frequency misalignment. The measured frequency noise power spectral density of the repetition rate exhibits an integrated residual frequency modulation of 1.4 Hz from 1 Hz to 100 kHz in our system. This value corresponds to the absorption peak fluctuation within a root mean square value of 0.19 cm-1 that is verified by both simulation and experimental result. Further, we can also simulate spectrum degradation as the fluctuation varies. After modifying misaligned sPectra and averaging, the measured result agrees well with the simulated spectrum based on the GEISA database.

关键词： optical frequency comb Infrared spectra molecular spectra

Beyond Performance of Learning Control Subject to Uncertainties and Noise: A Frequency-Domain Approach Applied to Wafer Stages

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 198-214页

作者： Fazhi Song Ning Cui Shuaiqi Chen Kai Zhang Yang Liu Xinkai Chen Jiubin Tan IEEE the Center of Ultra-precision Optoelectronic instrument Engineering Harbin Institute of Technology the Key Laboratory of Ultra-precision Intelligent instrumentation Ministry of Industry and Information Technology the State Key Laboratory of precision Electronic Manufacturing Technology and Equipment Guangdong University of Technology the Center of Ultraprecision Optoelectronic instrument Engineering Harbin Institute of Technology the Key Laboratory of Ultraprecision Intelligent instrumentation Ministry of Industry and Information Technology the department of Electronic and Information Systems Shibaura Institute of Technology

The increasingly stringent performance requirement in integrated circuit manufacturing, characterized by smaller feature sizes and higher productivity, necessitates the wafer stage executing a extreme motion with the accuracy in terms of nanometers. This demanding requirement witnesses a widespread application of iterative learning control(ILC), given the repetitive nature of wafer scanning. ILC enables substantial performance improvement by using past measurement data in combination with the system model knowledge. However, challenges arise in cases where the data is contaminated by the stochastic noise, or when the system model exhibits significant uncertainties, constraining the achievable performance. In response to this issue, an extended state observer(ESO) based adaptive ILC approach is proposed in the frequency *** being model-based, it utilizes only a rough system model and then compensates for the resulting model uncertainties using an ESO, thereby achieving high robustness against uncertainties with minimal modeling effort. Additionally, an adaptive learning law is developed to mitigate the limited performance in the presence of stochastic noise, yielding high convergence accuracy yet without compromising convergence speed. Simulation and experimental comparisons with existing model-based and data-driven inversion-based ILC validate the effectiveness as well as the superiority of the proposed method.

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Semi-classical theory and experimental research for polarization flipping in a single frequency laser with feedback effect

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Chinese Physics B 2012年第9期21卷 76-80页

作者：陈文学张书练张鹏曾召利 The State Key Laboratory of precision Measurement Technology and instrument Department of Precision InstrumentsTsinghua University

In this paper, we propose a semi-classical theory to successfully explain the polarization flipping in a single frequency laser. An experimental setup is built to verify this theory. The observed experimental phenomena are consistent with the theoretical analysis. We perform phase retardation measurements of birefringent components using this experimental system. The results show that the measurement repeatability is 0.12° and the measurement accuracy is 0.22°.

关键词： semi-classical theory interference birefringence