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Improved Bag-of-Words Model for Person Re-identification

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Tsinghua Science and Technology 2018年第2期23卷 145-156页

作者： lu tian Shengjin Wang Department of Electronic Engineering Tsinghua University Beijing 100084 China.

Person re-identification(person re-id) aims to match observations on pedestrians from different *** is a challenging task in real word surveillance systems and draws extensive attention from the *** existing methods are based on supervised learning which requires a large number of labeled data. In this paper, we develop a robust unsupervised learning approach for person re-id. We propose an improved Bag-of-Words(i Bo W) model to describe and match pedestrians under different camera views. The proposed descriptor does not require any re-id labels, and is robust against pedestrian variations. Experiments show the proposed i Bo W descriptor outperforms other unsupervised methods. By combination with efficient metric learning algorithms, we obtained competitive accuracy compared to existing state-of-the-art methods on person re-identification benchmarks, including VIPe R, PRID450 S, and Market1501.

关键词： person re-identification bag-of-words unsupervised learning feature fusion

New determination of the gravitational constant G

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National Science Review 2020年第12期7卷 1796-1797页

作者： Zheng-tian lu Hefei National Laboratory for Physical Sciences at the Microscale CAS Center for Excellence in Quantum Information and Quantum PhysicsUniversity of Science and Technology of China

A new and so far the most precise determination of the gravitational constant G has been made by Jun luo and colleagues at the Huazhong University of Science and Technology(HUST) [1].The combination of G with two other most fundamental physical constants,the speed of light c and Planck’s constant h,can together construct the natural units(*** units) of time,length and *** relationships inform us that,

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A novel progressive wave gyroscope based on acousto-optic effects

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Microsystems & Nanoengineering 2022年第5期8卷 81-90页

作者： lu tian Qiang Shen Honglong Chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospacea School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

We propose and numerically investigate a brand-new,high-sensitivity progressive wave gyroscope based on acoustooptic effects for the measurement of rotational angular *** the traditional surface acoustic wave(SAW)gyroscope,which uses shifts in the SAW frequency to characterize the rotational angular velocity,this study uses acousto-optic effects to detect changes in refractive index caused by mechanical strain,measuring the angular velocity by the output optical power intensity of the optical *** three-dimensional finite element analysis method is utilized to build an SAW excitation model and optical detection *** show that the sensitivity of the SAW gyroscope is highly dependent upon geometric parameters of the structure and that the mechanical strain induced by the progressive wave of the SAW can be effectively measured by the optical power intensity under the action of external angular *** superiority of the proposed structure is substantiated by its achievement of a theoretical sensitivity of 1.8647(mW/m^(2))/(rad/s)and high impact resistance of 220,000 *** means of normalization,the sensitivity of the proposed structure can be enhanced by four orders of magnitude compared to the traditional SAW *** novel structure combines the advantages of both conventional microscale vibrating gyroscopes and optical gyroscopes,providing a powerful solution for performance enhancement of SAW gyroscopes and,thereby,enabling application in the field of inertial devices.

关键词： resistance wave structure

The apparent state of droplets on a rough surface

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 233-238页

作者： CHEN XiaoLing lu tian Key Laboratory for Power Machinery and Engineering of Ministry of Education School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200030China

The factors influencing the state and wetting transition of droplets on a rough surface are both complex and obscure. The change in wetting is directly reflected by changes under the contact condition of the droplets with the surface. The recent study about the wettability of the superhydrophobic surface under the condensing condition arouses the new understanding about the apparent state of droplets on a rough surface. In this work, to validate the existence of droplets in an intermediate state, a microscale pillar topological polydimethylsiloxane (PDMS) surface was manufactured and its wettability under various conditions was studied. According to the experimental data, it is proposed that the wetting state of a rough surface may be embodied using the contact area ratio of a solid/liquid/gas droplet with the projective plane. A general calculation model for the apparent contact angle of droplets is given and expressed diagrammatically. It is found that the measured apparent contact angles of droplets at dif- ferent states on the surface falls within the range predicted by our proposed equation.

关键词： rough surface wettability apparent contact angle condensing condition

Probing the liquid-solid transition of petroleum macromolecules with terahertz time-domain spectroscopy

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Science China(Physics,Mechanics & Astronomy) 2018年第10期61卷 85-87页

作者： RenHe tian RiMa Bao lu tian Schoolof Public Management Northwest University Xi 'an 710127China Beijing Key Laboratory of Optical Detection Technology for Oil and Gas China University of Petroleum Beijing 102249 China School of Physics Northwest University Xi'an 710069 China

The formation of solid deposits or petroleum waxes con- stitutes a constantly recurring problem in petroleum macromolecule transportation. To solve this problem, representing and predicting the thermodynamic behavior of macromolecular products such as paraffin waxes and lubricating greases is essential. In this regard, terahertz time- domain spectroscopy （THz-TDS） has recently received great attention with the expectation that it will provide new insights into complex macromolecular systems such as skeletal vibrations, side-chain vibration, and the vibration of hydrocarbon bonds. In this paper, THz-TDS was used as a fast method for the detection of phase transition without the need for sample manipulation. Thus, the optical properties of

关键词：大分子光谱学时间域石油 THz-TDS 固体液体探查

Ultrafast magnetization enhancement and spin current injection in magnetic multilayers by exciting the nonmagnetic metal

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Science China(Physics,Mechanics & Astronomy) 2023年第12期66卷 158-168页

作者： Wen-tian lu Zhe Yuan Xiaohong Xu Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuan 030032China Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China

A systematic investigation of spin injection behavior in Au/FM(FM=Fe and Ni)multilayers is performed using the superdiffusive spin transport *** exciting the nonmagnetic layer,the laser-induced hot electrons may transfer spin angular momentum into the adjacent ferromagnetic(FM)metals resulting in ultrafast demagnetization or *** find that these experimental phenomena sensitively depend on the particular interface reflectivity of hot electrons and may reconcile the different observations in the *** by the ultrafast spin currents carried by the hot electrons,we propose the multilayer structures to generate highly spin-polarized currents for the development of future ultrafast spintronics *** spin polarization of the electric currents carried by the hot electrons can be significantly enhanced by the joint effects of bulk and interfacial spin ***,the intensity of the generated spin current can be optimized by varying the number of repeated stacking units and the thickness of each metallic layer.

关键词： spintronics ultrafast magnetodynamics spin polarization transport magnetic multilayer

Machine learning aided design of perovskite oxide materials for photocatalytic water splitting

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Journal of Energy Chemistry 2021年第9期30卷 351-359页

作者： Qiuling Tao tian lu Ye Sheng Long Li Wencong lu Minjie Li Department of Chemistry College of SciencesShanghai UniversityShanghai 200444China Materials Genome Institute Shanghai UniversityShanghai 200444China

Suffering from the inefficient traditional trial-and-error methods and the huge searching space filled by millions of candidates, discovering new perovskite visible photocatalysts with higher hydrogen production rate(RH_(2)) still remains a challenge in the field of photocatalytic water splitting(PWS). Herein, we established structural-property models targeted to RH_(2) and the proper bandgap(Eg) via machine learning(ML) technology to accelerate the discovery of efficient perovskite photocatalysts for PWS. The Pearson correlation coefficients(R) of leave-one-out cross validation(LOOCV) were adopted to compare the performances of different algorithms including gradient boosting regression(GBR), support vector regression(SVR), backpropagation artificial neural network(BPANN), and random forest(RF). It was found that the BPANN model showed the highest R values from LOOCV and testing data of 0.9897 and 0.9740 for RH_(2),while the GBR model had the best values of 0.9290 and 0.9207 for Eg. Furtherly, 14 potential PWS perovskite candidates were screened out from 30,000 ABO3-type perovskite structures under the criteria of structural stability, Eg, conduction band energy, valence band energy and RH_(2). The average RH_(2) of these14 perovskites is 6.4% higher than the highest value in the training data set. Moreover, the online web servers were developed to share our prediction models, which could be accessible in http://***/ocpmdm/material_api/ahfga3d9puqlknig(E_g prediction) and http://***/ocpmdm/material_api/i0 ucuyn3 wsd14940(RH_(2) prediction).

关键词： Perovskite Machine learning Online web service Photocatalytic water splitting Bandgap Hydrogen production rate

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

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Microsystems & Nanoengineering 2024年第2期10卷 47-56页

作者： lu tian Haitao Zhao Qiang Shen Honglong Chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an710072China

A surface acoustic wave(SAW)gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope *** a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system(MEMS)***,for the first time,we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers(FIDTs).Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves,which cause beam deflection and result in energy dissipation,this study uses FIDTs to concentrate the SAW energy based on structural features,resulting in better focusing performance and increased SAW *** experimental results reveal that the sensitivity of the structure is 1.51µV/(°/s),and the bias instability is 0.77°/s,which are improved by an order of magnitude compared to those of a traditional SAW ***,the FIDT component can enhance the performance of the SAW gyroscope,demonstrating its superiority for angular velocity *** work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

关键词： angular deflection gyroscope

Digital Cancellation Scheme and Hardware Implementation for High-Order Passive Intermodulation Interference Based on Hammerstein Model

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China Communications 2019年第9期16卷 165-176页

作者： Xiaqing Miao lu tian School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China China Academy of Electronics and Information Technology Beijing 100041China

Passive intermodulation(PIM)interference urgently needs to be solved in the satellite communication system,owing to degrading the whole *** research contributions to the cancellation method for PIM were focused on the analog domain,however,the PIM distortion cannot be eliminated completely with the ***,some researchers attempt to tackle the problem through digital signal processing,nevertheless,the proposed methods were not suitable for the practical satellite communication *** this paper,we present a general scheme for the adaptive feedforward PIM ***-order PIM signals at baseband are estimated by modeling the PIM distortion with Hammerstein model in the digital *** on the reconstructed PIM signal,we adopt the least mean square algorithm to adaptively mitigate the PIM interference for tracking the variation of *** time and frequency synchronization of PIM are based on the correlation of the peak of received signals with the corresponding reconstructed PIM *** experimental results show that the scheme can effectively cancel the PIM interference,and achieve an interference suppression gain more than 20dB.

关键词： satellite communication passiveintermodulation interference digital cancellation Hammerstein model