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Geometry-based non-line-of-sight error mitigation and localization in wireless communications

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Science China(Information Sciences) 2019年第10期62卷 149-163页

作者： Jingyu HUA Yejia YIN Anding WANG Yu ZHANG Weidang lu School of Information and Electronic Engineering Zhejiang Gongshang University Zhejiang Provincial Key Laboratory of Information Processing Communication and Networking College of Information Engineering Zhejiang University of Technology

Recently, positioning services have received considerable attention. The primary source of the positioning error is non-line-of-sight(NLOS) propagation. To address this problem, we propose a novel NLOS mitigation scheme, in which the geometric relationship between a base station and a mobile station is *** makes it possible to identify range measurements corrupted by NLOS errors, and the mobile station can then estimate its position through line-of-sight(LOS) measurements. Moreover, the threshold of the NLOS detector is derived via a hybrid method using both the analytical derivation and computer simulation, which significantly reduces the difficulty of identifying thresholds. After identifying the NLOS measurements, a two-step weighted-least-squares algorithm is used to obtain the localization, in which both range and angle measurements are considered. The simulation results reveal that the proposed algorithm yields a high identification probability of NLOS measurements, which results in improved localization performance.

关键词： wireless localization non-line-of-sight error geometry cellular network residual

Evolution of the texture and mechanical properties of 2060 alloy during bending

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International Journal of Minerals,Metallurgy and Materials 2015年第9期22卷 966-971页

作者： Xiao Jin Bao-qin Fu Cheng-lu Zhang Wei Liu Laboratory of Advanced Materials School of Materials Science and Engineering Tsinghua University Key Laboratory for Radiation Physics and Technology Institute of Nuclear Science and Technology Sichuan University

In this study, we examined the evolution of the texture and mechanical properties of 2060 （T8） alloy during bending. A pixel rotation method （PRM） was proposed and used to characterize the textural evolution during bending determined by electron backscatter diffraction. The results showed that the textural components changed insignificantly, with the exception of a decrease in the cube texture. The tensile and yielding properties of the alloy were evaluated at three different orientations with respect to the rolling direction. The mechanical strength was found to increase in three directions with decreasing bending radius; thus, it was concluded that the 2060 （T8） alloy sheet satisfies the usage requirement after bending deformation.

关键词： aluminum-lithium alloys bending texture mechanical properties

Block dual Toeplitz Operators on the Orthogonal Complements of Fock Spaces

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1967-1988页

作者： Jian Xiang DONG Chun Xu XU Yu Feng lu School of Mathematical Sciences Dalian University of TechnologyDalian 116024P.R.China School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006P.R.China

In this paper,we characterize the boundedness and compactness of the block dual Toeplitz operators acting on the orthogonal complement of the Fock spaces,and the compactness of the finite sum of two dual Toeplitz oper... 详细信息

关键词： Block dual Toeplitz operators boundedness compactness Fock space (semi)-commutator

Effects of Strain Rate and Deformation Temperature on Microstructures and Hardness in Plastically Deformed Pure Aluminum

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Journal of Materials Science & Technology 2011年第1期27卷 1-7页

作者： F. Huang N.R. Taot K. lu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China

The microstructures and hardness of pure Al samples subjected to plastic deformation with different tem- peratures and strain rates were investigated. The results showed that the strain-induced grain refinement is significantly benefited by increasing strain rate and reducing deformation temperature. The saturated size of refined subgrains in Al can be as small as about 240 nm in cryogenic dynamic plastic deformation （DPD）. Grain boundaries of the DPD Al samples are low-angle boundaries due to suppression of dynamic recovery during deformation. Agreement of the measured hardness with the empirical Hall-Petch relation extrapolated from the coarse-grained Al implies that the low-angle boundaries can contribute to strengthening as effective as the conventional grain boundaries.

关键词： Dynamic plastic deformation Microstructure Hardness Strain rate Temperature

Study on carbon emission calculation method and carbon reduction indexes of urban building stock

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Science China(Technological Sciences) 2024年第9期67卷 2706-2726页

作者： YANG Liu ZHANG Nan lu Mei luO ZhiXing DOU Mei State Key Laboratory of Green Building Xi’an University of Architecture and TechnologyXi’an 710055China School of Architecture Xi’an University of Architecture and TechnologyXi’an 710055China School of Language Literature and LawXi’an University of Architecture and TechnologyXi’an 710055China School of Management Xi’an University of Architecture and TechnologyXi’an 710055China China Southwest Architectural Design and Research Institute Corp.Ltd. Chengdu 610041China

Carbon emissions associated with buildings are a major source of urban emissions. To put forward the methods and strategies to curb carbon emissions from urban building stock, it is not only necessary to establish a carbon emission calculation method for fine statistical analysis, but also to evaluate carbon emissions of urban planning schemes with applicable indexes. Currently,researches mainly focus on carbon emissions of individual buildings. When expanded to urban building stock, the calculation faces the lack of basic data, inadequate spatial analysis and unspecific carbon reduction indexes. Therefore, this study proposes a bottom-up calculation method for urban building stock, conducts spatial analysis based on carbon balance of urban grids, reveals the coupling mechanism between urban carbon reduction indexes and grid carbon emissions, and systematically establishes a carbon-reduction-oriented urban planning method that comprises calculation, analysis and evaluation, which is applied to Xi'an,China. This study provides a theoretical reference for cities to formulate carbon reduction targets and implement planning strategies by evaluating and predicting carbon emissions from urban building stock.

关键词： carbon emissions urban building stock calculation method carbon reduction index

A comparative study and evaluation of sulfamethoxazole adsorption onto organo-montmorillonites

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Journal of Environmental Sciences 2014年第12期26卷 2535-2545页

作者： Laifu lu Manglai Gao Zheng Gu Senfeng Yang Yuening Liu State Key Laboratory of Heavy Oil Processing College of Science China University of Petroleum

Three organo-montmorillonites were prepared using surfactants, and their adsorption behaviors toward sulfamethoxazole（SMX） were investigated. The surfactants used were cetyltrimethyl ammonium bromide（CTMAB）, 3-（N,N-dimethylhexadecylammonio） propane sulfonate（HDAPS） and 1,3-bis（hexadecyldimethylammonio）-propane dibromide（BHDAP）. The properties of the organo-montmorillonites were characterized by X-ray diffraction, scanning electron microscopy and N2adsorption–desorption isotherm measurements. Results showed that the interlayer spacing of montmorillonite was increased and the surface area as well as the morphology were changed. Batch adsorption experiments showed that the surfactant loading amount had a great effect on the adsorption of SMX. The adsorption process was p H dependent and the maximum adsorption capacity was obtained at p H 3 for HDAPS-Mt, while CTMAB-Mt and BHDAP-Mt showed a high removal efficiency at 3–11. The adsorption capacity increased with the initial SMX concentration and contact time but decreased with increasing solution ionic *** data were best described by the pseudo second-order model. Equilibrium data were best represented by the Langmuir model, and the Freundlich constant（n） indicated a favorable adsorption process. The maximum adsorption capacity of SMX was 235.29 mg/g for CTMAB-Mt, 155.28 mg/g for HDAPS-Mt and 242.72 mg/g for BHDAP-Mt. Thermodynamic parameters were calculated to evaluate the spontaneity and endothermic or exothermic nature. The adsorption mechanism was found to be dominated by electrostatic interaction,while hydrophobic interaction played a secondary role.

关键词： Organo-montmorillonite Adsorption Sulfamethoxazole Cetyltrimethyl ammonium bromide Zwitterionic surfactant Gemini surfactant

A method for pulsar searching:combining a two-dimensional autocorrelation profile map and a deep convolutional neural network

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Research in Astronomy and Astrophysics 2021年第7期21卷 155-170页

作者： Long-Qi Wang Jing Jin lu Liu Yi Shen Department of Control Science and Engineering Harbin Institute of TechnologyHarbin 150001China

In pulsar astronomy, detecting effective pulsar signals among numerous pulsar candidates is an important research topic. Starting from space X-ray pulsar signals, the two-dimensional autocorrelation profile map(2 D-APM) feature modelling method, which utilizes epoch folding of the autocorrelation function of X-ray signals and expands the time-domain information of the periodic axis, is proposed. A uniform setting criterion regarding the time resolution of the periodic axis addresses pulsar signals without any prior information. Compared with the traditional profile, the model has a strong anti-noise ability, a greater abundance of information and consistent characteristics. The new feature is simulated with double Gaussian components, and the characteristic distribution of the model is revealed to be closely related to the distance between the double peaks of the profile. Next, a deep convolutional neural network(DCNN)is built, named Inception-Res Net. According to the order of the peak separation and number of arriving photons, 30 data sets based on the Poisson process are simulated to construct the training set, and the observation data of PSRs B0531+21, B0540-69 and B1509-58 from the Rossi X-ray Timing Explorer(RXTE) are selected to generate the test set. The number of training sets and the number of test sets are 30 000 and 5400, respectively. After achieving convergence stability, more than 99% of the pulsar signals are recognized, and more than 99% of the interference is successfully rejected, which verifies the high degree of agreement between the network and the feature model and the high potential of the proposed method in searching for pulsars.

关键词： methods:data analysis methods:statistical X-rays:stars

Dynamics and formation of vortices collapsed from ring dark solitons in a two-dimensional spin–orbit coupled Bose–Einstein condensate

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Frontiers of physics 2022年第4期17卷 185-193页

作者： Peng-Hong lu Xiao-Fei Zhang Chao-Qing Dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China Department of Physics Shaanxi University of Science and TechnologyXi’an 710021China

We consider the dynamics and formation of vortices from ring dark solitons in a two-dimensional Bose–Einstein condensate with the Rashba spin–orbit coupling based on the time-dependent coupled Gross–Pitaevskii *** with previous results,the system exhibits complex dynamical behaviors in the presence of the spin–orbit *** the modulation of the spin–orbit coupling,not only the lifetime of ring dark solitons is greatly prolonged,but also their attenuation kinetics is significantly *** two shallow ring dark solitons with the equal strength of the spin–orbit coupling,the radius of ring dark solitons increases to a maximum value over time and then shrinks into a minimum *** to the effect of the snake instability,ring dark solitons split into a series of ring-like clusters of vortex pairs,which perform complex *** indicates that the system is strongly dependent on the presence of the spin–orbit ***,the effect of different initial modulation depths on the dynamics of ring dark solitons is investigated.

关键词： Bose–Einstein condensate Rashba spin–orbit coupling ring dark solitons vortex pairs

Near Infrared Star Centroid Detection by Area Analysis of Multi-Scale Super Pixel Saliency Fusion Map

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Tsinghua Science and Technology 2019年第3期24卷 291-300页

作者： Xiaohu Yuan Shaojun Guo Chunwen Li Bin lu Shuli Lou the Department of Automation Tsinghua University the National Innovation Institute of Defense Technology Naval Aeronautical University Yantai University

The centroid location of a near infrared star always deviates from the real center due to the effects of surrounding radiation. To determine a more accurate center of a near infrared star, this paper proposes a method to detect the star's saliency area and calculate the star's centroid via the pixels only in this area, which can greatly decrease the effect of the radiation. During saliency area detection, we calculated the boundary connectivity and gray similarity of every pixel to estimate how likely it was to be a background pixel. Aiming to simplify and speed up the calculation process, we divided the near infrared starry sky image into super pixel maps at multi-scale by Simple Linear Iterative Clustering(SLIC). Second, we detected the saliency map for every super pixel map of the image. Finally, we fused the saliency maps according to a weighted coefficient that is determined by the least square method. For the images used in our experiment, we set the multi-scale super pixel numbers to 100, 150,and 200. The results show that our method can obtain an offset variance of less than 0.27 for the center coordinates compared to the labelled centers.

关键词： near infrared starry star saliency Simple Linear Iterative Clustering (SLIC)