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Mining Object Similarity for Predicting Next Locations

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Journal of Computer Science & Technology 2016年第4期31卷 649-660页

作者： Meng Chen Xiaohui Yu yang liu School of Computer Science and Technology Shandong University Jinan 250101 China School of Information Technology York University Toronto M3J1P3 Canada

Next location prediction is of great importance for many location-based applications. With the virtue of solid theoretical foundations, Markov-based approaches have gained success along this direction. In this paper, we seek to enhance the prediction performance by understanding the similarity between objects. In particular, we propose a novel method, called weighted Markov model （weighted-MM）, which exploits both the sequence of just-passed locations and the object similarity in mining the mobility patterns. To this end, we first train a Markov model for each object with its own trajectory records, and then quantify the similarities between different objects from two aspects： spatial locality similarity and trajectory similarity. Finally, we incorporate the object similarity into the Markov model by considering the similarity as the weight of the probability of reaching each possible next location, and return the top-rankings as results. We have conducted extensive experiments on a real dataset, and the results demonstrate significant improvements in prediction accuracy over existing solutions.

关键词： weighted Markov model next location prediction object similarity

Remediation of arsenic contaminated soil by sulfidated zero-valent iron

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Frontiers of Environmental Science & Engineering 2021年第5期15卷 85-95页

作者： Junlian Qiao yang liu Hongyi yang Xiaohong Guan Yuankui Sun State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and EngineeringTongji UniversityShanghai200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092China

In this study,the influences of sulfidation on zero-valent iron(ZVI)performance toward As(Ⅴ)immobilization in soil were systemically *** was found that,compared to unamended ZVI,sulfidated ZVI(S-ZVI)is more favorable to immobilize As(Ⅴ)in soil and promote the conversion of water soluble As to less mobile Fe-Mn bound ***,under the optimal S/Fe molar ratio of 0.05,almost all of the leached As could be sequestrated by>0.5 wt.%S-ZVI within 3 *** the presence of HA could decrease the desorption of As from soil,HA inhibited the reactivity of S-ZVI to a greater *** experiments further proved the feasibility of applying S-ZVI on soil As(Ⅴ)*** importantly,to achieve a good As retention performance,S-ZVI should be fully mixed with soil or located on the downstream side of As *** test simulating the flooding conditions in rice culture revealed there was also a good long-term stability of soil As(Ⅴ)after S-ZVI remediation,where only 0.7%of As was desorbed after 30 days of *** separation was employed to separate the immobilized As(Ⅴ)from soil after S-ZVI amendment,where the separation efficiency was found to be dependent of the iron dosage,liquid to soil ratio,and reaction *** characteristic leaching procedure(TCLP)tests revealed that the leachability of As from soil was significantly reduced after the S-ZVI amendment and magnetic separation *** these findings provided some insights into the remediation of As(Ⅴ)-polluted soil by ZVI.

关键词： Soil As(Ⅴ) Sulfidation Zero-valent iron Magnetic separation

Unbiased Condition of the Dispersion Effects Estimator in Unreplicated Two-Level Factorial Experiments

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Journal of Systems Science & Complexity 2016年第6期29卷 1716-1736页

作者： yang liu LI Jihong WANG Yu Department of Applied Mathematics Shanxi University of Finance and Economics Computer Center Shanxi University

This article presents a general form of the estimator for identifying dispersion effects from unreplicated two-level factorial experiments,and shows that the widely used estimators such as the BH,MH,and AMH estimators are all special cases of the proposed one,designated as the G *** unbiased condition of the G estimator is proved,and a lower bound of variance of the G estimator is provided.A simulation based on a realistic design illustrates the variation of the variance and MSE(mean square error) of the G estimator on different *** estimator may be more flexible and has better performance than other methods such as the BH and MH estimators by appropriately selecting the coefficients.

关键词： Dispersion effects location-dispersion model unreplicated factorial experiments.

Determination of Elastoplastic Mechanical Properties of the Weld and Heat Affected Zone Metals in Tailor-Welded Blanks by Nanoindentation Test

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 911-918页

作者： MA Xiangdong GUAN Yingping yang liu Key Laboratory of Advanced Forming & Stamping Technology and Science of Ministry of Education Yanshan University

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

关键词： tailor-welded blanks elastoplastic mechanical properties nanoindentation test Erichsen cupping test

Experimental realization of single-shot nonadiabatic holonomic gates in nuclear spins

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Science China(Physics,Mechanics & Astronomy) 2017年第8期60卷 1-7页

作者： Hang Li yang liu GuiLu Long State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Collaborative Innovation Centre of Quantum Matter School of Nuclear Science and Engineering North China Electric Power University Tsinghua National Laboratory for Information Science and Technology

Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to realize a general one-qubit gate. Based on two recent reports, we construct two Hamiltonians and experimentally realized nonadiabatic holonomic gates by a single-shot implementation in a two-qubit nuclear magnetic resonance （NMR） system. Two noncommuting one-qubit holonomic gates, rotating along .~ and ~ axes respectively, are implemented by evolving a work qubit and an ancillary qubit nonadiabatically following a quantum circuit designed. Using a sequence compiler developed for NMR quantum information processor, we optimize the whole pulse sequence, minimizing the total error of the implementation. Finally, all the nonadiabatic holonomic gates reach high unattenuated experimental fidelities over 98%.

关键词： nonadiabatic holonomic quantum computation nuclear magnetic resonance quantum process tomography

Flight safety measurements of UAVs in congested airspace

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Chinese Journal of Aeronautics 2016年第5期29卷 1355-1366页

作者： Xiang Jinwu liu yang Luo Zhangping School of Aeronautic Science and Engineering Beihang University

Describing spatial safety status is crucial for high-density air traffic involving multiple unmanned aerial vehicles （UAVs） in a complex environment. A probabilistic approach is proposed to measure safety situation in congested airspace. The occupancy distribution of the airspace is represented with conflict probability between spatial positions and UAV. The concept of a safety envelope related to flight performance and response time is presented first instead of the conventional fixed-size protected zones around aircraft. Consequently, the conflict probability is performance-dependent, and effects of various UAVs on safety can be distinguished. The uncertainty of a UAV future position is explicitly accounted for as Brownian motion. An analytic approximate algorithm for the conflict probability is developed to decrease the computational consumption. The relationship between safety and flight performance are discussed for different response times and prediction intervals. To illustrate the applications of the approach, an experiment of three UAVs in formation flight is performed. In addition, an example of trajectory planning is simulated for one UAV flying over airspace where five UAVs exist. The validation of the approach shows its potential in guaranteeing flight safety in highly dynamic environment.

关键词： Airspace safety situation Conflict probability Flight conflict Navigation UAV

Prescribed Performance Finite-Time Tracking Control for Uncertain Nonlinear Systems

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Journal of Systems Science & Complexity 2019年第3期32卷 803-817页

作者： JING Yuanwei liu yang ZHOU Shaowei College of Information Science and Engineering Northeastern University Shenyang 110819 China College of Mathematics and Systems Science Shandong University of Science and Technology Qingdao 266590 China

This work investigates the finite-time tracking control problem for a class of uncertain strict-feedback nonlinear systems from a new perspective. First, a novel concept called finite-time performance function (FTPF) is defined. Further, a new sufficien t condition of finite-time st ability is derived and the tracking error can converge to a predefined region within a finite-time interval. The design process of the proposed technique is simpler. Finally, four simulation examples are carried out to illustrate the effectiveness of presented method.

关键词： Finite-time boundedness prescribed performance control uncertain nonlinear systems

Predictor and ESO-based adaptive tracking control of heterogeneous vehicle platoon

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Science China(Technological Sciences) 2024年第9期67卷 2842-2852页

作者： SUN ZhiZe liu yang ZHANG LinChuang College of Control Science and Engineering Bohai UniversityJinzhou 121013China College of Automation and Electronic Engineering Qingdao University of Science and TechnologyQingdao 266061China College of Information Science and Technology Bohai UniversityJinzhou 121013China

This paper investigates the distributed adaptive platoon tracking problem of third-order heterogeneous vehicles subject to model uncertainties. The design process is divided into two steps. Firstly, an adaptive tracking controller is designed for the dynamic leading vehicle. And then, the distributed adaptive controllers are established for followers. Moreover, the predictor technique is used to improve the estimate performance of the adaptive law, and the total disturbance is approximated and compensated by the variable gain nonlinear extended state observers(NESOs) driven by the estimation error. By introducing the variable gain hyperbolic tangent tracking differentiator(HTTD), the “complexity explosion” problem is avoided. The feasibility and effectiveness of the proposed protocol are verified by simulation tests.

关键词： variable gain NESOs heterogeneous vehicles platoon tracking predictor

Exosomal let-7a-5p derived from human umbilical cord mesenchymal stem cells alleviates coxsackievirus B3-induced cardiomyocyte ferroptosis via the SMAD2/ZFP36 signal axis

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第5期25卷 422-437页

作者： Xin LI Yanan HU Yueting WU Zuocheng yang yang liu Hanmin liu Department of Pediatric Pulmonology and Immunology West China Second University HospitalSichuan UniversityChengdu 610041China Key Laboratory of Birth Defects and Related Diseases of Women and Children(Sichuan University) Ministry of EducationChengdu 610041China NHC Key Laboratory of Chronobiology(Sichuan University) Chengdu 610041China The Joint Laboratory for Lung Development and Related Diseases of West China Second University Hospital Sichuan University and School of Life Sciences of Fudan UniversityWest China Institute of Women and Children's HealthWest China Second University HospitalSichuan UniversityChengdu 610041China Sichuan Birth Defects Clinical Research Center West China Second University HospitalSichuan UniversityChengdu 610041China Department of Pediatrics the Third Xiangya HospitalCentral South UniversityChangsha 410013China

Viral myocarditis(VMC)is one of the most common acquired heart diseases in children and ***,its pathogenesis is still unclear,and effective treatments are *** study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes(CMCs)induced by coxsackievirus B3(CVB3).CVB3 was utilized for inducing the VMC mouse model and cellular *** echocardiography,left ventricular ejection fraction(LVEF),and left ventricular fractional shortening(LVFS)were implemented to assess the cardiac *** CVB3-induced VMC mice,cardiac insufficiency was observed,as well as the altered levels of ferroptosis-related indicators(glutathione) peroxidase 4(GPX4),glutathione(GSH),and malondialdehyde(MDA).However,exosomes derived from human umbilical cord mesenchymal stem cells(hucMSCs-exo)could restore the changes caused by CVB3 ***-7a-5p was enriched in hucMSCs-exo,and the inhibitory ffect of hucMSCs-exoa-ie-pmimo on CVB3-induced ferroptosis was higher than that of hucMSCs-exommie N(NC:negative control).Mothers against decapentaplegic homolog 2(SMAD2)increased in the VMC group,while the expression of zinc-finger protein 36(ZFP36)***-7a-5p was confirmed to interact with SMAD2 messenger RNA(mRNA),and the SMAD2 protein interacted directly with the ZFP36 *** SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related ***,the levels of GPX4,solute carrier family 7,member 11(SLC7A11),and GSH were lower in the SMAD2 overexpression plasmid(oe-SMAD2)+let-7a-5p mimic group than in the oe-NC+let-7a-5p mimic group,while those of MDA,reactive oxygen species(ROS),and Fe^(2+)*** conclusion,these data showed that ferroptosis could be regulated by mediating SMAD2 ***-let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36,which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.

关键词： Exosome Let-7a-5p Mothers against decapentaplegic homolog 2(SMAD2) Coxsackievirus B3(CVB3) Ferroptosis