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Ladle Furnace Temperature Prediction Model Based on Large-scale Data With Random Forest

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IEEE/CAA Journal of Automatica Sinica 2017年第4期4卷 770-774页

作者： xiaojun wang Key Laboratory of Advanced Design and Intelligent Computing Ministry of EducationDalian UniversityDalian 116622 China

In ladle furnace, the prediction of the liquid steel temperature is always a hot topic for the researchers. The most of the existing temperature prediction models use small sample set. Today, the precision of them can not satisfy practical production. Fortunately, the large sample set is accumulated from the practical production process. However, a large sample set makes it difficult to build a liquid steel temperature model. To deal with the issue, the random forest method is preferred in this paper, which is a powerful regression method with low complexity and can be designed very quickly. It is with the parallel ensemble structure,uses sample subsets,and employs a simple learning algorithm of sub-models. Then, the random forest method is applied to establish a temperature model by using the data sampled from the production process. The experiments show that the random forest temperature model is more precise than other temperature models.

关键词： Ladle furnace random forest regression tree temperature prediction

Interval analysis method and convex models for impulsive response of structures with uncertain-but-bounded external loads

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Acta Mechanica Sinica 2006年第3期22卷 265-276页

作者： Zhiping Qiu xiaojun wang Institute of Solid Mechanics Beijing University of Aeronautics and Astronautics Beijing 100083 China

Two non-probabilistic, set-theoretical methods for determining the maximum and minimum impulsive responses of structures to uncertain-but-bounded impulses are presented. They are, respectively, based on the theories of interval mathematics and convex models. The uncertain-but-bounded impulses are assumed to be a convex set, hyper-rectangle or ellipsoid. For the two non-probabilistic methods, less prior information is required about the uncertain nature of impulses than the probabilistic model. Comparisons between the interval analysis method and the convex model, which are developed as an anti-optimization problem of finding the least favorable impulsive response and the most favorable impulsive response, are made through mathematical analyses and numerical calculations. The results of this study indicate that under the condition of the interval vector being determined from an ellipsoid containing the uncertain impulses, the width of the impulsive responses predicted by the interval analysis method is larger than that by the convex model; under the condition of the ellipsoid being determined from an interval vector containing the uncertain impulses, the width of the interval impulsive responses obtained by the interval analysis method is smaller than that by the convex model.

关键词： Impulsive response Interval analysis method Convex model Uncertain-but-bounded impulse

Safety estimation of structural systems via interval analysis

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Chinese Journal of Aeronautics 2013年第3期26卷 614-623页

作者： wang xiaojun wang Lei Qiu Zhiping Institute of Solid Mechanics Beihang University

Considering that the uncertain information has serious influences on the safety of structural systems and is always limited, it is reasonable that the uncertainties are generally described as interval sets. Based on the non-probabilistic set-theoretic theory, which is applied to measuring the safety of structural components and further combined with the branch-and-bound method for the probabilistic reliability analysis of structural systems, the non-probabilistic branch-and-bound method for determining the dominant failure modes of an uncertain structural system is given. Meanwhile, a new system safety measuring index obtained by the non-probabilistic set-theoretic model is investigated. Moreover, the compatibility between the classical probabilistic model as well as the proposed interval-set model will be discussed to verify the physical meaning of the safety measure in this paper. Some numerical examples are utilized to illustrate the validity and feasibility of the developed method.

关键词： Interval analysis Non-probabilistic branch-and-bound method Non-probabilistic set-theoretic measure Structural reliability

Prospects for the Future Development of China’s Space Transportation System

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Space(Science & Technology) 2021年第1期2021卷 188-194页

作者： xiaojun wang China Academy of Launch Vehicle Technology Beijing 100076China

At present,the world has developed to a new stage of large-scale access to space,which has put forward higher requirements for the development of space *** the historical mission of building a space power,focusing on the construction of the China’s space transportation system,this paper studied the development situation of the space transportation system in the world,summarized the development status of the China’s space transportation,combined with future development requirements,and put forward prospects for the future development of the China’s space transportation system.

关键词： transportation summarized system

Role of Al_(18)B_4O_(33) Whisker in MAO Process of Mg Matrix Composite and Protective Properties of the Oxidation Coating

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Journal of Materials Science & Technology 2013年第3期29卷 267-272页

作者： Yanqiu wang xiaojun wang Kun Wu Fuhui wang Corrosion and Protection Laboratory Education Ministry Key Laboratory of Superlight Materials and Surface TechnologyHarbin Engineering University School of Materials Science and Engineering Harbin Institute of Technology State Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of Sciences

Selective growth of oxidation coating was observed with Al18B4O33 crystal whisker as reinforced phase） on Mg matrix composite Al18B4O33w/AZ91 （a composite when this composite was treated by microarc oxidation （MAO） technique, and then the role of Al18B4O33 whisker in the process of MAO was analyzed. The protective properties of MAO coating also were investigated. Scanning electron microscopy （SEM） was used to characterize the existing state of Al18B4O33 whisker in MAO process and the microstructure of MAO coating. Corrosion resistance of the bare and coated composite was evaluated by immersion corrosion test and potentiodynamic polarizing test. Wear resistance of MAO coating was investigated by a ball-on-disc friction and wear tester. The results showed that sparking discharge did not occur on Al18B4O33 whisker and the whisker existed in the coating as a heterogeneous phase when MAO coating grew on the composite; then the whisker would be covered gradually with growing thick of the coating. Corrosion current density of the coated composite was decreased by 4 orders of magnitude compared with that of the uncoated composite; excellent corrosion resistance was closely related to the compact whisker-coating interface since Al18B4O33 whisker did not induce structural defects. The coating also exhibited high wear resistance and a slight adhesive wear tendency with bearing steel as its counterpart material.

关键词： Mg matrix composite Whisker Microarc oxidation (MAO) Coating Corrosion resistance

Probabilistic prediction on three-dimensional roughness of discontinuity based on two-dimensional traces under rock tunnel excavation based on Bayesian theory

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Underground Space 2024年第1期14卷 338-356页

作者： Qi Zhang Yuechao Pei xiaojun wang xiaojun Li Yixin Shen School of Civil Engineering Southeast UniversityNanjing 211189China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

Three-dimensional(3D)roughness of discontinuity affects the quality of the rock mass,but 3D roughness is hard to be measured due to that the discontinuity is invisible in the ***-dimensional(2D)roughness can be calculated from the visible traces,but it is difficult to obtain enough quantity of the traces to directly derive 3D roughness during the tunnel *** this study,a new method using Bayesian theory is proposed to derive 3D roughness from the low quantity of 2D roughness *** more accurately calculating 3D roughness,a new regression formula of 2D roughness is established firstly based on wavelet *** new JRC3D prediction model based on Bayesian theory is then developed,and Markov chain Monte Carlo(MCMC)sampling is adopted to process JRC3D prediction *** discontinuity sample collected from the literature is used to verify the proposed *** groups with the sampling size of 2,3,4,and 5 of each group are randomly sampled from JRC2D values of 170 profiles of the discontinuity,*** research results indicate that 100%,90%,85%,and 60%predicting JRC3D of the sample groups corresponding to the sampling size of 5,4,3,and 2 fall into the tolerance interval[JRC_(true)–1,JRC_(true)+1].It is validated that the sampling size of 5 is enough for predicting *** sensitivities of sampling results are then analyzed on the influencing factors,which are the correlation function,the prior distribution,and the prior *** discontinuity across the excavation face at ZK78+67.5 of Daxiagu tunnel is taken as the tunnel engineering application,and the results further verify that the predicting JRC3D with the sampling size of 5 is generally in good agreement with JRC3D true values.

关键词： Rock discontinuity Joint roughness coefficient Tunnel excavation Bayesian theory Markov chain Monte Carlo sampling

Universal quantum computation with qudits

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1712-1717页

作者： LUO MingXing wang xiaojun Information Security and National Computing Grid Laboratory Southwest Jiaotong University State Key Laboratory of Information Security (Institute of Information Engineering Chinese Academy of Sciences) School of Electronic Engineering Dublin City University

Quantum circuit model has been widely explored for various quantum applications such as Shors algorithm and Grovers searching *** of previous algorithms are based on the qubit *** a proposal for a universal circuit is given based on the qudit system,which is larger and can store more *** order to prove its universality for quantum applications,an explicit set of one-qudit and two-qudit gates is provided for the universal qudit *** one-qudit gates are general rotation for each two-dimensional subspace while the two-qudit gates are their controlled *** comparison to previous quantum qudit logical gates,each primitive qudit gate is only dependent on two free parameters and may be easily *** experimental implementation,multilevel ions with the linear ion trap model are used to build the qudit systems and use the coupling of neighbored levels for qudit *** controlled qudit gates may be realized with the interactions of internal and external coordinates of the ion.

关键词： universal qudit gate qudit circuit linear ion

NEW DESIGN OF ROBUST OPTIMAL ARBITRARY TIME-DELAY FILTER

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Chinese Journal of Mechanical Engineering 2007年第2期20卷 64-68页

作者： wang xiaojun SHAO Huihe Department of Automation Shanghai Jiaotong University Shanghai 200240 China

Zero placement method in the frequency domain is utilized to design robust multi-hump EI optimal arbitrary time-delay filter （OATF） by placing two or more filter zeros near the system poles. A total insensitive OATF can be also achieved if the problem of insensitivity to damping errors is considered. This design strategy is easier to derive and implement. Applications in the anti-swing control of overhead cranes verify the fine performance of this strategy. A better suppression of the load vibrations is obtained using the proposed new OATF, which is more robust to the variation of the cable length.

关键词： Optimal arbitrary time-delay filter (OATF) Residual vibration Overhead crane

PROBABILISTIC DAMAGE IDENTIFICATION OF STRUCTURES WITH UNCERTAINTY BASED ON DYNAMIC RESPONSES

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Acta Mechanica Solida Sinica 2014年第2期27卷 172-180页

作者： xiaojun wang Chen Yang Lei wang Zhiping Qiu Institute of Solid Mechanics Beihang University QIAN-Xuesen Laboratory of Space Technology China Accademy of Space Technology

The probabilistic damage identification problem with uncertainty in the FE model parameters, external-excitations and measured acceleration responses is studied. The uncertainty in the system is concerned with normally distributed random variables with zero mean value and given covariance. Based on the theoretical model and the measured acceleration responses, the probabilistic structural models in undamaged and damaged states are obtained by two-stage model updating, and then the Probabilities of Damage Existence （PDE） of each element are calculated as the damage criterion. The influences of the location of sensors on the damage identification results are also discussed, where one of the optimal sensor placement techniques, the effective independence method, is used to choose the nodes for measurement. The damage identification results by different numbers of measured nodes and different damage criterions are compared in the numerical example.

关键词： damage identification model updating uncertainty probabilistic approach dynamic response