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Saliency detection of infrared image based on region covariance and global feature

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Journal of Systems Engineering and Electronics 2018年第3期29卷 483-490页

作者： liu Songtao JIANG Ning liu Zhenxing JIANG Kanghui Department of Information Operation Dalian Naval Academy

In order to better represent infrared target features under different environments, a saliency detection method based on region covariance and global feature is proposed. Firstly, the region covariance features on different scale spaces and different image regions are extracted and transformed into sigma features,then combined with central position feature, the local salient map is generated. Next, a global salient map is generated by gray contrast and density estimation. Finally, the saliency detection result of infrared images is obtained by fusing the local and global salient maps. The experimental results show that the salient map of the proposed method has complete target features and obvious edges,and the proposed method is better than the state of art method both qualitatively and quantitatively.

关键词： saliency detection region covariance gray contrast density estimation

Simultaneous Prediction for Multiple Key Performance Indicators in Semiconductor Wafer Fabrication

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Chinese Journal of Electronics 2016年第6期25卷 1159-1165页

作者： CAO Zhengcai liu Xuelian HAO Jinghua liu Min College of Information Science and Technology Beijing University of Chemical Technology Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Department of Automation Tsinghua University

The prediction and key factors identification for lot Cycle time(CT) and Equipment utilization(EU) which remain the Key performance indicators(KPI)are vital for multi-objective optimization in semiconductor manufacturing industry. This paper proposes a prediction methodology which predicts CT and EU simultaneously and identifies their key factors. Bayesian neural network(BNN) is used to establish the simultaneous prediction model for Multiple key performance indicators(MKPI),and Bayes theorem is key solution in model complexity controlling. The closed-loop structure is built to keep the stability of MKPI prediction model and the weight analysis method is the basis of identifying the key factors for CT and EU. Compared with Artificial neural network(ANN)and Selective naive Bayesian classifier(SNBC), the simulation results of the prediction method of BNN are proved to be more feasible and effective. The prediction accuracy of BNN has been obviously improved than ANN and SNBC.

关键词： Prediction for MKPI Cycle time Equipment utilization BNN Key factors identification

Quasi-static simulation of droplet morphologies using a smoothed particle hydrodynamics multiphase model

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Acta Mechanica Sinica 2019年第1期35卷 32-44,I0002页

作者： Xiangwei Dong Jianlin liu Sai liu Zengliang Li Department of Engineering Mechanics College of Pipeline and Civil EngineeringChina University of Petroleum (East China)Qingdao 266580China College of Mechanical and Electronic Engineering China University of Petroleum (East China)Qingdao 266580China

Numerical simulation of the morphology of a droplet deposited on a solid surface requires an efficient description of the three-phase contact line. In this study, a simple method of implementing the contact angle is proposed, combined with a robust smoothed particle hydrodynamics multiphase algorithm (Zhang 2015). The first step of the method is the creation of the virtual liquid-gas interface across the solid surface by means of dummy particles, thus the calculated surface tension near the triple point serves to automatically modulate the dynarnic contact line towards the equilibrium state. We simulate the evolution process of initially square liquid lumps on fiat and curved surfaces. The predictions of droplet profiles are in good agreement with the analytical solutions provided that the macroscopic contact angle is accurately implemented. Compared to the normal correction method, the present method is straightforward without the need to manually alter the normal vectors. This study presents a robust algorithm capable of capturing the physics of the static welling. It may hold great potentials in bio-inspired superhydrophobic surfaces, oil displacement, microfluidics, ore floatation, etc.

关键词： Smoothed particle hydrodynamics Virtual interface method Multiphase flow Macroscopic contact angle Droplet morphology Curved surfaces

Digital twin dynamic-polymorphic uncertainty surrogate model generation using a sparse polynomial chaos expansion with application in aviation hydraulic pump

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CHINESE JOURNAL OF AERONAUTICS 2024年第12期37卷 231-244页

作者： liu, Dong Wang, Shaoping Shi, Jian liu, Di Beihang Univ Sch Automat Sci & Elect Engn Beijing 100191 Peoples R China Tianmushan Lab Hangzhou 310023 Peoples R China

Full lifecycle high fidelity digital twin is a complex model set contains multiple functions with high dimensions and multiple variables. Quantifying uncertainty for such complex models often encounters time-consuming challenges, as the number of calculated terms increases exponentially with the dimensionality of the input. This paper based on the multi-stage model and high time consumption problem of digital twins, proposed a sparse polynomial chaos expansions method to generate the digital twin dynamic-polymorphic uncertainty surrogate model, striving to strike a balance between the accuracy and time consumption of models used for digital twin uncertainty quantification. Firstly, an analysis and clarification were conducted on the dynamic-polymorphic uncertainty of the full lifetime running digital twins. Secondly, a sparse polynomial chaos expansions model response was developed based on partial least squares technology with the effectively quantified and selected basis polynomials which sorted by significant influence. In the end, the accuracy of the proxy model is evaluated by leave-one-out cross-validation. The effectiveness of this method was verified through examples, and the results showed that it achieved a balance between maintaining model accuracy and complexity. (c) 2024 The Authors. Published by Elsevier Ltd on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY license (http://***/licenses/ by/4.0/).

关键词： Digital Twin Uncertainty surrogate model Dynamic-polymorphic uncertainty Sparse polynomial chaos expansions Aviation hydraulic pump

Changes of China’s Status in the Global System and Its Influencing Factors:A Multiple Contact Networks Perspective

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Chinese Geographical Science 2024年第2期34卷 265-279页

作者： liu Jian liu Jibin YANG Qingshan CAI Sikai liu Jie School of Geographical Sciences Northeast Normal UniversityChangchun 130024China Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains Ministry of EducationChangchun 130024China School of Architecture and Planning Jilin Jianzhu UniversityChangchun 130118China School of Geographical Sciences Liaoning Normal UniversityDalian 116029China

Clarifying China’s position in the global system is an important logical basis for developing national *** much research has been done on China’s development status,most studies have been based on country comparisons or institutional *** today’s networked era in which the global economy,trade,personnel,and information are closely connected,studies on China’s global position and its status changes and influencing factors in multiple contact networks are still *** this study,from the perspective of diverse global contact networks,we constructed economic,cultural,and political influence indices to explore the changes and influencing factors on China’s status in the global system from 2005 to *** results show that during the study period,China’s global influence in the fields of economic ties,cultural exchanges,and political contacts increased significantly,but its influ-ence in the fields of cultural exchanges and political contacts lagged far economic *** pattern of China’s economic influence on various economies around the world has shown a transformation from an‘upright pyramid’to an‘inverted pyramid’*** proportion of these economies in low-influence zones has decreased from more than 60%in 2005 to less than 20%in ***’s cultural and political influence on various economies around the world has increased significantly;however,for the former,the percentage of high-influence areas is still less than 20%,whereas for the latter the percentage of these economies in medium-and high-influence areas is still less than 50%.Analyses such as a scatter plot matrix show that geographical proximity,economic globalization,close cooperation with developing countries,and a proactive and peaceful foreign policy are important factors in improving China’s status in the diverse global network system.

关键词： global system economic ties cultural exchanges political contacts multiple contact networks China’s status

Electrical switching of spin-polarized current in multiferroic tunneling junctions

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npj Computational Materials 2022年第1期8卷 1877-1885页

作者： Ligong Zhang Yuchen Wang Xiaoyan liu Fei liu School of Integrated Circuits Peking University100871BeijingChina Beijing Advanced Innovation Center for Integrated Circuits 100871BeijingChina

The generation and manipulation of spin-polarized current are critical for spintronic *** this work,we propose a mechanism to generate and switch spin-polarized current by an electric field in multiferroic tunnel junctions(MFTJs),with symmetric interface terminations in an antiparallel magnetic *** such devices,different spin tunneling barriers are realized by the magnetoelectric coupling effect,resulting in a spin-polarized *** reversing the electric polarization of the ferroelectric layer,the spin polarization of current is efficiently switched for the exchange of spin tunneling *** first-principles quantum transport calculations,we show that a highly spin-polarized current is obtained and manipulated by the electric field in hafnia-based MFTJs based on the proposed *** also demonstrate that four resistance states are realized in Co/HfO_(2)/Co junctions with asymmetric interface *** work provides a promising approach for realizing the electrical control of spin current for spintronic applications.

关键词： mechanism. polarized tunneling

STUDIES ON STRUCTURAL AND MECHANICAL PROPERTIES UNDER ISOSTATIC COMPRESSION WITH LARGE-SCALE DISCRETE ELEMENT SIMULATIONS

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Acta Mechanica Solida Sinica 2014年第2期27卷 129-136页

作者： Jianguo liu Qicheng Sun Feng Jin Qingkai liu State Key Laboratory of Hydroscience and Engineering Tsinghua University High Performance Computing Center Institute of Applied Physics and Computational Mathematics

Granular systems undergo a jamming transition at point J simply by increasing the packing fraction. A large-scale parallel discrete element code （THDEM： TsingHua Discrete Element Method） was used to obtain a satisfying statistical description of the structural and me- chanical properties near point J. The isostatic compressions of 100,000 polydispersed frictionless particles were simulated on high performance computers to clearly observe the sophisticated con- figurations of force chains. The first peak of the pair correlation function, coordination number, spatial distribution of the packing fraction, and stress were calculated to analyze their variations with increasing packing fraction. The critical packing fraction at point J is determined to be 0.62. The incremental stress and coordination number from point J scale well with the power law, and coincide with previous theoretical predications. The distribution of the packing frac- tion is a normal distribution around the average value. The standard deviation decreases with increasing packing fraction, indicating the system is more uniform with a denser packing.

关键词： granular matter jamming transition force chains parallel computing

Sulfate reducing bacterial community and in situ activity in mature fine tailings analyzed by real time qPCR and microsensor

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Journal of Environmental Sciences 2016年第6期28卷 141-147页

作者： Hong liu Shuying Tan Tong Yu Yang liu Department of Civil and Environmental Engineering University of Alberta

Sulfate reducing bacteria（SRB） play significant roles in anaerobic environments in oil sands mature fine tailings（MFTs）. Hydrogen sulfide（H2S） is produced during the biological sulfate reduction process. The production of toxic H2S is one of the concerns because it may hinder the landscape remediation efficiency of oil sands tailing ponds. In present study, the in situ activity and the community structure of SRB in MFT and gypsum amended MFT in two settling columns were investigated. Combined techniques of H2S microsensor and dissimilatory sulfite reductase β-subunit（dsrB） genes-based real time quantitative polymerase chain reaction（qPCR） were applied to detect the in situ H2S and the abundance of SRB. A higher diversity of SRB and more H2S were observed in gypsum amended MFT than that in MFT, indicating a higher sulfate reduction activity in gypsum amended MFT; in addition, the activity of SRB varied as depth in both MFT and gypsum amended MFT： the deeper the more H2S produced. Long-term plans for tailings management can be assessed more wisely with the information provided in this study.

关键词： Sulfate reducing bacteria Hydrogen sulfide Oil sands tailing Molecular biology Microsensor

Adsorption of Quaternary Ammonium Compounds onto Activated Sludge

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Journal of Water Resource and Protection 2011年第2期3卷 105-113页

作者： rong Ren Dongfang liu Kexun Li Jie Sun Chong Zhang 不详

The performance of activated sludge in the removal of tetradecyl benzyl dimethyl ammonium chloride (C14BDMA) by adsorption from aqueous solution was investigated with different PH, contact time, ionic strength and temperature. Equilibrium was achieved within 2 h of contact time. The adsorption capacity increased largely with increasing solution pH and remained constant above pH 9. The ionic strength had a negative effect on C14BDMA removal. The adsorption isotherms were analyzed by Langmuir and Freundlich isotherm models, and equilibrium partitioning data was described well by both models. Kinetics data was best described by the pseudo second-order model. Experimental results indicated that the adsorption was favorable at lower temperatures. Thermodynamic parameters, including the Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0), were also calculated. These parameters indicated that adsorption of C14BDMA onto activated sludge was feasible, spontaneous and exothermic in the temperature range of 15-35℃. The activated sludge was shown to be an effective adsorbent for C14BDMA.

关键词： Activated Sludge Adsorption Kinetics Quaternary Ammonium Compounds Thermodynamics Analysis