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Reducing the biases in shortwave cloud radiative forcing in tropical and subtropical regions from the perspective of boundary layer processes

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Science China Earth Sciences 2016年第7期59卷 1427-1439页

作者： SUN Wen qi li li Juan WANG Bin State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences Ministry of Education Key Laboratory for Earth System Modeling Center of Earth System Science Tsinghua University

Biases in shortwave cloud radiative forcing(SWCF), which cause overestimates in tropical regions and underestimates in subtropical marine stratocumulus regions, are common in many climate models. Here, two boundary layer processes are investigated in the atmospheric model GAMIL2, entrainment at the top of the boundary layer and longwave radiative cooling at the top of stratocumulus clouds, in order to reduce biases and reveal the mechanisms underlying these processes. Our results show that including the entrainment process in the model can reduce negative SWCF biases in most tropical regions but increases positive SWCF biases in subtropical marine stratocumulus regions. This occurs because entrainment reduces the low-level cloud fraction and its cloud liquid water content by suppressing the vertical turbulent diffusion in the boundary layer and decreasing the relative humidity when warm and dry free atmosphere is entrained in the boundary layer. Longwave radiative cooling at the top of stratocumulus clouds can enhance turbulent diffusion within the stratocumulus-topped boundary layer. When combined with the entrainment process, longwave radiative cooling reduces the positive SWCF biases in subtropical marine stratocumulus regions that are observed using the entrainment process alone. The incorporation of these two boundary layer processes improves the simulated SWCF in tropical and subtropical regions in GAMIL2.

关键词： SWCF GAMIL2 Boundary layer Entrainment Stratocumulus

Bandwidth adaption for kernel particle filter

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Journal of Systems Engineering and Electronics 2011年第2期22卷 340-346页

作者： Fu li Guangming Shi Fei qi li Zhang School of Electronic Engineering Xidian University Xi'an 710071 P. R. China

A novel particle filter bandwidth adaption for kernel particle filter （BAKPF） is proposed. Selection of the kernel bandwidth is a critical issue in kernel density estimation （KDE）. The plug-in method is adopted to get the global fixed bandwidth by optimizing the asymptotic mean integrated squared error （AMISE） firstly. Then, particle-driven bandwidth selection is invoked in the KDE. To get a more effective allocation of the particles, the KDE with adap- tive bandwidth in the BAKPF is used to approximate the posterior probability density function （PDF） by moving particles toward the posterior. A closed-form expression of the true distribution is given. The simulation results show that the proposed BAKPF performs better than the standard particle filter （PF）, unscented particle filter （UPF） and the kernel particle filter （KPF） both in efficiency and estimation precision.

关键词： kernel density estimation adaptive bandwidth kernel,particle filter.

Effect of MgO on structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions in Si–Mn deoxidized steel

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Journal of Iron and Steel Research International 2024年第11期31卷 2774-2787页

作者： qi Xu Yao-qing Meng Jian-li li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan430081HubeiChina

To avoid coarse crystallization of glassy inclusions in Si–Mn deoxidized steel during hot rolling, the effect of MgO on the structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions was investigated. The results showed that the crystallization temperature of the oxide melts decreased with increasing MgO content from 0 to 15.7 wt.%, which suggested that the addition of MgO would increase the temperature range of the crystalline transition. The increase in MgO content could decrease the crystallization activation energy of inclusions. With the increase in MgO content, the relative fractions of O_(Si)^(0) and O_(Si)^(1) structure units increased, and those of structure units O_(Si)^(2), O_(Si)^(3), and O_(Si)^(4) decreased, increasing the depolymerization degree of the silicate structure. The crystallization ratio of glassy inclusions in the steel crucible increased from 19.7% to 98.3% with increasing MgO content from 0 to 15.7 wt.%. The addition of MgO improved the crystallization ability of inclusions, because MgO provides free oxygen O_(2−) to destroy the bridging oxygens and form non-bridging oxygens O^(−), which depolymerizes silicate network structure and simplifies the [SiO_(4)]-tetrahedral structure. In addition, MgO would promote the precipitation of the Mg-containing phases with a high melting point. When the MgO content was increased above 12.1 wt.%, MgO·Al_(2)O_(3) and 2MgO·SiO_(2) crystalline phases would precipitate from the inclusions.

关键词： Si-Mn deoxidized steel Glassy inclusion Structure Crystallization Plasticization

Chinese Relation Extraction on Forestry Knowledge Graph Construction

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Computer Systems Science & Engineering 2021年第6期37卷 423-442页

作者： qi Yue Xiang li Dan li College of Information and Computer Engineering Northeast Forestry UniversityHarbin150040China

Forestry work has long been weak in data integration;its initial state will inevitably affect the forestry project development and *** Graph(KG)can provide better abilities to organize,manage,and understand forestry *** Extraction(RE)is a crucial task of KG construction and information *** researches on relation extraction have proved the performance of using the attention ***,these methods focused on the representation of the entire sentence and ignored the loss of *** lack of analysis of words and syntactic features contributes to sentences,especially in Chinese relation extraction,resulting in poor *** on the above observations,we proposed an end-to-end relation extraction method that used Bi-directional Gated Recurrent Unit(BiGRU)neural network and dual attention mechanism in forestry KG *** dual attention includes sentence-level and word-level,capturing relational semantic words and direction *** enhance the performance,we used the pre-training model FastText to provide word vectors,and dynamically adjusted the word vectors according to the *** used forestry entities and relationships to build forestry KG and used Neo4j to store forestry *** method can achieve better results than previous public models in the SemEval-2010 Task 8 *** training the model on forestry dataset,results showed that the accuracy and precision of FastText-BiGRU-Dual Attention exceeded 0.8,which outperformed the comparison methods,thus the experiment confirmed the validity and accuracy of our *** the future,we plan to apply forestry KG to question and answer system and achieve a recommendations system for forestry knowledge.

关键词： Forestry KG RE BiGRU dual attention FastText

An Example of Embedded Singular Continuous Spectrum for Discrete Schrödinger Operators

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1837-1849页

作者： Zheng qi FU Xiong li Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

We present an example of a potential such that the corresponding discrete Schrödinger operator has singular continuous spectrum embedded in the absolutely continuous spectrum.

关键词： Sparse potentials singular continuous spectrum Prüfer variables

Admissible model noise upper bound with constraint of stochastic passage characteristics

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Journal of Systems Engineering and Electronics 2011年第4期22卷 565-571页

作者： Guoqing qi Yinya li li Chen Andong Sheng Automation School Nanjing University of Science and Technology Nanjing 210094 P. R. China Artillery & Air Defence Forces Institute of Equipment & Technologies Headquarters of the General Equipment of PLA Beijing 100012 P. R. China

In some object tracking systems, the moving object future position is an area （i.e., target area）. It is a successful estimation strategy if the predicted points fall in the target area. If the object makes a sudden maneuvering, the prediction may get out of the target area easily which may make the tracking system lose the object. The aim is to investigate the admissible maximum object maneuvering intensity, which is characterized as model noise variance, for such kind of tracking system. Firstly, the concept of stochastic passage characteristics over the boundary of target area and their relationship with prediction error variance are described. Secondly, the consistency among the indices of regional pole, prediction error variance and stochastic passage characteristics is analyzed. Thirdly, the multi-indices constraints are characterized by a set of bi-linear matrix inequalities （BMIs）. Then, the admissible maximum model noise variance and the satisfactory estimation strategy are presented by iteratively solving linear matrix inequalities （LMIs） to approximate BMIs. Finally, a numerical example is proposed to demonstrate the obtained resuits.

关键词： stochastic passage characteristic target area modelnoise bi-linear matrix inequality (BMI).

Low Dimensional Chaos from the Group Sunspot Numbers

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 435-440页

作者： qi-Xiu li Ke-Jun li National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Graduate School of Chinese Academy of Sciences Beijing 100049

We examine the nonlinear dynamical properties of the monthly smoothed group sunspot number Rg and find that the solar activity underlying the time series of Rg is globally governed by a low-dimensional chaotic attractor. This finding is consistent with the nonlinear study results of the monthly Wolf sunspot numbers. We estimate the maximal Lyaponuv exponent （MLE） for the Rg series to be positive and to equal approximately 0.0187 ± 0.0023 （month^- 1）. Thus, the Lyaponuv time or predictability time of the chaotic motion is obtained to be about 4.46 ± 0.5 years, which is slightly different with the predictability time obtained from Rz. However, they both indicate that solar activity forecast should be done only for a short to medium term due to the intrinsic complexity of the time behavior concerned.

关键词： Sun activity - Sun sunspot - chaos - Sun Wolf sunspot numbers

Advances in Compact Manufacturing for Shape and Performance Controllability of Large-scale Components-A Review

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 7-21页

作者： qiN Fangcheng li Yongtang qi Huiping JU li School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China

Research on compact manufacturing technology for shape and performance controllability of metallic components can reanze the simplification and high-reliability of manufacturing process on the premise of satisfying the requirement of macro/micro-structure. It is not only the key paths in improving performance, saving material and energy, and green manufacturing of components used in major equipments, but also the challenging subjects in frontiers of advanced plastic forming. To provide a novel horizon for the manufacturing in the critical components is significant. Focused on the high-performance large-scale components such as bearing rings, flanges, railway wheels, thick-walled pipes, etc, the conventional processes and their developing situations are summarized. The existing problems including multi-pass heating, wasting material and energy, high cost and high-emission are discussed, and the present study unable to meet the manufacturing in high-quality components is also pointed out. Thus, the new techniques related to casting-rolling compound precise forming of rings, compact manufacturing for duplex-metal composite rings, compact manufacturing for railway wheels, and casting-extruding continuous forming of thick-walled pipes are introduced in detail, respectively. The corresponding research contents, such as casting ring blank, hot ring rolling, near solid-state pressure forming, hot extruding, are elaborated. Some findings in through-thickness microstructure evolution and mechanical properties are also presented. The components produced by the new techniques are mainly characterized by fine and homogeneous grains. Moreover, the possible directions for fin＇ther development of those techniques are suggested. Finally, the key scientific problems are first proposed. All of these results and conclusions have reference value and guiding significance for the integrated control of shape and performance in advanced compact manufacturing.

关键词： compact manufacturing shape and performance controllability high-performance ring parts thick-walled pipes

Novel localized wave solutions of the (2+1)-dimensional Boiti–Leon–Manna–Pempinelli equation

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Communications in Theoretical Physics 2020年第12期72卷 105-115页

作者： li Sun Jiaxin qi Hongli An College of Sciences Nanjing Agricultural UniversityNanjing210095China

Based on a special transformation that we introduce,the N-soliton solution of the(2+1)-dimensional Boiti–Leon–Manna–Pempinelli equation is *** applying the long wave limit and restricting certain conjugation conditions to the related solitons,some novel localized wave solutions are obtained,which contain higher-order breathers and lumps as well as their *** particular,by choosing appropriate parameters involved in the N-solitons,two interaction solutions mixed by a bell-shaped soliton and one breather or by a bell-shaped soliton and one lump are constructed from the 3-soliton *** solutions including two breathers,two lumps,and interaction solutions between one breather and two bell-shaped solitons,one breather and one lump,or one lump and two bell-shaped solitons are constructed from the4-soliton *** interaction solutions mixed by one breather/lump and three bell-shaped solitons,two breathers/lumps and a bell-shaped soliton,as well as mixing with one lump,one breather and a bell-shaped soliton are constructed from the 5-soliton *** study the behaviors that the obtained interaction solutions may have,we present some illustrative numerical simulations,which demonstrate that the choice of the parameters has a great impacts on the types of the solutions and their propagation *** method proposed can be effectively used to construct localized interaction solutions of many nonlinear evolution *** results obtained may help related experts to understand and study the interaction phenomena of nonlinear localized waves during propagations.

关键词： Boiti-Leon-Manna-Pempinelli equation Hirota bilinear method localized interaction wave solution