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The Link between Stochastic Differential Equations with Non-Markovian Coefficients and Backward Stochastic Partial Differential Equations

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Acta Mathematica Sinica,English Series 2021年第3期37卷 447-457页

作者： Lin LIN Fang XU qi zhang School of Arts and Sciences Shanghai Dianji UniversityShanghai 201306P.R.China School of Mathematical Sciences Fudan UniversityShanghai 200433P.R.China

In this paper, we conjecture and prove the link between stochastic differential equations with non-Markovian coefficients and nonlinear parabolic backward stochastic partial differential equations, which is an extension of such kind of link in Markovian framework to non-Markovian *** from Markovian framework, where the corresponding partial differential equation is deterministic, the backward stochastic partial differential equation here has a pair of adapted solutions, and thus the link has a much different form. Moreover, two examples are given to demonstrate the applications of the derived link.

关键词： Backward stochastic partial differential equations stochastic differential equations nonMarkovian coefficients Girsanov transformation Feynman–Kac formula

Consecutive Methylation Catalyzed by TsrM,an Atypical Class B Radical SAM Methylase

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Chinese Journal of Chemistry 2022年第14期40卷 1693-1698页

作者： Runze Wu Wei Ding qi zhang Department of Chemistry Fudan UniversityShanghai 200433China State Key Laboratory of Microbial Metabolism School of Life Sciences&BiotechnologyShanghai Jiao Tong UniversityShanghai200240China

TsrM is a cobalamin-dependent radical S-adenosylmethionine(SAM)methyltransferase belonging to the Class B radical SAM methylase(RSM)*** enzyme catalyzes the C-2 methylation of L-tryptophan to produce 2-methyltrytophan(2-MeTrp),an intermediate involved in the biosynthesis of thiostrepton *** this work,we report characterization of an unexpected activity of TsrM,which carries out an additional methylation reaction on the product 2-MeTrp.A series of isotopic labeling studies and assays with different Trp analogs revealed that TsrM is able to transfer a methyl group from SAM to the C4 of 2-MeTrp to produce 2,*** results reveal the intriguing substrate specificity of TsrM,further expanding the reaction promiscuity of the radical SAM superfamily enzymes.

关键词： Biosynthesis Biotransformations Catalytic promiscuity Enzyme Methyltransferase

Applying sub-band energy extraction to noise cancellation of ultrasonic NDT signal

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第8期9卷 1134-1140页

作者： qi zhang Pei-wen QUE Wei LIANG Institute of Automation Detection Shanghai Jiao Tong University Shanghai 200240 China

In ultrasonic non-destructive tests, the echo signal at the flaw is highly complex due to the interference of multiple echoes with random amplitudes and phases, and is disturbed by all kinds of noises, such as thermal noise, digitalization noise, and structure noise. In this paper, the ultrasonic signal was decomposed by empirical mode decomposition (EMD) to obtain the in-trinsic mode function (IMF) components according to ultrasonic defect echo signals occuring at the corresponding time, and the energy of the ultrasonic signal was concentrated. The IMF component selection criterion based on sub-band energy extraction was proposed to extract the ultrasonic signal component accurately and automatically from IMF components. When the selected IMF components were filtered by a band pass filter, the signal-to-noise ratio (SNR) was enhanced greatly.

关键词： Empirical mode decomposition (EMD) Signal-to-noise ratio (SNR) De-noising Non-destructive testing (NDT) Intrinsic mode function (IMF)

Strong motion characteristics of the M_w 6.6 Lushan earthquake,Sichuan,China——an insight into the spatial difference of a typical thrust fault earthquake

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 203-216页

作者： Hu Jinjun zhang Wenbo Xie Lili zhang qi Jiang Zhijun Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration College of Earth Science University of Chinese Academy of Science School of Civil Engineering Harbin Institute of Technology

Near-field strong ground motions are useful for engineering seismology studies and seismic design, but dense observation networks of damaging earthquakes are still rare. In this study, based on the strong-motion data from the M w 6.6 Lushan earthquake, the ground motion parameters in different spatial regions are systematically analyzed, and the contributions from different effects, like the hanging-wall effect, directivity effect, and attenuation effect are separated to the extent possible. Different engineering parameters from the observed ground motions are compared with the local design response spectra and a new attenuation relation of Western China. General results indicate that the high frequency ground motion, like the peak ground acceleration, on two sides of the fault plane is sensitive to the hanging-wall effect, whereas the low frequency ground motion, like the long period spectral acceleration, in the rupture propagation direction is affected by the directivity effect. Moreover, although the M w 6.6 Lushan earthquake is not a large magnitude event, the spatial difference of ground motion is still obvious; thus, for a thrust faulting earthquake, in addition to the hanging effect, the directivity effect should also be considered.

关键词： Lushan earthquake near-fi eld ground motion direct

Mechanical behaviors of warm and ice-rich frozen soil stabilized with sulphoaluminate cement

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Journal of Mountain Science 2024年第1期21卷 335-345页

作者： WANG Honglei zhang Hu zhang Jianming zhang qi YIN Zhenhua State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China School of Civil Engineering and Transportation Northeast Forestry UniversityHarbin 150040China National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment CCCC First Highway Consultants Co.LtdXi'an 710065China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

The warm and ice-rich frozen soil is characterized by high unfrozen water content, low shear strength and large compressibility, which is unreliable to meet the stability requirements of engineering infrastructures and foundations in permafrost regions. In this study, a novel approach for stabilizing the warm and ice-rich frozen soil with sulphoaluminate cement was proposed based on chemical stabilization. The mechanical behaviors of the stabilized soil, such as strength and stress-strain relationship, were investigated through a series of triaxial compression tests conducted at -1.0℃, and the mechanism of strength variations of the stabilized soil was also explained based on scanning electron microscope test. The investigations indicated that the strength of stabilized soil to resist failure has been improved, and the linear Mohr-Coulomb criteria can accurately reflect the shear strength of stabilized soil under various applied confining pressure. The increase in both curing age and cement mixing ratio were favorable to the growth of cohesion and internal friction angle. More importantly, the strength improvement mechanism of the stabilized soil is attributed to the formation of structural skeleton and the generation of cementitious hydration products within itself. Therefore, the investigations conducted in this study provide valuable references for chemical stabilization of warm and ice-rich frozen ground, thereby providing a basis for in-situ ground improvement for reinforcing warm and ice-rich permafrost foundations by soil-cement column installation.

关键词： Permafrost regions Frozen soil Mechanical behavior Chemical stabilization Ground improvement Ground modification

Difluoromethylation of 2-Hydroxychalcones Using Sodium 2-Chloro-2,2-difluoroacetate as Difluoromethylating Agent

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Chemical Research in Chinese Universities 2015年第3期31卷 362-366页

作者： WANG Wei HUA Mingqing HUANG Yan zhang qi zhang Xiaoyan WU Jingbo zhang qi School of Chemistry and Chemical Engineering Jiangsu University Zhenjiang 212013 P.R.China Hainan Provincial Key Laboratory of Fine Chemistry Hainan University Haikou 570228 P. R. China

Difluoromethylation of 2-hydroxychalcones using sodium 2-chloro-2,2-difluoroacetate as the difluoro- methylating agent was developed. Under facile conditions, a wide range of aryl difluoromethyl ethers were obtained in yields of 36%--80%. It is noteworthy that the new addition products, 2,2-difluoro-2H-benzofuran derivatives, were also synthesized in the reactions. The yield of 2,2-difluoro-2H-benzofuran derivative could be up to 35% when 3-methyl-2-hydroxychalcone was used as the reactant. A plausible reaction mechanism was proposed.

关键词： Difluoromethylation 2-Hydroxychalcone 2-Difluoromethoxychalcone 2,2-Difluoro-2H-benzofuran

Clustering by data competition

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Science China(Information Sciences) 2013年第1期56卷 65-77页

作者： LU ZhiMao zhang qi Pattern Recognition and Natural Computation Laboratory Harbin Engineering University

Clustering analysis is an unsupervised method to find out hidden structures in *** partitional clustering algorithms are sensitive to the selection of initial exemplars,the outliers and *** this paper,a novel technique called data competition algorithm is proposed to solve the *** the concept of aggregation field model is defined to describe the partitional clustering ***,the exemplars are identified according to the data ***,the members will be assigned to the suitable *** competition algorithm is able to avoid poor solutions caused by unlucky initializations,outliers and noise,and can be used to detect the coexpression gene,cluster the image,diagnose the disease,distinguish the variety,*** provided experimental results validate the feasibility and effectiveness of the proposed schemes and show that the proposed approach of data competition algorithm is simple,stable and *** experimental results also show that the proposed approach of data competition clustering outperforms three of the most well known clustering algorithms K-means clustering,affinity propagation clustering,hierarchical clustering.

关键词： data mining clustering analysis partitional clustering data competition

Analysis on Long-Term Change of Sea Surface Temperature in the China Seas

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Journal of Ocean University of China 2013年第2期12卷 295-300页

作者： LIU qinyu zhang qi Physical Oceanography Laboratory and Key Laboratory of Ocean-Atmosphere Interaction and Climate in Universities of Shandong Ocean University of China

Long-term change of sea surface temperature （SST） in the China Seas from 1900 to 2006 is examined based on two different observation datasets （HadlSSTI and HadSST3）. Similar to the Atlantic, SST in the China Seas has been well observed during the past 107 years. A comparison between the reconstructed （HadISSTI） and un-interpolated （HadSST3） datasets shows that the SST wanning trends from both datasets are consistent with each other in most of the China Seas. The warming trends are stronger in winter than in summer, with a maximum rate of SST increase exceeding 2.7℃ （100year）-I in the East China Sea and the Taiwan Strait during winter based on HadISSTI. However, the SST from both datasets experienced a sudden decrease after 1999 in the China Seas. The estimated trend from HadlSSTI is stronger than that fi＇om HadSST3 in the East China Sea and the east of Taiwan Island, where the difference in the linear SST warming trends are as large as about 1℃ （100year）-I when using respectively HadISST1 and HadSST3 datasets. When compared to the linear winter warnling trend of the land surface air temperature （1.6℃ （100 year）-1）, HadSST3 shows a more reasonable trend of less than 2.1℃（ 100 year）-1 than HadISST 1 ＇s trend of larger than 2.7℃ （ 100 year）-1 at the mouth of the Yangtze River. The restllts also indicate large uncertainties in the estimate of SST warming patterns.

关键词： long-term linear trend sea surface temperature China Seas, reconstructed data un-interpolated data uncertainties

Towards Efficient Robotic Software Development by Reusing Behavior Tree Structures for Task Planning Paradigms

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Complex System Modeling and Simulation 2023年第4期3卷 357-380页

作者： Shuo Yang qi zhang College of Systems Engineering National University of Defense TechnologyChangsha 410072China

interaction pipelines while maintaining interfaces for task-specific *** Structural-BT framework supports the modular design of structure functionalities and allows easy extensibility of the inner planning flows between BT *** the Structural-BT framework,software engineers can develop robotic software by flexibly composing BT structures to formulate the skeleton software architecture and implement task-specific algorithms when *** the experiment,this paper develops robotic software for diverse task scenarios and selects the baseline approaches of Robot Operating System(ROS)and classical BT development frameworks for *** quantitatively measuring the reuse frequencies and ratios of BT structures,the Structural-BT framework has been shown to be more efficient than the baseline approaches for robotic software development.

关键词： robotic software modeling and development software architecture task planning paradigm behavior tree modeling