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A Novel CFC-12 Hydrolysis Catalyst: WO_3/SnO_2

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Chinese Chemical Letters 2000年第1期11卷 87-88页

作者： zhen MA wei ming HUA Yi TANG Zi GAO (Department of Chemistry, Fudan University, Shanghai 200433) Department of Chemistry Fudan University Shanghai 200433 China

The catalytic hydrolysis of dichlorodifluoromethane (CFC-12) was investigated over WO_3/SnO_2 solid acid which was prepared by impregnating Sn(OH)_4 with aqueous ammonium metatungstate followed by evaporating, drying and calcining in air. The CFC-12 conversion over WO_3/SnO_2 at 330'C remained above 99.5% during 150 h on stream, however, parent metal oxides showed rare catalytic decomposition activity.

关键词： Environmental catalysis Freon decomposition, WO_3/SnO_2 catalyst.

Symmetry and monotonicity of positive solutions to Schr?dinger systems with fractional p-Laplacians

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Applied Mathematics(A Journal of Chinese Universities) 2022年第1期37卷 52-72页

作者： MA Ling-wei ZHANG zhen-qiu School of Mathematical Sciences Tianjin Normal UniversityTianjin 300387China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071China

In this paper,we first establish narrow region principle and decay at infinity theorems to extend the direct method of moving planes for general fractional p-Laplacian *** virtue of this method,we investigate the qualitative properties of positive solutions for the following Schrodinger system with fractional p-Laplacian{(-△)^(s)_(p)u+au^(p-1)=f(u,v),(-△)^(t)_(p)v+bv(p-1)=g(u,v),where 0

关键词： fractional p-Laplacian Schr?dinger systems direct method of moving planes radial symmetry monotonicity nonexistence

Breaking and mining-induced stress evolution of overlying strata in the working face of a steeply dipping coal seam

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International Journal of Coal Science & Technology 2021年第4期8卷 614-625页

作者： Xiaolou Chi Ke Yang zhen wei State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001AnhuiChina Institute of Energy Hefei Comprehensive National Science CenterHefei 230031AnhuiChina Key Laboratory of Mining Coal Safety and Construction Efficiency of Anhui Province and Ministry of Education Anhui University of Science and TechnologyHuainan 232001AnhuiChina

The breaking features and stress distribution of overlying strata in a steeply dipping coal seam(SDCS)differ significantly from those in a near-horizontal *** this study,the laws governing the evolution of vertical stress release and shear stress concentration in the overlying strata of coal seams with different dip angles are derived via numerical simulation,rock mechanics tests,acoustic emissions,and field ***,the stress-driven dynamic evolution of the overlying strata structure,in which a shear stress arch forms,is *** breaking the lower pari of the overlying strata,the shear stress transfers rapidly to the upper part of the working *** damaged zone of the overlying strata migrates upward along the dip direction of the working *** gangue in the lower part of the working face is compacted,leading to an increase in vertical *** the dip angle of the coal seam increases,the overlying strata fail suddenly under the action of shear ***,the behavioral response of the overlying strata driven by shear stresses in the longwall working face of an SDCS is identified and analyzed in *** present research findings reveal the laws governing the behavior of mine pressure in the working face of an SDCS,which in turn can be used to establish the respective on-site guidance.

关键词： Steeply dipping coal seam Migration of overlying strata Stress evolution Dynamic response

∞-Tilting Subcategories in Extriangulated Categories

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 151-160页

作者： zhen ZHANG Jiaqun wei Shance WANG Department of Mathematics Qilu Normal UniversityJinan 250200China Institution of Mathematics School of Mathematics ScienceNanjing Normal UniversityNanjing 210023China

In this paper, the authors introduce a new definition of ∞-tilting(resp. cotilting) subcategories with infinite projective dimensions(resp. injective dimensions) in an extriangulated category. They give a Bazzoni characterization of ∞-tilting(resp. cotilting)subcategories. Also, they obtain a partial Auslander-Reiten correspondence between ∞-tilting(resp. cotilting) subcategories and coresolving(resp. resolving) subcategories with an E-projective generator(resp. E-injective cogenerator) in an extriangulated category.

关键词： Extriangulated category ∞-Tilting subcategory Auslander-Reiten correspondence Bazzoni characterization

Preparation and performance evaluation of the slickwater using novel polymeric drag reducing agent with high temperature and shear resistance ability

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Petroleum Science 2024年第2期21卷 1113-1121页

作者： ming-wei Zhao zhen-Feng Ma Cai-Li Dai weiWu Yong-Quan Sun Xu-Guang Song Yun-Long Cheng Xiang-Yu Wang National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao266580ShandongChina Shandong Key Laboratory of Oilfield Chemistry China University of Petroleum(East China)Qingdao266580ShandongChina Sinopec Shengli Oilfield Dongying257001ShandongChina Department of Chemical and Materials Engineering University of AlbertaEdmontonAB T6G 1H9Canada East China Petroleum Bureau of Sinopec Nanjing210011JiangsuChina

Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction ***,their performance is severely affected at high *** reducing agent is the key to determine the drag reducing performance of *** this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant *** slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and *** contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ***,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing ***,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.

关键词： Unconventional resources Polymeric drag reducing agent Slickwater High drag reduction rate Temperature resistance

Learning to select pseudo labels: a semi-supervisedmethod for named entity recognition

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Frontiers of Information Technology & Electronic Engineering 2020年第6期21卷 903-916页

作者： zhen-zhen LI Da-wei FENG Dong-sheng LI Xi-cheng LU College of Computer National University of Defense TechnologyChangsha 410073China

Deep learning models have achieved state-of-the-art performance in named entity recognition(NER);the good performance,however,relies heavily on substantial amounts of labeled *** some specific areas such as medical,financial,and military domains,labeled data is very scarce,while unlabeled data is readily *** studies have used unlabeled data to enrich word representations,but a large amount of entity information in unlabeled data is neglected,which may be beneficial to the NER *** this study,we propose a semi-supervised method for NER tasks,which learns to create high-quality labeled data by applying a pre-trained module to filter out erroneous pseudo *** labels are automatically generated for unlabeled data and used as if they were true *** semi-supervised framework includes three steps:constructing an optimal single neural model for a specific NER task,learning a module that evaluates pseudo labels,and creating new labeled data and improving the NER model *** results on two English NER tasks and one Chinese clinical NER task demonstrate that our method further improves the performance of the best single neural *** when we use only pre-trained static word embeddings and do not rely on any external knowledge,our method achieves comparable performance to those state-of-the-art models on the CoNLL-2003 and OntoNotes 5.0 English NER tasks.

关键词： Named entity recognition Unlabeled data Deep learning Semi-supervised method

An Understanding of the Meaning Behind Boson-Description in the Collective Motion of Nuclei

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Chinese Physics Letters 2000年第8期17卷 562-564页

作者： Lu Da-hai YANG Li-ming DENG wei-zhen CHEN Xiao-Lin ZHANG Jian-wei Department of Physics Peking UniversityBeijing 100871 Department of Technical Physics Peking UniversityBeijing 100871

A possible meaning of boson-description for the collective motion of nuclei as a fermion system is *** is shown that the use of boson-description comes out naturally from the requirement of independent separation of t... 详细信息

关键词： collective separation boson

Static output feedback stabilization for systems with time-varying delay based on a matrix transformation method

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Science China(Information Sciences) 2015年第1期58卷 188-200页

作者： LIU zhen wei ZHANG HuaGuang SUN QiuYe College of Information Science and Engineering Northeastern University State Key Laboratory of Synthetical Automation for Process Industries Northeastern University

This paper is concerned with the problem of static output feedback stabilization for linear systems with time-varying delay. A novel controller design is proposed based on a matrix transformation method with a new equation condition, which can solve the controller gain more easily and avoid complicated calculations of the non-linear matrix inequality. Then, the corresponding criteria can be obtained by combining the matrix transformation method and the ideas of non-uniformly dividing delay interval, which can guarantee the asymptotic stability of the closed-loop systems and calculate the satisfactory controller gain. Finally, two numerical examples are provided to verify the effectiveness of the proposed design scheme.

关键词： static output feedback matrix transformation method time-varying delay non-uniformly dividing delay interval equation condition

Millet/peanut intercropping at a moderate N rate increases crop productivity and N use efficiency,as well as economic benefits,under rain-fed conditions

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Journal of Integrative Agriculture 2023年第3期22卷 738-751页

作者： LIU Zhu NAN zhen-wu LIN Song-ming YU Hai-qiu XIE Li-yong MENG wei-wei ZHANG zheng WAN Shu-bo Shandong Academy of Agricultural Sciences Jinan 250100P.R.China Agronomy College Shenyang Agricultural UniversityShenyang 110866P.R.China College of Life Sciences Shandong Normal UniversityJinan 250014P.R.China

Cereal and legume intercropping has been widely adopted to increase crop productivity in sustainable farming systems *** different intercropping combinations,millet and peanut intercropping can be adapted to most waterlimited ***,there are few studies on the differences in yield characteristics and nitrogen use efficiency between millet/peanut intercropping and monocultures under different nitrogen (N) application *** objective of this study was to determine the yield advantages and economic benefits,as well as the appropriate N application rate,of millet/peanut intercropping.A two-yearfield experiment was conducted with three cropping patterns (monoculture millet,monoculture peanut and millet/peanut intercropping) and four N rates (0,75,150 and 225 kg ha^(-1)).The results showed that the land equivalent ratio (LER) and net effect (NE) of the intercropping system reached their highest levels at the N input of 150 kg ha^(-1)in 2018 and 2019 (1.04 for LER,0.347 Mg ha^(-1)for NE,averaged across two years).Millet was the dominant crop in the intercropping system (aggressivity of millet and peanut (Amp)>0,competitive ratio of millet and peanut (CRmp)>1),and millet yields achieved their highest values at N inputs of 225 kg ha^(-1)for monoculture and 150 kg ha^(-1)for *** reached its highest levels with N inputs of 150 kg ha^(-1)for all planting patterns over the two *** combined with an N input of 150 kg ha^(-1)achieved the highest net income of 2 791 USD ha^(-1),with a benefit-cost ratio of 1.56,averaged over the two *** the perspective of economics and agricultural sustainable development,millet/peanut intercropping at 150 kg N ha^(-1)seems to be a promising alternative to millet or peanut monoculture.

关键词： millet peanut intercropping N input yield economics