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A hybrid-stress element based on Hamilton principle

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Acta Mechanica Sinica 2010年第4期26卷 625-634页

作者： Song Cen Tao Zhang Chen-Feng Li Xiang-Rong Fu Yu-qiu long Department of Engineering Mechanics School of Aerospace Tsinghua University Beijing 100084 China Civil and Computational Engineering Centre School of Engineering Swansea University Swansea SA2 8PP UK College of Water Conservancy and Civil Engineering China Agriculture University Beijing 100083 China Department of Civil Engineering Tsinghua University Beijing 100084 China

A novel hybrid-stress finite element method is proposed for constructing simple 4-node quadrilateral plane elements, and the new element is denoted as HH4-3fl here. Firstly, the theoretical basis of the traditional hybrid-stress elements, i.e., the Hellinger-Reissner variational principle, is replaced by the Hamilton variational principle, in which the number of the stress variables is reduced from 3 to 2. Secondly, three stress parameters and corresponding trial functions are introduced into the system equations. Thirdly, the displacement fields of the conventional bilinear isoparametric element are employed in the new models. Finally, from the stationary condition, the stress parameters can be expressed in terms of the displacement parameters, and thus the new element stiffness matrices can be obtained. Since the required number of stress variables in the Hamilton variational principle is less than that in the Hellinger-Reissner variational principle, and no additional incompatible displacement modes are considered, the new hybrid-stress element is simpler than the traditional ones. Furthermore, in order to improve the accuracy of the stress solutions, two enhanced post-processing schemes are also proposed for element HH4-3β. Numerical examples show that the proposed model exhibits great improvements in both displacement and stress solutions, implying that the proposed technique is an effective way for developing simple finite element models with high performance.

关键词： Finite element Hamilton variational principle Hybrid-stress element Post-processing schemes

Redundancy Elimination in GPRS network

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第4期7卷 477-482页

作者： qiu Qin-long ZHANG Dong-mei MA Jian ZHANG Da-jiang National Key Lab of Switching Technology and Telecommunication Network Beijing University of Posts ＆ Telecommunications Beijing 100876 China Nokia Research Centre Beijing 100013 China

The mechanisms of TCP’s retransmission and reset will result in redundant packets. These redundant packets are often sent unnecessarily to the user over a slow last-hop link delaying useful traffic. This is a problem for wide-area wireless links, such as General Packet Radio Service (GPRS), because unnecessary transmissions waste already limited radio bandwidth, battery power at the mobile terminal and incurs monetary cost due to charging by data volume. The paper first describes a GPRS model, then discusses how to eliminate the redundant packets in GPRS network and presents the simulation results in Network Simulation 2 (NS 2). The more traffic is, the more the network can benefit. In heavy traffic, it can even get more than 30% improvement in throughput. Average delay and loss percent are also lowered.

关键词： GPRS TCP Redundancy Elimination Network Simulation 2 (NS 2)

Abscisic acid negatively regulates post-penetration resistance of Arabidopsis to the biotrophic powdery mildew fungus

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Science China(Life Sciences) 2017年第8期60卷 891-901页

作者： Xiang Xiao Xi Cheng Kangquan Yin Huali Li Jin-long qiu State Key Laboratory of Plant Genomics Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Pytohormone abscisic acid （ABA） plays important roles in defense responses. Nonetheless, how ABA regulates plant resistance to biotrophic fungi remains largely unknown. Arabidopsis ABA-deficient mutants, aba2-1 and aba3-1, displayed enhanced resistance to the biotrophic powdery mildew fungus Golovinomyces cichoracearum. Moreover, exogenously administered ABA increased the susceptibility of Arabidopsis to G. cichoracearum. Arabidopsis ABA perception components mutants, abil-1 and abi2-1, also displayed similar phenotypes to ABA-deficient mutants in resistance to G. cichoracearum. However, the resistance to G. cichoracearum is not changed in downstream ABA signaling transduction mutants, abi3-1, abi4-1, and abi5-1. Microscopic examination revealed that hyphal growth and conidiophore production of G. cichoracearum were compromised in the ABA deficient mutants, even though pre-penetration and penetration growth of the fimgus were not affected. In addition, salicylic acid （SA） and MPK3 are found to be involved in ABA-regulated resistance to G. cichoracearurn. Our work demonstrates that ABA negatively regulates post-penetration resistance of Arabidopsis to powdery mildew fungus G. cichoracearum, probably through antagonizing the function of SA.

关键词： abscisic acid powdery mildew biotrophic fungus disease resistance salicylic acid

Synthesis of Piperazic Acid-Containing Cyclodepsipeptide Core of Verucopeptin

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Chinese Journal of Chemistry 2023年第17期41卷 2077-2081页

作者： Yuanjun Sun Wenhao Tang Mei Wang Huxin Ni Ya-qiu long Laboratory of Medicinal Chemical Biology College of Pharmaceutical SciencesJiangsu Province Engineering Research Centerof Precision Diagnostics and Therapeutics DevelopmentSoochow UniversitySuzhouJiangsu 215123China

Comprehensive SummaryChemically,N1 nitrogen of piperazic acid is more nucleophilic than N2 nitrogen,but amide bonds predominantly formed at N2 nitrogen are prevalent in piperazic acid-containing natural products,with only one exception of *** two orthogonal protecting groups of nitrogen are often employed to realize selective coupling of N2 nitrogen,resulting in increased synthetic steps and low synthetic ***,we develop selective deprotection of N2-Cbz from the N1,N2-diCbz-piperazic acid-containing peptide to form the N2 amide exclusively,avoiding the tedious orthogonal protection strategy which is commonly applied when the easily-accessible N1,N2-diCbz-piperazic acid is used as the synthetic *** employ this selective-deprotection strategy to achieve an efficient synthesis of piperazic acid-containing cyclodepsipeptide core of verucopeptin with an overall yield of 21%from commercially/readily available building blocks.

关键词： Natural products Piperazic acid Verucopeptin Total synthesis Regioselectivity

城市轨道交通联调联试问题分析和管理优化探讨

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工程建设与设计 2024年第9期 109-113页

作者：黄育斌邱兴隆钟杰铁科院(深圳)研究设计院有限公司广东深圳518057

以深圳市某地铁线路的联调联试为例,通过分析联调联试问题台账,剖析全过程各类问题及其产生原因,总结联调联试重难点和管理经验,提出针对性措施和管理优化思路,如做好工程建设整体进度控制,在管理上更加重视施工质量和成品保护工作等。

关键词：城市轨道交通联调联试问题分析管理优化

Sliding Mode Control with Unidirectional Auxiliary Surfaces Based on Double Power Reaching Law and Disturbance Observer

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Sliding Mode Control with Unidirectional Auxiliary Surfaces ...

Density functional theory study of structural stability for gas hydrate

第36届中国控制会议

作者： Wutong Xu long qiu Dian Sheng Qing Liang Department of Automation University of Science and Technology of China

ISBN: (纸本)9781538629185

For a class of nonlinear continuous systems,this paper proposes a sliding mode control with unidirectional auxiliary surfaces（UAS-SMC） based on a double power reaching law and a disturbance observer（DO）.Firstly,according to the nonlinear continuous systems,the switching surfaces and the controller based on the proposed law and DO are designed to weaken the chattering phenomenon caused by disturbance ***,theoretical analyses prove that the system states can converge to the switching surfaces in a finite time and slide to the origin on the surface *** formula of the convergence time was ***,the simulation results show that the UAS-SMC method based on double power reaching law（UASDPRLSMC） has faster convergence speed and better ability to suppress the chattering than ordinary UAS-SMC and UAS-SMC based on the power reaching law（UASPRL-SMC）.

关键词： Nonlinear continuous system Sliding mode control Double power reaching law Disturbance observer Unidirectional auxiliary surface

来源： cnki会议评论

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cnki会议

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Chinese Physics B 2018年第4期27卷 272-275页

作者： Ping Guo Yi-long qiu long-long Li Qiang Luo Jian-Fei Zhao Yi-Kun Pan State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Chengdu 610500 China

Using the first-principles method based on the density functional theory（DFT）,the structures and electronic properties of different gas hydrates（CO2,CO,CH4,and H2） are investigated within the generalized gradient *** structural stability of methane hydrate is studied in this *** results show that the carbon dioxide hydrate is more stable than the other three gas hydrates and its binding energy is-2.36 e V,and that the hydrogen hydrate is less stable and the binding energy is-0.36 e *** cages experience repulsion from inner gas molecules,which makes the hydrate structure more *** the electronic properties of two kinds of water cages,the energy region of the hydrate with methane is low and the peak is close to the left,indicating that the existence of methane increases the stability of the hydrate *** the methane molecule in water cages and a single methane molecule,the energy of electron distribution area of the former is low,showing that the filling of methane enhances the stability of hydrate structure.

关键词： first principles gas hydrate binding energy stability

Accelerated effect on Mitsunobu reaction via bis-N-tert-butoxycarbonylation protection of 2-amino-6-chloropurine and its application in a novel synthesis of penciclovir

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第10期14卷 760-766页

作者： Li-yan DAI qiu-long SHI Jing ZHANG Xiao-zhong WANG Ying-qi CHEN Department of Chemical and Biological Engineering Zhejiang University

Solubility of 2-amino-6-chloropurine in Mitsunobu solvents could be significantly improved after its exocyclic amino group is protected via *** bis-Boc protected 2-amino-6-chloropurine also shows excellent activity and N9 selectivity in the coupling with various alcohols by a Mitsunobu ***,a new practical and efficient method is established for the synthesis of penciclovir(PCV) from bis-Boc-2-amino-6-chloropurine 9 and the side chain of 5-(2-hydroxyethyl)-2,2-dimethyl-1,3-dioxane 5—the latter being a more easily prepared cyclic precursor of the diacetate side chain used in the conventional *** coupling of 9 with 5 proceeded regioselectively at a N9 position of purine derivative for a good yield under Mitsunobu conditions.

关键词： 2-amino-6-chloropurine Mitsunobu reaction bis-Boc protection Penciclovir(PCV)

Role of the PTEN signaling pathway in autism spectrum disorder

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Neuroscience Bulletin 2013年第6期29卷 773-778页

作者： Jing-Wen Lv Tian-Lin Cheng Zi-long qiu Wen-Hao Zhou Department of Neonatology Children's Hospital of Fudan University Institute of Neuroscience Shanghai Institute of Biological SciencesChinese Academy of Sciences

Autism is an etiologically heterogeneous group of neurodevelopmental disorders,diagnosed mostly by the clinical behavioral *** concept that the tumor-related gene PTEN plays a critical role in autism spectrum disorder has emerged over the last *** this review,we focus on the essential role of the PTEN signaling pathway in neuronal differentiation and the formation of neural circuitry,as well as genetic mouse models with Pten ***,accumulated data suggest that the effect of PTEN on neural stem-cell development contributes significantly to the pathophysiology of autism spectrum disorders.

关键词： PTEN TSC1/2 autism synapse neural stem cells