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Progress in Natural Science:Materials International 2006年第7期16卷 706-711页

作者： GAO Song, WANG Xiaoying and BAO Shanglian ( Laboratory of Medical Physics & Engineering, Peking university, Beijing 100871, china department of Radiology, The First Affiliated Hospital of Peking university, Beijing 100034, china) Peking Univ Lab Med Phys & Engn Beijing 100871 Peoples R China Peking Univ Affiliated Hosp 1 Dept Radiol Beijing 100034 Peoples R China

Diffusion time and diffusion gradient strength are two important parameters of pulsed gradient spin echo (PGSE) that is the most commonly used method in diffusion-weighted magnetic resonance imaging. However, the effects of the diffusion time on the mean diffusivity (MD) in previous studies are controversial. In this study, a new experimental protocol was designed to evaluate the effects of the two parameters on the results of PGSE. It was found that MD decreased significantly with the increased diffusion time or increased diffusion gradient strength, which cannot be explained by the previous theories. Through theoretical analysis, we found the flaw in the pulsed gradient spin echo (PGSE) method, which is the explanation for the controversial results of diffusion time obtained by oth- ers.

关键词： diffusion time diffusion gradient strength diffusion-weighted imaging diffusion tensor imaging mean diffusivity.

Progress of Proximity Sensors for Potential Applications in Electronic Skins

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Transactions of Tianjin university 2024年第1期30卷 40-62页

作者： Runnan Zou Yanhong Tong Jiayi Liu Jing Sun Da Xian Qingxin tang Center for Advanced Optoelectronic Functional Materials Research Key Lab of UV-Emitting Materials and Technology of Ministry of EducationNortheast Normal UniversityChangchun 130024China

Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial *** proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of *** article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi ***,their working mechanism,materials,preparation methods,and research progress are discussed in ***,we summarize the future challenges in developing fl exible proximity sensors.

关键词： Capacitive proximity sensors Triboelectric proximity sensors Gate-enhanced proximity sensors Flexible wearable devices Electronic skins

Principal Model Analysis Based on Bagging PLS and PCA and Its Application in Financial Statement Fraud

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Journal of Systems Science and Information 2024年第2期12卷 212-228页

作者： Xiao LIANG Qiwei XIE Chunyan LUO Liang tang Yi SUN School of Economics and Management Beijing University of TechnologyBeijing 100124China Shanghai Tongtu Semiconductor technology Co. LtdShanghai 210203China School of Finance Anhui University of Finance&EconomicsBengbu 233000China

Motivated by the Bagging Partial Least Squares(Bagging PLS)and Principal Component Analysis(PCA)algorithms,a novel approach known as Principal Model Analysis(PMA)method is introduced in this *** the proposed PMA algorithm,the PCA and the Bagging PLS are *** this method,multiple PLS models are trained on sub-training sets,derived from the training set using the random sampling with replacement *** regression coefficients of all the sub-PLS models are fused in a joint regression coefficient *** final projection direction is then estimated by performing the PCA on the joint regression coefficient ***,the proposed PMA method is compared with other traditional dimension reduction methods,such as PLS,Bagging PLS,Linear discriminant analysis(LDA)and *** results on six public datasets demonstrate that our proposed method consistently outperforms other approaches in terms of classification performance and exhibits greater ***,it is employed in the application of financial statement fraud *** and other five algorithms are utilized to financial statement fraud which concerned by the academic community,and the results indicate that the classification of PMA surpassed that of the other methods.

关键词： principal model analysis partial least squares principal component analysis dimension reduction ensemble learning financial statement fraud detection

Miktoarms hyperbranched polymer brushes:One-step fast synthesis by parallel click chemistry and hierarchical self-assembly

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Science china Chemistry 2010年第12期53卷 2461-2471页

作者： HAN Yi & GAO Chao MOE Key Laboratory of Macromolecular Synthesis and Functionalization department of Polymer Science and Engineering,Zhejiang university,Hangzhou 310027,china 1. MOE Key Laboratory of Macromolecular Synthesis and Functionalization department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click *** parallel click grafting strategy was demonstrated to be highly efficient (～100%),very fast (～ 2 h) and well controllable to the amphilicity of molecular *** adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily *** resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) *** spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic *** brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of *** addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.

关键词： miktoarms molecular brushes hyperbranched polyglycerol amphiphilic self-assembly

Analysis of the cause of crack in cold rolling of QSn6.5-0.1 strip

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Journal of Central south university of technology 2001年第2期8卷 94-98页

作者： ZHANG Sheng hua 1,QIN Ye xia 1,LOU Hua fen 2,LU Jun pan 2,ZHONG Wei jia 2 (1 department of Materials Science and Engineering, Central south university, Changsha 410083, china 2.Luoyang Copper Processing Company, Luoyang 471000, china) 1. department of Materials Science and Engineering Central South University 410083 Changsha China 2. Luoyang Copper Processing Company 471000 Luoyang China

In order to know the cause of cracks in cold rolling of QSn6.5 0.1 copper alloy strip, a lot of experiments and analysis were done. The microstructure changes of QSn6.5 0.1 were investigated by means of metallurgical microscope. The morphology of cracks and surface defects were examined using scanning electron microscope. Macroscopic residual stresses produced in every process during manufacturing in the QSn6.5 0.1 strip were measured by X ray diffraction method and hole drilling method. The results show that the cracks in the QSn6.5 0.1 cold rolling strip were caused due to the derivation of metallurgical defects, such as SnO 2, S, fine looses,the inverse segregation unable to clear up when milling, and the accumulation of all kinds of resi dual stresses. When the accumulation of the residual stress reaches the material′s breaking strength, the cracks will be generated. Several measures to avoid the development of these kinds of cracks were put forward, such as: controlling the casting technology, improving homogenization annealing procedure (680 ℃/7 h) and milling quality(using the second milling when necessary), working out a more reasonable rolling technology to ensure intermediate annealing in time.

关键词： QSn6.5 0.1 cold rolling strip crack metallurgical defect residual stress

Train post‑derailment behaviours and containment methods:a review

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Railway Engineering Science 2024年第1期32卷 59-80页

作者： Zhao tang Yuwei Hu Shuangbu Wang Liang Ling Jianjun Zhang Kaiyun Wang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 610031China National Centre for Computer Animation Bournemouth UniversityDorsetUK

Railway accidents,particularly serious derailments,can lead to catastrophic ***,it is essential to prevent derailment escalation to reduce the likelihood of severe *** post-derailment behaviours and containment methods play a critical role in preventing derailment escalation and providing passive safety protection and accident prevention in the event of a ***,despite the increasing attention on this field from academia and industry in recent years,there is a lack of systematic exploration and summarization of emerging applications and containment methods in train post-derailment *** this reason,this paper presents a comprehensive review of existing studies on train post-derailment behaviours,encompassing various topics such as post-derailment contact-impact models,dynamic modelling and simulation techniques,and the primary factors influencing post-derailment ***,this review introduces and elucidates substitute guidance mechanisms(SGMs),which serve as railway-specific passive safety protection and accident prevention *** various types of SGMs are depicted,and their ongoing developments and applications are explored in *** review additionally points out several unresolved challenges including the adverse effects of SGMs,and proposes future research directions to advance the theoretical understanding and practical application of train post-derailment behaviours and containment *** review seeks to be a valuable reference for railway industry professionals in preventing catastrophic derailment consequences through post-derailment containment methods.

关键词： Railway passive safety Railway accident prevention Post-derailment behaviours Substitute guidance mechanisms(SGMs) Contact-impact model

The Predatory Function of Three Spiders to Two Insect Pests in Rice Within a Multi-species Co-existence System

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Agricultural Sciences in china 2002年第4期1卷 391-396页

作者： LI Jian-quan, SHEN Zuo-rui and ZHAO Zhi-mo( College of Plant Protection , china Agricultural university, Beijing 100094 , P.R. china department of Plant Protection , south-west Agricultural university, Chongqing 400716 , P.R. china) College of Plant Protection China Agricultural University Beijing 100094 P. R. China department of Plant Protection Southwest Agricultural University Chongqing 400716 P. R . China

The prey-seeking behavior of three spiders (X1-Pirata subpiraticus, X2-Clubiona japonicola and X3-Tetragnatha japonica) for brown plant hopper (X4-Nilaparvata lugens) and rice spittle bug (X5-Cal-litettix versicolor) was investigated, as well as how interference between and within species occurred, by using a quadratic regression rotational composite design. Six predation models derived from the analysis of interactions among and within predators and preys were developed. The total predatory capacity of spiders on rice insect pests after coexistence for one day can be expressed as follows: Y3 = 32.795 + 2.25X1 + 1.083X2 + 0.5X3 + 10.167X4 + 3.167X5 - 1.67X12 - 2.42X22 - 3.295X32 - 0.045X42 + 0.455X52 - 3.125X1X2 + 0.375X1X3 -0.625X1X4 - 0.375X1X5 + 0.375X2X3 - 0.875X2X4 + 0.125X2X5 + 0.375X3X4 - 0.375X3X5 + 0.125X4X5. The principal efficiency analysis using this model indicated that increases in insect pest density significantly increased predation by predators; this was much greater than the effect of any single predator. X4 had a greater effect than X5; however, X4 and X5 demonstrated little interspecific interference and even promoted each other and increased predation rates as the densities of the two pests increased. Among the three predators, an increase in the density of X, had the greatest effect on the increase in predation, X3 had the second, X2 the third greatest effect. As predator density increased inter- and intra-species interference occurred, which were largely related to the size, activity, niche breadth, niche overlap and searching efficiency of the predators. X2 produced the greatest interference between different individuals and between any other predator species. X3 had the second greatest, which reduced predation levels at high predator densities. Because of these factors, the highest predation rate was obtained at a prey density of 120 per 4 rice-hills. The optimal proportion of the three predators in the multi-predator prey system was X1: X2:

关键词： Spiders Predation Bio-control Intra-species relationships Co-existence system Interaction Intraspecific competition Interspecific competition Animal behavior Natural enemies Rice insect pest

A novel multi-functional cell-based microphysiometer

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Progress in Natural Science:Materials International 2006年第8期16卷 808-816页

作者： XU Ying, XU Gaixia, LIU Qingjun, CAI Hua, LI Yan, LI Rong and WANG Ping (Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of Education Ministry, department of Biomedical Engineering, Zhejiang university, Hangzhou 310027, china State Key Laboratory of Transducer technology, Chinese Academy of Sciences, Shanghai 200050, china) [a]Biosensor National Special Laboratory Key Laboratory of Biomedical Engineering of Education Ministry Department of Biomedical Engineering Zhejiang University Hangzhou China [b]State Key Laboratory of Transducer technology Chinese Academy of Sciences Shanghai China

This paper presents a novel multi-functional microphysiometer for simultaneous measurements of several extracellular ion concentrations and action potential measurement in living cells based on MLAPS (multi-light addressable potentiometric sensor). In the microphysiometer, sorts of sensitive membranes are illuminated in parallel with n light sources at working frequencies, and the response amplitudes of each frequency component can be measured on-line by parallel processing algorithm. In the experiments, the relations of the extracellular environmental H+, Na+, K+, Ca2+ under the effects of western medicines (dilantin, phenobarbital sodium) and Chinese drugs (scutellaria, medlar, hemlock parsley) were analyzed, and the effects of several drugs were evaluated. Moreover, the action potential signals of different cell types (cardiac myocytes and neurons) could be measured and analyzed by LAPS. By detecting these parameters, the system can monitor the real-time process of the cell metabolism and action potential, observe the functional responses of different kinds of membrane-bound receptors, and evaluate the activities of drugs.

关键词： multi-functional microphysiometer cell-based biosensor cellular ion concentration measurement cellular action potential.

Scanning electron microscopic studies on digestive tract mucosa of mullet

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Acta Oceanologica Sinica 1991年第4期10卷 603-608页

作者： Guo Shuhua, Li YuheGuo Jinxiao Test and Computation Centre, Nankai university, Tianjin, china department of Biology, Nankai university, Tianjin, china

In this paper,scanning electron microscopic studies on digestive tract mucosa of mullet (Liza haematocheila) are presented. This reveals the mucosal ultrastructural characteristics of the oesophagus, stomach and intestine of mullet (Liza heamatocheila). These characteristics are closely related to diets (plankton,benthic algae and organic debris) ,markedly different from those of herbivorous and carnivorous fishes.

关键词： length

EXISTENCE AND ASYMPTOTIC BEHAVIOR OF THE SOLUTIONS FOR A NONLINEAR ELLIPTIC EQUATION ARISING IN ASTROPHYSICS

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Acta Mathematica Scientia 2006年第2期26卷 229-245页

作者：唐仲伟 School of Mathematical Sciences Beijing Normal university Beijing 100875China

The author first analyzes the existence of ground state solutions and cylindrically symmetric solutions and then the asymptotic behavior of the ground state solution of the equation -△u =φ（r）u^p-1, u 〉 0 in R^N, u ∈ D^1,2（R^N）, where N ≥ 3, x = （x^1,z） ∈ R^K×R^N-K,2 ≤ K ≤ N,r = ｜x′｜. It is proved that for 2（N-s）/（N-2）〈 p 〈 2^＊ = 2N/（N - 2）, 0 〈 s 〈 2, the above equation has a ground state solution and a cylindrically symmetric solution. For p = 2^＊, the above equation does not have a ground state solution but a cylindrically ***, and when p close to 2^＊, the ground state solutions are not cylindrically symmetric. On the other hand, it is proved that as p close to 2＊, the ground state solution Up has a unique maximum point xp = （x′p, Zp） and as p → 2^＊, ｜x′p｜ → r0 which attains the maximum of φ on R^N. The asymptotic behavior of ground state solution Up is also given, which also deduces that the ground state solution is not cylindrically symmetric as p goes to 2^＊.

关键词： Cylindrical symmetry asymptotic behavior ground state solution