检索结果-南通市图书馆

Acta Mechanica Sinica 2011年第5期27卷 833-839页

作者： Fan Zhan Yu-bo Fan Xiao-Yan deng Key Laboratory for Biomechanics and Mechanobiologyof Ministry of Education School of Biological Science and Medical EngineeringBeihang University 100191 Beijing China

Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the *** our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end *** order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow *** numerical models were created based on our previous experimental *** simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion *** present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.

关键词： Platelet near-wall concentration · Swirling flow · Small-caliber arterial grafts · End-to-end anastomosis

Variations of optic properties of water under action of static magnetic field

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第23期52卷 3179-3182页

作者： deng bo PANG XiaoFeng School of Life Science and Technology University of Electronic Science and Technology of China Chengdu 610054 China

Effects of static magnetic field on optic properties of water are investigated by infrared spectroscopy, ultraviolet spectroscopy and X-ray diffraction, respectively. The ultraviolet spectroscopy experiments show the changes of properties of water under action of static magnetic field, in the region of 191 to 400 nm. The infrared experiment shows that the water exposed in a magnetic field had saturation and memory effects. The magnetized effects increased with increasing exposed time, but were weakened with increasing of time when the magnetic field was removed. In the X-ray experiment, the strength of diffraction increased also, after the water was exposed in magnetic field. Meanwhile, the shift of peak and increase of strength of X-ray diffraction of magnetized water added with nanoFe3O4 occurred as compared with that of pure water added with nano Fe3O4. This result suggests that the magnetized wa- ter has certain magnetism. Finally, these phenomena are simply explained by the molecular structure of water and the theory of magnetization of water.

关键词：红外线光谱学紫外线光谱学 X衍射静力学磁铁

Finite Difference/Element Method for a Two-Dimensional Modified Fractional Diffusion Equation

在线全文

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2012年第4期4卷 496-518页

作者： na Zhang Weihua deng Yujiang Wu School of Mathematics and Statistics Lanzhou UniversityLanzhou 730000China

We present the finite difference/element method for a two-dimensional modified fractional diffusion *** analysis is carried out first for the time semi-discrete scheme,and then for the full discrete *** time discretization is based on the L1-approximation for the fractional derivative terms and the second-order backward differentiation formula for the classical first order derivative *** use finite element method for the spatial approximation in full discrete *** show that both the semi-discrete and full discrete schemes are unconditionally stable and ***,the optimal convergence rate is ***,some numerical examples are tested in the case of one and two space dimensions and the numerical results confirm our theoretical analysis.

关键词： Modified subdiffusion equation finite difference method finite element method stability convergence rate

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

身心性命:宋明理学的历史阐释与现代建构

河南社会科学 2025年第1期33卷 102-110页

作者：邓国坤浙江大学哲学学院浙江杭州310058 贵州大学哲学学院贵州贵阳550000

身心性命之学乃是宋明理学的一种历史阐释范式,也是现代学者对于宋明理学的新建构。身心性命阐释为宋代至今的学者一直使用,它不仅是宋明理学的概称,而且指向宋明理学的主要内涵或旨向,包括身心之学、性理之学、天命之学。它既包含内圣... 详细信息

身心性命之学乃是宋明理学的一种历史阐释范式,也是现代学者对于宋明理学的新建构。身心性命阐释为宋代至今的学者一直使用,它不仅是宋明理学的概称,而且指向宋明理学的主要内涵或旨向,包括身心之学、性理之学、天命之学。它既包含内圣的维度,也包含外王的维度。身心性命阐释涵具身心—性理—天命的思想结构:由身心而通达性理,由性理而通达天命。在此基础上构建起来的新理论可称为身心性命之学。它的特征包括以身、心、性、命的统一体为研究领域;以身心、性理、天命的次第研究为进路;具有体用合一,由实践而超越的途径,以天人合一为终极理想的基本特征。它指明了宋明理学的研究领域、思想结构、主要特征等,为今人阐释与重构宋明理学提供了一个新的思路与经验。

关键词：宋明理学身心性理天命

A two-level meta-heuristic approach for the minimum dominating tree problem

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2023年第1期17卷 229-231页

作者： Caiquan XIONG Hang LIU Xinyun WU na deng School of Computer Science Hubei University of TechnologyWuhan 430068China

1 Introduction The minimum dominating tree(MDT)problem was first proposed by Zhang et al.[1]to produce a routing backbone of a *** et al.[2]proved that the MDT problem is NP-hard and introduced an approximation framework for solving *** important MDT problem algorithms are the artificial bee colony(ABC_DT)algorithm and ant colony optimization(ACO_DT)algorithm proposed by Sundar and Singh[3],the evolutionary algorithm with guided mutation(EA/G-MP)proposed by Chaurasia and Singh[4],the variable neighborhood search algorithm proposed by Dražićet al.[5],one improved artificial bee colony(ABC_DTP)algorithm proposed by Singh and Sundar[6],and a hybrid algorithm combining genetic algorithm proposed by Hu et al.[7].In this paper,we develop a two-level meta-heuristic(TLMH)for solving the MDT problem,aiming to find a dominating tree with the minimum weight for a given graph.

关键词： artificial dominating Singh

Projected Runge-Kutta methods for constrained Hamiltonian systems

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2016年第8期37卷 1077-1094页

作者： Yi WEI Zichen deng Qingjun LI bo WANG Department of Applied Mathematics Northwestern Polytechnical University Department of Engineering Mechanics Northwestern Polytechnical University Mechanical and Aerospace Engineering Oklahoma State University

Projected Runge-Kutta （R-K） methods for constrained Hamiltonian systems are proposed. Dynamic equations of the systems, which are index-3 differential-algebraic equations （DAEs） in the Heisenberg form, are established under the framework of Lagrangian multipliers. R-K methods combined with the technique of projections are then used to solve the DAEs. The basic idea of projections is to eliminate the constraint violations at the position, velocity, and acceleration levels, and to preserve the total energy of constrained Hamiltonian systems by correcting variables of the position, velocity, acceleration, and energy. Numerical results confirm the validity and show the high precision of the proposed method in preserving three levels of constraints and total energy compared with results reported in the literature.

关键词： projected Runge-Kutta (R-K) method differential-algebraic equation(DAE) constrained Hamiltonian system energy and constraint preservation constraint violation

Flight dynamics characteristics of canard rotor/wing aircraft in helicopter flight mode

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第7期32卷 1577-1587页

作者： Honggang GAO Ao HE Zhenghong GAO Yang na Yangping deng School of Aeronautics Northwestern Polytechnical University

The aerodynamic layout of the Canard Rotor/Wing(CRW) aircraft in helicopter flight mode differs significantly from that of conventional helicopters. In order to study the flight dynamics characteristics of CRW aircraft in helicopter mode, first, the aerodynamic model of the main rotor system is established based on the blade element theory and wind tunnel test results. The aerodynamic forces and moments of the canard wing, horizontal tail, vertical tail and fuselage are obtained via theoretical analysis and empirical formula. The flight dynamics model of the CRW aircraft in helicopter mode is developed and validated by flight test data. Next, a method of model trimming using an optimization algorithm is proposed. The flight dynamics characteristics of the CRW are investigated by the method of linearized small perturbations via Simulink. The trim results are consistent with the conventional helicopter characteristics, and the results show that with increasing forward flight speed, the canard wing and horizontal tail can provide considerable lift,which reflects the unique characteristics of the CRW aircraft. Finally, mode analysis is implemented for the linearized CRW in helicopter mode. The results demonstrate that the stability of majority modes increases with increasing flight speed. However, one mode that diverges monotonously,and the reason is that the CRW helicopter mode has a large vertical tail compared to the conventional helicopter. The results of the dynamic analysis provide optimization guidance and reference for the overall design of the CRW aircraft in helicopter mode, and the model developed can be used for control system design.

关键词： Canard rotor/wing aircraft Dynamics analysis Flight dynamics Helicopter Linearization Model building

Air-tolerant direct reductive N-methylation of amines using formic acid via simple inorganic base catalysis

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2020年第1期31卷 111-114页

作者： Yan Huang Wei deng bo-Lin Lin School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai 201418China School of Technology and Physical Science ShanghaiTech UniversityShanghai 201210China

The construction of N-methyl amine moieties is an important reaction that has found numerous *** of new methylation agents that are more environmentally benign than classical agents,such as iodomethane and methyl sulfate,is still highly ***,we report a convenient protocol for direct reductive N-methylation of amines using formic acid as the methylation agent via simple inorganic base *** present protocol operates under transition-metal-free and air-tolerant *** the catalyst,K2 HPO4,and the reductant,polymethylhydrosiloxane(PMHS),are cheap and easily separable from the crude reaction product *** investigations suggest that the reaction occur through the formation of an acetal inte rmediate followed by the C-N bond formation.

关键词： Air tolerant N-Methylation Formic acid Simple inorganic bas Transition-metal-free

Paraffin wax as a diluent for extraction and separation of trivalent gallium, indium, and thallium with 2,6-bis-(l'-phenyl-3'-methyl-5'-oxopyrazole-4') pyridineacyl

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2003年第2期22卷 86-90页

作者： Gao Jinzhang deng Qiliang Peng bo Guo Xiaojun Chemistry & Chemical Engineering College Northwest Normal University Lanzhou 730070

A method is proposed for the extraction and separation of trivalent gallium,indium and thallium from their corresponding aqueous solutions at 65 deg C with 2,6-bis-(1'-phenyl-3'-methyl-5'-oxopyrazole-4') pyridineacyl (H_2PMBPP or H_2A) using molten paraffinwax as a diluent. The values of pH_(1/2) for extraction of gallium, indium and thallium are2.62,4.32 and 4.93, respectively. Gallium can he extracted by H_2PMBPP at a lower acid medium. Theeffect of solvent and the composition of the extracted species are reported. And the thermodynamicdata of the extraction are also obtained.

关键词： separation in inorganic chemistry solvent extraction gallium indium thallium H_2PMBPP

Precision of the Chinese Space Station Telescope(CSST)stellar radial velocities

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第4期21卷 207-215页

作者： Yang Sun Ding-Shan deng Hai-bo Yuan Department of Astronomy Beijing Normal UniversityBeijing 100875China

The Chinese Space Station Telescope(CSST)spectroscopic survey plans to deliver high-quality low-resolution(R>200)slitless spectra for hundreds of millions of targets down to a limiting magnitude of about 21 mag,covering a large survey area(17500 deg^(2))and a wide wavelength range(255-1000 nm by three bands GU,GV,and GI).In this work,we use empirical spectra of the Next Generation Spectral Library to simulate the CSST stellar spectra at R=250,and investigate their capabilities in measuring radial *** find that velocity uncertainties depend strongly on effective temperature,weakly on metallicity for only FGK stars,and hardly on surface *** is possible to deliver stellar radial velocities to a precision of about 3 kms^(-1)for AFGKM stars,and about 10 km s^(-1)for OB stars,at signal-to-noise ratio(SNR)of *** uncertainties using single GU/GV/GI band spectra are also *** the same SNR,the GU band performs best,the GV band the second best,and then the GI *** effects of spectral normalization and the imperfect template on velocity measurements are investigated and found to be very *** uncertainties caused by wavelength calibration are considered and found to be *** the possible precision of radial velocities,the CSST spectroscopic survey can enable interesting science such as searching for hyper-velocity *** of our results are also discussed.

关键词： methods:data analysis methods:statistical stars:fundamental parameters stars:kinematics and dynamics