检索结果-南通市图书馆

A numerical investigation into the solids phase chromatography using a combined continuous and discrete approach

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Particuology 2008年第6期6卷 557-571页

作者： Wei yang fang yang Yulong Ding Institute of Particle Science & Engineering University of Leeds Leeds LS2 9JT UK On visiting from University of Birmingham Edgbaston Birmingham B15 2TT UK

Solids phase chromatography for particle classification is based on different retention times of particles with different properties when they are elutriated through a confined geometry. This work aims at a fundamental understanding of such a technology by using the combined continuous and discrete method. A packed bed is employed as the model confined geometry. The numerical method is compared first with experimental observations, followed by a parametric analysis of the effects on the flow hydrodynamics and solids behaviour of various parameters including the number of injected particles, the superficial gas velocity, the contact stiffness and the diameter ratio of the packed column to the packed particles. The results show that the modelling captures some important features of the flow of an injected pulse of fine particles in a packed bed. An increase in the number of injected particles or the superficial gas velocity reduces the retention time, whereas the contact stiffness does not show much effect over the range of 5 × 10^2 to 5× 10^4 N/m. It is also found that the effect on the retention time of the diameter ratio of the packed column to the packed particles seems complex showing a non-monotonous dependence.

关键词： Solids phase chromatography Gas-solid two-phase flows Packed bed Combined continuous and discrete method Modelling

On Compact Hermitian Manifolds with Flat Gauduchon Connections

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2018年第8期34卷 1259-1268页

作者： Bo yang fang yang ZHENG School of Mathematical Sciences Xiamen University Xiamen 361005 P. R. China Department of Mathematics Zhejiang Normal University Jinhua 321004 P. R. China Department of Mathematics The Ohio State University 231 West 18th Avenue Columbus OH 43210 USA

Given a Hermitian manifold （M-n,g）, the Gauduchon connections are the one parameter family of Hermitian connections joining the Chern connection and the Bismut connection. We will call△=（1-s/2）△c＋s/2△b the s-Gauduchon connection of M, where △c and △b are respectively the Chern and Bismut connections. It is natural to ask when a compact Hermitian manifold could admit a flat s-Gauduchon connection. This is related to a question asked by Yau. The cases with s = 0 （a flat Chern connection） or s = 2 （a flat Bismut connection） are classified respectively by Boothby in the 1950s or by the authors in a recent joint work with Q. Wang. In this article, we observe that if either s 〉 4＋2√3 ≈ 7.46 or s 〈 4- 2√3≈ 0.54 and s ≠ 0, then g is Kahler. We also show that, when n = 2, g is always Kahler unless s=2. Therefore non-Kahler compact Gauduchon fiat surfaces are exactly isosceles Hopf surfaces.

关键词： Hermitian manifolds Hermitian connections Kahler manifolds

Image segmentation algorithm based on high-dimension fuzzy character and restrained clustering network

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2014年第2期25卷 298-306页

作者： Baoping Wang yang fang Chao Sun Science and Technology on UAV Laboratory Northwestern Polytechnical University

An image segmentation algorithm of the restrained fuzzy Kohonen clustering network （RFKCN） based on high- dimension fuzzy character is proposed. The algorithm includes two steps. The first step is the fuzzification of pixels in which two redundant images are built by fuzzy mean value and fuzzy median value. The second step is to construct a three-dimensional （3-D） feature vector of redundant images and their original images and cluster the feature vector through RFKCN, to realize image seg- mentation. The proposed algorithm fully takes into account not only gray distribution information of pixels, but also relevant information and fuzzy information among neighboring pixels in constructing 3- D character space. Based on the combination of competitiveness, redundancy and complementary of the information, the proposed algorithm improves the accuracy of clustering. Theoretical anal- yses and experimental results demonstrate that the proposed algorithm has a good segmentation performance.

关键词： image segmentation high-dimension fuzzy character,restrained fuzzy Kohonen clustering network (RFKCN).

Electrokinetic mixing of two fluids with equivalent conductivity

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第2期35卷 256-260页

作者： fang yang Wei Zhao Guiren Wang Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education School of Life SciencesJilin UniversityChangchun 130012China Institute of Photonics and Photon-technology International Scientific and Technological Cooperation Base of Photoelectric Technology and Functional Materials and ApplicationNorthwest UniversityXi’an 710127China Department of Mechanical Engineering University of South CarolinaColumbiaUSA

Electrokinetic(EK)micromixers have been widely studied in the past decade for biochemical applications,biological and chemical analysis,***,almost all EK mixers require different electrical conductivity between the two fluids to be mixed,which has greatly limited their wide applications,in cases where the two streams to be mixed have equivalent electrical *** we show that mixing enhancement between two fluids with identical conductivity can be achieved in an EK micromixer with conductive sidewalls,where the electric field is in transverse direction of the *** results revealed that the mixing became stronger with increased conductivity *** mixing method provides a novel and convenient strategy for mixing two liquids with the same or similar electrical conductivity in microfluidic systems,and could potentially serves as a powerful tool for sample preparation in applications such as liquid biopsy,and environmental monitoring,etc.

关键词： Microfluidics Microchannels Mixing Electrokinetics Micromixer

A novel approach to minimizing material loss for computer numerical control flank-regrinding of worn end mills

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2023年第3期18卷 219-231页

作者： Liming WANG yang fang Jianping yang Jianfeng LI School of Mechanical Engineering Shandong UniversityJinan 250061China National Demonstration Center for Experimental Mechanical Engineering Education Shandong UniversityJinan 250061China Key Laboratory of High Efficiency and Clean Mechanical Manufacture(Ministry of Education) Shandong UniversityJinan 250061China

Flanks of end mills are prone to wear in a long machining *** is widely used in workshops to restore the flank to an original-like ***,the traditional method involves material waste by trial and error and dramatically decreases the potential ***,over-cut would happen to the flutes of worn cutters in the regrinding processes because of improper wheel *** study presented a new approach to planning the wheel path for regrinding worn end mills to minimize material loss and recover the *** planning,a scaling method was developed to determine the maximum size of the new cutter according to the similarity of cutter shapes before and after ***,the wheel path is first generated by envelope theory to regrind the worn area with a four-axis computer numerical control grinder according to the new size of ***,a second regrinding strategy is applied to recover the flute shape over-cut in the first ***,the proposed method is verified by an *** showed that the proposed approach could save 25%of cutter material compared with the traditional method and ensure at least three regrinding *** work effectively provides a general regrinding solution for the worn flank with maximum material-saving and regrinding period.

关键词： flank-regrinding worn end mill wheel position and orientation material loss over-cut

Pluriclosed Manifolds with Constant Holomorphic Sectional Curvature

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2022年第6期38卷 1094-1104页

作者： Pei Pei RAO fang yang ZHENG School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331P.R.China

A long-standing conjecture in complex geometry says that a compact Hermitian manifold with constant holomorphic sectional curvature must be Kèahler when the constant is non-zero and must be Chern flat when the constant is *** conjecture is known in complex dimension 2 by the work of Balas-Gauduchon in 1985(when the constant is zero or negative)and by Apostolov±Davidov±Muskarov in 1996(when the constant is positive).For higher dimensions,the conjecture is still largely *** this article,we restrict ourselves to pluriclosed manifolds,and confirm the conjecture for the special case of Strominger Kèahler-like manifolds,namely,for Hermitian manifolds whose Strominger connection(also known as Bismut connection)obeys all the Kaèhler symmetries.

关键词： Pluriclosed manifold Hermitian manifold Strominger connection holomorphic sectional curvature

Control System Development and Experimental Study on Ultrasonic Vibration Feeding

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2011年第6期24卷 1083-1088页

作者： ZENG Xianghui QI Lehua HUANG Hua LI yang yang fang School of Mechatronics Northwestern Polytechnical University Xi＇an 710072 China Key Laboratory of Modern Design and Integrated Manufacturing Technology of Ministry of Education Northwestern Polytechnical University Xi ＇an 710072 China

Ultrasonic vibration feeding（UVF） method which can quantitatively feed and precisely deposit fine powder is a potential technique for micro *** excitation sources transmit vibration to capillary though the third medium for most UVF *** vibrator is directly touched with the capillary can transmit mechanical energy on the capillary as much as possible,and the powder feeding can be controlled more ***,there are few reports about it.A direct UVF system which integrates the function of micro feeding,process observing,and powder forming was developed in this *** order to analyze the effect of the system factors on feeding,a group of L9（3^3） orthogonal experiments are selected to confirm the effect of level change of *** three factors are capillary nozzle diameter,amplitude and *** flow rate was stable for each combined factors,and the optimum combination for the minimum flow rate are choosing small capillary,small amplitude,and triangular wave *** whole process of feeding includes start point,middle stage and stop *** of feeding was synchronized to vibration when the amplitude of capillary nozzle is larger than critical ***,the feeding process enters the middle stage,the feeding state is observed by the CCD,and it is very stable in the middle *** of feeding can＇t be eliminated during the stop *** features of the deposited powder lines are analyzed; the overflow can be diminished by choosing small capillary and appropriate ratio of the capillary nozzle diameter to the particle *** characters lattices were deposited to validate the ability of quantitatively feeding and fixed feeding of *** of all powder dots show normal distribution,and more than 60% dots are concentrated from 550 μm to 650 μm,and the average diameter for all the dots is 597 μ*** dots positions are well approached to their scheduled positions,and the maximum deviation is 0.27 *** new direct

关键词： ultrasonic vibration feeding (UVF) capillary orthogonal experiment start/stop control quantitatively feeding fixed feeding

Parametric Narrow-Band InISAR 3D Imaging Based on Compressed Sensing

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2020年第3期29卷 508-514页

作者： WANG Baoping ZHANG Yan fang yang SONG Zuxun Science and Technology on UAV Laboratory Northwestern Polytechnical University School of Electronic and Information Northwestern Polytechnical University

For muti-scatter point target and undersampled data, tradintional imaging method has a poor precision for imaging result and spin angular *** view of the above problems, this paper proposes a narrow-band Interferometric inverse synthetic aperture radar(InISAR) 3-dimensional(3D) Compressed sensing imaging method based on the joint spin angle velocity error parameter estimation. First, a sparse model of narrow-band spin target is constructed. Then, the image entropy is used as the criterion function to search the optimal angle velocity by the joint reconstruction ***, the image of the target is obtained by interference processing. The simulation results show that compared with the traditional method, the estimation of spin angular velocity and the imaging result are more accurate in proposed method.

关键词： InISAR 3D imaging Narrow-band Spin angular velocity Compressed sensing Joint reconstruction iteration

Superparamagnetic iron oxide nanoparticles assembled magnetic nanobubbles and their application for neural stem cells labeling

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第4期63卷 124-132页

作者： Jing Li Zhenqiang Feng Ning Gu fang yang State Key Laboratory of Bioelectronics Jiangsu Key Laboratory for Biomaterials and DevicesSchool of Biological Sciences and Medical EngineeringSoutheast UniversityNanjing 210096China

Micro/nanobubbles for use as ultrasound contrast agents have been fabricated with different shell *** various biomedical nanoparticles have been embedded in the shells of bubbles,the composite structures have shown promising applications in multi-modal imaging,drug/gene delivery,and biomedical *** this study,we developed a new gas-liquid interface self-assembly method to prepare magnetic nanobubbles embedded with superparamagnetic iron oxide nanoparticles(SPIONs).The diameter of the generated assembled nanobubbles was 227.40±87.21 nm with a good polydispersity index(PDI)of *** the condition of 150 compression cycles,the nanobubble concentration could reach about 6.12×10^(9)/*** electron microscopy(TEM)and scanning electronic microscopy(SEM)demonstrated that the assembled nanobubbles had a hollow gas core with SPIONs adsorbed on the ***(US)imaging and magnetic resonance imaging(MRI)experiments indicated that the assembled magnetic nanobubbles exhibited good US and MR contrast ***,the assembled magnetic nanobubbles were used to label neural stem cells under ultrasound *** 40 s US exposure,the magnetic nanobubbles could be delivered into cells with 2.80 pg Fe per cell,which could be observed in the intracellular endosome by *** with common incubation methods,the ultrasound exposure method did not introduce the potential cytotoxicity of transfection reagents and the efficiency was about twice as high as the efficiency of ***,the assembled magnetic nanobubbles prepared through the pressure-driven gas-liquid interface assembly approach could be a potential US/MRI dual model imaging nanocarrier for regenerative applications.

关键词： magnetic shells bubble