检索结果-南通市图书馆

A Solver for Helmholtz System Generated by the Discretization of Wave Shape Functions

在线全文

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2013年第6期5卷 791-808页

作者： long yuan Qiya Hu Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China LSEC Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

An interesting discretization method for Helmholtz equations was introduced in ***[1].This method is based on the ultra weak variational formulation(UWVF)and the wave shape functions,which are exact solutions of the governing Helmholtz *** this paper we are concerned with fast solver for the system generated by the method in[1].We propose a new preconditioner for such system,which can be viewed as a combination between a coarse solver and the block diagonal preconditioner introduced in[13].In our numerical experiments,this preconditioner is applied to solve both two-dimensional and three-dimensional Helmholtz equations,and the numerical results illustrate that the new preconditioner is much more efficient than the original block diagonal preconditioner.

关键词： Helmholtz equation ultra weak variational formulation wave shape functions preconditioner iteration counts

Preliminary study on qualitative and quantitative detection of norfloxacin based on terahertz spectroscopy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2017年第5期10卷 262-268页

作者： long yuan Li Bin Beijing Research Center for Information Technology in Agriculture Beijing 100097China Key Laboratory of Agri-informatics Ministry of AgricultureBeijing 100097China Beijing Key Laboratory of Digital Plant Beijing 100097China

Norfloxacin is a kind of quinolone bactericide which is widely used in food industry,livestock feed and medicine *** present,how to develop a rapid,convenient and accurate technique for qualitative and quantitative detection of norfloxacin is still a *** this study,Terahertz Time-domain Spectroscopy technology(THz-TDS)was used to explore qualitative and quantitative analysis of ***-five norfloxacin samples with different levels were *** pure norfloxacin powder was mixed with polyethylene(PE)powder together and made into tablets by tablet-making *** minimum detection concentration was 10%and the maximum detection concentration evaluated in the paper was 90%.Then,terahertz(THz)spectra of each sample were measured on K15 THz-TDS *** multiple linear regressions and the partial least squares regression algorithms were used to establish a model to make quantitative *** the results,two typical fingerprint peaks of norfloxacin in terahertz band were observed at 0.944 THz and 1.206 THz,and the correlation coefficient and the root mean square error of the established model reached 0.9908 and 0.0481,respectively,which showed that the model performed well for the *** preliminary study indicates that THz spectroscopy has great potential for future screening applications to detect the presence of norfloxacin residues in food,livestock feed and medicine industries.

关键词： Terahertz spectroscopy norfloxacin qualitative and quantitative detection model correlation coefficient

Some Results on Space-Like Self-Shrinkers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2016年第1期32卷 69-82页

作者： Hua Qiao LIU yuan long XIN School of Mathematics and Information Sciences He'nan University Institute of Mathematics Fudan University

We study space-like self-shrinkers of dimension n in pseudo-Euclidean space Rm^m＋n with index m. We derive drift Laplacian of the basic geometric quantities and obtain their volume estimates in pseudo-distance function. Finally, we prove rigidity results under minor growth conditions in terms of the mean curvature or the image of Gauss maps.

关键词： Space-like self-shrinker pseudo-distance volume growth rigidity

Free torsion of thin-walled structural members of open-and closed-sections

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2014年第1期35卷 25-32页

作者： long-yuan LI D.EASTERBROOK School of Marine Science and Engineering University of Plymouth

Free torsion of thin-walled structures of open- and closed-sections is a classical elastic mechanics problem, which, in literature, is often solved by the method of membrane analogy. The method of membrane analogy, however, can be only applied to structures of a single material. If the structure consists of both open- and closed-sections, the method of membrane analogy is difficult to be applied. In this paper, a new method is presented for solving the free torsion of thin-walled structures of open- and/or closed- sections with multiple materials. By utilizing a simple statically indeterminate concept, torsional equations are derived based on the equilibrium and compatibility conditions. The method presented here not only is very simple and easy to understand but also can be applied to thin-walled structures of combined open- and closed-sections with multiple materials.

关键词： torsion thin-walled open-section closed-section shear flow shear stress

Hybrid rice achievements, development and prospect in China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2015年第2期14卷 197-205页

作者： MA Guo-hui yuan long-ping China National Hybrid Rice Research and Development Centre

This article reviews the history and progress of hybrid rice development. Hybrid rice research was initiated back in 1964, and commercialized in 1976. Three-line and two-line system hybrid rice were developed in 1974 and 1995, respectively. Research on super hybrid rice, which was first launched by Ministry of Agriculture, China in 1996, is discussed, and the great progress of super hybrid rice had been achieved with a new yield record by 15.4 t ha^-1 in the 6.84 ha demonstration location in Xupu, Hunan Province, China in 2014. And the mechanism of heterosis, the techniques of hybrid seed production and the modern field managements in hybrid rice over the past decades are also discussed. Additionally, this article dealt with the intellectual property protection（IPR） and development of hybrid rice seed industry in China. Major factors that constrain hybrid rice development are analyzed and possible solutions to this problems are proposed. Finally, the authors present methods to further increase production yield, and propose an improvement for breeding super high-yielding hybrid rice based on these methods.

关键词： hybrid rice research & development achievement & progress constraint super high yield breeding

Erosion and Corrosion of Mild Steel and Stainless Steel in Sodium Carbonate/Bicarbonate Solution Bearing Alumina Particle

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2004年第4期11卷 52-55页

作者： yuan Qing-long LIANG Hong-da Taiyuan University of Technology

With a rotating cylinder electrode apparatus,the polarization behaviors of the mild steel and the stainless steel 0Cr18Ni9 in NaHCO3(0.5M)+Na2CO3(0.5M)solution with and without erodent particles were investigated and *** results show that the rotation speed of cylinder hardly affects the polarization behavior of sample in solution without particles but exerts a great influence on that with *** rotation speed,the free corrosion potential shifts to positive direction and the oxygen limiting current density *** the mild steel and stainless steel 0Cr18Ni9 experience a significant increase of the mass loss by increasing erosion,and erosive wear was dominated by severe *** insufficient mechanical strength of both materials leads to a low resistance to particle *** peripheral velocities of the rotating cylinder enhances the corrosion rate of the mild *** stainless steel 0Cr18Ni9,due to a high erosive wear,also suffers from similar erosion-corrosion damage,despite that its corrosion resistance is much higher than that of the mild steel.

关键词： steel erosion corrosion polarization behavior rotation speed

Maser Emission of Relativistic Electrons Spiralling and Drifting in Curved Magnetic Fields

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2007年第2期7卷 304-316页

作者： Jiong Liu Ye-Fei yuan Xiao-long Deng Center for Astrophysics University of Science and Technology of China Hefei 230026

Synchro-curvature radiation describes the emission from a relativistic charged particle which is moving and spiralling in a curved magnetic field. We investigate the maser emission for synchro-curvature radiation including drift of the guiding center of the radiating electron. It is shown that under some conditions the absorption coefficient can be negative, so maser can happen. These conditions are different from those needed for maser emission of curvature radiation including drift of the charged particles. We point out that our results, including the emissivity, can reduce to these of curvature radiation. Previously it was found that synchro-curvature radiation can not generate maser in vacuum, but we argue that synchrocurvature radiation including drift can generate maser even in vacuum. We discuss the possibilities of the potential applications of the synchro-curvature maser in modeling gamma ray bursts and pulsars.

关键词： masers - plasmas - radiation mechanisms non-thermal

Improved Energy Conversion Efficiency of ZnO/Polythiophene Solar Cell in Ga-Doped ZnO Nanorod Array Photoanode

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2016年第6期32卷 979-984页

作者： WU Jie LIU Huanhuan yuan long HOU Changmin State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China

We reported the fabrication and doping effect of Ga-doped ZnO nanorods/electropolymerized polythio-phene（e-PT） hybrid photovoltaic（h-PV） devices. Ga-Doped ZnO nanorod array photoanode devices were fabricatedvia hydrothermally growing nanorods on sol-gel spin-coating ZnO seed layer, and then the nanorod array was im-mersed into a thiophene solution to yield a thin polythiophene film by electrochemically polymerization. Afterwards,a thin layer of A1 was deposited on the surface of polythiophene to make an electrode for photovoltaic *** ZnO nanorods with different Ga-doping contents were characterized by means of X-ray diffraction（XRD）, scan-ning electron micrograph（SEM） and X-ray photoelectron spectroscopy（XPS）. Photovoltaic J-V characterization wasperformed on the e-PT/ZnO bilayer and bulk heterojunction（BHJ） devices. Though the unsubstituted polythiophene isnot an ideal polymer material for solar cells with high power conversion efficiency, it is a sound model for the studyon the effect of dopant in hybrid materials. The results indicate that doping Ga can substantially improve the powerconversion efficiency of the ZnO-polythiophene solar cell.

关键词： Solar cell Energy conversion Ga-Doped ZnO

Nd3-xAExFe5O12： Hydrothermal Synthesis, Structure and Magnetic Properties

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2017年第6期33卷 869-875页

作者： WU Jie yuan long WANG Shan HOU Changmin State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China Department of Materials Science and Engineering Jilin Institute of Chemical Technology Jilin 132022 P. R. China

Rare-earth ferrite garnet is one of the most important materials applied in microwave transducer and in- frared magneto-optical devices, etc. Nd3-xAExFe5O12（AE=Ca, Sr） crystals, which have cubic structure with the space group ofIa-3 d and lattice constants over 1.26 nm, were prepared via the mild hydrothermal method. The structural, morhpology and magnetic properties were characterized by means of powder X-ray diffraction, scanning electronic microscopy, as well as vibrating sample magnetometer and M6ssbauer spectroscopy, respectively. M6ssbaner spectroscopy demonstrates the coexistence of Sr2＋, Ca2＋ and Nd3＋ at the C sites of the dodecahedrons for different substituted garnets. The crystal shape is dodecahedron, and the particle sizes are decreased with increasing the Ca and Sr doping concentrations. By recording the magnetic hysteresis loops and M-T curves at different temperatures, it can be seen that with the increasing x, the saturation magnetization values decrease while the coercive forces increase under the condition of high temperatures.

关键词： Garnet structure Magnetic property M6ssbauer spectrum