检索结果-南通市图书馆

THE ASYMPTOTIC FORMULA FOR F2（x）

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science in china,Ser.A 1987年第3期 262-278页

作者：陆鸣皋 department of mathematics university of Science and technology of china Hefei

Let G（n） denote the number of nonisomorphic groups of order n and Fk（x） denote the number of n≤x for which G（n）=k. It is shown in this paper that F-2（x）=e（-γ）x/（log3x）2+O（x（log4x）2）/（log3x）3), whe... 详细信息

关键词： THE ASYMPTOTIC FORMULA FOR F2

Mixed symmetry states and isospin excitation in N = Z nucleus ^(52)Fe

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2008年第12期51卷 1845-1852页

作者： ZHANG JinFu↑, Lü LiJun, BAI HongBo & LIANG MingZhi department of Physics, Chifeng university, Chifeng 024001, china department of Physics Chifeng University Chifeng China

The interacting boson model with isospin (IBM-3) was applied to study the band structure and electromagnetic transition properties of the low-lying states in the even-even N = Z nucleus 52Fe. The isospin excitation states with T = 0, 1 and 2 were identified, and compared with the available data. The study shows that the 2+3 state is the lowest mixed symmetry state in 52Fe. The excitation energy of the second 0+2 state with T = 0 in nucleus 52Fe was identified. The model calculations with the data show a reasonably good agreement.

关键词： energy level isospin mixed symmetry states electromagnetic transitions

Experimental Study on Non-proportional Multiaxial Strain Cyclic Characteristics and Ratcheting of U71Mn Rail Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & technology 2002年第1期18卷 13-16页

作者： Guozheng KANG, Qing GAO, Lixun CAI, Yafang SUN and Xianjie YANGdepartment of applied Mechanics and Engineering, Southwest Jiaotong university, Chengdu 610031, china [ Manuscript received December 4, 2000, in revised form February 20, 2001] Dept. of Appl. Mech. and Eng. Southwest Jiaotong Univ. Chengdu 610031 China

An experimental study was carried out on the strain cyclic characteristics and ratcheting of U71Mn rail steel subjected to non-proportional multiaxial cyclic loading. The strain cyclic characteristics were researched under the strain-controlled circular load path. The ratcheting was investigated for the stress-controlled multiaxial circular, elliptical and rhombic load paths with different mean stresses, stress amplitudes and their histories. The experiment shows that U71Mn rail steel features the cyclic non-hardening/softening, and its strain cyclic characteristics depend greatly on the strain amplitude but slightly on its history. However, the ratcheting of U71Mn rail steel depends greatly not only on the values of mean stress and stress amplitude, but also on their histories. In the meantime, the shape of load path and its history also apparently influence the ratcheting. The ratcheting changes with the different loading paths.

关键词： U71 Mn steel Ratcheting Cyclic plasticity Non-proportional load

A study of different fluid droplets impacting on a liquid film

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2008年第1期5卷 62-66页

作者： Huang Qiyu Zhang Holden Petroleum Engineering department The University of Tulsa Tulsa OK 74104 USA Beijing Key Laboratory of Urban Oil and Gas Distribution technology China University of Petroleum Beijing 102249China

Knowledge of droplet dynamics provides the basis of predicting pressure drops, holdups and corrosion inhibitor distribution in multiphase flow. Droplet size and its distribution also determine the separation efficiency between different phases. Experimental observations were conducted for droplet impingements with different fluids, droplet sizes and velocities, and film thicknesses. The observed transition boundaries were compared with the models developed by different authors. For impingement on a deep pool surface, the Marengo and Tropea correlation for splashing does not agree with the experimental results in this study. The Bai and Gosman critical Weber number for bouncing agrees with the water results but not the oil results. Three new correlations for transition boundaries between bouncing, coalescence, jetting and splashing were proposed and compared with the experimental observations.

关键词： Droplet liquid film transition boundary high-speed video

Synthesis and Structure of trans-1,2-Bisaromatic Heterocycle Substituted Cyclopropanes

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 1989年第1期5卷 50-60页

作者： Wang Changsheng, Pan Jiaxing and Gao Zhenheng (department of Chemistry, Nankai university, tianjin) Yao Xinkan, Wang Ruji and Wang Honggen (Central Laboratory, Nankai university, tianjin)

Trans-1,2-bis(2 ' -(5 ' -phenyl-1 ' , 3 ' , 4 '-oxadiazolyl ) ) cyclopropane (BDCP) and its eleven substituted novel derivatives were synthesized. Besides four derivatives of l,2-bis(2'-(5'-phenyl-l ' , 3 ' , 4 ' -ox-adiazo1yl))ethane (BPDS) were also synthesized as model compounds. The crystal structure of ethyl BDCP was determined and the cyclopropane ring was found to be able to transmit conjugation between the aromatic groups directly bonding with it by studying the ultraviolet and fluorescent spectra of the above compounds.

关键词： Cyclopropane ethane 1,3,4-oxadiazole UV and FL spectra conjugation

A symmetric geometric measure and the dynamics of quantum discord

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第4期22卷 94-102页

作者：蒋峰建吕海江闫新虎石名俊 department of Modern Physics University of Science and Technology of China School of Information Engineering Huangshan University

A symmetric measure of quantum correlation based on the Hilbert–Schmidt distance is presented in this paper. For two-qubit states, we considerably simplify the optimization procedure so that numerical evaluation can be performed efficiently. Analytical expressions for the quantum correlation are attained for some special states. We further investigate the dynamics of quantum correlation of the system qubits in the presence of independent dissipative environments. Several nontrivial aspects are demonstrated. We find that the quantum correlation can increase even if the system state is suffering from dissipative noise. Sudden changes occur, even twice, in the time evolution of quantum correlation. There exists a certain correspondence between the evolution of quantum correlation in the systems and that in the environments, and the quantum correlation in the systems will be transferred into the environments completely and asymptotically.

关键词： quantum correlation geometric measure

Studying　the　Mode－Spectra　Characteristics　of　An　Above－Threshold　Biased　Semiconductor　Laser

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1994年第1期B3卷 11-16页

作者： XIA Guangqiong WU Zhengmao CHEN Jianguo LU Yucun(Optoelectronics department, Sichuan university,Chengdu 610064, china) Sichuan Univ Chengdu China

ＳｔｕｄｙｉｎｇｔｈｅＭｏｄｅ－ＳｐｅｃｔｒａＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＡｎＡｂｏｖｅ－ＴｈｒｅｓｈｏｌｄＢｉａｓｅｄＳｅｍｉｃｏｎｄｕｃｔｏｒＬａｓｅｒ￥ＸＩＡＧｕａｎｇｑｉｏｎｇ；ＷＵＺｈｅｎｇｍａｏ；Ｃ... 详细信息

ＳｔｕｄｙｉｎｇｔｈｅＭｏｄｅ－ＳｐｅｃｔｒａＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＡｎＡｂｏｖｅ－ＴｈｒｅｓｈｏｌｄＢｉａｓｅｄＳｅｍｉｃｏｎｄｕｃｔｏｒＬａｓｅｒ￥ＸＩＡＧｕａｎｇｑｉｏｎｇ；ＷＵＺｈｅｎｇｍａｏ；ＣＨＥＮＪｉａｎｇｕｏ；ＬＵＹｕｃｕ...

关键词： semiconductor laser ray trace method mode suppression ratio carrier density

Intelligent direct analysis of physical and mechanical parameters of tunnel surrounding rock based on adaptive immunity algorithm and BP neural network

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 Pharmaceutical Analysis 2009年第1期21卷 22-30页

作者： Xiao-rui Wang1,2, Yuan-han Wang1, Xiao-feng Jia31.School of Civil Engineering and Mechanics,Huazhong university of Science and technology, Wuhan 430074,china 2.department of Civil Engineering,Nanyang Institute of technology,Nanyang 473004,china 3.department of Chemistry and Bioengineering,Nanyang Institute of technology,Nanyang 473004,china. School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China department of Civil Engineering Nanyang Institute of Technology Nanyang 473004 China department of Chemistry and Bioengineering Nanyang Institute of Technology Nanyang 473004 China

Because of complexity and non-predictability of the tunnel surrounding rock, the problem with the determination of the physical and mechanical parameters of the surrounding rock has become a main obstacle to theoretical research and numerical analysis in tunnel engineering. During design, it is a frequent practice, therefore, to give recommended values by analog based on experience. It is a key point in current research to make use of the displacement back analytic method to comparatively accurately determine the parameters of the surrounding rock whereas artificial intelligence possesses an exceptionally strong capability of identifying, expressing and coping with such complex non-linear relationships. The parameters can be verified by searching the optimal network structure, using back analysis on measured data to search optimal parameters and performing direct computation of the obtained results. In the current paper, the direct analysis is performed with the biological emulation system and the software of Fast Lagrangian Analysis of Continua (FLAC3D. The high non-linearity, network reasoning and coupling ability of the neural network are employed. The output vector required of the training of the neural network is obtained with the numerical analysis software. And the overall space search is conducted by employing the Adaptive Immunity Algorithm. As a result, we are able to avoid the shortcoming that multiple parameters and optimized parameters are easy to fall into a local extremum. At the same time, the computing speed and efficiency are increased as well. Further, in the paper satisfactory conclusions are arrived at through the intelligent direct-back analysis on the monitored and measured data at the Erdaoya tunneling project. The results show that the physical and mechanical parameters obtained by the intelligent direct-back analysis proposed in the current paper have effectively improved the recommended values in the original prospecting data. This is of p

关键词： adaptive immunity algorithm BP neural network physical and mechanical parameters surrounding rock direct-back analysis

Coumarin-glycoside and Ferulate from Peucedanum decursivum

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2000年第4期11卷 315-318页

作者： Ling Yi KONG Nian Huan YAO (department of Natural Medicinal Chemistry, china Pharmaceutical university. Nanjing 210038) Dept. of Natural Medicinal Chemistry China Pharmaceutical University Nanjing 210038 China

Two new compounds named decuroside VI(1) and decursidate (2) were isolated from the roots of Peucedanum decursivum - a traditional Chinese medicine. Their structures were elucidated on the basis of chemical evidence a... 详细信息

关键词： Peucedanum decursivum decuroside VI decursidate