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971.
电磁场中空间思维的构建 总被引:1,自引:0,他引:1
利用电子线路实验实现了用变量脉冲扰动法控制离散混沌 .该方法只用单一输出信号作为反馈信号 ,每隔一定的脉冲间隔将其加到系统的某些变量中去 ,适当调节脉冲间隔和反馈系数 ,可得到多个稳定的周期轨道 .该方法不仅适用于一维和二维离散系统 ,也适用于三维或更高维的离散系统 . 相似文献
972.
Determination of power-time curves of Staphylococcus aureus growth and study of promoter action of a ginseng 总被引:1,自引:0,他引:1
Yu Xiufang Zhang Honglin Li Zhiping Hang Hu Lu Maosun Yuan Jiurong 《Journal of Thermal Analysis and Calorimetry》1997,50(3):499-503
The powervs. time curves ofStaphylococcus aureus were determined by using a 2277 Thermal Activity Monitor (Sweden). By means of a new model of microorganism growth, the growth rate constants at different concentrations of ginseng and the minimum concentration were calculated from these curves. 相似文献
973.
Jeong Won Kang Ki Ryang Byun Ju Yul Lee Sun Cheol Kong Young Wan Choi Ho Jung Hwang 《Physica E: Low-dimensional Systems and Nanostructures》2004,24(3-4):349-354
We investigated potassium ion transport in the (5, 5) carbon nanotube by using classical molecular dynamics simulations under applying external force fields. This can be applied to nanoscale ionic-field-effect devices. As the applying external force field increases, the potassium ions rapidly go through the nanochannel. Under the low external force fields, the thermal fluctuation of the nanochannel affected on the tunneling of the potassium ions, whereas the effects of the thermal fluctuation were negligible under the high external force fields. 相似文献
974.
Radiation damage of highly oriented pyrolitic graphite (HOPG) samples have been investigated following irradiation with 215 MeV Ne and 209 MeV Kr ions, available at U-400 cyclotron, Dubna. A freshly cleaved HOPG surface was irradiated perpendicularly to the sample surface (c plane). A low ion irradiation dose was used (1012 ions/cm2) in order to avoid damage overlap. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are useful methods allowing direct observation of surface defects. The observations were made after irradiation without any further sample preparation. The experimental results are compared to computer simulations (TRIM code) and primary knonked-on atomic spectrum calculations (LET code). Clear distinction can be made between surface features attributed to nuclear stopping effects and defects owing to electronic stopping mechanisms. 相似文献
975.
Calculation of interband magneto-optical transition linewidth in Ge by combined projection technique
Youn Ju Lee Yong Jai Cho Chang Ho Choi Jung Young Sug Sang Don Choi 《Zeitschrift für Physik B Condensed Matter》1995,97(1):55-58
Using a combined projection technique, we calculate the line-shape function for the magneto-optical direct interband transition in an electron-phonon system. From the plot of the absorption power vs the frequency of the electro-magnetic wave, we obtain the linewidth in Ge at 300 K, where only the deformation potential phonon scattering is taken into account. The obtained value (1.7 meV) is compared with the experimental value (2.0 meV) of Burstein et al. [11]. 相似文献
976.
Wang Yi Chen Zhiping Zhang Kecun Department of Scientific Computing Applied Softwares Faculty of Science Xi''''an Jiaotong University Xi''''an China. 《高校应用数学学报(英文版)》2006,(4)
In order to study the effect of different risk measures on the efficient portfolios (frontier) while properly describing the characteristic of return distributions in the stock market, it is assumed in this paper that the joint return distribution of risky assets obeys the multivari-ate t-distribution. Under the mean-risk analysis framework, the interrelationship of efficient portfolios (frontier) based on risk measures such as variance, value at risk (VaR), and expected shortfall (ES) is analyzed and compared. It is proved that, when there is no riskless asset in the market, the efficient frontier under VaR or ES is a subset of the mean-variance (MV) efficient frontier, and the efficient portfolios under VaR or ES are also MV efficient; when there exists a riskless asset in the market, a portfolio is MV efficient if and only if it is a VaR or ES efficient portfolio. The obtained results generalize relevant conclusions about investment theory, and can better guide investors to make their investment decision. 相似文献
977.
A method was devised to determine the isomeric composition of an ionic mixture using collisionally activated decomposition mass spectrometry. Compared with the more rigorous approach based on collision cross-sections reported previously, the main advantage of the proposed method is its experimental simplicity. Both the internal consistency and the accuracy of the method were tested for mixtures of isobaric ions, i.e. ions with the same nominal mass-to-charge ratios. 相似文献
978.
979.
980.
The molecular structure of [Zn(O2CC6H4NO2‐p)2(pyridine)2] exhibits a distorted N2O2 tetrahedral geometry around the zinc atom owing to the presence of monodentate p‐nitrobenzoate ligands; the molecule has twofold symmetry. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献