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25 September 2008, Volume 2008 Issue 5 Previous Issue    Next Issue

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Computational study on the non-Newtonian boundary-layer impact problem(Chinese) HOU Lei;CAI Li 2008, 2008 (5):  1-9.  Abstract ( 3578 )   PDF (3080KB) ( 572 )   Save Moving boundary-layer simulation in the crash safety analysis is one of the most important projects in mathematical modeling.The research on the theory and application for the complex non-Newtonian properties in various testing conditions have been interesting and difficult problems especially in the auto-crash safety engineering process.In this paper an application of boundary-layer computing for the non-Newtonian rate type impact hardening and shear thinning problems.The accurate mathematical prediction would supply ultimate research tool for the passive safety analysis in such scale.The posteriori estimate combined with HPC 2D/3D modeling technique would supply effective methods in the research. Related Articles | Metrics

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Exploration of boundary layer solutions in magnetic-current coupling problems (Chinese) HOU Lei;HAN Yue-hong;LI Jin-long 2008, 2008 (5):  10-16,5.  Abstract ( 3108 )   PDF (1310KB) ( 672 )   Save The MHD equations are complicated non-linear systems.This paper obtained equations which are linear in the complex space from MHD.The procedure of solving the equations needs the matching of the "external" solution and the "internal" solution.Central difference with the second R-K and central difference with the fourth order R-K not only improve the speed of analysis,but also assure the algorithm’s precision.The results are effective and robust.The paper analyzed the effects of the parameters Gand KI on the eigen-functionh of differential equations. Related Articles | Metrics

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Bivariate option pricing with GARCH-NIG model and dynamic copula(English) ZHANG Jing;DOMINIQUE Guégan;CHAI Jun 2008, 2008 (5):  17-26,4.  Abstract ( 3769 )   PDF (1444KB) ( 490 )   Save GARCH process was developed with the combination of dynamic copula for pricing bivariate contingent claims.Inorder to take into account the stylized factors in finance,such as skewness,leptokurtosis and fat tails,NIG distribution was fitted for residuals.Furthermore,the dynamic copula method was applied to describe the dependence structure between the underlying assets.The approach was illustrated with call-on-max option of Shanghai and Shenzhen Stock Composite Indices.The results showed the advantage of the suggested approach. Related Articles | Metrics

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Some theorems about the H-value rule(Chinese) LIANG Yi-kong;CHAI Jun 2008, 2008 (5):  27-34.  Abstract ( 5421 )   PDF (1240KB) ( 570 )   Save Further study was given in this paper to the H value as a standard for evaluation of the quality of a security set. The H value in terms of its related parameters was characterized. An inequality which the changed H value satisfies after removing the "worst" security from the set was proved. Related Articles | Metrics

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Nonnegative matrices decomposable into products of irreducible nonnegative matrices(English) WU Hong-lin 2008, 2008 (5):  35-44.  Abstract ( 3763 )   PDF (186KB) ( 454 )   Save This paper gave a necessary and sufficient condition for an n times n nonnegative matrix to be decomposed into a product of irreducible nonnegative matrices. It also showed that when such a decomposition is possible, the number of factors can be required to be at most three. The methods used here are constructive, and the factors can be presented. Related Articles | Metrics

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Bounds for eigenvalues of Hadamard product and Fan product of matrices (Chinese) DU Kun 2008, 2008 (5):  45-50.  Abstract ( 4362 )   PDF (216KB) ( 668 )   Save This paper found a new type upper bound of ρ(A。B) which was the spectral radius of the Hadamard product of two nonnegative matrices A and B by using Cauchy—Schwitz inequality and compared the new type upper bound with the classical results. In the same way, this paper found a new type lower bound of т(A★B),which was the minimum eigenvalue of the Fan product of two M--matrices A and B. Related Articles | Metrics

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Construct systems of orthogonal idempotents(Chinese) PAN Chang-yuan;CHEN Xue-ping;ZHANG Ying-shan 2008, 2008 (5):  51-58,6.  Abstract ( 3286 )   PDF (260KB) ( 495 )   Save An algorithm for constructing systems of orthogonal idempotents was expounded. By exhausting the symmetry partition and taking full advantage of simultaneous diagonalization to several matrices, we got some systems of orthogonal idempotents. The class idempotent function composing systems of orthogonal idempotents is one of the fundamental tools in constructing symmetry functions and it plays an important role in symmetry designs. Related Articles | Metrics

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Estimating and testing parameter for Buhlmann-Straub model(Chinese) TANG Guo-qiang; 2008, 2008 (5):  59-65.  Abstract ( 3671 )   PDF (291KB) ( 589 )   Save In this Paper, the parameters and random effect of Buhlmann-Straub credibility model were researched.Two-stage estimate was used to estimate the parameter and F-test was used to test the random effect.In two-stage estimate, used orthogonal transformation to estimate aggregate average and fitting constants method to estimate variance which was unbiased.Used regression sum of squares to get the F-test statistic in order to test the random effect, the power of the test is increasing function of the test variance. AT last, the methods were used in a example that get good result. Related Articles | Metrics

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Balanced generalized LS estimation of the regressive coefficient QIU Hong-bing;LUO Ji; 2008, 2008 (5):  66-71,1.  Abstract ( 3418 )   PDF (240KB) ( 463 )   Save Based on the idea of balanced loss function, a new measuring standard for the estimations of uperiorities was proposed for general linear models. Under the new standard, the balanced generalized LS estimation of the regressive coefficient was derived. The necessary and sufficient condition for its unbiasedness was discussed and its superiority over BLUE in terms of the mean square error matrix criterion was studied. Related Articles | Metrics

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Dirichlet problem of semi linear singular perturbation elliptic equations(Chinese) ZHU Zhen-bo;NI Ming-kang; 2008, 2008 (5):  72-77,8.  Abstract ( 3409 )   PDF (461KB) ( 401 )   Save Using transformation of coordinates of M.Vishik and L.Lyusternik, the method of boundary function was used to construct the uniformly valid asymptotic solutions of the Dirichlet problem of semi-linear singular perturbation elliptic equations.Under the uniformly valid asymptotic solutions obtained,the upper and lower solutions were constructed which satisfied the condition of Amann and guranteed the existence of the solution.Finally,the reminder estimation was made. Related Articles | Metrics

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Dependence of Hausdorff measure and dimension with the metric of the underlying space(Chinese) CHEN Hai-long;GUI Yong-xin 2008, 2008 (5):  78-83,1.  Abstract ( 3927 )   PDF (279KB) ( 482 )   Save This paper discussed the construction of metric space on the nested geometrical object. Given a nested geometrical object K in Rn and a continuous gauge function h(t), a new metric p was constructed on K such that 0<Hh (K)<+∞ in the new metric space (K, p). Particularly, if the gauge function is h(t)=ts, then for any positive finite number s, it's also possible to construct a new metric p on K such that ~$\mathscrHh (K)=1 and dimPK=dimBK=dimHK=s. Related Articles | Metrics

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MWNTs doped with bromine and surface modification by polystyrene(Chinese) TANG Guo-qiang;LIANG Dan;HAN Fei-fei;WANG Hong-min;JIN Sheng-song;XU Xue-cheng 2008, 2008 (5):  84-89.  Abstract ( 4046 )   PDF (452KB) ( 732 )   Save Bromine,as a dopant was adsorbed onto MWNTs to enhance the electrical conductivity of MWNTs. MWNTs were also modified by polystyrene. TEM and FESEM indicate that the modification of polystyrene improved the dispersion of Br-MWNTs in polymer matrix while the electrical conductivity of Br-MWNTs did not decrease. Related Articles | Metrics

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Magnetization property and magneto-impedance of dc Jouleannealed CuBe/insulator/NiCoP composite wire(Chinese) CHENG Jin-ke;;PAN Hai-lin;HE Jia-kang;YUAN Wang-zhi 2008, 2008 (5):  91-97.  Abstract ( 3374 )   PDF (652KB) ( 380 )   Save CuBe/insulator/NiCoP composite wire was produced by electroless-deposition and annealed using Joule annealing method with a dc current of 2 A for 2 min, in which the influence of current annealing on giant magneto-impedance (GMI) effect was investigated. The results showed that the GMI effect in the composite wire can be greatly enhanced by dc Joule annealing. The GMI ratio increases from 42.3% of as-deposited sample to 693.1%, about 15.4 times. The property of magnetization and the enhancement mechanism of GMI effect were analyzed in terms of complex permeability and equivalent circuit. Because the dc Joule annealing can release the internal stress and change the magnetic structure of specimen,Δμ′ and Δμ″of annealed composite wire is much greater than that of as-deposited, resulting in the enhancement of GMI effect. Related Articles | Metrics

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Giant magnetostrictive effect in Tb/Fe/Dy nano-multilayer filmsunder different deposition temperatures(Chinese) LI Xiao-dong;HUANG Su-mei;PAN Li-kun;CHEN Yi-wei;YANG Xie-long;SUN Zhuo 2008, 2008 (5):  98-103.  Abstract ( 3173 )   PDF (478KB) ( 427 )   Save Tb/Fe/Dy nano-multilayer films were deposited by multi-targets magnetron sputtering system at room temperature and substrate temperature of 300 ℃. The nano-multilayer films have large perpendicular anisotropy and high coercive force than the TbDyFe single layer film, and show giant magnetostrictive effect though they have perpendicular anisotropy. The nano-multilayer film deposited by substrate temperature of 300 ℃ has enhanced low field giant magnetostrictive effect because the nano-crystalline of TbDyFe with Laves phase structure segregates from the amorphous matrix. Related Articles | Metrics

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Influence of sputtering modes on the microstructure andmagnetic properties of NiFe/Cu composite wires(Chinese) JIANG Ling;RUAN Jian-zhong;ZHAO Qiang;WANG Qing-jiang;ZHAO Zhen-jie 2008, 2008 (5):  104-109.  Abstract ( 3417 )   PDF (547KB) ( 400 )   Save In this work, we adopted two sputtering modes to prepare the NiFe/Cu composite wires: (i) the intermittent deposition mode; and (ii) the continuous deposition mode. SEM images confirmed that the intermittent deposition mode leads to interface creation among deposited layers. XRD results showed that the intermittently deposited sample has a better crystallite and a grain growth. GMI effect has been used as a tool to analyze the magnetic properties of the samples. The results showed that the sputtered magnetic layers exhibit good soft magnetic properties, and the composite wires showed large GMI effect. The MI profile for the intermittently deposited composite wire shows two peaks, which can be a result of the different magnetic properties of the inner and the outer magnetic layers. The inherent stresses are partially relaxed through heat treatment. The GMI effect of the composite wire is enhanced, and the magnetic properties of the two magnetic layers become similar. Related Articles | Metrics

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Study of dinosaur fossils from Chuxiong area by synchrotronX-ray fluorescence microprobe imaging(Chinese) YANG Qun;WANG Yi- lin 2008, 2008 (5):  110-115.  Abstract ( 3980 )   PDF (616KB) ( 378 )   Save Four dinosaur fossils from three counties of Chuxiong area were tested with synchrotron x-ray fluorescence microprobe. The tests provide images of nine metal elements（Ca, Mn, Fe, Cu, Ta, Zn, Rb, Sr and Y） within each microarea of 2 mm×2 mm on the fossil sections. Particularly, the images of Ta and Rb were obtained for the first time for dinosaur fossils. The results show that metal elements are heterogeneously distributed at least in the test areas. In detail, the distribution of Cu is similar with that of Ta. However, Ca is enveloped by Y at some area of dinosaur fossils, The work demonstrats that synchrotron light source x-ray fluorescence microprobe is powerful and valuable for studing dinosaur fossils in geology and paleontology. Related Articles | Metrics

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Characteristics of main natural disasters and coping strategies in Shanghai(Chinese) CHEN Zhen-lou;WANG Jun;LIU Min;YU Li-zhong;XU Shi-yuang 2008, 2008 (5):  116-125.  Abstract ( 11440 )   PDF (786KB) ( 909 )   Save The paper pointed out that with global warming, sea level rising and the accelerated urbanization process, the intensity and frequency of natural disasters, and vulnerability of society and economy are growing quickly. Therefore, in order to seek effective disaster prevention and relief measures, natural disasters become hotspots for international society and academy. In Shanghai, one of the major big cities in eastern coastal areas of China, typhoons, rainstorms, storm surges and other natural disasters occur frequently, and often cause serious damages. The characteristics of these disasters are analyzed in detail. Facing the serious situation of risk mitigation and disaster prevention in Shanghai, several countermeasures should be adopted in order to improve Shanghai’s responding ability to natural disasters, which include taking strict precautions against serious natural disasters, developing disaster risk assessment methods and technologies, improving comprehensive disaster relief systems, establishing operational emergency plans, strengthening emergency shelters, relieve the disaster after-effects, promoting volunteer teams for emergency responses and rescues, carrying out disaster prevention publicity and disaster management personnel education. Related Articles | Metrics

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Marine hazards in Shanghai coastal regions and corresponding countermeasures: Lessons from the storm surge disaster of Burma (Chinese) GONG Mao-xun;DU Pan-jun;XUE Zhi-gang 2008, 2008 (5):  126-133.  Abstract ( 6635 )   PDF (2278KB) ( 598 )   Save The paper firstly reviewed the serious storm surge disaster in Myanmar in May of this year, pointing out that global warming, leading to extreme natural disasters. Then analyzed marine hazards in Shanghai coastal regions. Their causes were identified in detail. Gave a description of the existing service for early warning and emergency control of marine hazards in Shanghai. Finally detail suggestions were put forward for countermeasures for these hazards. Related Articles | Metrics

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Talk about the ice and snow calamity in South China and measures coping with severe weather disasters in Shanghai(Chinese) LI Yong-ping 2008, 2008 (5):  134-140.  Abstract ( 4082 )   PDF (575KB) ( 558 )   Save The Talk firstly gave a detailed description of the calamity caused by heavy ice, snow and frost in South China including Shanghai during early 2008. Their causes were analyzed.Problems and weakness in coping with the disaster by our society were pointed out. Secondly, main weather disasters in Shanghai areas were classified. Finally, some suggestions are proposed referring to how to improve long-term weather forecast, enhance cooperation between different institutes in our society , give publicity much knowledge on meteorology, etc. Related Articles | Metrics