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基于GARCH模型的石油价格变动模拟 总被引:1,自引:1,他引:0
石油是一种特殊的商品,是国家重要的战略物资,世界各国都十分重视其价格变动问题,因为油价变化会影响到各国经济发展,甚至国家安全。因此,本文采用GARCH模型,通过基于Gibbs抽样的MCMC方法分析了国际市场石油价格的分布特征,对石油价格波动的异方差特性进行描述和模拟,实证分析结果说明从石油价格波动序列峰度系数和平方价格波动序列自相关函数的描述来看,基于t分布的模型模拟效果优于基于正态分布的模型,这一结论反映了石油价格波动序列的分布特性。 相似文献
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Yu-hai WU~ 《中国科学A辑(英文版)》2007,50(7):925-940
This paper concerns the number and distributions of limit cycles in a Z_2-equivariant quintic planar vector field.25 limit cycles are found in this special planar polynomial system and four different configurations of these limit cycles are also given by using the methods of the bifurcation theory and the qualitative analysis of the differential equation.It can be concluded that H(5)≥25=5~2, where H(5)is the Hilbert number for quintic polynomial systems.The results obtained are useful to study the weakened 16th Hilbert problem. 相似文献
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钟摆系统是一类典型的分段光滑系统,结合Filippov系统刻画语言,解释了当钟摆无能量补充时,钟摆最终会停止在滑动集上的原因.利用数值模拟的方法,给出钟摆系统在有能量补充时,存在极限环的条件.最后,结合环域定理证明了一般的钟摆模型存在唯一稳定的极限环. 相似文献
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考察了阳极溶出伏安法测定ZSM-5催化剂中Cu2 和Ni2 的可行性。实验采用玻碳汞膜电极为工作电极的三电极系统,在pH=0.73的0.24 mol.L-1HCl底液中,Cu2 在-0.25 V(vs.SCE)附近有一个灵敏的一阶导数溶出峰,其峰高与Cu2 在0.01~0.325μg.mL-1范围内有较好的线性关系,检出限为0.004596μg.mL-1,相关系数为0.9991,回收率在98.00%~100.5%,精密度在2.27%~5.14%;在pH=9.41的0.06 mol.L-1NH4OH-NH4Cl底液中,Ni2 在-0.30 V(vs.SCE)附近有一个灵敏的一阶导数溶出峰,此峰高与Ni2 在0.5~5.5μg.mL-1范围内有较好的线性关系,检出限为0.4422μg.mL-1,相关系数为0.9996,回收率在98.12%~101.7%,精密度在3.64%~6.21%。常见干扰离子Fe3 、Zn2 、Cd2 、Ni2 、Al3 等对镍和铜的分析无影响。用本法对ZSM-5催化剂中Cu2 、Ni2 含量进行了测定,获得了满意的结果。 相似文献
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用单调有界定理证明了数列{Γ(n+1/2)/√nΓ(n/2)}+∞n=1的奇子列和偶子列极限的存在性,并给出了该数列的极限为1/√2.本文所得结果对帮助学生更好理解概率统计论中t分布密度函数的极限函数的证明有一定指导作用. 相似文献
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运用分支函数的方法研究了Logistic映射出现稳定三周期点的参数窗口,借助软件Singular 2.0.3运用多元多项式的Grobner基并结合严格局部分析的方法给出Logistic映射出现稳定三周期点时的参数值范围,最后数值模拟方法对所得的结果进行了验证,并指出伪轨现象. 相似文献
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ASYMMETRY PARAMETERS AND DIFFERENTIAL CROSS SECTIONS FOR PHOTOIONIZATION-EXCITATION OF HELIUM 下载免费PDF全文
Asymmetry parameter β2 for photoionization of helium leaving the He+ ion in the n=2 level and differential cross sections(DCSs) in the n=2,3,4 levels with photon emission angle θ=900 are provided at photon energies 69-76.8 eV employing the R-matrix method with a 20-term target representation, in which five polarization orbitals \bar{6}l are included. The asymmetry parameter β2 and the DCS, in the n=2 level in the region of 69-73 eV, are in good agreement with available experimental and theoretical results. Above the n=3 threshold, we present new theoretical results along with measurements. No theoretical and experimental results can be used to compare with the present calculations of the DCSs for photoionization into the He+ ion in the n=3,4 levels. 相似文献
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Electron scattering from argon in a laser field is investigated empolying the second-order perturbation theory. The absolute differential cross sections of e-Ar scattering with multiphoton exchange in special scattering geometries G1 (for small-angle scattering) and G2 are calculated. Our results are found to be better than other theoretical results as compared with the experimental data. 相似文献