A stochastic averaging method for predicting the response of quasi partially integrable and non-resonant Hamiltoniansystems to fractional Gaussian noise （fGla） with the Hurst index 1/2〈H〈l is proposed. The average...A stochastic averaging method for predicting the response of quasi partially integrable and non-resonant Hamiltoniansystems to fractional Gaussian noise （fGla） with the Hurst index 1/2〈H〈l is proposed. The averaged stochastic differential equa-tions （SDEs） for the first integrals of the associated Hamiltonian system are derived. The dimension of averaged SDEs is less thanthat of the original system. The stationary probability density and statistics of the original system are obtained approximately fromsolving the averaged SDEs numerically. Two systems are worked out to illustrate the proposed stochastic averaging method. It isshown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of originalsystem agree well, and the computational time for the former results is less than that for the latter ones.展开更多
目的制备具有不同官能团(-CH3、-COOH、-OH、两性基团)的聚对苯二甲酸丁二醇酯(PBT)平板膜,并了解其对血浆蛋白吸附情况与对白细胞、血小板的黏附效果。方法利用紫外改性的方法,将不同单体接枝到PBT表面,得到PBT-AA(-COOH)、PBT-HEMA(-...目的制备具有不同官能团(-CH3、-COOH、-OH、两性基团)的聚对苯二甲酸丁二醇酯(PBT)平板膜,并了解其对血浆蛋白吸附情况与对白细胞、血小板的黏附效果。方法利用紫外改性的方法,将不同单体接枝到PBT表面,得到PBT-AA(-COOH)、PBT-HEMA(-OH)、PBT-SMDB(两性基团)并进行表征。采用ELISA测定吸附的人血清白蛋白(HSA)、纤维蛋白原(Fgn)含量,扫描电镜(SEM)观察黏附白细胞、血小板数量。结果 HSA吸附量(μg/cm2),PBT、PBT-AA分别为:15.05±4.51vs 35.61±6.91(P<0.01);Fgn吸附量(μg/cm2),PBT、PBT-HEMA、PBT-SMDB分别为:19.85±1.93 vs 14.93±4.05 vs 17.04±2.10(P<0.05)。4种材料在吸附HSA、Fgn前后,黏附的WBC、Plt均发生明显变化(P<0.01)。结论 Fgn对2种血小板和白细胞的黏附均有促进作用,而HSA对白细胞的黏附有一定抑制性。通过四种材料的比较发现,PBT-AA滤除白细胞及保留血小板的效果更好。展开更多
This paper presents a new type of base isolation system, i. e. , slide-limited friction (S-LF) base isolation system . Based on this system, the harmonic and subharmonic periodic response of S-LF subjected to harmonic...This paper presents a new type of base isolation system, i. e. , slide-limited friction (S-LF) base isolation system . Based on this system, the harmonic and subharmonic periodic response of S-LF subjected to harmonic motions is investigated by using Fourier-Galerkin-Newton (FGN) method with Flo-quet theory. The dynamic response of S-LF subjected to earthquake ground motions is calculated with a high order precision direct integration method, and the numerical results are presented in maximum acceleration response spectra of superstructure and maximum sliding displacement response spectrum form. The comparison of isolating effects of S-LF, pure-friction base isolation system (P-F) and resilient-friction base isolation system (R-FBI) shows that the isolating property of S-LF is superior to those of P-F and R-FBI. Finally, by analyzing an engineering example, it is observed that the distribution of the maximum shear between floors and absolute acceleration of S-LF to earthquake ground motion is very different from that of traditional structures.展开更多
Modeling of network traffic is a fundamental building block of computer science. Measurements of network traffic demonstrate that self-similarity is one of the basic properties of the network traffic possess at large ...Modeling of network traffic is a fundamental building block of computer science. Measurements of network traffic demonstrate that self-similarity is one of the basic properties of the network traffic possess at large time-scale. This paper investigates the change of non-stationary self-similarity of network traffic over time,and proposes a method of combining the discrete wavelet transform (DWT) and Schwarz information criterion (SIC) to detect change points of self-similarity in network traffic. The traffic is segmented into pieces around changing points with homogenous characteristics for the Hurst parameter,named local Hurst parameter,and then each piece of network traffic is modeled using fractional Gaussian noise (FGN) model with the local Hurst parameter. The presented experimental performance on data set from the Internet Traffic Archive (ITA) demonstrates that the method is more accurate in describing the non-stationary self-similarity of network traffic.展开更多
The self similarity of the network traffic has great influences on the performance. But there are few analytical or even numerical solutions for such a model. So simulation becomes the most efficient method for resear...The self similarity of the network traffic has great influences on the performance. But there are few analytical or even numerical solutions for such a model. So simulation becomes the most efficient method for research. Fractal Gaussian noise (FGN) is the most popularly used self similar model. This paper presented an FGN generator based on fast Fourier transform (FFT). The study indicates that this algorithm is fairly fast and accurate.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11172259,11272279,11321202,and 11432012)
文摘A stochastic averaging method for predicting the response of quasi partially integrable and non-resonant Hamiltoniansystems to fractional Gaussian noise （fGla） with the Hurst index 1/2〈H〈l is proposed. The averaged stochastic differential equa-tions （SDEs） for the first integrals of the associated Hamiltonian system are derived. The dimension of averaged SDEs is less thanthat of the original system. The stationary probability density and statistics of the original system are obtained approximately fromsolving the averaged SDEs numerically. Two systems are worked out to illustrate the proposed stochastic averaging method. It isshown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of originalsystem agree well, and the computational time for the former results is less than that for the latter ones.
文摘目的制备具有不同官能团(-CH3、-COOH、-OH、两性基团)的聚对苯二甲酸丁二醇酯(PBT)平板膜,并了解其对血浆蛋白吸附情况与对白细胞、血小板的黏附效果。方法利用紫外改性的方法,将不同单体接枝到PBT表面,得到PBT-AA(-COOH)、PBT-HEMA(-OH)、PBT-SMDB(两性基团)并进行表征。采用ELISA测定吸附的人血清白蛋白(HSA)、纤维蛋白原(Fgn)含量,扫描电镜(SEM)观察黏附白细胞、血小板数量。结果 HSA吸附量(μg/cm2),PBT、PBT-AA分别为:15.05±4.51vs 35.61±6.91(P<0.01);Fgn吸附量(μg/cm2),PBT、PBT-HEMA、PBT-SMDB分别为:19.85±1.93 vs 14.93±4.05 vs 17.04±2.10(P<0.05)。4种材料在吸附HSA、Fgn前后,黏附的WBC、Plt均发生明显变化(P<0.01)。结论 Fgn对2种血小板和白细胞的黏附均有促进作用,而HSA对白细胞的黏附有一定抑制性。通过四种材料的比较发现,PBT-AA滤除白细胞及保留血小板的效果更好。
文摘This paper presents a new type of base isolation system, i. e. , slide-limited friction (S-LF) base isolation system . Based on this system, the harmonic and subharmonic periodic response of S-LF subjected to harmonic motions is investigated by using Fourier-Galerkin-Newton (FGN) method with Flo-quet theory. The dynamic response of S-LF subjected to earthquake ground motions is calculated with a high order precision direct integration method, and the numerical results are presented in maximum acceleration response spectra of superstructure and maximum sliding displacement response spectrum form. The comparison of isolating effects of S-LF, pure-friction base isolation system (P-F) and resilient-friction base isolation system (R-FBI) shows that the isolating property of S-LF is superior to those of P-F and R-FBI. Finally, by analyzing an engineering example, it is observed that the distribution of the maximum shear between floors and absolute acceleration of S-LF to earthquake ground motion is very different from that of traditional structures.
基金the National High Technology Research and Development Program (863) of China(Nos. 2005AA145110 and 2006AA01Z436)the Natural Science Foundation of Shanghai of China(No. 05ZR14083)the Pudong New Area Technology Innovation Public Service Platform of China(No. PDPT2005-04)
文摘Modeling of network traffic is a fundamental building block of computer science. Measurements of network traffic demonstrate that self-similarity is one of the basic properties of the network traffic possess at large time-scale. This paper investigates the change of non-stationary self-similarity of network traffic over time,and proposes a method of combining the discrete wavelet transform (DWT) and Schwarz information criterion (SIC) to detect change points of self-similarity in network traffic. The traffic is segmented into pieces around changing points with homogenous characteristics for the Hurst parameter,named local Hurst parameter,and then each piece of network traffic is modeled using fractional Gaussian noise (FGN) model with the local Hurst parameter. The presented experimental performance on data set from the Internet Traffic Archive (ITA) demonstrates that the method is more accurate in describing the non-stationary self-similarity of network traffic.
文摘The self similarity of the network traffic has great influences on the performance. But there are few analytical or even numerical solutions for such a model. So simulation becomes the most efficient method for research. Fractal Gaussian noise (FGN) is the most popularly used self similar model. This paper presented an FGN generator based on fast Fourier transform (FFT). The study indicates that this algorithm is fairly fast and accurate.
