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921.
This paper presents a new smooth memristor oscillator,
which is derived from Chua's oscillator by replacing Chua's diode
with a flux-controlled memristor and a negative conductance. Novel
parameters and initial conditions are dependent upon dynamical behaviours
such as transient chaos and stable chaos with an intermittence
period and are found in the smooth memristor oscillator. By using
dynamical analysis approaches including time series, phase portraits
and bifurcation diagrams, the dynamical behaviours of the proposed
memristor oscillator are effectively investigated in this paper. 相似文献
922.
An analytical solution for calculating the triaxial stress state around a cylindrical opening in an elastoplastic cohesive medium is developed. Magnitude of the slip zones around a cylindrical opening in crack-weakened rock masses is considered by modifying the existing strength criterion for rocks of different types. The disturbance coefficient, the geological strength index and the other strength parameters are also investigated. 相似文献
923.
The system associated with fluid particle motions of the stretch-twist-fold (STF) flow has displayed rich and attractive dynamic properties. Detailed research on the system has been done in this work. By using a high-dimensional generalization of the Melnikov method, the explicit parametric conditions for the existence of periodic solutions in the system can be determined. Then, by using the new-KAM-like theorems for perturbations of a three-dimensional generalized Hamiltonian system, the criteria for the existence of invariant tori in the STF flow have been obtained. In addition, one new first integral is found. On the basis of it, nonexistence of chaos in the system at α=0 is rigorously proved. Nonexistence of homoclinic orbits is also proved in the system if some conditions hold. And an interesting phenomenon is found, where the unit circle in the (y,z)-plane is filled with heteroclinic orbits of the system at α=0. The system with α=0 is also successfully reduced to a generalized Hamiltonian system, and further transformed to slowly varying oscillators. 相似文献
924.
925.
35MeV/u 40 Ar+197 Au反应中热核的碎裂密度 总被引:1,自引:0,他引:1
许多提取核反应过程中熵产生的方法只适用于高能核反应过程 ,而约化d的产额方法可以用于较低能量的重离子核反应中 .对于 3 5MeV/u40 Ar+ 197Au的核反应过程 ,利用这种方法所得的熵和约化带电粒子多重性提取的熵结果一致 .对于后角热核发射体系 ,实验提取的核温度为 ( 4.7± 1 .2 )MeV ,熵为S/A =2 .5± 0 .5,根据实验提取的熵和核温度可以确定其碎裂密度小于 0 .1 ρ0 相似文献
926.
Strong ultraviolet and violet photoluminescence from Si-based anodic porous alumina films 总被引:5,自引:0,他引:5
J.H. Wu X.L. Wu N. Tang Y.F. Mei X.M. Bao 《Applied Physics A: Materials Science & Processing》2001,72(6):735-737
We have investigated photoluminescence (PL) from Si-based anodic porous alumina films formed by real-time controlled anodization
of electron-beam evaporated Al films. As-anodized samples show three strong PL bands at 295, 340, and 395 nm. These bands
blueshift and their intensities decrease after the samples are annealed. When the annealing temperature increases to 1000 °C,
the blueshift becomes specially pronounced and meanwhile the structures of the films develop toward crystalline Al2O3. Based on discussions on the thermal annealing behaviors of the PL and PL excitation spectra, we suggest that optical transitions
in oxygen-related defects, F+ (oxygen vacancy with one electron) centers, are responsible for the observed ultraviolet and violet PL.
Received: 24 July 2000 / Accepted: 24 February 2001 / Published online: 3 May 2001 相似文献
927.
用相对论多组态 (HXR)方法 ,详细计算了类Ne氪离子 4d 2 p类Na 3l4l′双电子伴线波长和强度因子 ,并模拟了实验光谱 ,解释了最新利用激光气体靶产生的 0 .5 2 5~ 0 .5 5 5nm范围的氪X Ray光谱 ,计算结果与实验符合得相当好。此外 ,还讨论了组态相互作用对双电子伴线结构的影响。 相似文献
928.
929.
Fu Bao Xi 《数学学报(英文版)》2001,17(4):631-642
In this paper we consider a random evolution equation with small perturbations, and show how to construct coupled solutions
to the equations. As applications, we prove the Feller continuity of the solutions and the existence and uniqueness of invariant
measures. Furthermore, we establish a large deviations principle for the family of invariant measures as the perturbations
tend to zero.
Received March 20,1998, Accepted June 1, 2000 相似文献
930.