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181.
给出了可数状态空间中时间随机环境下可逗留随机游动的一个统一模型,对于一维紧邻时间随机环境下的随机游动,在一定的条件下,讨论它的极限性质和中心极限定理,该结论类似于空间随机环境下的随机游动的有关结论. 相似文献
182.
183.
High voltage electron microscopy studies have been performed on irradiated pure silica and borosilicate glasses to check their long-term stability when these materials are employed near high energy radioactive sources, such as in fusion reactors and during the storage of nuclear waste. The intense energetic beam of electrons produced by the Harwell 1 MeV microscope, ranging from 1017 to 1020 e/cm2/s has been focused upon specimens of various composition and impurity content at different temperatures up to about 850°C. Pure silica samples have also been bombarded with 46.5 MeV Ni+6 ions at the Variable Energy Cyclotron. It is found that while no significant changes are detectable in pure irradiated silica, clear evidence is present in complex borosilicate glasses for the growing of large defect clusters (over 1000 Å, resembling gas bubbles) after electron doses of about 8.5 × 1019 e/cm2 and dose rates exceeding 2 × 1018 e/cm2/sec. Moreover, small regions, about 100 Å wide, scattering electrons more than the matrix are also present. The nature of this fine microstructure has been established as a phase separation into crystalline tridymite. The observations are discussed in terms of their dependence on temperature, sample thickness, dose and dose rates. 相似文献
184.
对一类五次平面多项式微分系统进行了定性分析.给出原点的中心与等时中心条件及极限环的存在性.研究了此系统无穷远点的性态,该无穷远点是高次奇点,并运用把大角域分为若干小角域的方法对此高次奇点在不定号情形下轨线的分布情况进行讨论. 相似文献
185.
《Journal of Nonlinear Mathematical Physics》2013,20(3):311-338
We indicate how one can extend any dynamical system (namely, any system of nonlinearly coupled autonomous ordinary differential equations) so that the extended dynamical system thereby obtained is either isochronous or asymptotically isochronous or multi-periodic, namely its generic solutions are either completely periodic with a fixed period or tend asymptotically, in the remote future, to such completely periodic functions or are multi-periodic (or become multi-periodic only asymptotically, in the remote future). In all cases the scale of the periodicity can be arbitrarily assigned. Moreover, the solutions of the extended systems are generally well approximated by those of the original, unmodified, systems, up to a constant rescaling of the independent variable (time), as long as their evolution is considered over time intervals short with respect to the (arbitrarily assigned) periodicities characterizing the extended systems. Several examples are displayed. In some cases the general solution of these dynamical systems is also exhibited; in others, this is impossible inasmuch as the models being manufactured are extensions of dynamical systems displaying chaotic evolutions, such as, for instance, the well-known Lorenz model of 3 nonlinearly coupled ODEs. 相似文献
186.
《Journal of Nonlinear Mathematical Physics》2013,20(1):111-120
A simple technique is identified to manufacture solvable nonlinear dynamical systems, and in particular three classes whose generic solutions are, respectively, isochronous, multi-periodic, or asymptotically isochronous. 相似文献
187.
Since the quality factor of an acoustic wave resonator (AWR) reached 1011, AWRs have been regarded as a good carrier of quantum information. In this paper, a scheme to construct a NOON state with two AWRs assisted by a nitrogen‐vacancy‐center ensemble (NVE) is proposed. The two AWRs cross each other vertically, and the NVE is located at the center of the crossing. By considering the decoherence of the system and using resonant interactions between the AWRs and the NVE, and the single‐qubit operation of the NVE, a NOON state can be achieved with a fidelity higher than 98.8% when the number of phonons in the AWR is . 相似文献
188.
189.
《International journal of quantum chemistry》2018,118(13)
One of the most serious candidates for safe storage of high hydrogen densities is ammonia borane, AB. Likewise, one of the most versatile catalysts known is gold in the form of atomic clusters. Taking these elements into account, in this work a density functional theory ‐based study about initial activation, detachment, and diffusion of ammonia borane hydrogen on gold tetramer, as a catalyst model, is developed. It was found that the total process is exergonic and that the hydrogen diffusion occurs with very low energy barriers. The process has a hydrogen detachment energy barrier lower than the one of the uncatalyzed AB, and that is easily overcome by the energy expelled in the previous stage of formation of the initial activated species. Additionally, all the process is assisted by the fluxionality of the gold cluster, and occurs via a unique catalytically activated initial species, which contains a three‐center simultaneous interaction at the catalytically activated zone. 相似文献
190.
Ján Jakubík 《Czechoslovak Mathematical Journal》2008,58(1):1-14
Freytes proved a theorem of Cantor-Bernstein type for algbras; he applied certain sequences of central elements of bounded
lattices. The aim of the present paper is to extend the mentioned result to the case when the lattices under consideration
need not be bounded; instead of sequences of central elements we deal with sequences of internal direct factors of lattices.
This work was supported by Science and Technology Assistance Agency under the contract No APVT-51-032002. 相似文献