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991.
An-Wei Li 《Nonlinear dynamics》2011,66(4):689-694
In this paper, we investigated the influence of color noise on pattern formation in a predator–prey model. When the model
has no noise, it exhibits wave dynamics. A series of numerical simulations showed that break-up of waves will emerge when
noise is added. Furthermore, stationary pattern can be induced by noise. The obtained results may point out that noise can
have great effect on spatial complexity of ecosystems. 相似文献
992.
We provide an affirmative answer to the C
r
-Closing Lemma, r ≥ 2, for a large class of flows defined on every closed surface. 相似文献
993.
Electrohydrodyamic (EHD) heat transfer enhancement and flow control methods are becoming increasingly popular in engineering
science and applications both in terrestrial and low gravity applications. The correct choice of the working fluid is essential
for the design and performance of EHD hardware and can pose challenge because some working fluids with favorable EHD properties
can be unstable or hazardous. In this paper key properties and criteria for the selection of working fluids for single-phase
(liquid) as well as gas–liquid and vapor–liquid two-phase electrohydrodynamic experiments and applications are discussed.
Key physical and electrical properties as well as environmental and safety issues are reviewed for the sample fluids PF-5052,
FC-72, R141b, cyclohexane and pure water. Microgravity experiments impose additional demands on the selection of the working
fluids. Some of these demands are addressed by contrasting bubble dimensions and shapes at detachment, estimated using a simple
thermodynamic model, in terrestrial and microgravity conditions with and without electric fields. Data are obtained using
a simplified analytical model and verified experimentally. 相似文献
994.
This study reveals that Fourier transform infrared is an effective analytical tool in probing the extent of hydrolysis of
cerium and gadolinium acetylacetonates dissolved in methanol. It is found that these acetylacetonates have relatively fast
hydrolysis rates at the early stage of hydrolysis (<6 h). However, their hydrolysis rates become very slow beyond 6-h of hydrolysis
and decrease to near zero after 55-h of hydrolysis. As a result, hydrolysis cannot be completed even after 170 h at room temperature.
These phenomena suggest that the first and second acetylacetone ligands chelated to Ce3+ and Gd3+ ions can actually be hydrolyzed with relative ease at room temperature, similar to alkoxide ligands. It is the last acetylacetone
ligand that is very difficult to be hydrolyzed. 相似文献
995.
996.
997.
This paper studies the control for synchronization of a four-dimensional system via a single variable, and a linear feedback
controller and an adaptive controller are proposed. Based on the Lyapunov stability theory, the correctness of the proposed
methods is strictly demonstrated. The numerical simulations further show their effectiveness. 相似文献
998.
Konrad Eichhorn Colombo Vladislav V. Kharton Alexandre P. Viskup Andrei V. Kovalevsky Aliaksandr L. Shaula Olav Bolland 《Journal of Solid State Electrochemistry》2011,15(2):329-347
A gas turbine power plant for CO2 capture, based on oxygen-permeable membranes with mixed ionic-electronic conductivity, was analysed with respect to long-term
stability by means of numerical simulation. Due to the attractive transport and physicochemical properties of mixed-conducting
La2NiO4+δ, this nickelate was selected as a prototype membrane material for this application. Experiments showed very slow degradation
of La2NiO4+δ membranes at oxygen chemical potentials close to atmospheric conditions, which are associated with kinetic demixing and other
microstructure-related factors. Interaction with CO2 in the intermediate temperature range also leads to lower oxygen permeation, whilst increasing oxygen pressure may cause
partial phase decomposition and microstructural changes, thus again limiting the range of possible operation conditions. The
relevant operational constraints were included in a detailed membrane-based gas turbine power plant model. The membrane performance
degradation with time was approximated by a linear function with average rate of 3.3% per 1,000 operation hours. Furthermore,
performance deterioration of the gas turbine compressor and turbine were also considered. Simulations revealed that the power
plant is substantially affected by degradation of the ceramic membranes and turbomachinery components. The already rather
small operating window was further narrowed when compared with a conventional gas turbine power plant. Two different designs
of the membrane-based power plant were analysed: (1) with and (2) without additional combustors (afterburners) between the
membrane reactor and the gas turbine. Afterburners increase thermal efficiency as well as power output, but also lead to non-negligible
CO2 emissions. In order to have a frame of comparison, results for a conventional gas turbine power plant with degradation of
turbomachinery components are also presented. Simulations representing changes in ambient temperature and fuel composition
as well as failure incidents were executed to analyse the susceptibility of the gas turbine power plant to external and internal
changes. 相似文献
999.
1000.
Mereology is the logic of part—whole concepts as they are used in many different contexts. The old chemical metaphysics of
atoms and molecules seems to fit classical mereology very well. However, when functional attributes are added to part specifications
and quantum mechanical considerations are also added, the rules of classical mereology are breached in chemical discourses.
A set theoretical alternative mereology is also found wanting. Molecular orbital theory requires a metaphysics of affordances
that also stands outside classical mereology. 相似文献