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排序方式: 共有69条查询结果,搜索用时 234 毫秒
41.
42.
Lijun Pan Jinde Cao 《Communications in Nonlinear Science & Numerical Simulation》2012,17(3):1332-1343
In this paper, we consider the stochastic quasi-synchronization for the delayed networks with parameter mismatches and stochastic perturbation mismatch by using intermittent control. Based on Lyapunov stability theory, inequality techniques and the properties of Weiner process, several sufficient conditions are obtained to ensure stochastic quasi-synchronization for delayed networks. Meanwhile, numerical simulations are offered to show the effectiveness of our new results. 相似文献
43.
Željko D. Čupić Ljiljana Z. Kolar‐Anić Slobodan R. Anić Stevan R. Maćešić Jelena P. Maksimović Marko S. Pavlović Maja C. Milenković Itana Nuša M. Bubanja Emanuela Greco Stanley D. Furrow Rinaldo Cervellati 《Helvetica chimica acta》2014,97(3):321-333
The intermittency or intermittent bursting as the type of dynamic state when two qualitatively different behaviors replace one another randomly during the course of the reaction, although all the control parameters remain constant, is found in the Briggs? Rauscher oscillating system moderated by a very small amount of phenol. Within a range of phenol concentrations, the oscillation amplitude is diminished considerably, and after oscillations cease, they repeat intermittently, giving several bursts of oscillations. For the concentrations used here, the range of phenol concentrations where intermittent bursting oscillations occur in a closed reactor is ca. 1.8×10?5 to 3.6×10?5 M . Bursting also occurs in an open reactor and can be sustained indefinitely at 5.53×10?5 M concentration. The intermittent bursting behavior is robust, and can be achieved at a variety of conditions. 相似文献
44.
Spare parts are known to be associated with intermittent demand patterns and such patterns cause considerable problems with regards to forecasting and stock control due to their compound nature that renders the normality assumption invalid. Compound distributions have been used to model intermittent demand patterns; there is however a lack of theoretical analysis and little relevant empirical evidence in support of these distributions. In this paper, we conduct a detailed empirical investigation on the goodness of fit of various compound Poisson distributions and we develop a distribution-based demand classification scheme the validity of which is also assessed in empirical terms. Our empirical investigation provides evidence in support of certain demand distributions and the work described in this paper should facilitate the task of selecting such distributions in a real world spare parts inventory context. An extensive discussion on parameter estimation related difficulties in this area is also provided. 相似文献
45.
微波灰化-氢化物发生原子荧光光谱法测定植物油中微量铅 总被引:6,自引:0,他引:6
孙建刚 《光谱学与光谱分析》2003,23(4):793-796
采用微波灰化技术处理样品 ,运用断续流动 氢化物发生原子荧光光谱法测定植物油中的铅 ,探讨了微波灰化条件对铅测定的影响 ;研究了载流和样品酸度、还原剂浓度、基体改进剂以及载流流速对氢化物发生的影响。铅的线性范围为 1 0 0~ 2 0 0 μg·L-1,最低检出限为 0 31μg·L-1,相对标准偏差为 1 84 % ,回收率为 89 2 %~ 97 3%。 相似文献
46.
Aiko Miyamura Ideta Gouhei Tanaka Takumi Takeuchi Kazuyuki Aihara 《Journal of Nonlinear Science》2008,18(6):593-614
For several decades, androgen suppression has been the principal modality for treatment of advanced prostate cancer. Although
the androgen deprivation is initially effective, most patients experience a relapse within several years due to the proliferation
of so-called androgen-independent tumor cells. Bruchovsky et al. suggested in animal models that intermittent androgen suppression
(IAS) can prolong the time to relapse when compared with continuous androgen suppression (CAS). Therefore, IAS has been expected
to enhance clinical efficacy in conjunction with reduction in adverse effects and improvement in quality of life of patients
during off-treatment periods. This paper presents a mathematical model that describes the growth of a prostate tumor under
IAS therapy based on monitoring of the serum prostate-specific antigen (PSA). By treating the cancer tumor as a mixed assembly
of androgen-dependent and androgen-independent cells, we investigate the difference between CAS and IAS with respect to factors
affecting an androgen-independent relapse. Numerical and bifurcation analyses show how the tumor growth and the relapse time
are influenced by the net growth rate of the androgen-independent cells, a protocol of the IAS therapy, and the mutation rate
from androgen-dependent cells to androgen-independent ones.
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47.
48.
Randi Moe 《国际流体数值方法杂志》1993,16(11):967-988
In this paper a new type of transient multidimensional two-fluid model has been applied to simulate intermittent or slug flow problems. Three different approaches to modelling interfacial friction, including an interfacial tracking scheme, have been investigated. The numerial method is based on an implicit finite difference scheme, solved directly in two steps applying a separate equation for the pressure. 2D predictions of Taylor bubble propagation in horizontal and inclined channels have been compared with experimental data and analytical solutions. The 2D model has also been applied to investigate a number of special phenomena in slug flow, including slug initiation, bubble turning in downflow and the bubble centring process at large liquid flow rates. 相似文献
49.
The forces acting on the substrate in intermittent-contact-mode (IC mode, tapping mode) atomic force microscopy are not accessible to a direct measurement. For an estimation of these forces, a simple analytical model is developed by considering only the shift of the cantilever resonance frequency caused by Hertzian (contact) forces. Based on the relationship between frequency shift and tip–sample force for large-amplitude frequency-modulation atomic force microscopy, amplitude and phase versus distance curves are calculated for the intermittent contact mode, and the forces on the substrate are calculated. The results show a qualitative agreement with numerical calculations, yielding typical maximal forces of 50–150 nN. When working above the unperturbed resonance, forces are found to be significantly larger than below the resonance. 相似文献
50.
Daniela Acetti Christian Langel Elisabetta Brenna Claudio Fuganti Marco Mazzotti 《Journal of chromatography. A》2010,1217(17):2840-2846
The pharmaceutically relevant compound (RS,RS)-2-(2,4-difluorophenyl)butane-1,2,3-triol, an important intermediate in the production of different antifungal drugs, is synthesized in racemic form. For further use in the laboratory the compound has to be separated into its pure enantiomers. This work describes the different steps required to set up a chiral separation using intermittent simulated moving bed chromatography (I-SMB). Furthermore, the effect of feed concentration on the choice of the operating conditions is presented in the frame of the triangle theory. The experiments are carried out at increasing total feed concentration ranging from 3 to 15 g/L. The results demonstrate that a successful I-SMB separation could be carried out thus separating 4.5 g of the racemic mixture and fulfilling the specified purity specification of 98% for both enantiomers. 相似文献