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101.
102.
This paper deals with the chemotaxis-growth system: , , in a smooth bounded domain with zero-flux boundary conditions, where μ, δ, and τ are given positive parameters. It is shown that the solution exponentially stabilizes to the constant stationary solution in the norm of as provided that and any given nonnegative and suitably smooth initial data fulfills , which extends the condition in [8]. 相似文献
103.
This paper proposes a new Zernike modal gray map
reconstruction algorithm used in the nematic liquid crystal adaptive
optics system. Firstly, the new modal algorithm is described. Secondly,
a single loop correction experiment was conducted, and it showed
that the modal method has a higher precision in gray map
reconstruction than the widely used slope method. Finally, the
contrast close-loop correction experiment was conducted to correct
static aberration in the laboratory. The experimental results showed
that the average peak to valley (PV) and root mean square (RMS) of
the wavefront corrected by mode method were reduced from
2.501\lambda (\lambda =633~nm) and 0.610\lambda to
0.0334\lambda and 0.00845\lambda , respectively. The corrected
PV and RMS were much smaller than those of 0.173\lambda and
0.048\lambda by slope method. The Strehl ratio and modulation
transfer function of the system corrected by mode method were much
closer to diffraction limit than with slope method. These results
indicate that the mode method can take good advantage of the large
number of pixels of the liquid crystal corrector to realize high
correction precision. 相似文献
104.
With the popularity of the just-in-time system, more and more companies are operating with little or no inventories, which make them highly vulnerable to delays on supply. This paper discusses a situation when the supply of the commodity does not arrive at the depot on time, so that not enough of the commodity is available to be loaded on all vehicles at the start of the delivery period. New routing plans need to be developed in such a case to reduce the impact the delay of supply may have on the distribution company. The resulting vehicle routing problem is different from other types of vehicle routing problems as it involves waiting and multiple trips. Two approaches have been developed to solve the order release delay problem, both of which involve a Tabu Search algorithm. Computational results show the proposed approaches can largely reduce the disruption costs that are caused by the delayed supply and they are especially effective when the length of delay is long. 相似文献
105.
106.
G. Mušic D. Matko B. Zupancic 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(2):169-189
Modelling, synthesis, and simulation issues of the supervisory systems in process control are investigated in the paper. Petri nets are used as a basic modelling framework for the supervisory part of the system. It is shown how the final verification effort can be minimised by applying formal synthesis methods. A straightforward approach to the industrial implementation of the developed solutions is suggested by means of sequential function chart representation. A batch process cell case study is used to illustrate the described concepts. Corresponding continuous and discrete event models of the process cell units are developed and a co-ordinating supervisor is designed by the method of place invariants. The system is simulated by the continuous simulation tool Matlab-Simulink, which is enhanced for simulation of the sequential control logic represented by sequential function chart. 相似文献
107.
Ab initio lattice dynamics and piezoelectric properties of MgS and MgSe alkaline earth chalcogenides
S.?Saib N.?Bouarissa P.?Rodríguez-Hernández A.?Mu?oz 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(2):185-193
We have studied structural, elastic, dielectric, vibrational, and piezoelectric properties of rock-salt and zinc-blende Mg
alkaline earth chalcogenides (MgS, and MgSe) by using the plane-wave pseudopotential method within the local density approximation.
The calculated lattice constant, bulk modulus, and elastic constants for these compounds are found to be in good agreement
with experiment. The density functional perturbation theory has been employed to derive the Born effective charge and high-frequency
dielectric constant and to calculate phonon dispersion curves and density of states. The piezoelectric constant has also been
determined. The calculated results are compared with theory and experiment when available and showed reasonable agreement.
In other cases, our results are predictions. The pressure dependence of the studied quantities has been examined and discussed.
The pressure coefficients and mode Grüneisen parameters are determined. 相似文献
108.
A Muñoz ME McConney T Kosa P Luchette L Sukhomlinova TJ White TJ Bunning B Taheri 《Optics letters》2012,37(14):2904-2906
Despite numerous efforts, continuous wave (CW) lasing in dye doped, one-dimensional (1D) photonic bandgap cholesteric liquid crystal (CLC) structures has not been previously reported, to our knowledge. Here we report on the observation of lasing in such structures under both coherent (laser) and incoherent (LED) CW light excitation. To achieve this effect, we used a 1D-photonic bandgap structure made of a polymer stabilized CLC with a pitch gradient across the cell thickness. A spectral reflectivity profile of such a CLC structure reveals local minima in the area within a photonic stopband and close to it. The realization of lasing pumped by low power CW light sources opens the possibility of all-organic, compact, tunable CW lasers for display and medical applications. 相似文献
109.
内爆速度的测量是惯性约束聚变研究中的核心问题, 是判断聚变点火反应的关键物理量. 在神光II激光装置上, 利用KB显微镜配合时间分辨为10 ps的条纹相机, 对1600 J激光能量注入, 3倍频, 脉宽为1 ns黑腔辐射驱动CH靶球, 获得了清晰的辐射驱动内爆流线轨迹X射线图像. 通过流线轨迹图像给出了最大内爆速度为160 km/s. 利用Multi1D程序对内爆压缩流线和壳层速度变化进行了模拟, 实验数据和理论模拟较符合. 相似文献
110.
Freddy Muñoz Paulina Valenzuela William Gacitúa 《Applied Physics A: Materials Science & Processing》2012,108(4):1007-1014
In this study, Eucalyptus nitens species was nano-characterized to determine variability in nanomechanical properties within the cellular ultra-structure between the bark and wood fibers. Three factors, including site (2 levels), family (2 levels) and fiber type (bark and wood) were analyzed using three response variables, including the elastic modulus (E), hardness (H) and ductility ratio (E/H) in the middle lamella (ML) and the cell wall within the S2 layer. The results indicated significant differences for E S2 and H S2 when comparing fiber types: E S2≈12.52 GPa and H S2≈0.31 GPa for wood fiber and E S2≈10.81 GPa and H S2≈0.26 GPa for bark fiber. There is not statistically significant difference in ductility ratio (E/H) in S2 and ML between fiber types. These results indicate that bark and wood fibers can be used together or separately in the development of new composite materials and engineering products. 相似文献