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991.
In this paper, poly(ethylene terephthalate-co-isophthalate) was prepared and a series of PETI/SiO2 nanocomposites with different amounts of silica nanoparticles was synthesized by in situ polymerization. Optical properties of the resultant nanocomposites were investigated by WGW photoelectric haze meter and UV–Vis-NIR spectrophotometer. Chemical structure and its influence on spherulite size of nano-SiO2 were characterized by Fourier transformed infrared spectra and polarized optical microscopy, respectively. The differential scanning calorimetry results reveal that the addition of nano-SiO2 has an impact on the thermal performance of the nanocomposite. Different proportions of SiO2 were compared and the degree of crystallinity was found to have influence on optical properties of as-prepared nanocomposites. In addition, the results indicate that the low loading levels of SiO2 can improve the optical properties of the composite and an optimum content was selected. Possible reasons for this enhanced role might be the different combination structure of the nanocomposites when the amount of SiO2 varied. 相似文献
992.
993.
Haoxiang Jie Yizhong Wu Jianjun Zhao Jianwan Ding Liangliang 《Journal of Global Optimization》2017,67(1-2):399-423
The huge computational overhead is the main challenge in the application of community based optimization methods, such as multi-objective particle swarm optimization and multi-objective genetic algorithm, to deal with the multi-objective optimization involving costly simulations. This paper proposes a Kriging metamodel assisted multi-objective particle swarm optimization method to solve this kind of expensively black-box multi-objective optimization problems. On the basis of crowding distance based multi-objective particle swarm optimization algorithm, the new proposed method constructs Kriging metamodel for each expensive objective function adaptively, and then the non-dominated solutions of the metamodels are utilized to guide the update of particle population. To reduce the computational cost, the generalized expected improvements of each particle predicted by metamodels are presented to determine which particles need to perform actual function evaluations. The suggested method is tested on 12 benchmark functions and compared with the original crowding distance based multi-objective particle swarm optimization algorithm and non-dominated sorting genetic algorithm-II algorithm. The test results show that the application of Kriging metamodel improves the search ability and reduces the number of evaluations. Additionally, the new proposed method is applied to the optimal design of a cycloid gear pump and achieves desirable results. 相似文献
994.
Yong-Hong Lan Liang-Liang Wang Cai-Xue Chen Ding Lei 《Journal of Optimization Theory and Applications》2017,174(1):197-209
This paper presents an optimal sliding mode output tracking control scheme for a class of fractional-order uncertain systems. Firstly, an augmented fractional-order system, composed of the original system and the external system, is constructed to transform the optimal output tracking issue into the design problem of linear quadratic regulator. The optimal tracking control problem for the nominal augmented fractional-order system is then studied. Secondly, the fractional-integral sliding mode controller is introduced to robustify the augmented fractional-order system, which satisfy the matching conditions. As a result, the original system output can track the external system output trajectory effectively even the uncertainties exist. Finally, the developed design techniques are applied to the tracking control of fractional-order permanent magnet synchronous motor. The simulation results demonstrate the validity of this approach. 相似文献
995.
Chunxiao Ding Yun Sun Yuanguo Zhu 《Mathematical Methods in the Applied Sciences》2017,40(14):5079-5094
A new mathematical model included an exposed compartment is established in consideration of incubation period of schistosoma in human body. The basic reproduction number is calculated to illustrate the threshold of disease outbreak. The existence of the disease free equilibrium and the endemic equilibrium are proved. Studies about stability behaviors of the model are exploited. Moreover, control measure assessments are investigated in order to seek out effective control interventions for anti‐schistosomiasis. Then, the corresponding optimal control problem according to the model is presented and solved. Theoretical analyses and numerical simulations induce several prevention and control strategies for anti‐schistosomiasis. At last, a discussion is provided about our results and further work. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
996.
利用分子动力学计算机模拟方法研究了稠密流体中双原子分子的振动弛豫问题,证实了双原产分子的振动弛豫速率随着其非谐性的增大而加快,同时,其速率也随其质量因子的变大而加速。 相似文献
997.
弥散型核燃料元件热应力的计算模拟 总被引:2,自引:0,他引:2
针对弥散型燃料板的具体形状,选择了一种能够反映其实际变形特征的三维代表性体积单元作为研究对象;利用有限元法对其热力耦合行为进行了弹塑性分析,研究了热应力在燃料和基体中的分布特征. 相似文献
998.
GENERAL SOLUTION OF PLANE PROBLEM OF PIEZOELECTRIC MEDIA EXPRESSED BY "HARMONIC FUNCTIONS 总被引:4,自引:0,他引:4
I.IntroductionBecauseofthecouplingcharacteristicbetweenthemechanicaldeformationandthee1ectricaleffect,piezoelectricmaterialshavebeenwidelyusedintransducersandsmartstructures.Moreandmoreattentionshavebeenpaidonsuchmaterials,andgreatadvanceshavebeenmadeinva… 相似文献
999.
Energy relaxation processes initiated by sudden heating of the vibrational degree of freedom were studied with molecular dynamical
method. A unit cell of bee structure containing 128 diatomic molecules with periodic boundary conditions was considered. Compound
Morse potential was assumed as the atom-atom interactions. It was found that the logarithra of the equilibration time depends
linearly upon a factorf
21 which is proportional to the frequency ratio of the intra- and inter-molecular vibrations.
The project is supported by the National Natural Science Foundation of China. 相似文献
1000.
用三维光弹法测定了轴表面横向半椭圆裂纹的应力强度因子,并分析计算了应力强度因子修正系数,结果表明,应力强度因子的分布型式对加载条件和裂纹几何不敏感;修正系数对裂纹深度呈现对称分布趋势,仅取决于裂纹几何参数。 相似文献