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941.
A simple, inexpensive and one-step synthesis method of metal-containing carbon nanocapsules using an arc discharge in aqueous solution is reported. It was found that Ni, Co and Fe nanoparticles could be in situ encapsulated in carbon shells when the arc was performed respectively in aqueous solutions of NiSO4, CoSO4 and FeSO4. Transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction patterns of selected areas were used to determine the crystalline phase of the metal cores. To explain the formation mechanism of metal-containing carbon nanocapsules, a model of discharge in solution is proposed. This result presents a simply controllable way to synthesize metal-containing carbon nanocapsules. 相似文献
942.
Jun Yang Jianbao Li Hong Lin Xiaozhan Yang Xuguang Tong Gangfeng Guo 《Journal of Applied Electrochemistry》2006,36(8):945-950
In this paper, we describe the preparation of a porous nanosheet-stacked NiCo2O4 composite electrode using a novel electrophoretic deposition (EPD) calcination method. The effects of the deposition time and voltage, and of the calcination temperature have been investigated. The microstructure of the deposited films in the electrodes before and after calcination has also been investigated. The electrocatalytic properties of the electrodes have been investigated using cyclic voltammetry and polarization curves. The electrode films produced using this new technique have a porous structure composed of stacked hexagonal NiCo2O4 nanosheets. The resulting electrodes exhibit good electrocatalytic properties for water electrolysis. 相似文献
943.
944.
Jun-Hai Lv Mei Zhang Min Guo Wen-Chao Li Xi-Dong Wang 《International Journal of Applied Ceramic Technology》2007,4(6):571-577
NaNbO3 , KNbO3 , and K x Na(1− x ) NbO3 powders were successfully prepared by the hydrothermal method. The phase of the products was identified to be orthorhombic structure by X-ray diffraction (XRD) technique, and the XRD results revealed that the x value of the K x Na(1− x ) NbO3 gradually increased with the increase in the ratio of K+ to Na+ in alkaline solution. The morphology and the microstructure were investigated by scanning electron microscopy, energy-dispersive spectroscopy, and transmission electron microscopy, and the results indicated that the ratio of K+ to Na+ in the solution had a great effect on the morphology and the size of products. Na0.5 K0.5 NbO3 with morphotropic phase boundary composition could be synthesized when the molar ratio of K+ to Na+ was between 4:1 and 6:1 in the solution. A possible formation mechanism of the K x Na(1− x ) NbO3 crystal was also proposed based on the experimental results. 相似文献
945.
2D-to-3D conversion that would be a solution of the lack of 3D contents has been a worthy and challenging research field. In this paper, we propose a computer interactive conversion method to capture components which is used to generate 3D sequences. First, we divide the key frame into foreground and background, and then label the objects by convenient computer interactive operation. Depth information of objects is labeled after segmentation. Second, we use object tracking technique which synthesizes the advantages of kernel-based mean shift tracker and contour tracker to accomplish object depth capture for non-key frame. Finally, all the 3D information is prepared to render 3D sequences. After all, we propose our future work direction: a 2D-to-3D system which can generate 3D sequence interactively. 相似文献
946.
947.
Marwa A. Abd El-Fattah Moawad I. Dessouky Alaa M. Abbas Salaheldin M. Diab El-Sayed M. El-Rabaie Waleed Al-Nuaimy Saleh A. Alshebeili Fathi E. Abd El-samie 《International Journal of Speech Technology》2014,17(1):53-64
This paper proposes an adaptive Wiener filtering method for speech enhancement. This method depends on the adaptation of the filter transfer function from sample to sample based on the speech signal statistics; the local mean and the local variance. It is implemented in the time domain rather than in the frequency domain to accommodate for the time-varying nature of the speech signals. The proposed method is compared to the traditional frequency-domain Wiener filtering, spectral subtraction and wavelet denoising methods using different speech quality metrics. The simulation results reveal the superiority of the proposed Wiener filtering method in the case of Additive White Gaussian Noise (AWGN) as well as colored noise. 相似文献
948.
949.
Jie Sheng Wang Shuang Han Qiu Ping Guo 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2014,18(3):457-468
Conversion rate in the Polyvinylchloride (PVC) polymerizing process has a certain influence on the molecular weight of PVC, porosity, absorption rate of plasticizer, vinyl chloride monomer (VCM) residue and thermal stability. Therefore, a predictive model based on echo state networks (ESN) method optimized by the artificial fish swarm algorithm (AFSA) is proposed to predict the conversion velocity. Firstly, the hot balancing mechanisms of polymerizer and the influenced factors of convention rate of VCM are analyzed in details. Then the auxiliary variables of the predictive model kernel are selected by using the kernel principal component analysis method for reducing the model dimensionality. Thirdly, the structure parameters of the ESN are optimized by the AFSA to realize the nonlinear mapping between input and output variables of the discussed soft-sensor model. The artificial fish swarm behaviors, such as foraging, swarming, chasing, random, are introduced in details. Finally, simulation results show that the proposed model can significantly enhance the predictive accuracy and robustness of the technical index and satisfy the real-time control requirements of PVC polymerizing production process. 相似文献
950.
Ming-Cheng Guo Marie-Claude Heuzey Pierre J. Carreau 《Polymer Engineering and Science》2007,47(7):1070-1081
The cell structure and properties of branched and linear polypropylene (PP) foams containing organically modified nanoclay and maleic anhydride grafted polypropylene (PPMA) have been thoroughly investigated. X-ray diffraction (XRD) and melt rheometry were used to identify the structure and linear viscoelastic properties of the nanocomposites, as well as the effectiveness of two different compatibilizers. These nanocomposites were used in injection molding to investigate their foamability and the influence of experimental conditions such as chemical foaming agent concentration, shot size, back pressure, injection speed, as well as melt temperature and different injection methods on the resulting cell structure of the foams. Quite different results were obtained with the linear and the branched PP. While the foamability of the branched PP was intrinsically good, that of the linear one could largely be improved by modifying its rheological properties and favoring nucleation through the addition of nanoclay. The effect of cell structure on the dynamic mechanical properties of the foams was also investigated using dynamic mechanical analysis (DMA). POLYM. ENG. SCI., 47:1070–1081, 2007. © 2007 Society of Plastics Engineers 相似文献