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排序方式: 共有455条查询结果,搜索用时 552 毫秒
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Freeze‐dried and milled lignocellulose nanofibrils (LCNF) were used to reinforce polypropylene (PP) nanocomposites. The LCNF, containing up to 9% lignin, was obtained from residual Empty Palm Fruit Bunch (EPFB) fibers. Soy protein isolate (SPI) and hydroxypropyl cellulose (HPC) were tested as coupling agents as well as maleic anhydride grafted polypropylene (MAPP), which was used as a reference. A good level of dispersion of LCNF in the PP matrix while mechanical testing and thermal analyses indicated an improvement of the thermo‐mechanical behavior of the nanocomposites was revealed upon loading of the lignin‐containing nanofibrils. The tensile modulus of PP was increased by 15% upon the addition of 1% LCNF with SPI as a compatibilizer. Likewise, the thermal stability of the composites was most markedly enhanced. Overall, LCNF and SPI, two important bioresources, are introduced here for the development of novel and cost‐effective PP‐based composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43854. 相似文献
24.
Santolo Daliento Vincenzo d'Alessandro Pierluigi Guerriero Orlando Tari 《Progress in Photovoltaics: Research and Applications》2015,23(2):194-200
In this paper, the selective illumination approach is adopted to separately extract the shunt resistance of the individual subcells belonging to a tandem cell. The method relies on simple theoretical considerations and is based on the measurement of the current–voltage characteristic of the tandem cell by alternately keeping one of the subcells under dark conditions. Numerical simulations are employed to support the reliability of the technique, which is experimentally tested on micromorph devices deposited onto glass covered by a V‐shaped transparent conducting oxide and subject to different thermal treatments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
25.
P. Espinet‐Gonzlez C. Algora N. Núez V. Orlando M. Vzquez J. Bautista K. Araki 《Progress in Photovoltaics: Research and Applications》2015,23(5):559-569
A temperature accelerated life test on commercial concentrator lattice‐matched GaInP/GaInAs/Ge triple‐junction solar cells has been carried out. The acceleration of the aging has been accomplished by subjecting the solar cells at temperatures markedly higher than the nominal working temperature inside a concentrator, and the nominal photo‐current condition (820 X) has been emulated by injecting current in darkness. Three tests at different temperatures have been carried out. The failure distributions across the three test temperatures have been fitted to an Arrhenius–Weibull model. An Arrhenius activation energy of 1.59 eV was determined from the fit. The reliability functions and parameters of these solar cells at two nominal working conditions (80 and 100 °C) have been obtained. In both cases, the instantaneous failure rate function monotonically increases, that is, the failures are of the wear‐out kind. We have also observed that the reliability data are very sensitive to the nominal temperature condition. In fact, at a nominal working condition of 820 X and 80 °C, assuming that the concentration module works 5 h per day, the warranty time obtained for a failure population of 5% has been 113 years. However, for a nominal working condition of 820 X and 100 °C, the warranty time obtained for a failure population of 5% has been 7 years. Therefore, in order to offer a long‐term warranty, the working temperature could be a key factor in the design of the concentration photovoltaic systems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
26.
Fernando G. Souza Jr Marcos T. D. Orlando Ricardo C. Michel José Carlos Pinto Tainá Cosme Geiza E. Oliveira 《应用聚合物科学杂志》2011,119(5):2666-2673
Pressure‐sensitive polymers that simultaneously present reasonable electrical conducting properties, useful thermosetting behavior, and softness are hard to develop. To combine these properties into a single material, a cardanol‐based phenolic resin was prepared and blended in situ with polyaniline (PAni). The final polymer blend was composed of a soft solid material that could not be dissolved in ordinary solvents. Samples were characterized through X‐ray scattering, Fourier transform infrared (FTIR) spectroscopy, and electrical conductivity and pressure sensitivity measurements. FTIR results indicate that the insertion of PAni into the blends did not change the chemical nature of the resin. According to wide‐angle X‐ray scattering results, PAni was dispersed homogeneously in the final polymer samples; this improved the sensitivity of the electrical conductivity to pressure variations, as confirmed through electromechanical tests. Pressure sensitivity and electromechanical analyses indicated that the produced blends could be used as pressure‐sensing materials. Among the tested materials, the blends containing 5 wt % PAni·H2SO4 presented the largest compression sensitivity values. Finally, it was shown for the first time through XRD analyses under pressure that PAni chains were considerably disturbed by compressive stresses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
27.
In this paper, we describe the development of a system for evaluating an specific quality characteristic of recycled paper sheets using techniques of image analysis and pattern recognition. We call Bumpiness the phenomenon of interest, which is new in the literature on paper quality. This phenomenon is characterized by the appearance of macroscopic undulations on the paper sheet surface that may emerge shortly or some time after its production. We explore the detection and measurement of this defect by means of computer vision and statistical pattern recognition techniques that may allow early detection at the production site. Our goal is to give an scalar continuous measure of Bumpiness. We propose features computed from Gabor filter banks (GFB) and discrete wavelet transforms (DWT) for the characterization of paper sheet surface Bumpiness in recycled paper images. The starting point is to state the problem as a classification of the paper sheet images into two classes: low and high Bumpiness. In this setting we obtain, with both proposed texture modelling approaches (GFB and DWT), classification accuracies comparable to the agreement between human observers. The best performance is obtained using DWT features. Finally, we propose as the scalar index of Bumpines the fisher discriminant analysis (FDA) function defined on the space of the best features for the classification task. We perform an innovative validation process of this Bumpiness index, based on the ordering of random pairs of images, obtaining a very high agreement with the human observers. 相似文献
28.
Corradini M. L. Cristofaro A. Orlando G. 《Automatic Control, IEEE Transactions on》2010,55(2):419-425
29.
Orlando Soares Henrique Gonçalves António Martins Adriano Carvalho 《Renewable Energy》2010,35(8):1662-1670
This paper describes the models of a wind power system, such as the turbine, generator, power electronics converters and controllers, with the aim to control the generation of wind power in order to maximize the generated power with the lowest possible impact in the grid voltage and frequency during normal operation and under the occurrence of faults. The presented work considers a wind power system equipped with the doubly-fed induction generator and a vector-controlled converter connected between the rotor and the grid. The paper presents comparative results between proportional-integral controllers and neural networks based controllers, showing that better dynamic characteristics can be obtained using neural networks based controllers. 相似文献
30.
Sandra A. Mayén-Hernández Gerardo Torres-Delgado Rebeca Castanedo-Pérez Mario Gutiérrez Villarreal Alfredo Cruz-Orea Julio G. Mendoza Alvarez Orlando Zelaya-Angel 《Journal of Materials Science: Materials in Electronics》2007,18(11):1127-1130
ZnO + Zn2TiO4 thin films were obtained by the sol–gel method using precursor solutions with different Ti/Zn ratios in the 0.18–2.13 range.
The films were deposited on glass substrates and annealed in an open atmosphere at 550 °C. The oxide was characterized by
X-ray diffraction and photoacoustic (PA) spectroscopy. The films were constituted of polycrystalline ZnO for the lowest Ti/Zn
ratio (0.18), polycrystalline Zn2TiO4 for the 0.70 and 1.0 ratios, and mixes of both oxides for the intermediate ratios (0.32 and 0.50). For the highest ratios
studied (1.44 and 2.13), the films were amorphous. The energy band gap (Eg) values were determined from optical absorption spectra, measured by means of the PA technique spectra. Eg varied in the 3.15 eV (ZnO) to 3.70 eV (Zn2TiO4) range. 相似文献