共查询到20条相似文献,搜索用时 31 毫秒
1.
Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics. 相似文献
2.
In-process roughness measurement on moving surfaces 总被引:8,自引:0,他引:8
A new optical technique, which utilises the combined effects of interference and light scattering, was developed for surface roughness measurements. This paper presents the technique applicable to extracting the roughness of moving surfaces under high rotational speeds up to 3.7 m/s. The applicability of the technique to in-process roughness measurement was demonstrated with a cylindrical grinding process. 相似文献
3.
We report on the fractal analysis of digital speckle patterns experimentally generated using an optical setup to record the light scattered from metallic rough surfaces in the normal direction. Using the differential box counting technique, we have calculated the fractal dimension of digital speckle patterns for six samples with different roughness. Our results show a quadratic dependence between the surface roughness and the fractal dimension of the corresponding digital speckle pattern. As an application a method to determine the surface roughness of metallic surfaces is proposed. 相似文献
4.
Wen-feng Zhao Jun-fang Chen Ran Meng Hui Wang Yong-qi Xue 《Applied Surface Science》2010,256(7):2009-2012
An important concern in the deposition of Si:H films is to obtain smooth surfaces. Herein, we deposit the thin Si:H films using Ar-diluted SiH4 as feedstock gas in an inductively coupled plasma reactor. And we carry a real-time monitor on the deposition process by using optical emission spectrum technology in the vicinity of substrate and diagnose the Ar plasma radial distribution by Langmuir probe. Surface detecting by AFM and surface profilometry in large scale shows that the thin Si:H films have small surface roughness. Distributions of both the ion density and the electron temperature are homogeneous at h = 0.5 cm. Based on these experimental results, it can be proposed inductively coupled plasma reactor is fit to deposit the thin film in large scale. Also, Ar can affect the reaction process and improve the thin Si:H films characteristics. 相似文献
5.
用计算机处理薄膜表面复型电子显微照片,得到表面高度轮廓,提出了计算机定标方法,并计算了薄膜表面微结构参量. 相似文献
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M. A. Rebollo M. R. Landau E. N. Hogert N. G. Gaggioli M. Muramatsu 《Optics & Laser Technology》1995,27(6):355-356
There are mechanical and optical methods of measuring the roughness of surfaces. Mechanical methods are of a destructive type, while optical methods, although they are non-destructive, involve relatively complex systems and calculations. In this work a simple method is introduced, which allows one—through the direct observation of the speckle pattern—to make a visual correlation, comparing the first pattern with others obtained when the beam incidence angle varies. With this method it is possible to obtain results with acceptable accuracy for many industrial uses. 相似文献
8.
光学表面加工误差引起的散射是影响光学系统成像性能的重要因素.描述表面总散射能量的均方根粗糙度是评定光学表面粗糙度的通用指标,但因其未能体现散射能量的空间分布,在表征光学表面散射对具体光学系统杂散光性能影响时存在准确度不足的局限.本文基于全积分散射及双向散射分布函数理论,针对杂散光抑制要求提出一种光学表面粗糙度控制的新方法.首先通过分析确定光学表面纹理中影响系统杂散光的空间频率范围,然后度量该频率带限范围内的表面均方根粗糙度,作为控制光学表面粗糙度的指标.以太阳磁场望远镜(MFT)为例进行方法验证,确定主镜表面纹理有效频率范围为0—18 mm~(-1),分析了主镜表面带限均方根粗糙度对MFT杂散光性能的影响.结果表明,带限均方根粗糙度与MFT杂散光性能之间的关系稳定性能大幅提高,由此验证了采用带限均方根粗糙度描述光学表面粗糙度,能更为准确地控制其对具体光学系统杂散光性能的影响. 相似文献
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In this work, the principle of interferometry is used to assess the surface roughness of the machined surfaces. Interferometry produces an interference fringe pattern when two or more light waves interact with each other. It is one of the important tool for precision optical metrology and testing. Well-known advantages of the phase shifting interferometry include high measurement accuracy, rapid measurement, good result even with low contrast fringes and that the polarity of the wave front can be determined. In fringe projection techniques, a known optical fringe pattern is projected onto the surface of interest. The fringe pattern on the surface is perturbed in accordance with the profile of the test surface, thereby enabling direct derivation of surface profile.In this work, an attempt has been made to assess the surface roughness using a speckle fringe analysis method of five frame phase shift algorithm for machined surface (ground surface). As these fringes are too noisy, advanced filtering technique has been used so as to reduce noise and to get improved wrapped phase map from the phase shifted fringes. A phase unwrapping software has been developed using discrete cosine transform (DCT) to generate the three-dimensional (3-D) profiles. Finally, it is compared with Ra values measured using a mechanical stylus instrument, showing good agreement. 相似文献
11.
Surface roughness is one of the most important attributes of paper and its measurement is normally used in quality control applications. Currently, measurement of surface roughness is done by using air leakage, optical, or subjective methods. In this article, an acoustical method for the determination of surface roughness of papers is described. The method is applied off-line and uses the friction noise recorded when a small brush slide over the surface of the paper. The analysis is done consider the friction noise ranging from 300 Hz to 10 kHz. Considering that friction noise is associated to surface roughness, a signal analysis algorithm was developed to take advantage of this fact. The algorithm consists of a frequency-domain feature extraction routine and an artificial neural network that represents the variation of the spectral features in a roughness scale. The results show that an affordable and efficient friction noise based system can be used for measuring surface roughness of tissue papers and other soft surfaces as an alternative to other methods. 相似文献
12.
The Beckmann scalar scattering model based on the Kirchhoff approximation was used to investigate the scattering of light from periodic surfaces whose roughness amplitude is comparable to, and greater than, the illumination wavelength. Solutions by numerical integration were obtained for surfaces of different profiles and of different roughnesses. It was found that the scattering patterns from these surfaces were very different at large roughness amplitudes. As the incident angle was varied on a given surface, it was also observed that the intensity of any individual diffraction order oscillated and the degree of oscillation was directly related to roughness. By utilizing this property, a new procedure could be developed for surface roughness assessment. 相似文献
13.
G. Huang S. Simoëns I. Vinkovic C. Le Ribault S. Dupont G. Bergametti 《Journal of Turbulence》2016,17(5):518-541
As opposed to the log-region, the roughness sublayer present above rough surfaces is still poorly understood due to the complex interaction between wakes developing behind roughness elements. To investigate the spatially averaged flow velocity in this region, a data-set has been collected from several direct numerical simulations and wind-tunnel experiments available in the literature. A generalised law-of-the-wall has been derived, applicable to a roughness sublayer present over regularly distributed roughness elements. The key roughness parameter of this new law is the effective height ?, which characterises the interaction between the roughness and the outer flow in a temporally and spatially averaged sense. A morphometric study reveals that ? is closely related to a new roughness density parameter, λ2, that accounts for the roughness element shape and the inter-element spacing. This allows ? to be a universal parameter on roughness characterisation. The derived values of the classical roughness length z0 of the log-law compare well with previous experimental data and geometrical model predictions. Finally, the main properties of the roughness sublayer such as its height are discussed using the geometrical and the roughness parameters proposed in the study. 相似文献
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Performance Optimization of Phase-Shifting Interferometry Using Data Average on Wide Range Roughness Measurement 总被引:1,自引:0,他引:1
Min-Sik Jo 《Optical Review》2004,11(1):55-59
Performance optimization of phase-shifting interferometry was investigated using data average on wide range roughness measurement. The interferometry performance was strongly affected by data average and an optimal data averaging condition of minimal measurement error was found. The high limit roughness level which makes the data average available for the interferometry performance optimization providing a reproducible and smallest roughness was determined to be about 5 _A rms roughness. Therefore, the optimal interferometry performance absolutely required data average for finer surfaces than about 5 _A rms roughness. On the other hand, the optimal interferometry performance for surfaces rougher than about 10 _A rms required little data average. The reliability of the optimal performance of phaseshifting interferometry was checked. 相似文献
16.
Superhydrophobic films of poly(furfuryl alcohol)/multi-walled carbon nanotubes (PFA/MWNTs) composites have been obtained by using fluorocarbon-modified MWNTs (MWNT-OOCC7F15), PFA, and PTFE with a simple preparation method. The prepared films showed both high contact angle and small sliding angle for water droplets. The chemical compositions and microstructures of the resultant film surfaces were also investigated by means of infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscope, respectively. Both the formed multiscale roughness structures and the lower surface energy play an important role in creating the superhydrophobic surfaces of PFA/MWNTs composites. 相似文献
17.
This paper describes a speckle correlation technique for the determination of surface roughness, ranging from 1.6 to 50 μm. Instead of moving the laser beam, the specimen is rotated to achieve angular speckle correlation (ASC) in the far-field plane. The technique is simple and requires minimum optical alignment. The experimental results show a good agreement with the standard specimen of known roughness. An error analysis on the experiment has been carried out. Together with the theoretical curves, the roughness values can be easily related to the change of incidence angle at a particular visibility of the correlation fringes between two speckle patterns. 相似文献
18.
A.L. SampaioD.C. Lobão L.C.S. NunesP.A.M. dos Santos L. Silva J.A.O. Huguenin 《Optics and Lasers in Engineering》2011,49(1):32-35
In this paper, we present a study of metallic surface roughness using the Hurst exponent calculated from speckle pattern. A set of samples was prepared using polishing techniques and the roughness was directly measured by means of an optical profilometer. To study the H exponent, an experiment was performed by illuminating the samples using an expanded laser beam and the surface image was captured by a CCD camera. We applied techniques of the Hurst exponent calculation, traditionally calculated from surface profile, in the digitalized speckle patterns generated by the rough surfaces. We showed a clear dependence of the H exponent on roughness of the samples. We demonstrated that this tool is very sensitive to defects in the surfaces and can be used for roughness control. 相似文献
19.
Influence of surface roughness on water- and oil-repellent surfaces coated with nanoparticles 总被引:3,自引:0,他引:3
Chien-Te Hsieh Jin-Ming Chen Rong-Rong Kuo Ta-Sen Lin Chu-Fu Wu 《Applied Surface Science》2005,240(1-4):318-326
Various rough surfaces coated with titanium oxide nanoparticles and perfluoroalkyl methacrylic copolymer were conducted to explore the influence of surface roughness on the performance of water- and oil-repellence. Surface characteristics determined from nitrogen physisorption at −196 °C showed that the surface area and pore volume increased significantly with the extent of nanoparticle ratio, indicating an increase of surface roughness. Due to the surface nano-coating, the maximum contact angles of water and ethylene glycol (EG) droplets increased up to 56 and 48%, respectively, e.g. from 105° to 164° for water droplets and from 96° to 144° for EG droplets. The excellent water- and oil-repellence of the prepared surfaces was ascribed to this increase of surface roughness and fluorinated-contained surface. Compared with Wenzel model, the Cassie model yielded a fairly good fit to the simulation of contact angle with surface roughness. However, a derivation of 3°–10° at higher roughness still existed. This phenomenon was very likely due to the surface heterogeneity with different pore size distributions of the fractal surfaces. In this case, it was unfavorable for super repellency from rough surface with larger mesopore fraction because of its capillary condensation, reflecting that micropore provided more air resistance against wettability. 相似文献
20.
以6种具有典型特征的生成元构造了6个具有相同rms粗糙度的规则表面,用变分法计算了这些表面的分形维数,结果表明,分形维数可以将具有相同rms粗糙度的表面区分开来,它定量表征了表面的总体形貌。进一步将多重分形的方法应用到对这些表面的分析中,发现多重分形谱可以全面反映表面概率的分布特征。多重分形谱的宽度可以定量表征表面的起伏程度,多重分形谱最大、最小概率子集维数的差别可以统计表面最大、最小概率处的数目比例。
关键词:
粗糙度
分形维数
多重分形谱 相似文献