scholarly journals Partitioning of Terrain Features Based on Roughness

2018 ◽  
Vol 10 (12) ◽  
pp. 1985 ◽  
Author(s):  
Jiang Wu ◽  
Qinke Yang ◽  
Yuru Li
Keyword(s):  
Surface Roughness ◽  
Fundamental Problem ◽  
Shuttle Radar Topography Mission ◽  
General Effect ◽  
Discrimination Ability ◽  
Power Spectral ◽  
Directional Cosine ◽  
Local Vector ◽  
Basic Studies ◽  
Terrain Features

Surface roughness is a key parameter that reflects topographic characteristics and influences surface processes, and characterization of surface roughness is a fundamental problem in geoscience. In recent years, although there have been basic studies on roughness, few studies have compared the concept and quantification of roughness, and there have been few studies that have evaluated the ability of partition terrain features. Based on 1″ resolution Shuttle Radar Topography Mission (SRTM) data and previous studies, we selected the Qinba Mountain region of China and its adjacent areas as our study area, and used 13 different roughness algorithms to extract roughness in this study. Using spatial patterns and statistical distributions, the results were analyzed, and the best algorithm suited to partitioning terrain features was selected. We then evaluated the ability of the algorithm to distinguish the terrain morphology. The results showed the following: (1) The 13 algorithms were able to be classified into four types, that is, gradient (SLOPE), relief (root mean squared height, RMSH), local vector (directional cosine eigenvalue, DCE) and power-spectral (two-dimensional continuous wavelet transform, 2D CWT). (2) The SLOPE and RMSH algorithms were better able to express and distinguish terrain, as they were able to macroscopically distinguish between four types of terrain in the study areas. Based on power-spectral methods, 2D CWT had the same discrimination ability as the first two methods following a normalization transform, whereas the DCE method had a general effect and could only distinguish two types of terrain. (3) Different roughness algorithms had their own applicability for different terrain areas and application directions.

Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

2020 ◽  
Author(s):  
Yagya Dutta Dwivedi ◽  
Vasishta Bhargava Nukala ◽  
Satya Prasad Maddula ◽  
Kiran Nair
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Surface Roughness ◽  
Wind Speed ◽  
Atmospheric Turbulence ◽  
Surface Boundary ◽  
Low Frequencies ◽  
Surface Boundary Layer ◽  
Power Spectral ◽  
Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

Corrected power spectral density of the surface roughness of tire rubber sliding on abrasive material

2021 ◽  
Vol 153 ◽  
pp. 106632
Author(s):  
Hiro Tanaka ◽  
Kenta Okui ◽  
Yuki Oku ◽  
Hironori Takezawa ◽  
Yoji Shibutani
Keyword(s):  
Surface Roughness ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Abrasive Material ◽  
Tire Rubber ◽  
Power Spectral

scholarly journals Selected Physicochemical Properties of Diamond Like Carbon (DLC) Coating on Ti-13Nb-13Zr Alloy Used for Blood Contacting Implants

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5077
Author(s):  
Magdalena Antonowicz ◽  
Roksana Kurpanik ◽  
Witold Walke ◽  
Marcin Basiaga ◽  
Jozef Sondor ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Physicochemical Properties ◽  
Fundamental Problem ◽  
Circulatory System ◽  
Titanium Implants ◽  
Diamond Like Carbon ◽  
Dlc Coating ◽  
13Zr Alloy ◽  
Artificial Plasma ◽  
Modification Of Titanium

Despite high interest in the issues of hemocompatibility of titanium implants, particularly those made of the Ti-13Nb-13Zr alloy, the applied methods of surface modification still do not always guarantee the physicochemical properties required for their safe operation. The factors that reduce the efficiency of the application of titanium alloys in the treatment of conditions of the cardiovascular system include blood coagulation and fibrous proliferation within the vessel’s internal walls. They result from their surfaces’ physicochemical properties not being fully adapted to the specifics of the circulatory system. Until now, the generation and development mechanics of these adverse processes are not fully known. Thus, the fundamental problem in this work is to determine the correlation between the physicochemical properties of the diamond like carbon (DLC) coating (shaped by the technological conditions of the process) applied onto the Ti-13Nb-13Zr alloy designed for contact with blood and its hemocompatibility. In the paper, microscopic metallographic, surface roughness, wettability, free surface energy, hardness, coating adhesion to the substrate, impendence, and potentiodynamic studies in artificial plasma were carried out. The surface layer with the DLC coating ensures the required surface roughness and hydrophobic character and sufficient pitting corrosion resistance in artificial plasma. On the other hand, the proposed CrN interlayer results in better adhesion of the coating to the Ti-13Nb-13Zr alloy. This type of coating is an alternative to the modification of titanium alloy surfaces using various elements to improve the blood environment’s hemocompatibility.

Roughness Analysis of Episurfaces Grown on Ion-Beam Processed GaSb Substrates

2004 ◽  
Vol 829 ◽  
Author(s):  
K. Krishnaswami ◽  
D. B. Fenner ◽  
S. R. Vangala ◽  
C. Santeufemio ◽  
M. Grzesik ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Statistical Analysis ◽  
Ion Beam ◽  
Molecular Beam Epitaxial ◽  
Power Spectral ◽  
Sharp Point ◽  
Roughness Analysis ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam ◽  
Substrate Surfaces

ABSTRACTHigh-quality GaSb substrates with minimal surface roughness and thin, uniform oxide layers are critical for developing low-power, epitaxy-based, electronic and optoelectronic devices. Ion-beam processing techniques of gas-cluster ion beam (GCIB) and bromine ion-beam assisted etching (Br-IBAE) were investigated as to their potential for improving the suitability of substrate surfaces for molecular beam epitaxial (MBE) growth. Statistical analysis of the residual surface roughness provides insight into ion-beam processing and its impact on epitaxial growth. Images of episurfaces grown on chemical mechanical polished (CMP), Br-IBAE, and GCIB finished substrates were obtained using atomic force microscopy (AFM) and these were statistically analyzed to characterize their surface roughness properties. Autocorrelation analysis of the first two types of episurfaces showed a quick loss of correlation within ∼100 nm. The episurface with Br-IBAE also showed isotropic mound roughness with sharp point-like protrusions. The GCIB prepared episurfaces exhibited the formation of uniform step-terrace patterns with monatomic steps and wide terraces as indicated by the strong, long range (>0.5 μm) correlations. Statistical analysis of the GCIB episurfaces showed self-similar random fractal behavior over eight orders of magnitude in the power spectral density (PSD) with a fractal dimension of ∼2.5.

scholarly journals In Situ AFM Imaging of Adsorption Kinetics of DPPG Liposomes: A Quantitative Analysis of Surface Roughness

2019 ◽  
Vol 25 (3) ◽  
pp. 798-809
Author(s):  
Andreia A. Duarte ◽  
Joaquim T. Marquês ◽  
Francisco Brasil ◽  
Ana S. Viana ◽  
Pedro Tavares ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Hydrodynamic Diameter ◽  
Supported Lipid Bilayer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Power Spectral ◽  
Afm Imaging ◽  
Density Analysis ◽  
Power Spectral Density Analysis

AbstractThe adsorption of intact liposomes on surfaces is of great importance for the development of sensors and drug delivery systems and, also, strongly dependent on the surface roughness where the liposomes are adsorbed. In this paper, we analyzed, by using atomic force microscopy in liquid, the evolution of the morphology of gold surfaces and of poly(allylamine hydrochloride) (PAH) surfaces with different roughness during the adsorption of liposomes prepared with the synthetic phospholipid 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]. Our results reveal the following. On smooth surfaces of Au only and Au with PAH, the liposomes open and deploy on the substrate, creating a supported-lipid bilayer, with the opening process being faster on the Au/PAH surface. On rough substrates of Au coated with polyelectrolyte multilayers, the liposomes were adsorbed intact on the surface. This was corroborated by power spectral density analysis that demonstrates the presence of superstructures with an average lateral size of 43 and 87 nm, in accordance with two and four times the mean liposome hydrodynamic diameter of about 21 nm. In addition, this work presents an adequate and effective methodology for analysis of adsorption phenomena of liposomes on rough surfaces.

The Effect of Up-Cutting and Down-Cutting Directions on Materials Swelling in Ultra-Precision Raster Milling

2006 ◽  
Vol 532-533 ◽  
pp. 697-700 ◽  
Author(s):  
Ming Chu Kong ◽  
Wing Bun Lee ◽  
Chi Fai Cheung ◽  
Suet To
Keyword(s):  
Surface Roughness ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Surface Finish ◽  
Copper Alloys ◽  
Cutting Conditions ◽  
Power Spectral ◽  
Ultra Precision ◽  
Important Means ◽  
Cutting Direction

The influence of materials swelling across the steps on surface roughness under up-cutting and down-cutting direction in ultra-precision raster milling was investigated. The normalized extent of swelling is characterized by a swelling significance index, defined based on the power spectral density of the roughness profile. Materials swelling was found to be significant in ultra-precision raster milling, especially when copper alloys machined in the up-cutting direction. The findings in the present study provide an important means for improving the surface finish of the raster-milled surfaces and optimizing the cutting conditions.

Surface roughness and power spectral density study of SHI irradiated ultra-thin gold films

2009 ◽  
Vol 256 (2) ◽  
pp. 558-561 ◽  
Author(s):  
P. Dash ◽  
P. Mallick ◽  
H. Rath ◽  
A. Tripathi ◽  
Jai Prakash ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Gold Films ◽  
Power Spectral ◽  
Density Study

Evaluation of WEDM Surface Quality

2010 ◽  
Vol 97-101 ◽  
pp. 4080-4083 ◽  
Author(s):  
Lei Geng ◽  
Hua Yan Zhong
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Spectral Density ◽  
Surface Topography ◽  
Surface Quality ◽  
Power Spectral Density ◽  
Evaluation Method ◽  
Fractal Theory ◽  
Machined Surface ◽  
Power Spectral

The formation of WEDM surface is a complicated process. There are many factors which make machined surface topography have the characteristics of complex and irregular, and impact using performance of parts. The work investigated microscopic features of the WEDM surface topography based on power spectral density and fractal theory, and proposed power spectral density evaluation method of the WEDM surface. The fractal dimension of the WEDM surface was calculated by structure function method. The physical meaning of the fractal dimension of the WEDM surface was described. The result shows that topography of the WEDM surface exhibits strong fractal characteristics within a certain scale. The processing parameters and pulse power performance will affect the fractal dimension D. The fractal dimension D has a certain relationship with the surface roughness Ra. It is more reasonable to use the fractal dimension D as well as the surface roughness Ra together to evaluate WEDM surface quality.

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