Search results for "ROUGHNESS"
showing 10 items of 216 documents
Method of Discrimination of Surface Fractality
1993
Abstract A simple method for the discrimination of surface fractality is proposed. This method is based on the comparison of the nitrogen adsorption isotherm on a given sample with the "standard" isotherm on a smooth surface. The proposed comparative method makes it possible to determine the lower limit of the scale range of surface fractality. A thermodynamic method is recommended as a complement to fractal analysis in the scale range of about 10-1000 A. The results of the investigation of surface roughness are presented with examples of typical samples of silica gels, porous glasses, apatite, and coal.
Applying Experimental Research Management to a Technological Process using Taguchi's Method
2018
Abstract The surface quality is dependent on certain cutting process parameters that can vary, causing variations on the surface roughness. The main subject of this paper focuses on the experimental research management applied to a technological process whose final purpose was to determine an equation of the surface roughness depending on the process parameters, obtained by the Al7136 end milling process. The research method used in this paper is the Taguchi's method. According to the research management steps, in order to perform the experimental determination of the surface roughness, an experimental stand used to determine the objective function was presented. The surface roughness equat…
Electric-field-controlled reversible order-disorder switching of a metal tip surface
2018
While it is well established that elevated temperatures can induce surface roughening of metal surfaces, the effect of a high electric field on the atomic structure at ambient temperature has not been investigated in detail. Here we show with atomic resolution using in situ transmission electron microscopy how intense electric fields induce reversible switching between perfect crystalline and disordered phases of gold surfaces at room temperature. Ab initio molecular dynamics simulations reveal that the mechanism behind the structural change can be attributed to a vanishing energy cost in forming surface defects in high electric fields. Our results demonstrate how surface processes can be d…
Surface Reflectance: An Optical Method for Multiscale Curvature Characterization of Wear on Ceramic–Metal Composites
2020
Surface gradient characterization by light reflectance (SGCLR) is used for the first time for multiscale curvature calculations and discrimination of worn surfaces on six damaged ceramic&ndash
A semi-empirical approach for surface soil water content estimation from radar data without a-priori information on surface roughness
2006
Abstract In this study, the spatial distribution of soil water content in an agricultural area of 30 km 2 in Southern Italy has been estimated by using high-resolution space-borne Synthetic Aperture Radar data. Multi-polarised SAR images acquired during the SIR-C mission in April 1994 have been analysed by using the semi-empirical surface backscattering model derived by Oh, Y., Sarabandi K., Ulaby F.T., 1992. An empirical model and an inversion technique for radar scattering from bare soil surface. IEEE Trans. Geosci. Remote Sensing, 30(2), 370381. A site-specific calibration procedure of the cited model has been proposed to derive soil dielectric constant values without a-priori informatio…
Surface Soil Moisture Retrieval Using the L-Band Synthetic Aperture Radar Onboard the Soil Moisture Active–Passive Satellite and Evaluation at Core V…
2017
This paper evaluates the retrieval of soil moisture in the top 5-cm layer at 3-km spatial resolution using L-band dual-copolarized Soil Moisture Active–Passive (SMAP) synthetic aperture radar (SAR) data that mapped the globe every three days from mid-April to early July, 2015. Surface soil moisture retrievals using radar observations have been challenging in the past due to complicating factors of surface roughness and vegetation scattering. Here, physically based forward models of radar scattering for individual vegetation types are inverted using a time-series approach to retrieve soil moisture while correcting for the effects of static roughness and dynamic vegetation. Compared with the …
Power sensitivity analysis of multi-frequency, multi-polarized, multi-temporal SAR data for soil-vegetation system variables characterization
2017
Abstract: The knowledge of spatial and temporal variability of soil water content and others soil-vegetation variables (leaf area index, fractional cover) assumes high importance in crop management. Where and when the cloudiness limits the use of optical and thermal remote sensing techniques, synthetic aperture radar (SAR) imagery has proven to have several advantages (cloud penetration, day/night acquisitions and high spatial resolution). However, measured backscattering is controlled by several factors including SAR configuration (acquisition geometry, frequency and polarization), and target dielectric and geometric properties. Thus, uncertainties arise about the more suitable configurati…
Improving the Performance of Steel Machining Processes through Cutting by Vibration Control
2021
Machining processes through cutting are accompanied by dynamic phenomena that influence the quality of the processed surfaces. Thus, this research aimed to design, make, and use a tool with optimal functional geometry, which allowed a reduction of the dynamic phenomena that occur in the cutting process. In order to carry out the research, the process of cutting by front turning with transversal advance was taken into account. Additionally, semi-finished products with a diameter of Ø = 150 mm made of C45 steel were chosen for processing (1.0503). The manufacturing processes were performed with the help of two tools: a cutting tool, the classic construction version, and another that was the i…
Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets.
2021
Incremental sheet forming of titanium and its alloys has a significant role in modern manufacturing techniques because it allows for the production of high-quality products with complex shapes at low production costs. Stamping processes are a major contributor to plastic working techniques in industries such as automotive, aerospace and medicine. This article reviews the development of the single-point incremental forming (SPIF) technique in titanium and its alloys. Problems of a tribological and microstructural nature that make it difficult to obtain components with the desired geometric and shape accuracy are discussed. Great emphasis is placed on current trends in SPIF of difficult-to-fo…
Definition of performance requirements and test cases for offshore/subsea winch drive systems with digital hydraulic motors
2019
Abstract A subsea crane is normally mounted on a floating vessel and equipped with a winch system. The crane can operate in water down to 3000 m. The vessel tends to move up and down due to waves. This heave motion makes offshore lifting operations challenging. In order to ease the winch operation in rough sea, the winch can be equipped with additional systems like active heave compensation and constant tension. In active heave compensation and constant tension system, both motion and force control of the winch are important. This paper presents a digital displacement winch drive system and gives a description of challenges related to subsea lifting operations. The operation challenges are …