Results 1 - 10 of 14814
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[en] A least-squares minimization approach has been developed to determine depth from magnetic data. The approach is based on fitting a simple dike model convolved with the same horizontal gradient filter as applied to the observed magnetic data. The problem of depth determination from magnetic data has been transformed into a solution to a nonlinear equation of the form f (z) =0. Procedures are also formulated to estimate the effective magnetization inclination and the effective magnetization intensity. The method is applied to synthetic data with and without random errors. Finally, the method is applied to field example from Canada. In all cases determined, the depth parameter is found to be in good agreement with the actual depth. (author)
[en] This work presents a mechanism of deformation-twin-induced grain boundary failure, and demonstrates the mechanism using molecular dynamics simulations. Deformation twinning is observed as the dominant mechanism during tensile deformation of columnar nanocrystalline body-centered cubic Mo. As a twin approaches a grain boundary, local stress concentration develops due to the incompatible plastic deformations in the two neighboring grains. The magnitude of the stress concentration increases as the twin widens, leading to grain boundary cracking by nucleation and coalescence of microcracks/voids.
[en] First, the force model of roll is set up, and the temperature field is analyzed according to the properties of the processed material, which provides data support for the thermomechanical coupling analysis of roll. Then, The effect of the roll temperature field distribution, the equivalent stress distribution and the equivalent plastic strain distribution on the roll is analyzed by the sequential thermo mechanical coupling analysis of the roll. Finally, It provides theoretical support for studying the mechanism of roller damage and prolonging the life of rolls. (paper)
[en] We present a simple and cost-effective method to produce super hydrophobic surfaces in thermoplastic polymer substrates, which contain hierarchical micro/nano structures that resemble lotus leaves. The method involved the fabrication of an Al stamp through the sequential application of laser ablation and anodization to create micro- and nano-structures, respectively. The fabricated patterns on the Al stamp were replicated on the thermoplastic Cyclic olefin copolymer (COC) film surfaces through a hot embossing technique. Static water contact angles were measured to evaluate the hydrophobicity of the patterned COC surfaces. The static water contact angle on the micro/nano hierarchical structured COC surface was measured to be 162.3 .deg. on average. The hot embossing process was repeated 31 times with a nano-structured Al stamp, and the replicated COC surfaces showed consistent water contact angles
[en] Focus sensors and deflectometric sensors find widespread application in optical testing, especially where a large measurement range is required as in plastics or free-form optics. This note describes the design of a combined sensor for the simultaneous measurement of the height and the local slope of a surface under test in one single measurement spot. The opto-mechanical set-up and the metrological characteristics are described in detail and the benefits of the integrated measurement are stated, e.g. for the correction of the slope- dependent signal of the focus distance signal or the enhanced characterization of optical surfaces. First measurement results on a spherical micro mirror array are shown. (technical design note)
[en] Micro(nano)plastics, new emerging contaminants, are ubiquitously found in the environment due to continuous release and accumulation. Widespread micro(nano)plastics can increase their exposure to organisms, pose threats to the ecological environment and human health, and potentially result in global biodiversity changes. Research has been started on micro(nano)plastics regarding their environmental distribution, contamination sources, and methods and technologies for analysis, as well as the environmental impacts and ecological effects on organisms ingesting micro(nano)plastics. However, limited information focused on the consequences of global biodiversity has been reported and the research approaches on biodiversity change caused by micro(nano)plastics are still seldom developed. Recently, researchers in environmental and ecological groups have begun to be conscious of the relationship between micro(nano)plastics and biodiversity. Even so, more efforts are needed to assess the impacts of micro(nano)plastics on this subject, as well as the interactions between organisms and micro(nano)plastics.
[en] A Kolsky apparatus with numerous modifications has been designed for mechanical characterization of materials at high strain rates. These modifications include employing a highly precise optical table, pillow blocks with Frelon®-coated linear bearings as bar supports and a laser system for better precision bar alignment, etc. In addition, the striker bars were coated with Teflon® to minimize the friction with the gun barrel after removal of the conventional plastic sabots. This new design significantly simplifies the alignment process, improving the final alignment and calibration in the bar system; both are critical for validity and accuracy of the resulting data. An example of a dynamic experiment on a 6061 aluminum specimen by using this newly designed Kolsky bar is also presented