physical geometry
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2021 ◽  
Vol 71 (2) ◽  
pp. 282-288
Author(s):  
P. K. Karn ◽  
P. Kumar ◽  
Sudip Das

Computational investigations were carried out on an ogive-cylinder configuration having a slenderness ratio of 7.5. The geometry of the nose tip was generated based on the physical geometry of the nose tip observed under a scanning electron microscope. Time-dependent simulations were performed on the slender body at a diameter Reynolds number of 3.0×104. Results indicated that the onset of vortex asymmetry was mainly due to the micro-tip imperfection existing at the tip. It was also observed that the variation in the roll angle of the model affected the flow physics largely which has been experimentally observed by several researchers in the past. The computed results were in better agreement with the referenced experimental data.


2021 ◽  
pp. 53-74
Author(s):  
Ahmed Jawad ◽  
Mohd. Suffian bin Misran ◽  
Abu Salman Shaikat ◽  
Md. Tarek Ur Rahman Erin ◽  
Md. Mizanur Rahman

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1279
Author(s):  
Namrata Kanth ◽  
Weiheng Xu ◽  
Umesh Prasad ◽  
Dharneedar Ravichandran ◽  
Arunachala Mada Kannan ◽  
...  

Titanium dioxide (TiO2) is a promising photocatalyst that possesses a redox potential suitable for environmental remediation applications. A low photocatalytic yield and high cost have thus far limited the commercial adoption of TiO2-based fixed-bed reactors. One solution is to engineer the physical geometry or chemical composition of the substrate to overcome these limitations. In this work, porous polymethyl methacrylate (PMMA) substrates with immobilized TiO2 nanoparticles in fiber forms were fabricated and analyzed to demonstrate the influence of contaminant transport and light accessibility on the overall photocatalytic performance. The influences of (i) fiber porosity and (ii) fiber architecture on the overall photocatalytic performance were investigated. The porous structure was fabricated using wet phase inversion. The core-shell-structured fibers exhibited much higher mechanical properties than the porous fibers (7.52 GPa vs. non-testability) and maintained the same degradation rates as porous structures (0.059 vs. 0.053/min) in removing methylene blue with comparable specific surface areas. The highest methylene blue (MB) degradation rate (kMB) of 0.116 min−1 was observed due to increases of the exposed surface area, pointing to more efficient photocatalysis by optimizing core-shell dimensions. This research provides an easy-to-manufacture and cost-efficient method for producing PMMA/TiO2 core-shell fibers with a broad application in water treatment, air purification, and volatile sensors.


2020 ◽  
Vol 101 (2) ◽  
Author(s):  
Robert G. Buckley ◽  
Eric M. Schlegel
Keyword(s):  

The main purpose of this study is to analyze the thermo-mechanical behavior of the brake disc during the braking phase. Brakes must undergo through continuous use, so many issues surround their heating characteristics when it comes to their development, including contact region properties, material choice, and development of hot spots, associated physical geometry, and deformations. The coupled thermal-structural analysis is used to determine the deformation and the Von Misses stress established in the disc to enhance performance and life of the rotor disc. A comparison between analytical calculations and results obtained from Finite Element Analysis (ANSYS) is done and the values obtained from the analysis are in the range of allowable values. The experiment has been performed with different disc-geometries. Based on the experiment results we have performed ANSYS simulation for the disc-brake. Hence best suitable optimum design is suggested based on the performance, strength and rigidity criteria.


Vision ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 63
Author(s):  
Thomas V. Papathomas ◽  
Patrick Hughes

Two major uses of linear perspective are in planar paintings—the flat canvas is incongruent with the painted 3-D scene—and in forced perspectives, such as theater stages that are concave truncated pyramids, where the physical geometry and the depicted scene are congruent. Patrick Hughes pioneered a third major art form, the reverse perspective, where the depicted scene opposes the physical geometry. Reverse perspectives comprise solid forms composed of multiple planar surfaces (truncated pyramids and prisms) jutting toward the viewer, thus forming concave spaces between the solids. The solids are painted in reverse perspective: as an example, the left and right trapezoids of a truncated pyramid are painted as rows of houses; the bottom trapezoid is painted as the road between them and the top forms the sky. This elicits the percept of a street receding away, even though it physically juts toward the viewer. Under this illusion, the concave void spaces between the solids are transformed into convex volumes. This depth inversion creates a concomitant motion illusion: when a viewer moves in front of the art piece, the scene appears to move vividly. Two additional contributions by the artist are discussed, in which he combines reverse-perspective parts with forced and planar-perspective parts on the same art piece. The effect is spectacular, creating objects on the same planar surface that move in different directions, thus “breaking” the surface apart, demonstrating the superiority of objects over surfaces. We conclude with a discussion on the value of these art pieces in vision science.


2019 ◽  
Vol 9 (2) ◽  
pp. 154
Author(s):  
Zaqiatul Mardiah ◽  
Afdol Tharik Wastono ◽  
Abdul Muta’ali

<p class="TeksAbstrak">The present paper provides a cognitive linguistics (CL) framework for analyzing the semantic structure of Arabic spatial noun <em>fawqa</em> based on <em>Principled Polysemy Model </em>(PPM) of Tyler and Evans (2003). PPM approach can broaden the narrow view of classical cognitive linguists regarding the semantic variation in the concept of physical-geometry of a preposition. As a polysemous lexeme,<em> fawqa</em> used by Arabian native to express a broad range of meanings, not only spatial relation but also  non-spatial relation. The substantial sense of the lexeme is investigated using a large amount of corpus data (<em>corpus.kacst.edu.sa</em>) and applying the five steps of PPM approach. Through this approach, we ascertain that every single usage of <em>fawqa </em>expressing extended senses is always in its semantic network. Our study reveals that the usages of this lexeme in many situations and many cases show non-up down spatial relation, and non-physical relation, but they essentially refer to the primary sense.</p>


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