1,721,011 research outputs found
Failure Mechanisms Of Interfacial Coatings (Mcraly8Ysz) On High Temperature Solid Particle Erosion
No full textSadhana-Academy Proceedings In Engineering SciencesIn order to study the influence of the bond coat on the erosion resistance of the thermal barrier coating (TBC), two different bond coats (NiCrAlY and NiCoCrAY) were deposited onto Inconel 718 substrate by using Atmospheric Plasma Spray (APS). After that topcoat Yttria Stabilized Zirconia with the Y2O3 content of 8 weight (8YSZ) coatings were deposited by APS method onto the bond coats also. Alternative test rig compliant with the ASTM G211-14, was used in experiments. These experiments were performed at three different air temperatures (21 degrees C, 300 degrees C and 600 degrees C), three different erosive particle impact angles (30 degrees, 60 degrees and 90 degrees), constant particle impact velocity (similar to 97 m/s) and particle size (400 mu m Al2O3) after which, the erosion rate-impact angles results were obtained. Scanning electron microscopy (SEM) images, X-ray diffraction (XRD) analysis, Energy dispersive X-ray (EDX) mapping and EDX elemental analysis were conducted to assess the effectiveness of bond coating and ceramic topcoats to reduce wear at high temperatures. The importance of adhesion at the interface between bond coatings and ceramic topcoats was determined. However, erosion resistance generally increased with temperature, and this resistance effect tended to decrease with the presence of Cobalt
Surface Analysis of Erosion Resistance of Recycled PA 3200 GF Powders Produced by Selective Laser Sintering
No full textThis paper evaluates solid particle erosion (SPE) performance of samples produced via selective laser sintering (SLS) using fully recycled PA 3200 GF material, following ASTM G76-95 standards. For this purpose, six samples (30303 mm3) were printed at 0 degrees, 45 degrees, and 90 degrees in x-y and x-z planes with a 100-mu m layer thickness. SPE tests examined erosion at distinct impact angles (30 degrees, 45 degrees, 60 degrees, 90 degrees) and pressures (1, 2, 3 bars). Results showed higher particle velocities reduced erosion resistance, where 45 degrees x-y plane samples demonstrated superior resistance (erosion rates: 0.050, 0.100, 0.220 mg/g under 1, 2, 3 bars, respectively). The 30 degrees impact angle caused maximum erosion, while 90 degrees had the least. Samples positioned horizontally in the x-y plane were most sensitive to impact angles, with 10 higher erosion sensitivity than others. The study highlights how printing direction significantly affects SPE performance in SLS
Solid Particle Erosion Wear Behaviors Of Recycled Pa 3200 Gf Powders Produced By Selective Laser Sintering Method In Different Abrasive Environmental Conditions
No full textInstitute of Electrical and Electronics Engineers Inc.Additive manufacturing methods have been widely used in applications for material preference in our daily lives, especially by enabling the production of complex geometry materials with precise tolerances. The purpose of being preferred in industrial applications is to produce alternative materials thanks to the Selective Laser Sintering (SLS) production system, which offers additive manufacturing. For this reason, in order to adapt the SLS system to the test samples, samples of 25x25x3mm3 were produced from recycled PA 3200 GF powders to form a layer thickness of 100 μm.As a result of the impact of solid particles (especially aerospace systems, energy conversion plants, jet engines, helicopter rotor blades, etc.) with different properties on the material surface at certain velocity and angles, undesirable deformations occur on the material surface. In addition, this type of wear has a critical importance in the world economy. With this convergence, erosion wear tests were carried out in accordance with the international standard ASTM G76-95, prioritizing that material for the aerospace industry can be exposed to this type of wear thanks to the use of samples produced by additive manufacturing and containing recycling powders.In order to carry out solid particle erosion wear tests, especially for sand and dust effect, for the use of samples produced by SLS method and with a change in printing direction in different environmental conditions, taking into account the particle impact angle of 30°, 60° and 90°, under the influence of abrasive particles with Al2O3, SiO2 and C20 properties and experiments were carried out by modeling the operating conditions of 34 m/s impact velocity. Regardless of the printing direction effect, it was concluded that the highest erosion rate of the test materials in all groups occurred at the impact angle of 30°. Erodent properties also showed a dominant effect on the erosion wear mechanism. Moreover, the tangential and vertical efficiency of the abrasive particle impact have a significant effect on erosion wear. © 2022 IEEE
A class of congruence subgroups of hecke group H ( λ 5)
No full textIn [2], it is shown that, for some Hecke groups, unlike the modular group, two definitions of the principal congruence subgroups may not coincide and congruence and principal congruence subgroups of two important Hecke groups H (SICm), for m = 2 or 3, are classified and the quotients of H (SICm) with these normal subgroups are given. Here we obtain a classification of the congruence subgroups obtained as the kernel of reduction homomorphism for another important Hecke group H (lambda(5)) and also obtain the quotient groups. Finally the indices and abstract group structure of all these subgroups are determined
New relations for the normal subgroups of hecke groups
No full textFor an integer q ≥ 3, Hecke groups H(λq) are an important class of discrete groups with the most important member being the famous modular group obtained in the case of q = 3. They were defined by E. Hecke in 1936 when he was studying with Dirichlet series. There are a number of research papers on the properties of Hecke groups, their normal subgroups and the relation with regular maps. Here we add some recent results to state new relations between the parameters of the normal subgroups of Hecke groups and the corresponding regular maps which are also graphs in combinatorial sense by means of a new graph invariant called omega which was recently defined in 2018
Investigation of Automotive Primer and Basecoat Paint Surface's Adhesion by Solid Particle Erosion
No full textMillions of cars are sold around the world and tons of paint are used for these cars. Since the car paint industry is alive in this way, new developments in the paint sector have been taking place every day. It is important to determine how these developments affect paint erosion. Solid particle erosion wear is a subject that keeps its update for car paints and it always needs to be investigated in detail. The target of this experimental study is to investigate solid particle erosion behavior of a commercial acrylic/melamine primer surface and basecoat of automotive paint. As a erodent, silica particles having a weight of 1 to 5 kg were used. Tests were performed at 30°and 90°impact angle and particle velocity 23â€?m s-1. With this work, an idea about the adhesion of the car paint coatings to the material surface was obtained. © 2018 Author(s)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Inverse problem for albertson irregularity index
No full textGraph indices have attracted great interest as they give us numerical clues for several properties of molecules. Some indices give valuable information on the molecules under consideration using mathematical calculations only. For these reasons, the calculation and properties of graph indices have been in the center of research. Naturally, the values taken by a graph index is an important problem called the inverse problem. It requires knowledge about the existence of a graph having index equal to a given number. The inverse problem is studied here for Albertson irregularity index as a part of investigation on irregularity indices. A class of graphs is constructed to show that the Albertson index takes all positive even integers. It has been proven that there exists at least one tree with Albertson index equal to every even positive integer but 4. The existence of a unicyclic graph with irregularity index equal to m is shown for every even positive integer m except 4. It is also shown that the Albertson index of a cyclic graph can attain any even positive integer
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