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A novel approach for the rigid body guidance synthesis of planar RRPR linkages
Selma J. Rodríguez-González,Henry A. Suárez-Velásquez,J. Jesús Cervantes-Sánchez,José M. Rico-Martínez 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2
This paper demonstrates that the maximum number of poses that can be exactly reached by a planar RRPR linkage is four, while the design for five poses requires the relaxation of displacement constraints at one prescribed pose. To this end, a novel and explicit condition for the synthesis of RP dyads with five prescribed poses is correspondingly introduced. It leads to a new and efficient approach to synthesize planar RRPR linkages, which is equipped with a branching identification procedure. Two successful case studies are provided to validate the applicability of the proposed synthesis approach.
Mechanosynthesis of graphene nanoribbons from waste zinc–carbon batteries
Martínez-González J.,Reyes-Contreras D.,Vigueras-Santiago Enrique,Patiño-Carachure C.,Reyes-Esqueda J. A.,Castrejón-Sánchez V. H.,García-Orozco I. 한국탄소학회 2022 Carbon Letters Vol.32 No.2
The mechanosynthesis route is a physical top–down strategy to produce different nanomaterials. Here, we report the formation of graphene nanoribbons (GNRs) through this route using carbon bars recovered from discarded alkaline batteries as raw material. The mechanosynthesis time (milling time) is shown to have an influence on different features of the GNRs such as their width and edges features. TEM revealed the presence of GNRs with widths of 15.26, 8.8, and 23.55 nm for the milling times of 6, 12, and 18 h, respectively. Additionally, the carbon bars evolved from poorly shaped GNRs for the shortest milling time (6 h) to well-shaped GNRs of oriented sheets forming for the longest milling time. Besides GNRs, graphene sheets (GNS) of different sizes were also observed. The Raman analysis of the 2D bands identified the GNS signal and confirmed the GNRs nature. ID/IG values of 0.21, 0.32, and 0.40 revealed the degree of disorder for each sample. The in-plane sp2 crystallite sizes (La) of graphite decreased to 91, 60, and 48 nm with increasing peeling time. The RBLM band at 288 cm−1 confirmed the formation of the GNRs. Mechanosynthesis is a complex process and the formation of the GNRs is discussed in terms of a mechanical exfoliation, formation of graphene sheets and its fragmentation to reach GNR-like shapes. It is shown that the synthesis of GNRs through the mechanosynthesis route, besides the use of recycled materials, is an alternative for obtaining self-sustaining materials.
G. Domínguez‑Rodríguez,J. A. González‑Sánchez,J. Rosado‑Carrasco,G. Canto 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9
The recognitions of phases and precise grain boundaries based on metallographic images are useful for conducting micromechanicalsimulations, such as finite element analysis and peridynamics. In this work, those processes are automatized byusing a Sobel operator for identifying edges, which is normalized by different proposed Gaussian filters (on intensity, rugosity,or both). After that, a threshold is used to discretize the edges. Different neighboring pixel configurations, sensitive to edgeintensity, are proposed for thinning and cleaning the discretized edges, and hence, grain boundaries with a one-pixel thicknessare obtained. Then, the phase is selected by averaging color of each delimited grain. Finally, the precision on the phaserecognition was found to increase from 75.61 to 83.6% for the unmodified and the normalized Sobel operator, respectively.