Metallurgical Characterization and Mechanical Properties of Solid–Liquid Compound Casting of Aluminum Alloy: Steel Bimetallic Materials

Pavan Kalyan Kota,Govindaraju Myilsamy,Vaira Vignesh Ramalingam 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

Integration of two metallurgically distinct materials (bimetallic) is an inevitable advancement in the automotive andmarine field. In this context, this study investigates the fabrication, characterization, and properties of solid–liquid compoundcast aluminum alloy AA5052 and ferrous alloy (mild steel and galvanized iron) based bimetallic materials. Microstructuralevolution, microhardness, and tensile strength of the developed bimetallic material are investigated. The results show thatthe formation of cracks at the interface in AA5052/Mild Steel caused the joint failure in the course of preliminary testing. InAA5052/Galvanized Iron, the growth of intermetallics at the oxide-free steel surface results in a shear strength of 19.9 MPa. XRD analysis attests to the presence of brittle intermetallics and Al bond at the interface of AA5052/Galvanized Iron bimetallicmaterial, which in turn confirms the development of a metallurgical.

n-th power signed graphs

Siva Kota Reddy,Vijay,Lokesha 장전수학회 2009 Proceedings of the Jangjeon mathematical society Vol.12 No.3

A signed graph (marked graph) is an ordered pair S = (G, σ) (S = (G, μ)), where G = (V,E) is a graph called the underlying graph of S and σ : E → {+, −} (μ : V → {+, −}) is a function. The n-th power graph of a graph G = (V,E) is a graph Gn = (V,E'), with same vertex set as G, and has two vertices u and v are adjacent if their distance in G is n or less. Analogously, one can define the nth power signed graph of a signed graph S = (G, σ). Consider the marking μ on vertices of S defined as follows: each vertex v ∈ V , μ(v) is the product of the signs on the edges incident at v. The nth power signed graph of S is a signed graph Sn = (Gn, σ') where Gn is the underlying graph of Sn, where for any edge e = uv 2 Gn, 0(uv) = μ(u)μ(v). It is shown that for any signed graph S, its nth power signed graph Sn is balanced. We then give structural characterization of n-th power signed graphs. Two signed graphs S1 and S2 are switiching equivalent written S1 ~ S2, whenever there exists a marking μ of S1 such that the signed graph Sμ(S1) obtained by changing the sign of every edge of S1 to its opposite whenever its end vertices are of opposite signs, is isomorphic to S2. Further, we present solutions of some signed graph switching equations involving the line signed graph, complement and n-th power signed graph operations. One such equation (L(S))n ~ S generalizes a result of P. Siva Kota Reddy and M. S. Subramanya (L(S) ~ S) [11].

ALIAS FREE SUBBAND ADAPTIVE FILTER BASED ON RECURSIVE LEAST SQUARES ALGORITHM FOR FINITE WORD-LENGTH IMPLEMENTATION

Kota ENDO,Kiyoshi NISHIKAWA,Hitoshi KIYA 대한전자공학회 2006 ITC-CSCC :International Technical Conference on Ci Vol.2006 No.3

Quaternary deposits of the Gomakwon River stream basin

Kota Katsuki,Wook-Hyun Nahm,Jin-Young Lee 대한지질학회 2014 대한지질학회 학술대회 Vol.2014 No.10

Control Method of a Haptic Device with a Virtual Prismatic Joint

Kota Abe,Masamitsu Kurisu 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10

We are developing a multi-purpose haptic device which can represent various operation manners by changing control methods. Usually, operation manners for one device that can be represented by configuration constraints such as joint placement are limited. To overcome this limitation and to represent more operation manners, a virtual axis is introduced to the device. The virtual axis is one of the virtual configuration, and is the joint axes of virtual prismatic joints and revolute joints. The virtual axis is different from an actual configuration of the device and realized by controlling multiple actual axes in conjunction. When an operator manipulates the device which is represented by the virtual axis, the operator feels as if the axis exists. This paper describes a control method of the haptic device with a virtual prismatic joint axis. The virtual prismatic joint axis is realized by two-stage control with linearization and servo compensation. Verification experiments are conducted to confirm the effectiveness of the control method, and show that the virtual prismatic joint axis is represented to the device.

Feasibility Studies of a Vibration Wire Monitor and a Halo Scraper in the J-PARC L3BT

Kota Okabe,Kazami Yamamoto,Masahiro Yoshimoto,Michikazu Kinsho 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.7

In the Japan Proton Accelerator Research Complex (J-PARC) 3-GeV rapid cycle synchrotron(RCS), transverse beam halo diagnostics and scraping are required to increase the output beampower. Wire scanners and halo scrapers were used to measure the projected beam distributions todetermine the extent of beam halo formation at the linac 3-GeV beam transport line (L3BT). Inorder to determine more details of halo formation, we installed a vibration wire monitor (VWM) inthe L3BT for the beam halo measurement. The high sensitivity of the VWM makes it a prospectivetool for investigating the beam halo and weak beam scanning. Also, we developed a new verticalscraper system with a thin carbon foil to collimate the beam halo in the L3BT. In this paper, wewill report a preliminary result for the beam-halo measurement by using a VWM and a halo scraperat the L3BT, and we will discuss the potential of the VWM for beam-halo diagnostics.

Domain Adaptation for Agricultural Image Recognition and Segmentation Using Category Maps

Kota Takahashi,Hirokazu Madokoro,Satoshi Yamamoto,Yo Nishimura,Stephanie Nix,Hanwool Woo,Takashi K. Saito,Kazuhito Sato 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

Recognition accuracy obtained using deep learning drops precipitously when the training data are insufficient. This paper presents a data-expansion method for training of the transfer learning source domain. Using expanding images generated from weights on a category map as source data, we compared accuracies obtained from five derivative models and our previously reported method. Moreover, we obtained the result of domain adaptation between actual images and synthetic images using weights obtained during transfer learning. Based on those results, we verify whether the amount of training data can be expanded quantitatively and qualitatively. Experiment results obtained from two open benchmark datasets and our original benchmark dataset demonstrated that our proposed method outperforms the previous method under a guarantee of sufficient accuracy for the synthetic images.

Restacking-inhibited nitrogen-incorporated mesoporous reduced graphene oxides for high energy supercapacitors

Kota, Manikantan,Park, Ho Seok Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.3

<P><B>Abstract</B></P> <P>Graphene is considered a promising active electrode material due to a large surface area, high electronic conductivity, and chemical and mechanical stabilities for supercapacitor (SC) applications. However, the current bottleneck is the fabrication of restacking-inhibited graphene on an electrode level which otherwise loses the capability to achieve the aforementioned properties. Herein, we demonstrate the synthesis of restacking-inhibited nitrogen (N)-incorporated mesoporous graphene for high energy SCs. The melamine-formaldehyde acts as a restacking inhibitor by forming a bonding with reduced graphene oxide (RGO) through a condensation reaction and as an N precursor to be decomposed to create open pores and N sources upon heat treatment. The d-spacing increases up to 0.352nm and the surface area is as high as 698m<SUP>2</SUP> g<SUP>−1</SUP> with high mesoporosity, confirming restacking inhibition by N incorporation decomposed by melamine-formaldehyde. The restacking-inhibited RGO-based SC cells in organic electrolyte show the specific capacitance of 25.8Fg<SUP>−1</SUP>, the energy density of 21.8kWkg<SUP>−1</SUP> and 85% of capacitance retention for 5000 cycles, which are better than those of pristine RGO-based cells. These improved SC performances are attributed to the fast ion transport through a mesoporous channel in crumpled structure and the doping effect of N incorporation. This work provides a simple yet effective chemical approach to fabricate restacking-inhibited RGO electrodes for improved SC performances.</P>

Improving energy density of supercapacitors using heteroatom-incorporated three-dimensional macro-porous graphene electrodes and organic electrolytes

Kota, Manikantan,Jana, Milan,Park, Ho Seok Elsevier 2018 Journal of Power Sources Vol.399 No.-

<P><B>Abstract</B></P> <P>The synthesis of nitrogen- and sulfur-doped three-dimensional (3D) graphene architectures further treated by steam activation to increase surface area is reported in this study. Tetraethylammonium tetrafluoroborate (TEABF<SUB>4</SUB>) in propylene carbonate as an organic electrolyte is used to enlarge the voltage range of a supercapacitor (SC) for high energy density. The 3D nitrogen- and sulfur-doped, steam activated, reduced graphene oxides (N-SRGO and S-SRGO) contained 7.84% and 6.93% of N and S heteroatoms and feature 497 m<SUP>2</SUP> g<SUP>−1</SUP> and 525 m<SUP>2</SUP> g<SUP>−1</SUP> of surface area due to hieratical porosity of the substance. As shown in the galvanic charge/discharge curves, a range of 0–2.5 V in the 3D N-SRGO architectures showed the highest capacitance of 23.1 F g<SUP>−1</SUP>, delivering maximum energy and power densities of up to 20 W h kg<SUP>−1</SUP> and 6190 W kg<SUP>−1</SUP>. The rate capability and cycle stability over 5000 cycles were evaluated to be 63% and 68%, respectively, for N-SRGO. This study provides a systematic way to improve energy density of SCs by combining heteroatom-doped 3D graphene architecture with an organic TEABF<SUB>4</SUB>/PC electrolyte.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The 3D hieratically porous doped graphene architecture is constructed. </LI> <LI> Heteroatoms are uniformly distributed onto the 3D graphene surface. </LI> <LI> A full cell supercapacitor is fabricated using organic electrolytes. </LI> <LI> Energy density of cell is enhanced improving specific capacitance and potential window. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A diverse assemblage of moths feeding on aphid honeydew

Kota Sakagami,Shinji Sugiura 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Adult butterflies and moths (Lepidoptera) use their proboscises to feed on flower nectar and other types of liquidfood. Aphids frequently secrete honeydew from their anuses, attracting various types of insects, such as ants. Adult lepidopterans are also known to feed on aphid honeydew. However, very few studies have clarified thespecies composition and morphology of moths feeding on aphid honeydew. In late June 2017, we found nocturnalmoths sipping honeydew secreted by Shivaphis celti and Sitobion cornifoliae (Hemiptera: Aphididae) onleaves of Celtis sinensis (Cannabaceae) and Cornus kousa (Cornaceae), respectively, at the edge of a secondaryforest in central Japan. The moths were observed to uncoil their proboscises and feed on honeydew on theleaves. No moths were observed to feed on honeydew directly from aphids. Nocturnal moths of 60 species (11families) and 16 species (7 families) were collected from honeydew on Ce. sinensis and Co. kousa leaves, respectively. Eleven moth species were shared between the two types of honeydew. The most abundant species,Oncocera semirubella (Lepidoptera: Pyralidae), accounted for 44.7% of all individuals. The sex ratio of O. semirubellawas female biased. Of the 65 moth species collected on aphid honeydew, 52.3% (34 species) have beenpreviously reported to visit flowers. Moths visiting honeydew had relatively short proboscises and small bodysize. These results suggest that aphid honeydew is an important, accessible food resource for moths of small size.