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MgAl2O4 foams obtained by combustion synthesis

Chemical engineering Transactions 2015年 43卷 1801-1806页

作者： Moraes, Graziela G. Pozzobom, Ida E.F. Fernandes, Celso P. Novaes De Oliveira, Antonio P. Graduate Program in Materials Science and Engineering - PGMAT Laboratory of Glass-Ceramic Materials - VITROCER Federal University of Santa Catarina - UFSC Florianópolis - SC88040 900 Brazil

ISBN: (纸本)9788895608341

This work aims to study magnesium aluminate (MgAl2O4) ceramic foams obtained by combustion synthesis in solution without the need of surfactants to stabilize *** ceramic suspension containing acetone (75 wt%), calcined powder (25 wt%) and a mixture of glycerine (80 % blonde glycerine and 20 % crude glycerine) in the fraction of 100 % with respect to solids was prepared in an alumina ball mill, for 60 min. Subsequently, the suspension was heated at 40 °C, for 30 min, until it became rigid. In order to promote foaming, the suspension was heated to 70 °C and then the following substances were added to it: 2.5 wt% distilled water, 25 wt% Al(NO3)3.9H2O), 12.5 wt% (Mg(NO3)2.6H2O) and 0.625 wt% of a glycerine mixture (80 % blonde glycerine and 20% crude glycerine). After additions the suspension was stirred for 5 min at 950 rpm in a mixer. The resulting foams were dried at 40 °C, for 24 h, in a muffle and fired in two steps, i.e., heating at 0.5 °C/min up to 600 °C/120 min and at 5 °C/min up to 1600 °C/120 *** obtained materials were characterized by SEM,TEM and from tomographic images. The results showed that the obtained magnesium aluminate foams have a high porosity (97 %), a high connectivity and pore sizes (diameters) between 30 and 1200 μm. Copyright © 2015, AIDIC ServiziS.r.l.

关键词： Pore size

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Production and characterisation of glass foams for thermal insulation

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Chemical engineering Transactions 2015年 43卷 1777-1782页

作者： Dias, Gabriella M.V. Arcaro, Sabrina Cesconeto, Francielly R. De Oliveira Maia, Bianca G. Pereira, Fabiano R. Novaes De Oliveira, Antonio P. Graduate Program in Materials Science and Engineering - PGMAT Laboratory of Glass-Ceramic Materials - VITROCER Federal University of Santa Catarina - UFSC Florianópolis-SC88040-900 Brazil

ISBN: (纸本)9788895608341

In this work, glass compositions from glass bottles with different colours and graphite (2 - 12 vol%) as the pore-forming agent were prepared for the production of materials with controlled porosity for applications where thermal and acoustic insulations are main technical requirements. The formulated compositions were, in a later stage, uniaxially pressed (40 MPa) and fired at different temperatures (800 - 950 °C) and cycles with holding times between 15 and 120 minutes. The results showed that it is possible to produce glass foams for thermal insulation from optimized compositions containing 90 vol% glass and 10 vol% graphite, fired between 800 and 950 °C for 30 minutes, which showed porosities between 53 and 76 %, with thermal conductivities between 0.16 and 0.08 W/mK and compressive strength between 20 and 4.6 MPa. The obtained glass foams are strong candidates for applications requiring thermal insulation with suitable combination of thermal conductivity, porosity and mechanical strength. Copyright © 2015, AIDIC Servizi S.r.l.

关键词： Thermal insulation

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A case study on statistical characterization and optimization of coercivity in cobalt ferrite nanoparticles

A case study on statistical characterization and optimizatio...

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作者： Cedeño-Mattei, Y. Sánchez-Peña, M.L. Lara-Rodríguez, Y. Perales-Pérez, Ó. Cabrera-Ríos, M. Engineering Science and Materials Department University of Puerto Rico at Mayagüez Mayagüez Puerto Rico Industrial Engineering Department University of Puerto Rico Mayagüez Mayagüez 00681-9000 Puerto Rico Graduate Program in Systems Engineering University of Nuevo León Nuevo León Mexico

Characterization and optimization of material properties during synthesis and processing are frequent problems in materials science and engineering. In the present paper, the use of design of experiments (DOE) to characterize and improve coercivity in cobalt ferrite nanoparticles is described. The sequence of experiments was planned to capitalize on previous experimental runs available. Emphasis is placed on the rationale for choosing the additional runs. The results reveal that the choice of an adequate initial experimental design can save effort and resources in arriving at useful conclusions upon which subsequent experimental runs can be planned, capitalizing on the initial experimental structure. A region with attractive solutions in terms of coercivity, including a local maximum, was identified through the experimental sequences described in this case study. © 2011 Authors.

关键词： Design of experiments

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Developing an atomic-level understanding of the mechanisms that govern CO2 sequestration mineral carbonation reaction processes

Developing an atomic-level understanding of the mechanisms t...

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2005 TMS Annual Meeting

作者： McKelvy, Michael J. Chizmeshya, Andrew V. G. Diefenbacher, Jason Béarat, Hamdallah Carpenter, R.W. Wolf, George Gormley, Deirdre Center for Solid State Science Arizona State University Tempe AZ 85287 United States Science and Engineering of Materials Graduate Program Arizona State University Tempe AZ 85287 United States Department of Chemistry and Biochemistry Arizona State University Tempe AZ 85287 United States

Mineral carbonation is an emerging CO2 sequestration candidate technology, which produces environmentally benign and geologically stable materials. The primary challenge is economically viable process development. Serpentine and olivine minerals are candidate feedstock materials of interest, due to their wide availability, low-cost, and rapid mineral carbonation potential. Cost-effectively enhancing their carbonation reactivity is critical to reducing mineral sequestration process cost. We will discuss our recent research into the mechanisms that govern serpentine and olivine mineral carbonation reaction processes, including in situ observations of the mineral carbonation process and a novel mechanistic approach to enhance carbonation reactivity that avoids the cost of mineral activation. Our goal is to develop the necessary atomic-level understanding to engineer improved carbonation materials and processes to reduce process cost.

关键词： Chemical reactions

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Assessment of the Morphology and Interaction of PHBV/Clay Bionanocomposites: Uses as Food Packaging

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Macromolecular Symposia 2016年第1期367卷 113-118页

作者： da Costa Reis, Dilson Cristino Lemos Morais, Ana Carolina de Carvalho, Laura Hecker Alves, Tatianny Soares Barbosa, Renata Federal University of Piauí Graduate Program in Materials Science Polymers and Conjugated Materials Research Group Av. Ininga S/N Ininga Teresina PiauíCEP 64049-550 Brazil Department of Materials Engineering Federal University of Piauí Technology Center TeresinaPiauí Brazil Federal University of Campina Grande Center Science and Technology Graduate Program in Materials Science and Engineering Campina GrandeParaíba Brazil

The production of plastic waste has caused serious environmental impacts. Since the conventional polymers represent one of the largest percentages of waste, a possible solution for this environmental problem is the use of nanoclay-biopolymers for the preparation of food packaging. The objective of this study was to evaluate the morphological structure of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites and vermiculite through scanning electronic microscopy (SEM) and to verify their packaging/food interaction through the total migration test. The systems were prepared with natural clay and organophilic clay by melt intercalation technique. The migration test was carried out according to the Resolution 105/99 by ANVISA. The SEM micrographs showed a small number of agglomerates for the natural systems and a more uniform structure for the organophilic systems. The migration results of all systems were within the maximum allowable limit for food packages, indicating a possible use of these materials without causing damage to food security. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： Biopolymers

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Study of Machine Learning Techniques for Damage Identification in a Beam 10th

Study of Machine Learning Techniques for Damage Identifica...

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10th International Conference on Wave Mechanics and Vibrations, WMVC 2022

作者： da Silva Coelho, Jefferson de Sousa, Amanda Aryda Silva Rodrigues Machado, Marcela Rodrigues Dutkiewicz, Maciej Department of Mechanical Engineering University of Brasília Campus Universitário Darcy Ribeiro Faculdade de Tecnologia - Asa Norte DF Brasília Brazil Post-Graduate Program - Integrity of Engineering Materials University of Brasília Campus Universitário Darcy Ribeiro Faculdade de Tecnologia - Asa Norte DF Brasília70910-900 Brazil Faculty of Civil Environmental Engineering and Architecture University of Science and Technology Bydgoszcz85-796 Poland

ISBN: (纸本)9783031157578

Damage is defined as any change to the material, geometry or boundary condition that can modify the structure’s properties or response. In the past, damage identification was performed through periodical inspection, non-destructive testing/non-destructive evaluation, or visual observation. Structural health monitoring (SHM) has emerged to transition from offline damage identification to near real-time and online damage assessment. Hence, SHM is a damage detection strategy to monitor a structure for a period using a series of continuous measurement devices, which then collect the system’s characteristics and subsequently perform statistical analysis to assess the current circumstances and health of the structure. One of the first steps for the study of SHM is damage detection followed by monitoring. Machine Learning (ML) techniques can be used to develop viable algorithms to make potential predictions. ML algorithms are therefore providing the tools needed to enhance the capabilities of SHM systems and provide intelligent solutions to past challenges. Preliminary studies have reviewed that the extension of ML into SHM has dramatically increased the system’s capabilities, providing innovative solutions to different research challenges. This work conducts a study of the use of ML to identify damage in a beam and discuss the challenge of usage, performance and implementation of each technique. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Decision trees

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Biomass-Based Discrete Furan Oligomers as materials for Electrochromic Devices

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ACS Sustainable Chemistry and engineering 2024年第1期12卷 459-469页

作者： Atayde, Eduardo C. Fong, Guan-Lun Yeh, Jyun-Yi Matsagar, Babasaheb M. Wang, Yu-Cheng Chen, De-Chian Peng, Chi-How Li, Yi-Pei Yamauchi, Yusuke Ho, Kuo-Chuan Wu, Kevin C.-W. Molecular Science and Technology Program Taiwan International Graduate Program (TIGP-MST) Academia Sinica No. 128 Sec. 2 Academia Road Taipei 11529 Taiwan Department of Chemistry National Tsing Hua University No. 101 Sec. 2 Kuang-Fu Road Hsinchu 30013 Taiwan Department of Chemical Engineering National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei 10617 Taiwan Sustainable Chemical Science and Technology Program Taiwan International Graduate Program (TIGP-SCST) Academia Sinica No. 128 Sec. 2 Academia Road Taipei 11529 Taiwan School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN) The University of Queensl Brisbane 4072 QLD Australia Department of Materials Process Engineering Graduate School of Engineering Nagoya University Nagoya 464-8603 Japan Institute of Polymer Science and Engineering National Taiwan University No.1 Sec. 4 Roosevelt Rd. Taipei 10617 Taiwan Department of Chemical Engineering and Materials Science Yuan Ze University No. 135 Yuandong Rd. Taoyuan 320 Taiwan

Electrochromic devices (ECDs) are materials that can undergo reversible changes in transmittance when exposed to different applied potentials. While many conjugated heterocyclic oligomers, such as oligothiophenes, have been developed for this purpose, there is no reported study on the use of discrete oligomeric furans as ECD materials. In this work, we introduce a furan trimer that can be utilized as a discrete electrochromic material, which transitions from light yellow to red and has a very high coloration efficiency of 1940 cm²/C at 507 nm. We propose that the reversible π-stack formation of the oligomer radical cations is behind this phenomenon, as evidenced by both experimental and computational results. The derivability of this oligomer from biomass and its facile synthesis make it an interesting alternative for other existing organic electrochromic materials. © 2023 American Chemical Society

关键词： electrochromism furan oligomer hydroxyalkylation−alkylation reaction solvatochromism π-stacks

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Multi-robot Map Exploration Based on Multiple Rapidly-Exploring Randomized Trees

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SN Computer science 2024年第1期5卷 31页

作者： Mukhopadhyay, Shayok Umari, Hassan Koirala, Koshish Electrical & Computer Engineering and Computer Science Department University of New Haven 300 Boston Post Rd West Haven 06516 CT United States Department of Electrical Engineering American University of Sharjah Sharjah P.O. Box 26666 United Arab Emirates Mechatronics Engineering graduate program American University of Sharjah Sharjah P.O. Box 26666 United Arab Emirates

A map is necessary for tasks such as path planning or localization, which are common to mobile robot navigation. However, a map may be unavailable if the environment in which a robot navigates is unknown. Creating a map requires an exploration algorithm. Such algorithms guide robots to boundaries that separate known portions of a map from the unknown portions. Such boundaries are known as frontiers. There are image processing-based algorithms that detect frontiers. The authors’ previous work uses two, i.e., local and global, rapidly exploring random trees (RRTs) for two-dimensional exploration using a single robot. The present work applies the above to a multiagent system with three robots. A market-based strategy is used to allocate exploration tasks to the robots. Results show that the developed exploration strategy successfully explores a map in a reasonable amount of time compared to image processing-based approaches, and also reduces the map exploration cost. This strategy is readily usable for three-dimensional exploration with drones. It is also shown that the usage of a local frontier detector along with a global frontier detector helps reduce exploration time compared to simply using a global frontier detector alone. As an outline to future work, the paper also shows an extension of the proposed approach towards three-dimensional mapping using a single robot. © 2023, The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd.

关键词： Exploration Mapping Multi-agent Navigation ROS RRT

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Implementation of Augmented Reality in Pretend Play Therapy for Children with Autism Spectrum Disorder 3

Implementation of Augmented Reality in Pretend Play Therapy ...

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3rd International Conference on Computing and Applied Informatics 2018, ICCAI 2018

作者： Syahputra, M.F. Angkasih, A.P. Purnamawati, S. Andayani, U. Abdullah, D. Sriadhi, S. Iskandar, A. Rosida, T.M. Fitriany, J. Sari, I.N. Utama, M.D. Nanuru, R.F. Department of Information Technology Faculty of Computer Science and Information Technology Universitas Sumatera Utara Medan Indonesia Department of Informatics Universitas Malikussaleh Aceh Utara Indonesia Department of Electrical Engineering Universitas Negeri Medan Indonesia Informatics Engineering STMIK AKBA Makassar Indonesia Graduate Program in Scientific Psychology Universitas Kristen Maranatha Indonesia Department of Pediatric Universitas Malikussaleh Aceh Utara Indonesia Departement of Social Science Education Program Post Graduate Program Universitas Kanjuruhan Malang Malang Indonesia Faculty of Social and Political Science Universitas Kristen Indonesia Maluku Indonesia Universitas Kristen Indonesia Maluku Ambon Indonesia

Autism Spectrum Disorder is a pervasive developmental disorder that will affect children in terms of interpersonal communication, social interaction, and imaginative levels in play. Many therapies to help the motor neuron performance is one of them Pretend Play. Pretend Play is a therapy that invites children in playing to demonstrate something else and tell how to use objects that are considered in the child's imagination. However, in the era of highly developed technology, many fields have used the Augmented Reality method as a visualization of various aspects. With this method researchers will present the therapeutic visualization of the block to 3D transportation tool that is useful for strengthening motor nerves and visual strength of the child. The system can run well during marker detection, marker movement, and 3D object display with the accuracy of precision angle and distance between virtual world with real world reach 100% with angle 0 at distance 31 cm and the maximum distance from the marker is 46 cm and the maximum angle is 30. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Augmented reality

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Atmospheric Pressure Plasma Jet Treatment of Human Hair Fibers

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Journal of Bio- and Tribo-Corrosion 2015年第1期1卷 1-10页

作者： Öngel, Cansu Keleş, Merve Acar, Erhan Birer, Özgür Department of Chemistry Koç University Rumeli Feneri Yolu Sariyer Istanbul34450 Turkey Department of Molecular Biology and Genetics Koç University Rumeli Feneri Yolu Sariyer Istanbul34450 Turkey Materials Science and Engineering Graduate Program Koç University Rumeli Feneri Yolu Sariyer Istanbul34450 Turkey KUYTAM Surface Science and Technology Center Koç University Rumeli Feneri Yolu Sariyer Istanbul34450 Turkey

Human hair fibers in virgin and dyed forms were treated with atmospheric pressure helium, helium/oxygen, argon, and argon/oxygen plasma jets at 20 W of power. The effects of 10-min plasma treatment on surface morphology and chemistry were studied by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The plasma treatment was quite effective for removing the organic residues from the surface and creating oxidized functional groups. Helium plasma had a mild cleaning effect on the surfaces while argon/oxygen plasma had the strongest corrosive effect. Mild hydrogen peroxide treatment for the same duration had neither the cleaning nor the oxidizing power of the plasma jets. These types of plasma jets have the potential to replace peroxide treatment. The corrosive jets can be used to restore dyed hair fibers. In addition, the jets can be used to clean the surfaces of hair fibers to prepare samples for analytical investigations where the organic residues may induce problems. © 2015, Springer International Publishing AG.

关键词： Plasma jets

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