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SSRN 2024年

作者： Santos, Jakeline RAIANE DORA DOS Raimundo, Rafael A. de Oliveira, João F.G.A. Hortencio, Johnnys da S. Loureiro, Francisco J.A. Macedo, Daniel A. Morales, Marco A. Gualandi, Isacco Tonelli, Domenica Gomes, Uílame U. Materials Science and Engineering Postgraduate Program UFRN Natal59078-970 Brazil Department of Industrial Chemistry "Toso Montanari" Industrial Chemistry UNIBO V.le Risorgimento 4 Bologna40136 Italy Department of Theoretical and Experimental Physics Federal University of Rio Grande do Norte UFRN Natal59078-970 Brazil Gleb Wataghin Institute of Physics - R. Sérgio Buarque de Holanda 777 - Cidade Universitária Campinas13083-859 Brazil Department of Chemistry Federal University of Paraíba UFPB João Pessoa58.051-900 Brazil TEMA - Centre for Mechanical Technology and Automation Mechanical Engineering Department University of Aveiro 3810-193 Portugal LASI - Intelligent Systems Associate Laboratory Portugal Materials Science and Engineering Postgraduate Program Federal University of Paraíba UFPB João Pessoa58051-900 Brazil

Global energy consumption increases year after year, causing the depletion of non-renewable sources. According to the International Energy Agency (IEA), global demand for electrical energy is expected to increase by 3.3% in 2024. Therefore, developing new renewable sources is urgent, including new devices for energy storage and conversion, particularly those governed by electrochemical reactions. Water splitting is a clean and sustainable technology capable of facing this issue by producing oxygen and hydrogen from water and electricity. However, a problem related to this technology is the slow kinetics, making it necessary to develop new electrocatalysts with high electrochemical performance. To meet this requirement, this work deals with for the first time a high entropy oxide with rock-salt structure synthesized by a green solgel synthesis using red seaweed (Rhodophyta) as polymerizing agent. Solgel synthesis allows the large-scale production of nanomaterials with high uniformity and dispersion of the chemical elements involved. The literature, which discussed the production of these oxides, reveals that agents harmful to the environment are applied during the synthesis steps, including sodium hydroxide, acetic acid, hexadecyltrimethylammonium bromide, urea, and ammonia. The composition of the high entropy oxide is (Mg0.2 Ni0.2 Co0.2 Cu0.2 Zn0.2 )O, it displays a low overpotential (336 mV vs. RHE at 10 mA cm-2 ), Tafel slope of 68 mV dec-1 , and excellent durability. The electrochemical performance of the high entropy oxide prepared in this work is superior to other electrocatalysts of the same class that were produced using transition metal-based precursors. © 2024, The Authors. All rights reserved.

关键词： Entropy

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Thermophysical properties of graphene-based nanofluids

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International Journal of Thermofluids 2021年 10卷

作者： Elsaid, Khaled Abdelkareem, Mohammad Ali Maghrabie, Hussein M. Sayed, Enas Taha Wilberforce, Tabbi baroutaji, Ahmad Olabi, A.G. Chemical Engineering Program Texas A& M University College StationTX United States Dept. of Sustainable and Renewable Energy Engineering University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates Center for Advanced Materials Research University of Sharjah PO Box 27272 Sharjah United Arab Emirates Chemical Engineering Department Minia University Elminia Egypt Department of Mechanical Engineering Faculty of Engineering South Valley University Qena83521 Egypt Mechanical Engineering and Design Aston University School of Engineering and Applied Science Aston Triangle BirminghamB4 7ET United Kingdom School of Engineering Faculty of Science and Engineering University of Wolverhampton Telford United Kingdom

Heat transfer operations are very common in the process industry to transfer a huge amount of thermal energy, i.e., heat, from one fluid to another for different purposes. Many fluids are used as heat transfer fluid (HTF), in which water is the most common HTF due to its high specific heat, availability, and affordability. However, conventional HTFs, including water, have a lower thermal conductivity, which is the most critical thermophysical property, hence decreased heat transfer efficiency. The addition of solid particles of highly thermally conductive material, specifically at nano-size, i.e., nanoparticles NPs, result in nanofluid NF, which has evolved over the last two decades as efficient HTF and have been investigated in a wide range of applications. Among NPs, graphene (Gr) based materials have shown very high potential as NF due to the very high thermal conductivity up to 5,000 W/m.K, hence higher thermal conductivity NF. This work aims to thoroughly discuss the thermophysical properties of Gr-based NFs, including thermal conductivity, heat capacity, density, and viscosity. The discussion focus on the thermophysical properties as it is the ultimate determinator of the heat transfer characteristics of the HTF, such as the convective and the overall heat transfer coefficient as well as the heat transfer capacity of the NF. The discussion expands to the relative enhancement in such thermophysical properties reaching up to a 40% increase in thermal conductivity, as the most critical thermophysical property. The discussion shows that Gr-based NF has a much higher thermal conductivity relative to widely studied metal oxide NF and at much lower content, and lower density and viscosity increase, which is critical for determining the pumping power requirements. Critical challenges facing the application of Gr-based NFs such as cost, stability, increased density and viscosity, and environmental impacts are thoroughly discussed with mitigation recommendations given.

关键词： Graphene

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Photoluminescence of bismuth Germanate Phosphors with a Silica-shell Structure

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Physics Procedia 2012年 29卷 91-96页

作者： M.J. Oviedo J.K. Han O. Contreras Z.S. Macedo G.A. Hirata J. McKittrick Programa de Posgrado en F'sica de Materiales CICESE-UNAM carretera Ensenada-Tijuana No. 3918 Ensenada B.C. MŽxico University of California at San Diego Materials Science and Engineering Program La Jolla CA 92093-0418 Centro de Nanociencias y Nanotecnolog’a UNAM Ensenada B.C. MŽxico Departamento de F'sica Universidade Federal de Sergipe Sao Cristva SE Brazil University of California at San Diego Mechanical and Aerospace Engineering La Jolla CA 92093-0411

An intense bluish-white emitting phosphor bi 4 Ge 3 O 12 (bGO) was synthesized by tartaric acid-assisted solgel method and covered with a SiO 2 nanolayer by the sol-gel method. The cubic crystal structure of bGO was confirmed by X-ray diffraction. Transmission electron microscopy analysis revealed the particle size to be in the range of 6-20 nm. Under excitation with 4.3 eV photons the bGO powders showed a PL contribution centered at 2.43 eV that corresponds to the typical bGO luminescence associated with 3 P 1 à 1 S0 of bi 3+ electron transitions. Radioluminescence measurements showed the predominant emission centered at 2.43 eV due to the intra-ionic bi3+ transitions. The PL emission of the silica coated bGO nanoparticles presented a luminescence enhancement of more than 200% compared with the uncoated nanoparticles. This enhancement in photoluminescence is proposed to be related to the reflectivity (refractive index) between air-silica-bGO layers.

关键词： bismuth germanate sol-gel silica coating photoluminescence

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Geometrical effect coupled with nanofluid on heat transfer enhancement in heat exchangers

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International Journal of Thermofluids 2021年 10卷

作者： Olabi, A.G. Wilberforce, Tabbi Sayed, Enas Taha Elsaid, Khaled Rahman, S.M.Atiqure Abdelkareem, Mohammad Ali Department of Sustainable and Renewable Energy Engineering University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates Mechanical Engineering and Design Aston University School of Engineering and Applied Science Aston Triangle BirminghamB4 7ET United Kingdom Center for Advanced Materials Research University of Sharjah PO Box 27272 Sharjah United Arab Emirates Chemical Engineering Department Minia University Elminia Egypt Chemical Engineering Program Texas A& M University College StationTX United States

This investigation summarized the application of nanofluids (NFs) in heat exchangers (HExs) with different geometries. The quest for heat devices with quick response for the industrial sector is still a major challenge that has been an active research direction over the years. Addressing this issue is likely to increase the capacity of several industries. There is a direct relationship between expanding the heat capacity and the pressure drop. The common approach in increasing the rate of heat transfer often leads to an increment in pressure drop. This study reviews and summarizes the investigations on various geometrical effects inside the channel combined with NF in HExs. This review explored the potential of NFs as possible heat transfer fluid in HExs. From a detailed literature review compiled and evaluated, it has been deduced that NFs application significantly improves the thermal efficiency of HExs. The investigation further evaluated plate, helical, as well as shell and tube HExs. The review explored NFs application in HExs and how they can significantly improve the HExs' thermal characteristics. It was deduced that the use of NFs improved the heat transfer both experimentally and numerically. This equally has a direct relation to energy savings as well as industrial waste heat. © 2021 The Author(s)

关键词： Heat exchangers

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Estimation of the main air pollutants from different biomasses under combustion atmospheres by artificial neural networks

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Chemosphere 2024年 352卷 141484页

作者： Monteiro, Thalyssa Oliveira Alves, Pedro Augusto Araújo da Silva de Almeida Nava barradas Filho, Alex Oliveira Villa-Vélez, Harvey Alexander Cruz, Glauber Postgraduate Program in Mechanical Engineering (PPGMEC) Department of Mechanics and Materials Federal Institute of Education Science and Technology of Maranhão (IFMA) Maranhão São Luís Brazil Postgraduate Program in Computer Science and Computational Mathematics (PPG-CCMC) Department of Computer Science University of São Paulo (USP) São Carlos São Paulo Brazil Data Analysis and Artificial Intelligence Laboratory (DARTi) Department of Computational Engineering Federal University of Maranhão (UFMA) Maranhão São Luís Brazil Department of Chemical Engineering Federal University of Maranhão (UFMA) Maranhão São Luís Brazil Processes and Thermal Systems Laboratory (LPSisTer) Department of Mechanical Engineering Federal University of Maranhão (UFMA) Maranhão São Luís Brazil

The production of biofuels to be used as bioenergy under combustion processes generates some gaseous emissions (CO, CO2, NOx, SOx, and other pollutants), affecting living organisms and requiring careful assessments. H... 详细信息

The production of biofuels to be used as bioenergy under combustion processes generates some gaseous emissions (CO, COb>2b>, NOb>xb>, SOb>xb>, and other pollutants), affecting living organisms and requiring careful assessments. However, obtaining such information experimentally for data evaluation is costly and time-consuming and its in situ obtaining for regional biomasses (e.g., those from Northeast brazil (NEb) is still a major challenge. This paper reports on the application of artificial neural networks (ANNs) for the prediction of the main air pollutants (CO, COb>2b>, NO, and SOb>2b>) produced during the direct biomass combustion (Nb>2b>/Ob>2b>:80/20%) with the use of ultimate analysis (carbon, hydrogen, nitrogen, sulfur, and oxygen). 116 worldwide biomasses were used as input data, which is a relevant alternative to overcome the lack of experimental resources in NEb and obtain such information. Cross-validation was conducted with k-fold to optimize the ANNs and performance was analyzed with the use of statistical errors for accuracy assessments. The results showed an acceptable statistical performance for all architectures of ANNs, with 0.001–12.41% MAPE, 0.001–5.82 mg Nm⁻³ MAE, and 0.03–52.30 mg Nm⁻³ RMSE, highlighting the high precision of the emissions studied. On average, the differences between predicted and real values for CO, COb>2b>, NO, and SOb>2b> emissions from NEb biomasses were approximately 0.01%, 10⁻⁶%, 0.14%, and 0.05%, respectively. Pearson coefficient provided consistent results of concentration of the ultimate analysis in relation to the emissions studied and effectiveness of the test set in the developed models. © 2024 Elsevier Ltd

关键词： brazilian northeastern Environmental statistics Evaluation metrics Gaseous emissions Predictive models Thermoconversion

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X-Ray Induced Degradation During Xps Analysis of Dicarboxylic Acid Powders

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SSRN 2023年

作者： Ferreira, José Mario Trindade, Gustavo F. Simonelli, George de Moraes Pires, Carlos Augusto Da Silva, Ana Cristina Morais Rossi, Jesualdo Luiz dos Santos, Luiz Carlos Lobato Johnson, Patrick Alfred Department of Materials Science and Engineering Iowa State University AmesIA50011 United States Faculty of Engineering and Physical Sciences University of Surrey SurreyGU2 7XH United Kingdom National Physical Laboratory Middlesex TeddingtonTW11 0LW United Kingdom Chemical Engineering Postgraduate Program Federal University of Bahia 40210-630 Brazil Nuclear and Energy Research Institute - IPEN São Paulo05508-000 Brazil University of Wyoming United States

It is widely recognized that exposure to X-rays during XPS analysis can decompose different materials, resulting in mass loss and changes in chemical composition. These effects are evident in the near-edge X-ray absorption structure spectra of dicarboxylic acid powders, posing a fundamental limit to sensitivity for surface chemical analysis. Understanding the chemistry and kinetics of radiation decomposition is necessary for the accuracy and validation of XPS analysis on dicarboxylic acids. Here we evaluate the impact of X-ray exposure on characterizing chemical changes in three different dicarboxylic acids with varying aliphatic carbon chain lengths. From this investigation we propose straightforward correlations relating the tendency for radiation-induced decomposition based on the chemical structure of the acids. We employed two types of spectra, those acquired with minimal interaction (snapshot) and high-resolution spectra obtained over an extended period, to show that normal analysis conditions are likely to degrade these type of materials. © 2023, The Authors. All rights reserved.

关键词： X ray photoelectron spectroscopy

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Thermal conductivity of indium arsenide nanowires with wurtzite and zinc blende phases

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Physical Review b 2011年第20期83卷 205416-205416页

作者： Feng Zhou Arden L. Moore Jessica bolinsson Ann Persson Linus Fröberg Michael T. Pettes Huijun Kong Lew Rabenberg Philippe Caroff Derek A. Stewart Natalio Mingo Kimberly A. Dick Lars Samuelson Heiner Linke Li Shi Materials Science and Engineering Program The University of Texas at Austin Austin Texas 78712 USA Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Solid State Physics Lund University Box 118 S-22100 Lund Sweden Physics Department and Materials Science Institute University of Oregon Eugene Oregon 97403 USA Institut d’Electronique de Microélectronique et de Nanotechnologie UMR CNRS 8520 Avenue Poincaré B.P. 60069 F-59652 Villeneuve d’Ascq France Cornell Nanoscale Facility Cornell University Ithaca New York 14850 USA CEA LITEN F-38054 Grenoble France University of California at Santa Cruz Jack Baskin School of Engineering Santa Cruz California 95064 USA Polymer & Materials Chemistry Box 124 Lund University S-22100 Lund Sweden

The thermal conductivity of wurtzite and zinc blende indium arsenide nanowires was measured using a microfabricated device, with the crystal structure of each sample controlled during growth and determined by transmission electron microscopy. Nanowires of both phases showed a reduction of the thermal conductivity by a factor of 2 or more compared to values reported for zinc blende indium arsenide bulk crystals within the measured temperature range. Theoretical models were developed to analyze the measurement results and determine the effect of phase on phonon transport. branch-specific phonon dispersion data within the discretized first brillouin zone were calculated from first principles and used in numerical models of volumetric heat capacity and thermal conductivity. The combined results of the experimental and theoretical studies suggest that wurtzite indium arsenide possesses similar volumetric heat capacity, weighted average group velocity, weighted average phonon-phonon scattering mean free path, and anharmonic scattering-limited thermal conductivity as the zinc blende phase. Hence, we attribute the differing thermal conductivity values observed in the indium arsenide nanowires of different phases to differences in the surface scattering mean free paths between the nanowire samples.

关键词： THERMAL conductivity INDIUM arsenide NANOWIRES WURTZITE SPHALERITE MICROREACTORS ELECTRON microscopy

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DEVELOPMENT AND CERTIFICATION OF HSLA-100 STEEL FOR NAVAL SHIP CONSTRUCTION - REPLY

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NAVAL ENGINEERS JOURNAL 1990年第4期102卷 103-104页

作者： CZYRYCA, EJ LINK, RE WONG, RJ AYLOR, DA MONTEMARANO, TW GUDAS, JP Ernest J. Czyryca:is a research project leader in the Metals and Welding Division of the David Taylor Research Center. He participated in the cooperative education program at the Center with Drexel University graduating in 1965 with a B.S. degree in metallurgical engineering. He has since received a B.S. degree in civil engineering in 1969 from Johns Hopkins University and an M.S. degree in engineering mechanics in 1970 from the Pennsylvania State University. In his career at the Center he has been involved in or managed major development programs in naval structural metals alloys for machinery applications failure analyses and fatigue and fracture research. Richard E. Link:is a mechanical engineer in the Metals and Welding Division of the David Taylor Research Center. He received his B.S. and M.S. degrees in Mechanical Engineering from the University of Maryland in 1984 and 1985 respectively. His work at the Center includes participation in structural and machinery alloy development programs and research in elastic-plastic fracture mechanics analysis methods. He is an active member of ASTM Committee E-24 on Fracture Testing and the Society for Experimental Mechanics. Richard J. Wong:is a metallurgist in the Metals and Welding Division of David Taylor Research Center. He received his B.S. in materials science from the University of California Berkeley in 1979 and a M.S. degree in engineering science from Catholic University in 1984. His work at the Center includes advanced joining processes weld process development and weldability analysis of naval structural materials. Denise A. Aylor:is a materials engineer in the Metals and Welding Division of the David Taylor Research Center. She received her B.S. degree in materials engineering from Virginia Tech in 1980 and her M.S. degree in materials science and engineering from The Johns Hopkins University in 1984. Her work at the Center has focused on corrosion and corrosion control research of various Navy metallic alloys and of composite materials. Thomas W. M

A significant tonnage of HY-100 steel has been used in the structural designs of new ships and submarines for weight reduction, where HT and HY-80 steels had been previously used. A reduction in hull fabrication costs and higher productivity can be achieved by substitution of an HSLA steel for HY-100. The significant factor in cost savings through use of HSLA steel in fabrication is the reduction or elimination of preheat for welding. based on the success of the HSLA-80 steel system, a program was initiated to develop and certify an HSLA-100 steel as a replacement for HY-100 in order to reduce fabrication costs. The alloy development and evaluation to support the certification of HSLA-100 steel plate and weldments for surface combatant structural and ballistic protection applications are summarized. HSLA-100 development consisted of three phases: (1) laboratory alloy development to formulate an interim specification; (2) trial steel mill plate production; and (3) plate production for the certification program. An interim specification for HSLA-100 steel plate was used as the basis for the commercial production of over 200 tons of HSLA-100 by domestic steel plate mills. The alloy design of HSLA-100 represents a significantly different metallurgy and microstructure than HSLA-80 steel, but retains the wettability of very low carbon steel. The certification program was conducted to establish the properties, welding characteristics, fabricability, and structural performance of HSLA-100 steel plate over a range of gages from 1/4 to 3 3/4 inches. The certification program included the characterization of production HSLA-100 steel plate mechanical, physical, and fracture properties; evaluation of wettability and welding process limits for structures of high restraint; studies of fatigue properties and effects of marine environments on HSLA-100; and the fabrication and evaluation of large scale structural models to validate the laboratory developed welding process parameters

关键词： Shipbuilding materials

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Magnetic structure and field-induced transitions in the triangular spin-1 antiferromagnet NiNb2O6: Observation of a triple point

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Physical Review b 2023年第22期108卷 224430-224430页

作者： Maruthi R Sobhit Singh Sayandeep Ghosh Mohindar S. Seehra bruno Weise Wilfrid Prellier Subhash Thota Department of Physics Indian Institute of Technology Guwahati Assam 781039 India Department of Physics B.M.S. College of Engineering Bangalore 560019 Karnataka India Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Department of Physics Chungnam National University Daejeon 34134 Republic of Korea Department of Physics Kunsan National University Gunsan 54150 Republic of Korea Department of Physics & Astronomy West Virginia University Morgantown West Virginia 26506 USA Leibniz-IFW Dresden Institute for Complex Materials D-01069 Dresden Germany CRISMAT laboratory Normandy University ENSICAEN UNICAEN National Center for Scientific Research 14000 Caen France

A comprehensive experiment-theory study on the magnetic field-induced spin-flip transitions (HC1 and HC2) and the field-temperature (H−T) phase diagram of nickel niobate (NiNb2O6) polycrystals is reported. Magnetic susceptibility (χ) measurements reveal the presence of quasi-one-dimensional magnetism with spin-1 Ni2+ Heisenberg spin chains, instead of Ising chains, along the easy axis (c axis). The ferromagnetic intrachain exchange-interaction strength, J0/kb (=4.20 K), between Ni2+ ions in the c axis is estimated from the molecular-field theory approximation. The interchain exchange interactions J1/kb=−1.335 K and J2/kb=−1.298 K have been determined from the experimentally obtained magnitudes of HC1=10.8 kOe and spin-saturated field HS=38 kOe. These magnitudes are consistent with the total magnetic exchange-interaction strength, J/kb=7.00 K obtained from χ−T data fitted with the Heisenberg linear chain model and our density-functional theory (DFT+U) calculations. The overall antiferromagnetic behavior of the NiNb2O6 system, correctly captured within our DFT+U calculations, occurs below TN=5.59±0.02 K as determined from the analysis of the specific heat (CP−T) data. The CP vs T data near TN is fitted to power-law expression CP=A|T−TN|−α yielding the critical exponent α=0.349(2) [0.349(1)] for T>TN (Tblished sources.

关键词： Magnetic interactions Magnetic phase transitions Magnetism Structural properties

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Phase and crystallite size analysis of (Ti1-xMox)C-(Ni,Cr) cermet obtained by mechanical alloying

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AIP Conference Proceedings 2018年第1期1945卷

作者： Suryana Muhammad Anis Azwar Manaf 1Materials Science Postgraduate Program Physics Department Universitas Indonesia Jl. Salemba Raya No.4 Jakarta 10430 Indonesia 2Department of Metallurgy and Materials Engineering Universitas Indonesia Depok 16424 Indonesia

In this paper, we report the phase and crystallite size analysis of (Ti1-xMox)C-(Ni,Cr) with x = 0-0.5 cermet obtained by mechanical alloying of Ti, Mo, Ni, Cr and C elemental powders using a high-energy shaker ball mill under wet condition for 10 hours. The process used toluene as process control agent and the ball to mass ratio was 10:1. The mechanically milled powder was then consolidated and subsequently heated at a temperature 850°C for 2 hours under an argon flow to prevent oxidation. The product was characterized by X-ray diffraction (XRD) and scanning electron microscope equipped with energy dispersive analyzer. Results shown that, by the selection of appropriate condition during the mechanical alloying process, a metastable Ti-Ni-Cr-C powders could be obtained. The powder then allowed the in situ synthesis of TiC-(Ni,Cr) cermet which took place during exposure time at a high temperature that applied in reactive sintering step. Addition to molybdenum has caused shifting the TiC XRD peaks to a slightly higher angle which indicated that molybdenum dissolved in TiC phase. The crystallite size distribution of TiC is discussed in the report, which showing that the mean size decreased with the addition of molybdenum.

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