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Optics and Photonics Conference (SBFoton IOPC), SBFoton International

作者： David Esteban Farfán-Guillén João Pedro Duarte Jankosz Neri Volpato Alexandre de Almeida Prado Pohl Graduate Program in Electrical and Computer Engineering (CPGEI) Federal University Technology-Parana Curitiba Brazil Graduate Program in Mechanical Engineering and Material Science Federal University Technology-Parana. Curitiba Brazil

A new polymethyl methacrylate-based light collector has been designed and fabricated with additive manufacturing to optimize the efficiency of VLC systems. It enhances the area of detection, leading to a ~ 1.9x increa... 详细信息

ISBN: (数字)9798350388176

ISBN: (纸本)9798350388183

关键词： Optical device fabrication Optical variables measurement Three-dimensional printing Optics Optical receivers Optical sensors Reliability Visible light communication Testing Photonics

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Carbon nanotube growth from Cu–Co alloys for field emission applications

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2004年第3期22卷 1286-1289页

作者： W. Hofmeister W. P. Kang Y. M. Wong J. L. Davidson Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville Tennessee 37235 Interdisciplinary Graduate Program in Material Science and Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235 Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 37235

We have developed a method of catalyst preparation for carbon nanotube (CNT) growth that uses solid-state diffusion to precipitate Co particles in a Cu matrix and control the size and size distribution of catalyst particles. Copper is an excellent electrical and thermal conductor, and has a small or negligible solubility for Co. Cu–Co alloys of approximately 5 atm% Co were formed in bulk by splat quenching the liquid alloy and on Si substrates by e-beam evaporation of the alloy, sputtering of the alloy, and sputter deposition of thin films of pure Cu and Co. The Co easily precipitates from dilute solutions of Cu–Co with heat treatment. These alloys and films were used to generate uniform distributions of Co precipitates, and CNTs were successfully grown by plasma enhanced chemical vapor deposition (PE-CVD) and thermal CVD on the materials. These alloys can be patterned by photolithography and sputtering in order to grow CNTs in defined locations. Therefore, the technique is amenable to very large scale silicon integration for field emission applications. The results of this work and data from field emission studies are presented herein.

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Synthesis and characterization of few-layered carbon nanotubes decorated with magnetic nanoparticles envisaging potential technological applications

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Surfaces and Interfaces 2025年 66卷

作者： da Silva, Wellington Marcos da Silva, Mauro Francisco Pinheiro de Souza, Rodrigo Nunes Silva, Alysson Martins Almeida Rodrigues, Alisson Mendes Santos, Alexandre Silva da Silva, SebastiãoWilliam Mohallem, Nelcy Della Santina Coaquira, José Antonio Huamaní Graduate Program in Materials Science (PPGCIMA) Faculty UnB Planaltina (FUP) University of Brasília DF Brasilia 73.345-010 Brazil International Center of Physics Institute of Physics Campus Universitário Darcy Ribeiro University of Brasilia DF Brasilia 70.910-900 Brazil Mechanical Engineering Department Faculty of Technology Campus Universitário Darcy Ribeiro University of Brasilia DF Brasilia 70.910-900 Brazil Institute of Physics University of Brasilia Campus Universitário Darcy Ribeiro DF Brasilia 70.910-900 Brazil Department of Chemistry Institute of Exact Sciences Federal University of Minas Gerais Belo Horizonte-MG MG 31270-901 Brazil

In this work, high-quality few-layered carbon nanotubes (CNTs) were synthesized using a novel iron-oxide/sulfur-based catalyst via the chemical vapor deposition method (CVD). To enable external magnetic control for potential technological applications, CNTs incorporating magnetic nanoparticles were also produced. An efficient synthesis route, employing a microwave-assisted reaction, was used to generate and integrate the iron oxide nanoparticles and CNTs. The synthesized nanomaterials were thoroughly characterized using X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA/DTA), transmission electron microscopy (TEM) and magnetic measurements. The results indicate that the few-layered CNTs (sample CNT-Ox) exhibit a magnetic response, which is further modified upon the incorporation of magnetic nanoparticles (sample CNT-Ox-Mag), suggesting an effective interaction between the CNTs and the magnetic nanoparticles. However, after a reduction process (sample CNT-Ox-Mag-Red), the magnetization increases approximately 20-fold compared to the other two samples. This significant enhancement reflects the presence of a substantial amount (∼48 %) of metallic iron primarily located within the CNTs channel. Raman spectroscopy revealed characteristic bands at 261 and 263 cm⁻¹, confirming the presence of single and few-layered CNTs. TEM images further demonstrate that the nanoparticles are encapsulated within the CNTs. These findings indicate the successful formation of a hybrid CNTs/magnetic nanoparticles system, which serve as a multifunctional platform with promising potential for technological applications. © 2025 Elsevier B.V.

关键词： Carbon nanotubes Magnetic nanoparticles Magnetic properties Novel catalyst Synthesis

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EXERGETIC ANALYSIS OF A SOLAR ENERGY-BASED HYDROGEN PRODUCTION SYSTEM 23

EXERGETIC ANALYSIS OF A SOLAR ENERGY-BASED HYDROGEN PRODUCTI...

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23rd World Hydrogen Energy Conference: Bridging Continents by H2, WHEC 2022

作者： Akci, Hilal Gunerhan, Huseyin Hepbasli, Arif Ege University Graduate School of Natural and Applied Science Mechanical Engineering Program Bornova Izmir35100 Turkey Ege University Faculty of Engineering Department of Mechanical Engineering Bornova Izmir35100 Turkey Yasar University Faculty of Engineering Department of Energy Systems Engineering Bornova Izmir35100 Turkey

ISBN: (纸本)9786250008430

In this study, energy, exergy and sustainability analyses are performed for a solar energy-based hydrogen production system, which is modeled with TRNSYS and engineering Equation Solver (EES) software packages. This system consists of solar photovoltaic panels (PVs), a controller, an electrolyzer, a metal hydride hydrogen tank used for hydrogen production and storage, and Proton Exchange Membrane Fuel Cell (PEMFC) for electricity storage. Dead state temperature is taken as 0 ºC. The results revealed that the PEMFC had the highest energy efficiency of 53.28%. Exergy efficiencies of the solar PV panel, the electrolyzer and the PEMFC were determined to be 9.66%, 60% and 29.39%, respectively. The exergetic sustainability index of the electrolyzer had the maximum value of 2.501. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.

关键词： Hydrogen production

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Microstructure evolution and local strengthening mechanisms in CoCrFeMnNi high entropy alloy joints reinforced with Inconel 625

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materials science and engineering: A 2025年 937卷

作者： Shen, Jiajia Yang, Jin Choi, Yeon Taek Gonçalves, Rita Pedro, Rodrigo Santana, D.A. Coury, F.G. Schell, N. Zeng, Zhi Kim, Hyoung Seop Oliveira, J.P. UNIDEMI Department of Mechanical and Industrial Engineering NOVA School of Science and Technology Universidade NOVA de Lisboa Caparica2829-516 Portugal CENIMAT/I3N Department of Materials Science NOVA School of Science and Technology Universidade NOVA de Lisboa Caparica2829-516 Portugal School of Materials Engineering Shanghai University of Engineering Science Shanghai201620 China Pohang790-794 Korea Republic of Graduate Program in Materials Science and Engineering Federal University of São Carlos Rodovia Washington Luís km 235 SP-310 São Carlos São Paulo13565-905 Brazil Helmholtz-Zentrum Hereon Institute of Materials Physics Max-Planck-Str. 1 Geesthacht21502 Germany School of Mechanical and Electrical Engineering University of Electronic Science and Technology of China Chengdu611731 China

In the fusion-based welding processes, filler materials are commonly used to adjust and improve the composition of the fusion zone with the aim of optimizing both microstructure and mechanical properties. However, in the field of welding high entropy alloys, the influence of different filler materials on the microstructure and mechanical response is still scarce, owing to the yet incipient usage of welding technologies for these novel, advanced engineering alloys. To bridge this knowledge gap, Inconel 625 filler wire was used during gas metal arc welding of the well-known CoCrFeMnNi high entropy alloy. To systematically analyze the microstructure evolution and mechanical properties of the welded joints, multiscale characterization techniques were employed. It is shown that the different regions of the welded joint possess distinct microstructural features due to the weld thermal cycle, which is further compounded in the fusion zone by the introduction of the filler material. The use of Inconel 625 filler promotes a solid solution strengthening effect in the fusion zone and became the main contributor to the yield strength of this region (302 MPa (via solid solution strengthening) vs 478 MPa (yield stress from tensile experiments). Since Hall-Petch strengthening is predominant in both base material and heat affected zone, but not on the fusion zone due to the large grain structure that developed, the addition of Inconel 625 filler demonstrates to be a feasible approach to increase the typically low fusion zone strength. By coupling microstructural characterization with mechanical property analysis, aided by the calculation of the strengthening mechanisms, we unveil processing, microstructure, property relationships, providing a broader basis for the widespread application of gas metal arc welding for high entropy alloys. © 2025 The Authors

关键词： Tensile testing

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Numerical evaluation of the pressure drop in multiphase flow of the catenary riser with the presence of leakage

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Defect and Diffusion Forum 2016年第1期366卷 157-165页

作者： De Almeida Tavares, Daniela Passos Simões Sarmento, Lígia Rafaely Barbosa Barbosa, Enivaldo Santos De Farias Neto, Severino Rodrigues De Lima, Antonio Gilson Barbosa Federal University of Campina Grande Center of Science and Technology Post Graduate Program in Chemical Engineering Campina GrandeParaíba58429-900 Brazil Federal University of Campina Grande Center of Science and Technology Petroleum Engineering Department Campina GrandeParaíba58429-900 Brazil Federal University of Campina Grande Center of Science and Technology Mechanical Engineering Department Campina GrandeParaíba58429-900 Brazil

The growing demand for oil brings the need for discovery of deeper reservoirs, especially of ultra-deepwater reservoirs. Thus, production in marine systems using components such as risers (flexible or rigid pipes) has been the focus of many studies in different areas. These ducts are used in the transportation of multiphase fluids (oil, water and gas) produced from the oil well located on the seabed to the platform surface. Due to the extreme conditions present in the offshore fields of production, the equipments that transport produced fluids operate close to their limits. So eventually, the flexible pipes may have structural integrity faults like leaks, which can cause production losses, accidents with victims and environmental disasters. The leak depends of a number of properties or parameters measured at the site of the leak, for example, integrity of the pipe material, release of fluids and noise emission characteristics or manifestation of some other type of signal behavior, variation of pressure drops close to the leak, among others. There are a variety of techniques available for detecting leaks, among which there is the mathematical modeling approach using computational techniques. In this context, this paper aims to study the fluid dynamics of a transient multiphase flow in a catenary riser in the presence of leakage. Herein a 3D Eulerian-Eulerian model was applied, including the turbulent model (RNG k-ϵ), using the commercial package ANSYS CFX® 15 to perform all simulations. The numerical results of velocity, volume fraction and pressure of the involved phases are presented and discussed. © 2016 Trans Tech Publications.

关键词： Drops

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The effects of brachial arterial stiffening on the accuracy of oscillometric blood pressure measurement: A computational model study

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Journal of Biomechanical science and engineering 2012年第1期7卷 15-30页

作者： Liang, Fuyou Liu, Hao Takagi, Shu Computational Science Research Program RIKEN 2-1 Hirosawa Wako Saitama Japan Graduate School of Engineering Chiba University 1-33 Yayoi-cho Inage-ku Chiba-shi Chiba Japan Department of Mechanical Engineering University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo Japan

Oscillometric noninvasive blood pressure measurement (ONBPM) is nowadays widely applied in health care. However, ONBPM has been found to exhibit large interindividual variability in accuracy. In the present study, we developed a theoretical model to describe the mechanics of the brachial arterial wall and particularly arterial stiffening dominated respectively by wall thickening and elastin degeneration. The model was incorporated into a cardiovascular-cuff model to investigate the effects of brachial arterial stiffening on the accuracy of ONBPM. It was found that wall-thickening-dominated arterial stiffening induced overestimate of the systolic pressure, whereas the elastin-degeneration-dominated arterial stiffening induced overestimate of both the systolic pressure and the diastolic pressure. The findings support the clinical observation that pseudo-hypertension is more prevalent in the elderly, and at the same time imply that arterial stiffness indices (e.g., compliance of artery, pulse wave velocity) assessed under the physiological pressure (generally between 70 and 150mmHg) conditions may be insufficient for assessing the accuracy of ONBPM. © 2012 by JSME.

关键词： Elastin

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Meter-scale heterostructure printing for high-toughness fiber electrodes in intelligent digital apparel

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Nature Communications 2025年第1期16卷 1-10页

作者： Lee, Gun-Hee Lee, Yunheum Seo, Hyeonyeob Jo, Kyunghyun Yeo, Jinwook Kim, Semin Bae, Jae-Young Kim, Chul Majidi, Carmel Kang, Jiheong Kang, Seung-Kyun Ryu, Seunghwa Park, Seongjun Medical Research Center Seoul National University Seoul South Korea Departments of Cogno-Mechatronics Engineering and Optics & Mechatronics Engineering Pusan National University Busan South Korea Department of Bio and Brain Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Program of Brain and Cognitive Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Graduate School of Semiconductor Technology Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Department of Materials Science and Engineering Seoul National University Seoul South Korea Department of Mechanical Engineering Carnegie Mellon University Pittsburgh PA United States Department of Chemistry Seoul National University Seoul Seoul South Korea School of Transdisciplinary Innovations Seoul National University Seoul South Korea Department of Biomedical Science College of Medicine Seoul National University Seoul South Korea Interdisciplinary Program in Bioengineering College of Engineering Seoul National University Seoul South Korea Department of Transdisciplinary Medicine Seoul National University Hospital Seoul South Korea

Intelligent digital apparel, which integrates electronic functionalities into clothing, represents the future of healthcare and ubiquitous control in wearable devices. Realizing such apparel necessitates developing meter-scale conductive fibers with high toughness, conductivity, stable conductance under deformation, and mechanical durability. In this study, we present a heterostructure printing method capable of producing meter-scale (~50 m) biphasic conductive fibers that meet these criteria. Our approach involves encapsulating deformable liquid metal particles (LMPs) within a functionalized thermoplastic polyurethane matrix. This encapsulation induces in situ assembly of LMPs during fiber formation, creating a heterostructure that seamlessly integrates the matrix’s durability with the LMPs’ superior electrical performance. Unlike rigid conductive materials, deformable LMPs offer stretchability and toughness with a low gauge factor. Through precise twisting using an engineered annealing machine, multiple fiber strands are transformed into robust, electrically stable meter-scale electrodes. This advancement enhances their practicality in various intelligent digital apparel applications, such as stretchable displays, wearable healthcare systems, and digital controls. © The Author(s) 2025.

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ENHANCING THE ELECTROCATALYTIC HYDROGEN EVOLUTION ACTIVITY OF BARE COPPER ELECTRODES THROUGH ULTRAFAST FEMTOSECOND LASER NANOSTRUCTURING 23

ENHANCING THE ELECTROCATALYTIC HYDROGEN EVOLUTION ACTIVITY O...

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23rd World Hydrogen Energy Conference: Bridging Continents by H2, WHEC 2022

作者： Ahmad, Shahbaz Egilmez, Mehmet Orhan, Mehmet F. Alnaser, Ali S. Material Science and Engineering Program American University of Sharjah Sharjah United Arab Emirates Department of Physics American University of Sharjah Sharjah United Arab Emirates Department of Mechanical Engineering American University of Sharjah Sharjah United Arab Emirates

ISBN: (纸本)9786250008430

In this study, we report on enhancing the surface area of bare copper electrodes via femtosecond laser processing for its application in alkaline water electrolysis. It is shown that the laser nanostructuring process creates unique and hierarchal nanostructures superimposed over spiky microstructures. Analysing the effect of various laser parameters indicate that scanning speed greatly effects the microstructures by decreasing its dimensions and increasing porosity. The results also shows that laser processing has significantly enhanced the surface area with spiky and superhydrophilic structures. Furthermore, this process is expected to improve the hydrogen evolution reaction (HER) kinetics by allowing more electrode to electrolyte interface, which can favor the enrichment and formation of protons on structured Cu cathode. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.

关键词： Femtosecond lasers

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Ablative performance of graded polyetherimide nanocomposite foams

Ablative performance of graded polyetherimide nanocomposite ...

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SAMPE Tech 2013 Conference and Exhibition

作者： Jiang, Wei Sundarram, Sriharsha S. Wong, Derek Koo, Joseph H. Li, Wei Nano and Bio Materials Processing and Manufacturing Lab. Dept. of Mechanical Engineering University of Texas at Austin Austin TX United States Material Science and Engineering Program United States KAI LLC Austin TX United States

ISBN: (纸本)9781934551158

Many current thermal protection systems employ polymer resins as an ablative material. Foamed polymer nanocomposites usually exhibit improved thermal properties compared to the solid counterparts. This study evaluates the ablative performance of foamed polyetherimide (PEI)- Clay-Kraton (PCK) nanocomposites for thermal protection applications. PEI was compounded with nanoclay to improve the flame retardant property and Kraton to mitigate the loss of ductility. The PCK nanocomposite samples were foamed using a batch solid-state foaming process under variable saturation and foaming conditions. The ablative performance of the samples was analyzed based on a standard burn test with respect to the material composition and foaming condition. The results show that graded PCK composite foams can be obtained using the solid state foaming process. The porous structure can be controlled by adjusting the process conditions, including saturation time and pressure. It is further shown that the ablative performance of the nanocomposite foam can be optimized among clay loading, Kraton loading, and porosity of the foams.

关键词： Nanocomposites

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