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4th International Conference on Science and Technology, ICST 2018

作者： Nadjib, Muhammad Suhanan Waluyo, Joko Department of Mechanical and Industrial Engineering Faculty of Engineering Gadjah Mada University Yogyakarta Indonesia Mechanical Engineering Study Program Faculty of Engineering Universitas Muhammadiyah Yogyakarta Yogyakarta Indonesia

ISBN: (纸本)9781538658130

This paper aims to reveal the characteristics of thermal energy release in a solar water heater (SWH) tank involving phase change materials (PCM) as thermal energy storage material. A bundle of cylindrical capsules was inserted in 31.37 liters of SWH tank. The capsule contains paraffin wax as latent type heat storage. K type thermocouples were mounted on the water side and the PCM side. Experiments was begun with the charging process using solar energy until water temperature exceeds the melting temperature of PCM. After that, a gradual discharging process is done to release the thermal energy from the tank. The SWH tank containing 17.3 liters of water can produce 60 liters of hot water with an average water temperature of 45.13 °. This condition is achieved when the average daily radiation intensity is 699.92 W/m2. The PCM has contributed in storing thermal energy during the discharging process. © 2018 IEEE.

关键词： Phase change materials

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Reverse engineering methodology applied for the design of a light aircraft composite wheel cover. Numerical simulations for aerodynamic and structural analysis

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AIP Conference Proceedings 2024年第1期3094卷

作者： Axel Fournier Malek Guenni Carles Morell-Moratal Nicolae-Emmanuel Raiu Irina-Carmen Andrei Adriana Ştefan Cristina Pelin Gina Florica Stoica Nicoleta Crişan Delia Prisecaru Cristian Stoica Anca Greculescu Corina-Elena Boşcoianu Emil Costea E.N.I.T. - École Nationale d’Ingénieurs de Tarbes Tarbes FRANCE University “POLITEHNICA” of Bucharest Faculty of Engineering in Foreign Languages French Stream Bucharest ROMANIA Universitat Politècnica de València Vilanova i la Geltrú School of Engineering (Universitat Politècnica de Catalunya) Valencia SPAIN University “POLITEHNICA” of Bucharest Faculty of Mechanical Engineering and Mechatronics Bucharest ROMANIA I.N.C.A.S. - National Institute for Aerospace Research “Elie Carafoli” B-dul Iuliu Maniu 220 Sector 6 Bucharest 061126 ROMANIA University “POLITEHNICA” of Bucharest Faculty of Mechanical Engineering and Mechatronics Machine Parts and Tribology Department Splaiul Independenfei 313 Sector 6 060042 Bucharest ROMANIA University “POLITEHNICA” of Bucharest Faculty of Industrial Engineering and Robotics Strength of Materials Department Splaiul Independenfei 313 Sector 6 060042 Bucharest ROMANIA COMOTI – Romanian Research and Development Institute for Gas Turbines B-dul Iuliu Maniu nr. 220D Sector 6 061126 Bucharest ROMANIA

This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for Aerospace Research "Elie Carafoli" – INCAS, as Research Partner of the University POLTEHNICA of Bucharest, as Organizer and EUROPEAN PROJECT SEMESTER Provider. The study case is a light aircraft wheel cover. The objectives are set to the determination of the body geometry by reverse engineering techniques, modeling and numerical simulations for aerodynamics and structural analysis. A scale reduced demonstrator was obtained through 3D printing.

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Design Requirements of Generic Hand Exoskeletons and Survey of Hand Exoskeletons for Rehabilitation, Assistive or Haptic Use

arXiv

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arXiv 2019年

作者： Sarac, Mine Solazzi, Massimiliano Frisoli, Antonio Department of Mechanical Engineering Stanford University StanfordCA Perceptual Robotics Scuola Superiore Sant’Anna Pisa Italy

Most current hand exoskeletons have been designed specifically for rehabilitation, assistive or haptic applications to simplify the design requirements. Clinical studies on post-stroke rehabilitation have shown that adapting assistive or haptic applications into physical therapy sessions significantly improves the motor learning and treatment process. The recent technology can lead to the creation of generic hand exoskeletons that are application-agnostic. In this paper, our motivation is to create guidelines and best practices for generic exoskeletons by reviewing the literature of current devices. First, we describe each application and briefly explain their design requirements, and then list the design selections to achieve these requirements. Then, we detail each selection by investigating the existing exoskeletons based on their design choices, and by highlighting their impact on application types. With the motivation of creating efficient generic exoskeletons in the future, we finally summarize the best practices in the literature. Copyright © 2019, The Authors. All rights reserved.

关键词： Motivation

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Stability of a planetary climate system with the biosphere species competing for resources

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Physical Review E 2021年第2期103卷 022202-022202页

作者： Sergey A. Vakulenko Ivan Sudakov Sergei V. Petrovskii Dmitry Lukichev Institute for Problems in Mechanical Engineering Russian Academy of Sciences St. Petersburg 199178 Russia Faculty of Control Systems and Robotics ITMO University Saint Petersburg 197101 Russia Department of Physics University of Dayton 300 College Park SC 111 Dayton Ohio 45469-2314 USA School of Mathematics and Actuarial Science University of Leicester Leicester LE1 7RH United Kingdom S. M. Nikol'skii Mathematical Institute Peoples' Friendship University of Russia (RUDN University) Moscow 117198 Russia

With the growing number of discovered exoplanets, the Gaia concept finds its second wind. The Gaia concept defines that the biosphere of an inhabited planet regulates a planetary climate through feedback loops such that the planet remains habitable. Crunching the “Gaia” puzzle has been a focus of intense empirical research. Much less attention has been paid to the mathematical realization of this concept. In this paper, we consider the stability of a planetary climate system with the dynamic biosphere by linking a conceptual climate model to a generic population dynamics model with random parameters. We first show that the dynamics of the corresponding coupled system possesses multiple timescales and hence falls into the class of slow-fast dynamics. We then investigate the properties of a general dynamical system to which our model belongs and prove that the feedbacks from the biosphere dynamics cannot break the system's stability as long as the biodiversity is sufficiently high. That may explain why the climate is apparently stable over long time intervals. Interestingly, our coupled climate-biosphere system can lose its stability if biodiversity decreases; in this case, the evolution of the biosphere under the effect of random factors can lead to a global climate change.

关键词： Climate research Ecology & evolution Planets & planetary systems

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A Quasi-Static Electrical Measurement Scheme for Probing Gas Reactions on Graphene Surface 32

A Quasi-Static Electrical Measurement Scheme for Probing Gas...

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32nd IEEE International Conference on Micro Electro mechanical Systems, MEMS 2019

作者： Liu, Huiliang Chu, Yao Liu, Yumeng Hayasaka, Takeshi Lopez, Lorenzo P. Copa, Vernalyn C. Wang, Xiaohao You, Zheng Lin, Liwei UC Berkeley United States Berkeley Sensor and Actuator Center AND Mechanical Engineering Department UC Berkeley United States Materials Science and Engineering Program College of Science University of the Philippines DilimanPA United States National Institute of Physics University of the Philippines DilimanPA United States

ISBN: (纸本)9781728116105

This work marks the first use of a quasi-static electrical measurement method on graphene field effect transistors (FET) to characterize sub-ppm level of toxic gases in air at room temperature. Compared with the state-of-art technology, three distinctive advances have been achieved: (1) a quasi-static electrical measurement scheme on graphene FETs without sweeping a large range gate voltage to avoid the dipole flipping or charge trapping problem;(2) the real-time estimation of the charge neutral point (\mathrm{V}-{\mathrm{CNP}}) and carrier mobility (\mu) of graphene during the exposure to sub-ppm toxic gases in air;and (3) the demonstration of differentiable characteristics of NO2 and formaldehyde by the extractions of their intrinsic charge transfer and Coulomb scattering characteristics. As such, the proposed quasi-static monitoring method can be used to sense and differentiate sub-ppm level toxic gases on graphene FETs without using an array of devices with different surface functionalization materials. © 2019 IEEE.

关键词： Graphene

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Laboratory experiments with application to a light aircraft composite wheel cover

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AIP Conference Proceedings 2024年第1期3094卷

作者： Axel Fournier Malek Guenni Carles Morell-Moratal Nicolae-Emmanuel Raiu Irina-Carmen Andrei Adriana Ştefan Cristina Pelin Gina Florica Stoica Nicoleta Crişan Delia Prisecaru Cristian Stoica Anca Greculescu Corina-Elena Boşbrcoianu Emil Costea E.N.I.T. - École Nationale d’Ingénieurs de Tarbes Tarbes FRANCE University “POLITEHNICA” of Bucharest Faculty of Engineering in Foreign Languages French Stream Bucharest ROMANIA Universitat Politècnica de València Vilanova i la Geltrú School of Engineering (Universitat Politècnica de Catalunya) Valencia SPAIN University “POLITEHNICA” of Bucharest Faculty of Mechanical Engineering and Mechatronics ROMANIA I.N.C.A.S. - National Institute for Aerospace Research “Elie Carafoli” B-dul Iuliu Maniu 220 Sector 6 Bucharest 061126 ROMANIA University “POLITEHNICA” of Bucharest Faculty of Mechanical Engineering and Mechatronics Machine Parts and Tribology Department Splaiul Independenfei 313 Sector 6 Bucharest 060042 ROMANIA University “POLITEHNICA” of Bucharest Faculty of Industrial Engineering and Robotics Strength of Materials Department Splaiul Independenfei 313 Sector 6 Bucharest 060042 ROMANIA COMOTI – Romanian Research and Development Institute for Gas Turbines B-dul Iuliu Maniu nr. 220D Sector 6 Bucharest 061126 ROMANIA

This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for Aerospace Research "Elie Carafoli" – INCAS, as Research Partner of the University POLTEHNICA of Bucharest, as Organizer and EUROPEAN PROJECT SEMESTER Provider. The study case is a light aircraft wheel cover. The objectives are set to the laboratory experiments in case of a light aircraft composite wheel cover.

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Effects of spatial uniformity of continuous and pulse laser irradiation on the microstructure and mechanical properties of Ti-6Al-4V in powder bed fusion

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Materials Today Communications 2025年 46卷

作者： Seunghwan Moon Seungmuk Ji Yoonseok Ko Min-Su Lee Tea-Sung Jun Dong-Ik Kim Jong-Souk Yeo School of Integrated Technology College of Computing Yonsei University Seoul 03722 Republic of Korea BK21 Graduate Program in Intelligent Semiconductor Technology Yonsei University Seoul 03722 Republic of Korea Center for Energy Materials Research Korea Institute of Science and Technology Seoul 02792 Republic of Korea Department of Mechanical Engineering Incheon National University Incheon 22012 Republic of Korea

Powder bed fusion of metals with laser beam (PBF-LB/M) using Ti-6Al-4V (Ti64) has enabled delicate fabrication of biocompatible medical implants. This research focuses on how the spatial uniformity of laser irradiation affects material under continuous wave (CW) and pulse width modulated (PWM) laser conditions, using a self-developed PBF-LB/M system. The volumetric energy density (VED) was used as a reference parameter in order to accurately compare the effects of CW and PWM lasers, but limitations of VED, which does not include spatial and kinetic factors, which are reinforced in the PWM laser process, were also considered. Results revealed that the uniform distribution of energy irradiation across the entire region brought similar porosities and Vickers hardness tendencies for CW and PWM laser processes. In contrast, the spatially nonuniform energy transfer resulted in a significantly higher porosity in the specimen fabricated using the PWM laser than that produced using the CW laser at the same VED, reducing compressive yield strength. The electron backscattered diffraction analysis showed no significant differences in the average grain size, phase distribution, and misorientation angle of the samples produced using CW and PWM lasers under the same VED. However, sharper grains with an aspect ratio of less than 0.3 were 7 % higher in specimens produced using the PWM laser. This study highlights the possibility of controlling the microstructure and mechanical properties in a wider range when using the PWM laser with spatially nonuniform irradiation.

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Control of a line following robot based on FSM estimation

Control of a line following robot based on FSM estimation

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作者： Toumpa, Alexia Kouris, Alexandros Dimeas, Fotios Aspragathos, Nikos Robotics Group Mechanical Engineering & Aeronautics University of Patras Greece Electrical and Electronic Engineering Department Imperial College London United Kingdom

Line following robots are becoming increasingly popular both in industrial and in domestic applications. In these real world environments, noisy or inaccurate measurements lead to ambiguous conclusions about the robot's state relative to the path. In this paper, a Finite State Machine is introduced that detects irregularities in the measurements from an array of reflectance sensors. Based on the estimated state, the FSM switches between a proposed variable-gain PD controller for line following and an open loop controller for handling special cases. Experimental evaluation demonstrates that the proposed approach reduces considerably the amount of errors caused by noisy measurements and improves the performance of the line following robot compared to a similar approach from the literature. © 2018

关键词： Robots

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Controlled photophoretic levitation of nanostructured thin films for near-space flight

arXiv

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arXiv 2020年

作者： Azadi, Mohsen Popov, George A. Lu, Zhipeng Eskenazi, Andy G. Bang, Ji Won Campbell, Matthew F. Hu, Howard Bargatin, Igor Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania PhiladelphiaPA United States Vagelos Integrated Program in Energy Research University of Pennsylvania PhiladelphiaPA United States Department of Chemistry University of Pennsylvania PhiladelphiaPA United States

We report light-driven levitation of macroscopic polymer films whose bottom surface is engineered to maximize the thermal accommodation coefficient. Specifically, we levitated centimeter-scale disks made of commercial 0.5-micron-thick mylar film coated with carbon nanotubes on one side. When illuminated with light intensity comparable to natural sunlight, the polymer disk heats up and interacts with incident gas molecules differently on the top and bottom sides, producing a net recoil force. This lift force is maximized at gas pressures corresponding to Knudsen number on the order of 0.3, and correspondingly, we observed the levitation of 0.6-cm-diameter disks in a vacuum chamber at pressures between 10 and 30 Pa. Moreover, we controlled the flight of the disks using a shaped beam that optically trapped the levitating disks. Our experimentally validated theoretical model predicts that the lift forces can be many times the weight of the films, allowing payloads of up to 10 milligrams for sunlight-powered low-cost microflyers in the upper atmosphere at altitudes of 50-100 km. Copyright © 2020, The Authors. All rights reserved.

关键词： Polymer films

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Experimental investigation of a cold storage box with Aceh locally produced hydrated salt as phase change materials: Effect of salt treatment 3

Experimental investigation of a cold storage box with Aceh l...

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3rd International Conference on Natural and Environmental Sciences 2019, ICONES 2019

作者： Gunawati Noor, N. Sebayang, K. Setiawan, A. Doctoral Program in Physics Faculty of Mathmatics and Natural Sciences Universitas Sumatera Utara Padang Bulan Medan20155 Indonesia Department of Physics Faculty of Mathmatics and Natural Sciences Universitas Syiah Kuala Darussalam Banda Aceh23111 Indonesia Mechanical Engineering Department Faculty of Engineering Universitas Malikussaleh Bukit Indah Lhokseumawe24352 Indonesia

This investigation aims to study heat transfer rates and temperature changes within a 5 litter cold box enveloped with water-salt solution as phase change material (PCM). The study begins with design and fabrication of a cold box followed by performance tests. Salt sample was collected from a traditional producer in Aceh Besar District, Indonesia. In order to understand the effect of pre-treatment, some of samples were heated at 400 and 600°C for 30 min and compare it with those untreated. Salt solution of each samples was prepared by adding 10 wt.% of salt into water and filled into eight PCM bottles. PCM charging procedure was performed in a refrigerator for 12 h. By placing eight bottle of PCM into the cold-box, thermal energy discharging process was monitored by using four thermocouples. The changes in temperature were recorded for eight hours. In general, result shows that pre-treatment of salt results in a positive effect on thermal energy storage capacity. The best performance of cold storage system was exhibited by PCM made of salt treated at 600 °C where the rate of temperature change within eight hours experiment is 0.055 °C/min. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Phase change materials

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