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High-Performance 3-D Fiber Network Composite Electrolyte Enabled with Li-Ion Conducting Nanofibers and Amorphous PEO-Based Cross-Linked Polymer for Ambient All-Solid-State Lithium-Metal Batteries

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Advanced Fiber Materials 2019年第1期1卷 46-60页

作者： Chaoyi Yan Pei Zhu Hao Jia Jiadeng Zhu R.Kalai Selvan Ya Li Xia Dong Zhuang Du Indunil Angunawela Nianqiang Wu Mahmut Dirican Xiangwu Zhang Fiber and Polymer Science Program Department of Textile EngineeringChemistry and ScienceWilson College of TextilesNorth Carolina State UniversityRaleighNC 27695-8301USA Department of Physics and Organic and Carbon Electronics Lab North Carolina State UniversityRaleighNC 27695-8301USA Department of Mechanical and Aerospace Engineering West Virginia UniversityMorgantownWV 26506USA

Solid electrolytes have gained attention recently for the development of next-generation Li-ion batteries since they can fun-damentally improve the battery stability and *** various types of solid electrolytes,composite solid electrolytes(CSEs)exhibit both high ionic conductivity and excellent interfacial contact with the *** active nanofib-ers into the polymer matrix demonstrates an effective method to fabricate ***,current CSEs based on traditional poly(ethylene oxide)(PEO)polymer suffer from the poor ionic conductivity of PEO and agglomeration effect of inorganic fillers at high concentrations,which limit further improvements in Li+conductivity and electrochemical ***,we synthesize a novel PEO based cross-linked polymer(CLP)as the polymer matrix with naturally amorphous structure and high room-temperature ionic conductivity of 2.40×10^(−4)S cm^(−1).Li_(0.3)La_(0.557)TiO_(3)(LLTO)nanofibers are incorporated into the CLP matrix to form composite solid electrolytes,achieving enhanced ionic conductivity without showing filler *** high content of Li-conductive nanofibers improves the mechanical strength,ensures the conductive network,and increases the total Li+conductivity to 3.31×10^(−4)S cm^(−1).The all-solid-state Li|LiFePO_(4)batteries with LLTO nanofiber-incorporated CSEs are able to deliver attractive specific capacity of 147 mAh g^(−1)at room temperature,and no evident dendrite is found at the anode/electrolyte interface after 100 cycles.

关键词： Cross-linked PEO polymer Li_(0.33)La_(0.55)TiO_(3)nanofibers Composite solid electrolyte All-solid-state batteries Ambient working temperature

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Non-linear optics at twist interfaces in h-BN/SiC heterostructures

arXiv

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arXiv 2023年

作者： Biswas, Abhijit Xu, Rui Alvarez, Gustavo A. Zhang, Jin Christiansen-Salameh, Joyce Puthirath, Anand B. Burns, Kory Hachtel, Jordan A. Li, Tao Iyengar, Sathvik Ajay Gray, Tia Li, Chenxi Zhang, Xiang Kannan, Harikishan Elkins, Jacob Pieshkov, Tymofii S. Vajtai, Robert Birdwell, A. Glen Neupane, Mahesh R. Garratt, Elias J. Ivanov, Tony Pate, Bradford B. Zhao, Yuji Zhu, Hanyu Tian, Zhiting Rubio, Angel Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Max Planck Institute for the Structure and Dynamics of Matter Center for Free-Electron Laser Science Luruper Chaussee 149 22761 Germany Department of Materials Science & Engineering University of Virginia CharlottesvilleVA22904 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States DEVCOM Army Research Laboratory RF Devices and Circuits AdelphiMD20783 United States Chemistry Division Naval Research Laboratory WashingtonDC20375 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Flatiron Institute New YorkNY10010 United States

Understanding the emergent electronic structure in twisted atomically thin layers has led to the exciting field of twistronics. However, practical applications of such systems are challenging since the specific angular correlations between the layers must be precisely controlled and the layers have to be single crystalline with uniform atomic ordering. Here, we suggest an alternative, simple and scalable approach where nanocrystalline two-dimensional (2D) film on three-dimensional (3D) substrates yield twisted-interface-dependent properties. Ultrawidebandgap hexagonal boron nitride (h-BN) thin films are directly grown on high in-plane lattice mismatched wide-bandgap silicon carbide (4H-SiC) substrates to explore the twist-dependent structure-property correlations. Concurrently, nanocrystalline h-BN thin film shows strong nonlinear second-harmonic generation and ultra-low cross-plane thermal conductivity at room temperature, which are attributed to the twisted domain edges between van der Waals stacked nanocrystals with random in-plane orientations. First-principles calculations based on time-dependent density functional theory manifest strong even-order optical nonlinearity in twisted h-BN layers. Our work unveils that directly deposited 2D nanocrystalline thin film on 3D substrates could provide easily accessible twist-interfaces, therefore enabling a simple and scalable approach to utilize the 2D-twistronics integrated in 3D material devices for next-generation nanotechnology. © 2023, CC BY.

关键词： Harmonic generation

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Effect of yaw angle on the global performances of Horizontal Axis Wind Turbine - QBlade simulation 22

Effect of yaw angle on the global performances of Horizontal...

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22nd National Conference on Thermodynamics with International Participation, NACOT 2019

作者： Husaru, D.E. B rsǎnescu, P.D. Zahariea, D. Mechanical Engineering Gheorghe Asachi Technical University of Iai Iai Romania Mechanical Engineering Mechatronics and Robotics Department Gheorghe Asachi Technical University of Iai Iai Romania Fluid Mechanics Fluid Machinery and Fluid Power Systems Department Gheorghe Asachi Technical University of Iasi Iasi Romania

The yaw angle has a great importance in the wind turbine working. Even though most of the large turbines have yaw mechanisms, they do not have an instant response. The aerodynamic forces and torque on the blades fluctuate, depending on the yaw angle. The design and the numerical simulation of the wind turbine were performed with the Blade Element Momentum method in open source QBlade software. The power coefficient, torque, thrust and power output generated by wind turbine in non-yawed flow were analysed. The simulations have been performed for non-yawed flow, in rotational speed range between 2100 and 3300 rpm and wind velocity of 15 m/s. Simulations for yaw angle range have been performed between 60 , with 5 step at rated rotational speed of 2700 rpm. The results are presented through charts for global parameters in both non-yawed flow, and yawed flow. The effect of yaw angle on global performances of the wind turbines is more important after the value of 25 when the power output decrease with about 15% from power output in non-yawed flow. The average value of the exponent from conventional relation of power coefficient in yawed flow is 1.77 in good concordance with experimental tests. © Published under licence by IOP Publishing Ltd.

关键词： Horizontal axis wind turbine

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Modeling and Analysis of SMA Actuator Embedded in Stretchable Coolant Vascular Pursuing Artificial Muscles

Modeling and Analysis of SMA Actuator Embedded in Stretchabl...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Jaeyeon Jeong Cheol Hoon Park Ki-Uk Kyung Department of Mechanical Engineering Korea Advanced Institute of Science and Technology(KAIST) Republic of Korea Depertment of Robotics & Mechatronics Korea Institute of Machinery and Materials(KIMM) Republic of Korea

ISBN: (数字)9781728173955

ISBN: (纸本)9781728173962

This paper proposes a muscle-like SMA (Shape Memory Alloy) actuator with an active cooling system for efficient response. An SMA coil spring is embedded into a stretchable coolant vascular for soften structure of robots. In order to design a flexible, lightweight, and fast-response soft actuator with the SMA coil spring and coolant circulation system, a modeling based approach has been conducted. Analysis of coolant effects has been conducted in aspects of heating speed, cooling speed, and energy consumption based on both theoretical and empirical studies. From thermomechanical and heat transfer model between SMA and coolant, the actuation times in the case of heating and cooling phase have been estimated. From experimental results, Mineral oil is selected as the optimal coolant, and the maximum actuation frequency was measured as 0.5Hz for 40% contraction lifting 1kg.

关键词： Springs Coolants Actuators Mathematical model Force Wires

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An untethered brittle star robot for closed-loop underwater locomotion

arXiv

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arXiv 2020年

作者： Patterson, Zach J. Sabelhaus, Andrew P. Chin, Keene Majidi, Carmel Department of Mechanical Engineering Carnegie Mellon University PittsburghPA15213 United States Robotics Institute Carnegie Mellon University PittsburghPA15213 United States

Soft robots are capable of inherently safer and more stable interactions with their environment since they can mechanically deform in response to unanticipated interactions. However, their complex mechanics can make operation difficult, particularly with tasks such as locomotion, and robust systems are needed for evaluating and testing new planning and control algorithms. In this work, we present the first mobile and untethered underwater crawling soft robot. PATRICK is a robotic testbed inspired by brittle stars that demonstrates closed-loop locomotion planning. PATRICK contains five soft legs actuated by a total of 20 shape-memory-alloy (SMA) wires, providing a rich variety of possible motions. This testbed is the first instance of real-time position tracking for an untethered soft crawling robot. Experiments demonstrate that a motion planner can command the robot to locomote to a goal state, given a simple set of motion primitives. This work demonstrates progress toward full autonomy of soft, mobile robotic systems. Copyright © 2020, The Authors. All rights reserved.

关键词： Stars

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Erratum to “Heusler alloys: Past, properties, new alloys, and prospects” [Progress Mater. Sci. 132 (2023) 101017]

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Progress in Materials Science 2023年 137卷

作者： Sheron S. Tavares Kesong Yang Marc A. Meyers Materials Science and Engineering Program University of California San Diego 92093-0418 USA Department of Nano and Chemical Engineering University of California San Diego 92093-0448 USA Center for Memory and Recording Research University of California San Diego 92093-040 USA Department of Mechanical and Aerospace Engineering University of California San Diego 92093-0411 USA

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Hybrid Actuator Design for a Gait Augmentation Wearable

arXiv

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arXiv 2020年

作者： Wan, Fang Wang, Zheng Franchuk, Brooke Hu, Xinyao Sun, Zhenglong Song, Chaoyang Fang Wan is an independent WuhanHubei China Department of Mechanical and Aerospace Engineering Monash University VIC3800 Australia Department of Mechanical and Aerospace Engineering University of British Columbia Canada Institute of Human Factors and Ergonomics Shenzhen University ShenzhenGuangdong China Institute of Robotics and Intelligent Manufacturing Chinese University of Hong Kong Shenzhen China Department of Mechanical and Aerospace Engineering Monash University VIC3800 Australia

— We describe a fluidic actuator design that replaces the sealed chamber of a hydraulic cylinder using a soft actuator to provide compliant linear compression with a large force (≥100 N) at a low operation pressure (≤50 kPa) for lower-limb wearable. The external shells constrain the deformation of the soft actuator under fluidic pressurization. This enables us to use latex party balloons as a quick and cheap alternative for initial design investigation. We found that the forces exerted by the soft material deformation are well-captured by the rigid shells, removing the necessity of explicitly describing the mechanics of the soft material deformation and its interaction with the rigid structure. One can use the classical Force, Pressure and Area formula factored with an efficiency parameter to characterize the actuator performance. Furthermore, we proposed an engineering design of the hybrid actuator using a customized soft actuator placed inside a single shell cavity with an open end for compression force. Our results show that the proposed design can generate a very high force within a short stroke distance. At a low input pressure of 50 kPa, the exerted block force is approaching only about 3% less than the classical equation predicted. The actuator is fitted to a new gait augmentation design for correcting knee alignment, which is usually challenging for actuators made from the purely soft material. Copyright © 2020, The Authors. All rights reserved.

关键词： Wearable technology

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MAPPER: Multi-agent path planning with evolutionary reinforcement learning in mixed dynamic environments

arXiv

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arXiv 2020年

作者： Liu, Zuxin Chen, Baiming Zhou, Hongyi Koushik, Guru Hebert, Martial Zhao, Ding Department of Mechanical Engineering Carnegie Mellon University United States School of Vehicle and Mobility Tsinghua University China Robotics Institute Carnegie Mellon University United States

Multi-agent navigation in dynamic environments is of great industrial value when deploying a large scale fleet of robot to real-world applications. This paper proposes a decentralized partially observable multi-agent path planning with evolutionary reinforcement learning (MAPPER) method to learn an effective local planning policy in mixed dynamic environments. Reinforcement learning-based methods usually suffer performance degradation on long-horizon tasks with goal-conditioned sparse rewards, so we decompose the long-range navigation task into many easier sub-tasks under the guidance of a global planner, which increases agents’ performance in large environments. Moreover, most existing multiagent planning approaches assume either perfect information of the surrounding environment or homogeneity of nearby dynamic agents, which may not hold in practice. Our approach models dynamic obstacles’ behavior with an image-based representation and trains a policy in mixed dynamic environments without homogeneity assumption. To ensure multi-agent training stability and performance, we propose an evolutionary training approach that can be easily scaled to large and complex environments. Experiments show that MAPPER is able to achieve higher success rates and more stable performance when exposed to a large number of non-cooperative dynamic obstacles compared with traditional reaction-based planner LRA* and the state-of-the-art learning-based method. Copyright © 2020, The Authors. All rights reserved.

关键词： Multi agent systems

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Evaluation of a Circumferential Extending Antagonist Actuator in a Soft Arm

Evaluation of a Circumferential Extending Antagonist Actuato...

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IEEE International Conference on Soft robotics (RoboSoft)

作者： Max Asselmeier Ross L. Hatton Yiğit Mengüç Gina Olson Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Urbana IL USA Collaborative Robotics and Intelligent Systems Institute Oregon State University Corvallis OR USA

ISBN: (数字)9781728165707

ISBN: (纸本)9781728165714

This paper presents a novel circumferential pneumatic actuator to be used as an antagonist in soft bending arms. The design is based on a McKibben actuator, and the circular shape is inspired by octopus musculature. The performance of the presented actuator is evaluated through characterization of individual actuators, as well as experimental analysis of the actuator's effect on the behavior of an existing soft bending arm segment. A stack of 16 circumferential actuators is capable of producing a force of 37 N when pressurized to 32 kPa and deflected to -15% strain. When the actuators are integrated into a 75 mm diameter soft arm, the arm is able to successfully lift 600 g (285% of its own mass) to 54% of the arm's original height, which is 2.2 times the maximum load for the arm without antagonistic actuators. When the soft arm with antagonistic actuators lifted 250 g at 40 kPa, the segment returned to 101% of its original height, compared to 59% for the arm segment without antagonistic actuators. Compared to existing antagonistic systems, this circumferential actuator produces high extension strokes and high forces at pressures below 100 kPa. The presented actuator is simple to manufacture and the design is complementary to the geometry of many soft arms, which makes the actuator a suitable choice to improve the arms' maximum load.

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Investigating effects of different flue-wall deformation modes on the performance of anode baking furnaces for aluminum electrolysis

Investigating effects of different flue-wall deformation mod...

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ASME 2019 International mechanical engineering Congress and Exposition, IMECE 2019

作者： Tajik, Abdul Raouf Zaidani, Mouna Shamim, Tariq Abu Al-Rub, Rashid K. Mechanical Engineering Department Khalifa University P.O. Box 127788 Abu Dhabi United Arab Emirates Aerospace Engineering Department Khalifa University P.O. Box 127788 Abu Dhabi United Arab Emirates Mechanical Engineering Department Northern Illinois University IL60115 United States Mechanical Engineering Program University of Michigan-Flint MI48502 United States

ISBN: (纸本)9780791859452

In carbon anode baking furnaces, temperature and quality of carbon anodes are significantly affected by the deformation of the flue-walls, where the flue-gases flow and combustion occur. Flue-walls aging gives rise to non-homogeneous baking of the carbon anodes and results in deterioration of the anode quality, which eventually causes instabilities in aluminum reduction cells and overconsumption of anodes and energy. It is imperative to develop a fully coupled 3D multi-physics computational model which takes into account a large number of physical phenomena that play vital roles in the baking process and are affected by the flue-wall deformation mode. In the present study, the effects of flue-wall deformation modes on flue-wall cavity gas flow and anode temperature distribution are investigated. The pressure and flow distributions for different levels of flue-wall deformation are demonstrated. It is perceived that a 100 mm convex mode of flue-wall deformation leads to under-baking of anodes by almost 20 degC. For the concave mode of deformation, since the packing coke thickness reduces, overbaking of anode occurs. The methodology and results presented in the present research can be employed effectively by the aluminum industry in modifying the furnace geometrical and operational parameters to enhance baking uniformity after flue-wall is deformed. Copyright © 2019 ASME.

关键词： Computational fluid dynamics

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