检索结果-内蒙古大学图书馆

Controlled tempering of lipid concentration and microbubble shrinkage as a possible mechanism for fine-tuning microbubble size and shell properties

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Zalloum, Intesar O. Sojahrood, Amin Jafari Paknahad, Ali A. Kolios, Michael C. Tsai, Scott S.H. Karshafian, Raffi Department of Physics Toronto Metropolitan University TorontoONM5B 2K3 Canada Department of Mechanical and Industrial Engineering Toronto Metropolitan University 350 Victoria Street TorontoONM5B 2K3 Canada A Partnership Between Toronto Metropolitan University St. Michael's Hospital 209 Victoria Street TorontoONM5B 1T8 Canada Keenan Research Centre for Biomedical Science Unity Health Toronto 209 Victoria Street TorontoONM5B 1W8 Canada Graduate Program in Biomedical Engineering Toronto Metropolitan University 350 Victoria Street TorontoONM5B 2K3 Canada

The acoustic response of microbubbles (MBs) depends on their resonance frequency, which is dependent on MB size and shell properties. Monodisperse MBs with tunable shell properties are thus desirable for optimizing and controlling MB behavior in acoustics applications. By utilizing a novel microfluidic method that uses lipid concentration to control MB shrinkage, we generate monodisperse MBs of four different initial diameters at three lipid concentrations (5.6, 10.0, and 16.0 mg/mL) in the aqueous phase. Following shrinkage, we measure MB resonance frequency and determine its shell stiffness and viscosity. The study demonstrates that we can generate monodisperse MBs of specific sizes and tunable shell properties by controlling MB initial diameter and aqueous phase lipid concentration. Our results indicate that the resonance frequency increases by 180-210% with increasing lipid concentration (from 5.6 to 16.0 mg/mL) while bubble diameter is kept constant. Additionally, we find that the resonance frequency decreases by 260-300% with increasing MB final diameter (from 5 to 12 μm), while lipid concentration is held constant. For example, our results depict that the resonance frequency increases by ~195% with increasing lipid concentration from 5.6 to 16.0 mg/mL, for ~11 μm final diameter MBs. Additionally, we find that the resonance frequency decreases by ~275% with increasing MB final diameter from 5 to 12 μm, when we use a lipid concentration of 5.6 mg/mL. We also determine that MB shell viscosity and stiffness increase with increasing lipid concentration and MB final diameter, and the level of change depends on the degree of shrinkage experienced by MB. Specifically, we find that by increasing the concentration of lipids from 5.6 to 16.0 mg/mL, the shell stiffness and viscosity of ~11 μm final diameter MBs increase by ~400% and ~200 %, respectively. This study demonstrates the feasibility of fine-tuning the MB acoustic response to ultrasound by tailoring MB initial

关键词： Shrinkage

Passive Quadrupedal Gait Synchronization for Extra Robotic Legs Using a Dynamically Coupled Double Rimless Wheel Model

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Gonzalez, Daniel J. Harry Asada, H. Robotics Research Center Department of Electrical Engineering and Computer Science United States Military Academy West PointNY10996 United States d’Arbeloff Laboratory for Information Systems and Technology Department of Mechanical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

The Extra Robotic Legs (XRL) system is a robotic augmentation worn by a human operator consisting of two articulated robot legs that walk with the operator and help bear a heavy backpack payload. It is desirable for the Human-XRL quadruped system to walk with the rear legs lead the front by 25% of the gait period, minimizing the energy lost from foot impacts while maximizing balance stability. Unlike quadrupedal robots, the XRL cannot command the human’s limbs to coordinate quadrupedal locomotion. Using a pair of Rimless Wheel models, it is shown that the systems coupled with a spring and damper converge to the desired 25% phase difference. A Poincaré return map was generated using numerical simulation to examine the convergence properties to different coupler design parameters, and initial conditions. The Dynamically Coupled Double Rimless Wheel system was physically realized with a spring and dashpot chosen from the theoretical results, and initial experiments indicate that the desired synchronization properties may be achieved within several steps using this set of passive components alone. Copyright © 2020, The Authors. All rights reserved.

关键词： Exoskeleton (robotics)

Numerical Investigation Against Laboratory Experiment: An Overview of Damage and Wind Loads on Structural Design

学校读者我要写书评

暂无评论

Procedia Structural Integrity 2020年 27卷 6-13页

作者： Aldias Bahatmaka Dong-Joon Kim Aditya Rio Prabowo Daewoo Shipbuilding and Marine Engineering (DSME).Co.Ltd Okpo 53305 South Korea Interdisciplinary Program of Marine Design Convergence Pukyong National University Busan 48513 South Korea Department of Naval Architecture and Marine Systems Engineering Pukyong National University Busan 48513 South Korea Department of Mechanical Engineering Universitas Sebelas Maret Surakarta 57126 Indonesia

The numerical approach is being used against experimental and solves engineering problems. In the engineering design, the structural and load analysis are a part of an important thing to show the effect of geometrical or the structure design. The main purpose is to review the influence of deckhouse height on the flow around the funnel and aft ship structure. In this review study, the fluid-structure and 3D steady RANS CFD are used to validate the result of simulations. Several aspects of the numerical approach, such as turbulence modeling, boundary conditions, inlet velocity, and pressure outlet to simulate wind load in CFD, ground surface roughness, and quantification of wind loads by computational fluid-structure and computational fluid dynamics (CFD) are summarized. A benchmarking study of the numerical approach against the experiment is emphasized. A comparative study among the numerical prediction on the wind tunnel demonstrated good agreement and satisfaction. Moreover, by numerical approach could handle the accurate results and show how the response to the ship structure that makes the dynamic interaction during wind loads events.

关键词： Fluid Structure Wind Loads Numerical Approach CFD Experimental

Three-dimensional kinematic metamaterial with tuneable directional permeability

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Yang, Yunfang Maiolino, Perla Chen, Yan You, Zhong Department of Engineering Science University of Oxford Parks Road OxfordOX1 3PJ United Kingdom Oxford Robotics Institute University of Oxford Parks Road OxfordOX1 3PJ United Kingdom Key Laboratory of Mechanism Theory Equipment Design of Ministry of Education Tianjin University Tianjin300072 China School of Mechanical Engineering Tianjin University Tianjin University Tianjin300072 China

Reconfigurable metamaterials are constructed from tessellation of deformable modules that give rise to a set of tuneable properties. To date, most research focuses on metamaterials that morph between final configurations along a single deformation path. Multi-pathway metamaterials that can transform into several different shapes according to various external stimuli are rare. Here we propose a kinematic based metamaterial with multiple predefined deformation paths. The inherent kinematic bifurcations of the deformable unit cells enable the metamaterial to switch among different paths under simple stimuli at one particular configuration, resulting in the enhancement of reconfigurability. The metamaterials demonstrated in this paper can provide multiple open channels in different orthogonal directions, making them suitable for multifunctional applications such as tuneable filters and reconfigurable wave guiding materials. © 2021, CC BY.

关键词： Metamaterials

From farm to land: Characteristics of biochar for agricultural purposes 27th

学校读者我要写书评

暂无评论

From farm to land: Characteristics of biochar for agricultur...

27th European Biomass Conference and Exhibition, EUBCE 2019

作者： de Souza, Débora Machado Kappler, Genyr Bueno, Andriele Brizolla Silva, Jenifer Lima da Modolo, Regina Célia Espinosa Moraes, Carlos Alberto Mendes Tarelho, Luís António da Cruz Brehm, Feliciane Andrade Graduate Program in Mechanical Engineering University of Vale do Rio dos Sinos-UNISINOS São LeopoldoRS93022-000 Brazil Graduate Program in Civil Engineering UNISINOS Portugal Undergraduate students in Environmental Engineering UNISINOS Portugal Department of Environment and Planning/CESAM University of Aveiro Aveiro3810193 Portugal

Agribusiness has a significant role in the life of billions of people and is an essential component in the economy of many countries. In Brazil agribusiness is one of the most prominent components in the economy and it accounted for 21% of the Gross Domestic Product in 2016. The soil is a non-renewable resource, and its adequate management becomes increasingly relevant to maintain its fertility and ensure the production of food to supply the population and industries in the food sector. The use of chemical fertilizers and mineral correctives is a requirement of modern agriculture and is practically indispensable for the management of crops. However, it is not an environmental friendly management technique method and may cause economic losses. On the other hand, there is an acknowledgment of nature-based solutions that contribute to improving soil quality while reducing the environmental burden from modern agrosystem. The choice for utilizing rice husk as biomass feedstock in this research is based on the current reality of Brazil, where there is an annual production of approximately 11.7 million tons of rice, from which around 20% become residue. Considering that Brazil has large areas of cultivation and that agriculture residues are still underutilized, the objective of this study was to evaluate the influence of biochar obtained from rice husk in the fertility of soil based on two parameters, which are porosity and water holding capacity. The conversion of agricultural residues into soil conditioners, i.e., closing the cycle of nutrients from farm to land, is an interesting option for sustainable resource management, which should also encompass the environmental, social and economic aspects. © 2019 ETA-Florence Renewable Energies.

关键词： Agriculture Biochar Biomass Fertilizers

A method for recognition of dynamic hand gestures based on wrist tendon sounds 22

学校读者我要写书评

暂无评论

A method for recognition of dynamic hand gestures based on w...

22nd IEEE International Conference on E-Health Networking, Application and Services, HEALTHCOM 2020

作者： He, Bailin Wang, Can Wang, Hao Li, Mengyao Duan, Shengcai Wu, Xinyu Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Hong Kong Samsung Electronics Guangdong-Hong Kong-Macao Joint Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China

ISBN: (纸本)9781728162676

Hand gesture recognition are widely applied in game industry and rehabilitation engineering. Some recognition methods based on physiological data are attracting attention. In this paper, a novel method for dynamic hand gesture recognition based on sounds of wrist tendon is proposed. Bone conduction sensors which automatically filter the ambient noise is utilized to collect the wrist tendon sounds of three types of dynamic hand gestures. Continuous Wavelet Transform(CWT) is utilized extract the features of sounds and Support Vector Machine(SVM) is utilized to train the classifier model. Five healthy subjects participated the experiment and the average test accuracy of three classes achieves 92.33%. The proposed method provides an effective perspective for hand gesture recognition. © 2021 IEEE.

关键词： Support vector machines

Development of A Learning-Based Terrain Classification Framework for Pushrim-Activated Power-Assisted Wheelchairs*

学校读者我要写书评

暂无评论

Development of A Learning-Based Terrain Classification Frame...

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Mahsa Khalili Keenan T. McConkey Kevin Ta Lyndia C. Wu H.F. Machiel Van der Loos Jaimie F. Borisoff School of Biomedical Engineering University of British Columbia Vancouver BC Canada Engineering Physics Program University of British Columbia Vancouver BC Canada Department of Mechanical Engineering University of British Columbia Vancouver BC Canada British Columbia Institute of Technology (BCIT)

ISBN: (数字)9781728119908

ISBN: (纸本)9781728119915

Pushrim-activated power-assisted wheels (PAPAWs) are assistive technologies that provide on-demand torque assistance to wheelchair users. Although the available power can reduce the physical load of wheelchair propulsion, it may also cause maneuverability and controllability issues. Commercially-available PAPAW controllers are insensitive to environmental changes, leading to inefficient and/or unsafe wheelchair movements. In this regard, adaptive velocity/torque control strategies could be employed to improve safety and stability. To investigate this objective, we propose a context-aware sensory framework to recognize terrain conditions. In this paper, we present a learning-based terrain classification framework for PAPAWs. Study participants performed various maneuvers consisting of common daily-life wheelchair propulsion routines on different indoor and outdoor terrains. Relevant features from wheelchair frame-mounted gyroscope and accelerometer measurements were extracted and used to train and test the proposed classifiers. Our findings revealed that a one-stage multi-label classification framework has a higher accuracy performance compared to a two-stage classification pipeline with an indoor-outdoor classification in the first stage. We also found that, on average, outdoor terrains can be classified with higher accuracy (90%) compared to indoor terrains (65%). This framework can be used for real-time terrain classification applications and provide the required information for an adaptive velocity/torque controller design.

关键词： Wheelchairs Radio frequency Support vector machines Wheels Feature extraction Torque Safety

Discovery of a reversible redox-induced order-disorder transition in a 10-cation compositionally complex ceramic

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Zhang, Dawei Chen, Yan Feng, Tianshi Yu, Dunji An, Ke Chen, Renkun Luo, Jian Program of Materials Science and Engineering University of California San Diego La Jolla CA92093 United States Neutron Scattering Division Oak Ridge National Laboratory Oak RidgeTN38731 United States Department of Mechanical & Aerospace Engineering University of California San Diego La Jolla CA92093 United States Department of NanoEngineering University of California San Diego La Jolla CA92093 United States

This study discovers a reversible order-disorder transition (ODT) in a 10-cation compositionally complex ceramic, (Nd0.15Pr0.15Dy0.8Ho0.8Er0.8Ti0.2Yb0.1Hf0.1Zr0.1Nb0.8)O7-δ, induced via annealing in oxidized vs. reduced environments at 1600οC. Notably, the 10-cation oxide remains a homogenous single-phase high-entropy solid solution before and after the ODT in the pyrochlore vs. fluorite structure that can be quenched. In-situ neutron diffraction reveals the oxygen vacancy formation and atomic displacement during this ODT. The temperature dependence of thermal conductivity is altered by the ODT. This study reveals a new pathway to induce ODT via a redox transition to tailor the properties of compositionally complex fluorite-based oxides. © 2021, CC BY.

关键词： Entropy

Intrinsic Exciton-Phonon Coupling and Tuning in ZnTe Nanowires Probed by Resonant Raman Scattering

学校读者我要写书评

暂无评论

Physical Review Applied 2020年第1期13卷 011001-011001页

作者： Yingyan Yi Jason K. Marmon Yuanping Chen Fan Zhang Tao Sheng Priyalal S. Wijewarnasuriya Haitao Zhang Yong Zhang Department of Electrical and Computer Engineering University of North Carolina at Charlotte Charlotte North Carolina 28223 USA School of Science Wuhan University of Technology Wuhan Hubei 430070 China Nanoscale Science Graduate Program University of North Carolina at Charlotte Charlotte North Carolina 28223 USA US Army Research Laboratory Adelphi Maryland 20783 USA Optical Science and Engineering Graduate Program University of North Carolina at Charlotte Charlotte North Carolina 28223 USA Department of Mechanical Engineering and Engineering Science University of North Carolina at Charlotte Charlotte North Carolina 28223 USA

We show in ZnTe that the 2LO to 1LO resonant Raman intensity ratio, a measure of electron-phonon coupling (EPC), exhibits a much larger intrinsic value than that previously reported and minimal change from bulk to 30 nm nanowires. However, the ratio can be tuned extrinsically over one order in magnitude controllably either during or after growth, and thus, allows for the programing of EPC or quantum information in nanoscale devices. This work helps to understand a matter of controversy in the literature for more than three decades, regarding the EPC size dependence in nanostructures, and provides unambiguous experimental results for validating EPC theories with reduced dimensionality.

关键词： Crystal defects Electron-phonon coupling Excitons Optoelectronics Nanowires Semiconductor compounds Photoluminescence Raman spectroscopy