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Vibration Energy Harvesting: A Review on Trends, Challenges & Future Direction

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Vibration Energy Harvesting: A Review on Trends, Challenges ...

IEEE International Conference on Emerging & Sustainable Technologies for Power & ICT in a Developing Society (NIGERCON)

作者： Sunday A. Afolalu Temitayo S. Ogedengbe Moses E. Emetere Stella I. Monye Monye N. Snow Dept. of Mechanical and Mechatronics Engineering Department Afe Babalola University Ado-Ekiti Nigeria Dept. of Mechanical Science University Johannesburg South Africa Dept. of Mechanical Engineering Department Nile University of Nigeria Abuja Dept. of Physics Program Bowen University Iwo Osun State Nigeria Dept. of Information Communication Technology University of Delta Agbor Delta State Nigeria

ISBN: (数字)9798331542559

ISBN: (纸本)9798331542566

The worldwide need for sustainable energy solutions has continued to attract the attention of researchers. One vital means for such provision is the harvesting of energy using various methods. This study therefore reviews the recent trends in energy harvesting. Methods such as vibration energy harvesting as well as electrostatic energy harvesting and their applications have been thoroughly discussed. The study also reviewed the challenges with this energy harvesting methods and finally concludes with the future directions of this topic. It is believed that the generation of energy if greatly boosted will drive the economy of any state and ultimately result in wealth generation for the economy.

关键词： Vibrations Humanities Electric potential Reviews Developing countries Market research Energy harvesting Electrostatics

Biodiesel Production Techniques and Merits: An Overview

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Biodiesel Production Techniques and Merits: An Overview

IEEE International Conference on Emerging & Sustainable Technologies for Power & ICT in a Developing Society (NIGERCON)

作者： Stella I. Monye Sunday A. Afolalu Moses E. Emetere Temitayo S. Ogedengbe Monye N. Snow Dept. of Mechanical and Mechatronics Engineering Department Afe Babalola University Ado-Ekiti Nigeria Dept. of Mechanical Science University Johannesburg South Africa Dept. of Physics Program Bowen University Iwo Osun State Nigeria Dept. of Mechanical Engineering Department Nile University of Nigeria Abuja Dept. of Information Communication Technology University of Delta Agbor Delta State Nigeria

ISBN: (数字)9798331542559

ISBN: (纸本)9798331542566

Biodiesel is gaining popularity due to its environmental benefits and renewable nature. Biomass has the potential to replace fossil fuels that release carbon dioxide into the atmosphere, it might as well make a significant contribution to reducing the greenhouse effect. It has, nevertheless, some setbacks including its demanding land and water use, the risk of losing arable lands to it and the impact of cutting and processing biofuel products. This study therefore reviews the production techniques and merits associated with biodiesel. This review projects the production and use of high-quality biodiesel, thereby paving the way for a more sustainable transportation future with reduced reliance on fossil fuels.

关键词： Heating systems Humanities Costs Reviews Greenhouse effect Transportation Production Carbon dioxide Fossil fuels Biofuels

Stratified Topological Autonomy for Long-Range Coordination (STALC)

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arXiv 2025年

作者： Dimmig, Cora A. Goertz, Adam Polevoy, Adam Gonzales, Mark Wolfe, Kevin C. Woosley, Bradley Rogers, John Moore, Joseph Johns Hopkins University Applied Physics Laboratory LaurelMD20723 United States Department of Mechanical Engineering Johns Hopkins University BaltimoreMD21218 United States DEVCOM Army Research Laboratory AdelphiMD20783 United States

Achieving unified multi-robot coordination and motion planning in complex environments is a challenging problem. In this paper, we present a hierarchical approach to long-range coordination, which we call Stratified Topological Autonomy for Long-Range Coordination (STALC). In particular, we look at the problem of minimizing visibility to observers and maximizing safety with a multi-robot team navigating through a hazardous environment. At its core, our approach relies on the notion of a dynamic topological graph, where the edge weights vary dynamically based on the locations of the robots in the graph. To create this dynamic topological graph, we evaluate the visibility of the robot team from a discrete set of observer locations (both adversarial and friendly), and construct a topological graph whose edge weights depend on both adversary position and robot team configuration. We then impose temporal constraints on the evolution of those edge weights based on robot team state and use Mixed-Integer programming (MIP) to generate optimal multirobot plans through the graph. The visibility information also informs the lower layers of the autonomy stack to plan minimal visibility paths through the environment for the team of robots. Our approach presents methods to reduce the computational complexity for a team of robots that interact and coordinate across the team to accomplish a common goal. We demonstrate our approach in simulated and hardware experiments in forested and urban environments. Copyright © 2025, The Authors. All rights reserved.

关键词： Multipurpose robots

Peak thermal conductivity measurements of boron arsenide crystals

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Physical Review Materials 2022年第6期6卷 L061601-L061601页

作者： Yuanyuan Zhou Chunhua Li Pawan Koirala Geethal Amila Gamage Hanlin Wu Sheng Li Navaneetha K. Ravichandran Hwijong Lee Andrei Dolocan Bing Lv David Broido Zhifeng Ren Li Shi Walker Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Department of Physics Boston College Chestnut Hill Massachusetts 02467 USA Department of Physics The University of Texas at Dallas Richardson Texas 75080 USA Department of Physics and Texas Center for Superconductivity University of Houston Houston Texas 77204 USA Department of Mechanical Engineering Indian Institute of Science Bangalore 560012 India Materials Science and Engineering Program Texas Materials Institute The University of Texas at Austin Austin Texas 78712 USA

Recent experiments have validated prior theories of unusual high thermal conductivity (κ) in boron arsenide (BAs) and revealed large κ variation associated with extended and point defects in the samples. The peak κ provides valuable insights into the competition between intrinsic phonon-phonon scattering processes and extrinsic boundary and defect scattering processes in BAs. However, prior measurement methods have not been able to measure the peak κ because of fundamental and technical limitations. Here, we report peak κ measurements of BAs crystals synthesized under different conditions with source materials of different purities via a vapor transport method. For three representative samples, the measured κ peak appears at temperatures between 120 and 150 K and varies from 410±60Wm−1K−1 to 830±100Wm−1K−1. The measured thermal conductivities agree with theoretical calculations across the full temperature range. The similar calculated and measured peak temperatures helps to narrow down the boundary scattering mean free path to be around 4 μm in two samples and 5 μm in another, while the variation of the peak magnitude reveals a one-order-of-magnitude difference in the strength of point defect scattering. The phonon-defect scattering behavior correlates well with the measured electronic Raman scattering background, the impurity concentrations revealed by secondary ion mass spectroscopy, and the Hall concentration and mobility of the p-type samples except for an anomalously high hole concentration that appears in one sample, which indicates nonuniform impurity distribution. The observed correlation clarifies the origins of extrinsic phonon scattering mechanisms in BAs crystals.

关键词： Crystal defects Hall effect Heat transfer Impurities Phonons Thermal conductivity Thermal properties

First principle prediction of structural distortions in the cuprates and their impact on the electronic structure

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arXiv 2023年

作者： Jin, Zheting Ismail-Beigi, Sohrab Department of Applied Physics Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States

Materials-realistic microscopic theoretical descriptions of copper-based superconductors are challenging due to their complex crystal structures combined with strong electron interactions. Here, we demonstrate how density functional theory can accurately describe key structural, electronic, and magnetic properties of the normal state of the prototypical cuprate Bi2Sr2CaCu2O8+x (Bi-2212). We emphasize the importance of accounting for energy-lowering structural distortions, which then allows us to: (a) accurately describe the insulating antiferromagnetic (AFM) ground state of the undoped parent compound (in contrast to the metallic state predicted by previous ab initio studies);(b) identify numerous low-energy competing spin and charge stripe orders in the hole-overdoped material nearly degenerate in energy with the AFM ordered state, indicating strong spin fluctuations;(c) predict the lowest-energy hole-doped crystal structure including its long-range structural distortions and oxygen dopant positions that match high-resolution scanning transmission electron microscopy (STEM) measurements;and (d) describe electronic bands near the Fermi energy with flat antinodal dispersions and Fermi surfaces that in agreement with angle-resolved photoemission spectroscopy (ARPES) measurements and provide a clear explanation for the structural origins of the so-called "shadow bands". We also show how one must go beyond band theory and include fully dynamic spin fluctuations via a many-body approach when aiming to make quantitative predictions to measure the ARPES spectra in the overdoped material. Finally, regarding spatial inhomogeneity, we show that the local structure at the CuO2 layer, rather than dopant electrostatic effects, modulates the local charge-transfer gaps, local correlation strengths, and by extension the local superconducting gaps. © 2023, CC BY.

关键词： Spin fluctuations

Structural, magnetic, and electronic properties of a GdAsSe single crystal: Experimental and theoretical studies

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Physical Review B 2024年第18期109卷 184420-184420页

作者： R. Kalaivanan Balaji Venkatesan B. Dundi Sri Chandana Rajesh Kumar Ulaganathan G. Senthil Murugan K. Moovendaran Joydev Khatua Li-Hsin Su W. Zhou Xiaofeng Xu Chia-Seng Chang Tien-Ming Chuang Yoshiyuki Iizuka I. Panneer Muthuselvam Horng-Tay Jeng Kwang-Yong Choi Raman Sankar Institute of Physics Academia Sinica Taipei 10617 Taiwan Department of Physics National Taiwan University Taipei 10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei 11529 Taiwan Department of Physics School of Basic and Applied Sciences Central University of Tamil Nadu Neelakudi Thiruvarur 610005 Tamil Nadu India Department of Physics Sungkyunkwan University Suwon 16419 Republic of Korea Department of Physics National Tsing Hua University Hsinchu 30013 Taiwan Department of Electro Physics National Yang Ming Chiao Tung University Hsinchu 300093 Taiwan School of Electronic and Information Engineering Changshu Institute of Technology Changshu 215500 China Department of Applied Physics Zhejiang University of Technology Hangzhou 310023 China Institute of Earth Sciences Academia Sinica Taipei 10617 Taiwan Department of Physics (MMV) Banaras Hindu University Varanasi 221005 Uttar Pradesh India Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan

We report high-quality single-crystal growth, x-ray diffraction, magnetic susceptibility [χ(T,H)], magnetization [M(H)], heat capacity [CP(T,H)], electrical resistivity [ρ(T,H)], and electron spin resonance (ESR) measurements of GdAsSe as functions of temperature and magnetic field. We identify an antiferromagnetic phase transition at TN∼11.9±0.2 K and construct magnetic phase diagrams for H||ab and H||c axes based on the χ(T,H) and CP(T,H) data. Isothermal M(H) curves along the H||ab direction at 3 K exhibit a field-induced spin orientation at HC∼3.78T. Both M(H) and χ(T,H) indicate an easy-plane-type anisotropy. The Curie-Weiss analysis of the high-temperature paramagnetic χ(T) yields a negative Weiss temperature, suggesting dominant antiferromagnetic interactions between the Gd ions. Magnetic entropy reaches 83% of R ln8 at TN. The presence of residual entropy above TN and the persistence of ESR critical broadening up to ∼3TN alludes to a degree of magnetic frustration in the studied material. The ρ(T) data above TN is well fitted to the Bloch-Grüneisen theory for metals. Further, density functional theory calculations reveal an antiferromagnetic ground state where the Gd atoms are coupled ferromagnetically in the ab plane and antiferromagnetically along the c axis.

关键词： Magnetic anisotropy Magnetic coupling Magnetic interactions Magnetic order Magnetism

Enhancing Fieldwork Productivity in Subsurface Characterization: Advancements in Data Acquisition with Masw-Ds

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SSRN

SSRN 2024年

作者： Hamdan, Hamdan Ali Kritikakis, George Elsamani, Mahmoud Harb, Mahmoud Abdel-Fattah, Mohamed Soupios, Pantelis University of Sharjah Petroleum Geosciences and Remote Sensing Program Department of Applied Physics and Astronomy United Arab Emirates Applied Geophysics Lab Technical University of Crete Greece United Arab Emirates Department of Geosciences College of Petroleum Engineering and Geosciences King Fahd University of Petroleum and Minerals Dhahran31261 Saudi Arabia

The Multichannel Analysis of Surface Waves (MASW) method utilizes low-frequency surface waves, to characterize the shallow subsurface layers. It is a very useful tool in geotechnical engineering for evaluating soil quality and mapping the characteristics of the upper sedimentary layers. Despite its efficiency, the limited productivity of conventional MASW due to its relatively slow data acquisition process presents a challenge, especially for large-scale projects, such as those carried out in the Gulf Cooperation Council (GCC) region. To address this issue, we introduce the Multichannel Analysis of Surface Waves-Dual Streamer (MASW-DS) technique to enhance fieldwork productivity by almost 90%. This approach involves towing two parallel land streamers simultaneously behind a truck and enabling the acquisition of data from the two adjacent MASW profiles with a single source activated between the two land streamers. Our study evaluates the precision and effectiveness of MASW-DS through a set of synthetic and real data testing across diverse sites, demonstrating its potential for expedited surveys and reduced project costs. While MASW-DS introduces assumptions that may impact the resulting S-wave profiles, our findings indicate its comparable performance to conventional MASW, with negligible differences in dispersion curves and promising results, even in challenging geological settings. The proposed technique managed to reproduce the S-wave profiles resulting from the classic MASW deployment in the framework of an acceptable error for engineers. These results prove the reliability of the MASW-DS technique for subsurface characterization while achieving significant time and cost savings. MASW-DS also holds the potential for further enhancement by towing more than two land streamers simultaneously, positioning it as a valuable and effective tool for geotechnical investigations and civil engineering projects worldwide. © 2024, The Authors. All rights reserved.

关键词： Geotechnical engineering

Effects of Artificial Collisions, Filtering, and Nonlocal Closure Approaches on Hermite-based Vlasov-Poisson Simulations

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arXiv 2024年

作者： Issan, Opal Chapurin, Oleksandr Koshkarov, Oleksandr Delzanno, Gian Luca Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA United States T-5 Applied Mathematics and Plasma Physics Group Los Alamos National Laboratory Los AlamosNM United States

Kinetic simulations of collisionless plasmas are computationally challenging due to phase space mixing and filamentation, resulting in fine-scale velocity structures. This study compares three methods developed to reduce artifacts related to limited velocity resolution in Hermite-based Vlasov-Poisson simulations: artificial collisions, filtering, and nonlocal closure approaches. We evaluate each method’s performance in approximating the linear kinetic response function and suppressing recurrence in linear and nonlinear regimes. Numerical simulations of Landau damping demonstrate that artificial collisions, particularly higher orders of the Lenard-Bernstein collisional operator, most effectively recover the correct damping rate across a range of wavenumbers. Moreover, Hou-Li filtering and nonlocal closures underdamp high wavenumber modes in linear simulations, and the Lenard-Bernstein collisional operator overdamps low wavenumber modes in both linear and nonlinear simulations. This study demonstrates that hypercollisions offer a robust approach to kinetic simulations, accurately capturing collisionless dynamics with limited velocity resolution. © 2024, CC BY.

关键词： Damping

Modeling multi-legged robot locomotion with slipping and its experimental validation

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arXiv 2023年

作者： Wu, Ziyou Zhao, Dan Revzen, Shai Robotics University of Michigan United States Mechanical Engineering University of Michigan United States Electrical Engineering and Computer Science University of Michigan United States Ecology and Evolutionary Biology University of Michigan United States Applied Physics Program University of Michigan United States

Multi-legged robots with six or more legs are not in common use, despite designs with superior stability, maneuverability, and a low number of actuators being available for over 20 years. This may be in part due to the difficulty in modeling multi-legged motion with slipping and producing reliable predictions of body velocity. Here we present a detailed measurement of the foot contact forces in a hexapedal robot with multiple sliding contacts, and provide an algorithm for predicting these contact forces and the body velocity. The algorithm relies on the recently published observation that even while slipping, multi-legged robots are principally kinematic, and employ a friction law ansatz that allows us to compute the shape-change to body-velocity connection and the foot contact forces. This results in the ability to simulate motion plans for a large number of contacts, each potentially with slipping. Furthermore, in homogeneous environments, this kind of simulation can run in (parallel) logarithmic time of the planning horizon. © 2023, CC BY.

关键词： Friction