检索结果-内蒙古大学图书馆

Sedimentation-driven one-step fabrication of bifunctional single-layered triboelectric nanogenerator from sol-state composite precursor

引用

Friction 2025年第2期13卷 49-56页

作者： Yoonsang Ra Dongik Kam Sunmin Jang Sumin Cho Donghan Lee Dongwhi Choi Department of Mechanical Engineering(Integrated Engineering Program) Kyung Hee UniversityGyeonggi 17104Republic of Korea

Although the triboelectric nanogenerator(TENG)has been highlighted as a promising mechanical energy harvester,the requirement of stacking the two individual layers,contact and conductive layers,has been ball and chain around the ankle of unleashing potential and an advantage of TENGs in their application expansion and ***,one-step fabrication of a single-layered bifunctional composite film-based TENG(BFTENG)driven by the sedimentation of a sol-state precursor is proposed for the extremely facile conversion of various ordinary items into energy *** BF-TENG consists of the polydimethylsiloxane(PDMS)matrix and a carbon nanopowder filler,and it includes both the dielectric part(DP)and conductive part(CP)in one single *** electrical percolation threshold of the incorporated concentration of carbon,ICC,for CP to act as a passage through which induced charges move in BF-TENGs is determined to be 1.0 wt%.The degree of carbon sedimentation in developing the proposed composite can be controlled by the curing speed and the probability of a crosslinking *** maximum peak power is approximately 0.093μW when the contact surface area is 78.5 mm2;the contact frequency is 8 Hz,and the connected load resistance is 9 MΩ.Based on these results,the electrical performance of BF-TENGs in response to various physical stimuli is characterized considering the mechanical energy sources available in daily ***,converting ordinary surfaces such as desks and human skin into BF-TENGs through a single coating procedure and harvesting energy to power an electric device are demonstrated as a proof-of-concept.

关键词： triboelectric nanogenerator one-step fabrication sedimentation bifunctional composite film

来源：评论

学校读者我要写书评

暂无评论

Studying the Impact of T4 and T6 Heat Treatments on Corrosion and mechanical Properties of 6082-Al Alloy Treated with Al-5Ti-1B Grain Refiner

引用

Journal of Bio- and Tribo-Corrosion 2025年第1期11卷 1-13页

作者： Abd El-Aziz, Kh. Saber, D. Materials Engineering Department Faculty of Engineering Zagazig University Zagazig44519 Egypt Mechanical Engineering Department College of Engineering Taif University Taif Saudi Arabia Industrial Engineering Program Mechanical Engineering Department College of Engineering Taif University Taif Saudi Arabia

The mechanical and corrosion characteristics of aluminum alloys can be influenced not only by the addition of grain refiners but also by heat treatment that modifies the microstructure and introduces variations in these characteristics. The purpose of this work was to examine how the mechanical properties and corrosion resistance of 6082-Al alloy with Al-5Ti-1B grain refiner are affected by both artificial and natural aging heat treatments. By using the permanent mold casting process, the required specimens of the investigated alloys were produced. A VHS-1000 microhardness testing apparatus is used to measure microhardness at a 100 g load. A sliding wear test is carried out using a pin-on-disk apparatus. Potentiodynamic polarization curves in a 3.5 weight percent NaCl solution are used to assess the corrosion behavior of every specimen. The current results revealed that the mechanical properties improved markedly with the additions of Al–5Ti-1B grain refiner to the investigated alloy, this is maybe due to the microstructure changes as a result of grain refiner additions. Although the addition of Al-5Ti-1B grain refiner to 6082-Al alloy improved the hardness and wear resistance, it showed a negative influence on the corrosion resistance of these alloys. The results also demonstrated that, when compared to as-cast condition, artificial heat treatment of 6082-Al alloy inoculated by Al-5Ti-1B grain refiner improved their hardness, wear resistance, and corrosion properties significantly. Furthermore, compared to natural aging heat treatment, artificial aging heat treatment demonstrated a noticeably improved level of hardness, wear, and corrosion behavior. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.

关键词： Aluminum corrosion

来源：评论

学校读者我要写书评

暂无评论

Comparison of Tribological Behavior of Hard Faced Fe-Based Metallic Composite Coatings Sprayed Using HVOF

引用

Journal of Bio- and Tribo-Corrosion 2025年第1期11卷 1-18页

作者： Soni, Piyush Kumar Prasad, C. Durga Manjunath, H.R. Tiwari, Amit Raju, Vadali Pitchi Athithan, Senthil Deshmukh, Khemraj Kumar, Anjani Department of Mechanical Engineering New Horizon College of Engineering Karnataka Bengaluru India Department of Mechanical Engineering RV Institute of Technology and Management Karnataka Bengaluru India Department of Mechanical Engineering Ramaiah Institute of Technology Karnataka Bengaluru560054 India Department of Mechanical Engineering Suresh Gyan Vihar University Jaipur India Mechanical Engineering Department & amp Principal Indur Institute of Engineering and Technology Siddipet India Department of Computer Science and Engineering Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram India Department of Biomedical Engineering Parul University Gujarat Vadodara India Mechanical Engineering Department Government Engineering College Arwal India

Fe-based alloys have recently become well-known for their ability to resist wear and corrosion. Iron, the primary component of alloys, is a cheaper option than alloys made from Co and Ni. There is a need for affordable and easily obtainable coatings based on iron. Coatings in the Fe–Ni–Cr system have demonstrated superior wear resistance compared to other commonly used Fe-based metallic coatings. The Fe-12Ni17Cr2.5Mo2.3Si0.03C based (Metco 41C) metallic coatings were applied onto boiler steel substrates using the High Velocity Oxy-Fuel (HVOF) spraying method. The coatings were examined using X-ray diffraction (XRD), a scanning electron microscope (SEM), and a microhardness tester to determine their density, porosity, microstructure, hardness, and surface roughness. The sliding wear behavior of the substrate and coatings was studied using the pin-on-disk tribometer. Figuring out the wear loss and coefficient of friction. Comparison was made of wear results between the substrate, coatings, and composite coatings. By combining these carbide powders with 30% SiC and WC-12Co particles, the coating’s wear resistance is enhanced in comparison to the Metco 41C coating. In comparison to boiler steel, the Metco 41C + SiC and Metco 41C + WC–Co coatings exhibited a roughly 70% and 40% reduction in volume loss compared with boiler steel respectively. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： HVOF thermal spraying

来源：评论

学校读者我要写书评

暂无评论

Development and Evaluation of Machine Learning Based Predictive Models for Tribological Properties of Blended Coatings at Elevated Temperature

引用

Journal of Bio- and Tribo-Corrosion 2025年第1期11卷 1-20页

作者： Jatavallabhula, Jagadesh Kumar Shabana, Shabana Pappula, Bridjesh Department of Mechanical Bioresources and Biomedical Engineering College of Science Engineering and Technology University of South Africa Florida Campus Johannesburg South Africa Department of Mechanical Engineering GST GITAM University Visakhapatnam India Johannesburg South Africa

The current research is undertaken to evaluate the Tribological properties like wear and Coefficient of Friction (CoF) of three popular blended coatings on a mild steel substrate at elevated temperature. The scope of the research also includes predicting the tribological properties by employing three Machine Learning (ML) based predictive models viz. Elastic Net, k-NN and Random Forest regressions. The regressions are fit and tested at different proportions of Training and Testing data to find the best proportion. Random Forest regression is observed to be the best fit based on the acceptable values of MSE and R-Squared. Random Forest regression model of wear yielded MSE and R-Squared values as 22.01 and 0.95 for Coating 1, 5.75 and 1 for Coating 2, and 14.13 and 1 for Coating 3, respectively. Likewise, Random Forest regression model of CoF yielded MSE and R-Squared values as 0.01 and 0.99 for Coating 1, 0 and 1 for Coating 2, and 0 and 1 for Coating 3, respectively. The deviation between the experimental and predicted results (tested data: experimental runs 3, 14, and 29) in wear using the Random Forest algorithm for Coating 1, Coating 2, and Coating 3 is found to be 21.18%, − 2.72%, and 0.42%;− 4.54%, − 13.87, and 2.57%;11.85%, 1.69%, and 1.89%, respectively. The deviation for CoF is found to be 6.29%, 1.56%, and 2.93%;− 0.86%, − 0.56%, and 0.20%;0.85%, − 0.19%, and 0.17%, respectively. The variance between the actual experimental and predicted results from Random Forest regression is observed to be relatively acceptable. © The Author(s) 2025.

关键词： Low carbon steel

来源：评论

学校读者我要写书评

暂无评论

A possible solution for noise attenuation material for urban buses: The downtown São Paulo case study

引用

Noise and Vibration Worldwide 2025年第3期56卷 137-147页

作者： Monteiro, Elvis C Avila, Antonio F Division Stellantis Betim Brazil Mechanical Engineering Graduate Studies Program Universidade Federal de Minas Gerais Belo Horizonte Brazil Department of Mechanical Engineering and Mechanical Engineering Graduate Studies Program Universidade Federal de Minas Gerais Belo Horizonte Brazil

Urban buses, particularly in large cities, are exposed to significant noise pollution. This paper presents a new family of materials at the micro/nano level designed for urban noise attenuation, specifically for application in urban buses. Melamine foam is combined in series with nanomembranes, creating a composite material that functions as a Helmholtz resonator. As sound waves pass over the nanomembranes, they are disturbed, and the sound resonates within the melamine foam. This interaction reduces the energy of the sound waves and enhances the noise absorption coefficient. In ten cases studied, the average sound absorption coefficient was approximately 89%, with peak frequencies ranging from 2400 Hz to 4300 Hz. The average thickness of the nanomembranes was around 5.0 µm, while the melamine foam had a thickness of 13 mm. The mean noise reduction achieved was about 11 dB, which depends on factors such as the morphology, thickness, and pore size of the nanomembranes. A case study conducted in downtown São Paulo demonstrated that applying these materials to urban buses can significantly reduce interior noise levels. Finally, the proposed system is fully scalable and adaptable for various applications where acoustic insulation is required. © The Author(s) 2025.

关键词： Noise pollution

来源：评论

学校读者我要写书评

暂无评论

Convex Approach to Real-Time Multiphase Trajectory Optimization for Urban Air Mobility

引用

Journal of Air Transportation 2025年第1期33卷 69-85页

作者： Wu, Yufei Deniz, Sabrullah Shi, Yang Wang, Zhenbo Department of Mechanical Aerospace and Biomedical Engineering University of Tennessee AIAA KnoxvilleTN37996 United States

Electric vertical takeoff and landing technology has emerged as a promising solution to alleviate ground transportation congestion. However, the limited capacity of onboard batteries enforces hard time constraints for vehicle operations in a complex urban environment. Therefore, a constrained, real-time trajectory optimization method is necessary to enable safe and energy-efficient vehicle flight. Unfortunately, most existing trajectory optimization methods suffer from low computational efficiency, unpredictable convergence processes, and strong dependence on a good initial trajectory. In this paper, we employ a successive convex programming approach to solve the multiphase minimum-energy-cost electric vertical takeoff and landing vehicle trajectory optimization problem for urban air mobility applications. The main contribution is the development and validation of two novel convexification methods that find approximate optimal solutions to the multiphase nonlinear trajectory optimization problem in real time by solving a sequence of convex subproblems. Specifically, the first method transforms the original nonlinear problem into a sequence of second-order cone programming problems through a convenient change of variables and lossless convexification, while the second approach achieves a similar goal without the need for control convexification. The resulting convex subproblems can be solved reliably in real time by advanced interior point methods. The proposed methods are demonstrated through numerical simulations of two different urban air mobility scenarios and compared with the solution obtained from GPOPS-II, a state-of-the-art general-purpose optimal control solver. Our proposed sequential convex programming methods can obtain near-optimal solutions with faster computational speed than GPOPS-II. © 2024 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Constrained optimization

来源：评论

学校读者我要写书评

暂无评论

Biomechanics-Informed Mechatronics Design of Comfort-Centered Portable Hip Exoskeleton: Actuator, Wearable Interface, Controller

IEEE Transactions on Medical Robotics and Bionics

引用

IEEE Transactions on Medical Robotics and Bionics 2025年第2期7卷 687-698页

作者： Rodriguez-Jorge, Daniel Zhang, Sainan Huang, Jin Sen Lopez-Sanchez, Ivan Srinivasan, Nitin Zhang, Qiang Zhou, Xianlian Su, Hao North Carolina State University Department of Mechanical and Aerospace Engineering RaleighNC27695 United States Tandon School of Engineering New York University Laboratory of Biomechatronics and Intelligent Robotics Department of Biomedical Engineering New YorkNY11201 United States The University of Alabama Department of Mechanical Engineering Department of Chemical & Biological Engineering TuscaloosaAL35401 United States New Jersey Institute of Technology Department of Biomedical Engineering NewarkNJ07102 United States

Exoskeletons can improve human mobility, but discomfort remains a significant barrier to their widespread adoption. This paper presents a comfort-centered mechatronics design of portable hip exoskeletons, comprising of three factors: (i) actuation, (ii) wearable interface, (iii) and assistive controller. We introduced an analytical multibody model to predict the human-exoskeleton contact forces during gait. Informed by this model, we designed a wearable interface that significantly improved the three considered objective metrics: (i) undesired contact forces at the wearable interface, (ii) wobbling, and (iii) metabolic reduction, and also the post-test evaluation via a System Usability Scale questionnaire as a subjective metric. Our experiments with two exoskeleton controllers (gait-based and reinforcement learning-based) demonstrated that the design of the wearable physical interface has a greater impact on reducing metabolic rate and minimizing wobbling than the choice of controller. Our actuation design method leads to highly backdrivable, lightweight quasi-direct drive actuators with high torque tracking performance. By leveraging this wearable design, we achieved up to 60% reduction in undesired contact forces, and a 74% reduction in exoskeleton wobbling in the frontal axis compared to a traditional configuration. Additionally, the net metabolic cost reduction was 18% compared to the no exoskeleton condition. © 2018 IEEE.

关键词： Exoskeleton (Robotics)

来源：评论

学校读者我要写书评

暂无评论

RGB Color-Discriminable Photonic Synapse for Neuromorphic Vision System

引用

Nano-Micro Letters 2025年第4期17卷 39-62页

作者： Bum Ho Jeong Jaewon Lee Miju Ku Jongmin Lee Dohyung Kim Seokhyun Ham Kyu-Tae Lee Young-Beom Kim Hui Joon Park Department of Organic and Nano Engineering&Human-Tech Convergence Program Hanyang UniversitySeoul 04763Korea Department of Semiconductor Engineering Hanyang UniversitySeoul 04763Korea Department of Mechanical Engineering Hanyang UniversitySeoul 04763Korea Department of Physics Inha UniversityIncheon 22212Korea

To emulate the functionality of the human retina and achieve a neuromorphic visual system,the development of a photonic synapse capable of multispectral color discrimination is of paramount ***,attaining robust color discrimination across a wide intensity range,even irrespective of medium limitations in the channel layer,poses a significant ***,we propose an approach that can bestow the color-discriminating synaptic functionality upon a three-terminal transistor flash memory even with enhanced discriminating *** incorporating the strong induced dipole moment effect at the excitation,modulated by the wavelength of the incident light,into the floating gate,we achieve outstanding RGB color-discriminating synaptic functionality within a remarkable intensity range spanning from 0.05 to 40 mW cm^(-2).This approach is not restricted to a specific medium in the channel layer,thereby enhancing its *** effectiveness of this color-discriminating synaptic functionality is demonstrated through visual pre-processing of a photonic synapse array,involving the differentiation of RGB channels and the enhancement of image contrast with noise ***,a convolutional neural network can achieve an impressive inference accuracy of over 94%for Canadian-Institute-For-Advanced-Research-10 colorful image recognition task after the *** proposed approach offers a promising solution for achieving robust and versatile RGB color discrimination in photonic synapses,enabling significant advancements in artificial visual systems.

关键词： Organic field-effect transistor Photonic synapse Excited-state dipole moment RGB color discrimination Neuromorphic visual system

来源：评论

学校读者我要写书评

暂无评论

The Effect of Dimple-Based TMJ Design and Its Biomechanical Effect on Reducing Stress

引用

Journal of Long-Term Effects of Medical Implants 2025年第2期35卷 33-39页

作者： Dommeti, Vamsi Krishna Rajaeirad, Mohadese Jamshidi, Nima Roy, Sandipan Department of Mechanical Engineering SRM Institute of Science and Technology Kattankulathur Kanchipuram Tamil Nadu Chennai603203 India Department of Biomedical Engineering University of Isfahan Isfahan81746-73441 Iran

Temporomandibular joint (TMJ) disorders significantly impact orofacial health and quality of life, necessitating effective interventions. This study presents a comprehensive finite element analysis (FEA) focusing on the design and material modifications of temporomandibular joint implants, with the aim of improving their long-term stability and performance. Accurate mandible models extracted from Computational Tomography (CT) scans were used to create three variations of implants, each attached using varying screw configurations ranging from 2 to 5 for each analysis. The variations included implants without dimples, implants with 10% dimples, and implants with 20% dimples. The FEA considered material properties of Titanium and Ti-Nb-Zr alloy for the implants. The FEA results revealed that for 10% dimples models, equivalent stress was reduced by 6.25% with two screws fixation and further decreased by 14.28% with three screws, irrespective of the implant volume, reaffirming the significance of screw fixation. The model secured with three screws exhibited the least amount of stress for both titanium and zirconium alloys and dimple implants showed promise in reducing stress levels, particularly in low bone density conditions. These findings not only underscore the potential advantages of dimple implants in facilitating bone in growth and stability at the bone-implant interface but also highlight the pivotal role of implant dimples in modulating stress levels. The study contributes valuable insights for future advancements in TMJ implantology, offering potential optimizations for implant design and clinical outcomes. © 2025 by Begell House, Inc.

关键词： Binary alloys

来源：评论

学校读者我要写书评

暂无评论

Mapping extreme vertical forces induced by air-wake on a simplified ship model

引用

Marine Systems and Ocean Technology 2025年第3期20卷 1-9页

作者： Setiawan, Heri Bhirawa, Tunggul Ocean Engineering Program Institut Teknologi Bandung Bandung Indonesia Department of Mechanical Engineering The University of Melbourne ParkvilleVIC Australia

Helicopters, the primary vehicles for aerial support in naval operations, are the subject of our study. As the helicopter navigates above the ship’s landing deck, the unsteady flows formed in this region will translate into fluctuating aerodynamic forces on the helicopter. Understanding these forces and their extreme nature is crucial for ensuring the safety and stability of helicopters during naval operations. However, it is observed that many studies overlook the extremes in wind fluctuations as a critical contributor to ship-helicopter operation safety. They mainly focused on the time-averaged parameters, such as mean velocity and turbulence intensity, to characterise the highly fluctuating air-wake flow. This study introduces a method to identify extreme air-wake-induced aerodynamic vertical forces, one possible extreme event that the aircraft may face as it approaches the landing deck. The vertical forces are quantified by calculating the vertical drag acting on the helicopter fuselage using the strip approach proposed by Stepniewski and Keys (Rotary-wing aerodynamics. Courier Corporation, New York, 1984). Example calculations are conducted using experimental air-wake data recorded without the influence of the rotor thrust (Setiawan et al in Ocean Eng 260:111931, 2022). On average, it is shown that the helicopter will face strong downward forces as it hovers above the ship’s landing deck. However, more importantly, there are several instances where the vertical drag acting on the fuselage reaches five times higher than the average value. This highlights the potential risks and the urgent need for quantifying extreme events related to ship -helicopter landing operations. © The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval 2025.

关键词： Ship models

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：