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ACS ES&T air 2025年第1期2卷 109-118页

作者： Sofie K Schwink Liora E Mael Thomas H Dunnington Maximilian J Schmid Jonathan M Silberstein Andrew Heck Nicholas Gotlib Michael P Hannigan Marina E Vance Environmental Engineering Program University of Colorado Boulder 1111 Engineering Drive Boulder Colorado 80309-0428 United States. Department of Mechanical Engineering University of Colorado Boulder 1111 Engineering Drive Boulder Colorado 80309-0427 United States. Department of Aerospace Engineering University of Colorado Boulder 429 UCB 3775 Discovery Drive Boulder Colorado 80303 United States.

Quantifying changes in the properties of smoke aerosols under varying conditions is important for understanding the health and environmental impacts of exposure to smoke. Smoke composition, aerosol liquid water content, effective density (ρ), and other properties can change significantly as smoke travels through areas under different ambient conditions and over time. During this study, we measured changes in smoke composition and physical properties due to oxidative aging and exposure to humidity. We found that smoke aging led to SOA formation and increases in ratios of organic carbon to elemental carbon. Aerosol liquid water content increased with increasing relative humidity (RH), and aged smoke took up more water than fresh smoke at all humidity levels, likely due to a combination of changes in aerosol surface polarity at low and medium RH and increases in surface area with aging at high RH. Growth factors ranged from 1.06 ± 0.08 for fresh smoke at low RH to 1.32 ± 0.08 for aged smoke at high RH. Oxidative aging and exposure to humidity led to increases in ρ. For 100 nm particles, ρ ranged from ∼1.2 for fresh smoke at low RH to ∼1.6 for aged smoke at high RH. Results from these experiments suggest that exposure to humidity leads to smoke restructuring and compaction and/or changes in surface chemistry.

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Scale-Invariant Specifications for Human-Swarm Systems

Field Robotics

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Field robotics 2025年 3卷 368-391页

作者： Joel Meyer Ahalya Prabhakar Allison Pinosky Ian Abraham Annalisa Taylor Millicent Schlafly Katarina Popovich Giovani Diniz Brendan Teich Borislava Simidchieva Shane Clark Todd Murphey The Center for Robotics and Biosystems at Northwestern University École Polytechnique Fédérale de Lausanne (EPFL) The Department of Mechanical Engineering at Yale University Unmanned Laboratory Raytheon BBN Technologies Systems and Technology Research

We present a method for controlling a swarm using its spectral decomposition—that is, by describing the set of trajectories of a swarm in terms of a spatial distribution throughout the operational domain—guaranteeing scale invariance with respect to the number of agents both for computation and for the operator tasked with controlling the swarm. We use ergodic control, decentralized across the network, for implementation. In the DARPA OFFSET program field setting, we test this interface design for the operator using the STOMP interface—the same interface used by Raytheon BBN throughout the duration of the OFFSET program. In these tests, we demonstrate that our approach is scale-invariant—the user specification does not depend on the number of agents; it is persistent—the specification remains active until the user specifies a new command; and it is real-time—the user can interact with and interrupt the swarm at any time. Moreover, we show that the spectral/ergodic specification of swarm behavior degrades gracefully as the number of agents goes down, enabling the operator to maintain the same approach as agents become disabled or are added to the network. We demonstrate the scale invariance and dynamic response of our system in a field-relevant simulator on a variety of tactical scenarios with up to 50 agents. We also demonstrate the dynamic response of our system in the field with a smaller team of agents. Lastly, we make the code for our system available.

关键词： User interfaces Space exploration Hardware Visualization Trajectory Touch sensitive screens Robot sensing systems Real-time systems Graphical models Distribution functions

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Graphene-functionalized textile composites for wearable Joule heating applications

Advanced Nanocomposites

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Advanced Nanocomposites 2025年 2卷 108-123页

作者： Omar Faruk Abbas Ahmed Ashfaqul Hoque Khadem Lu Jia Luyi Sun Department of Materials Science and Engineering Binghamton University State University of New York at Binghamton NY 13902 USA Polymer Program Institute of Materials Science and Department of Chemical & Biomolecular Engineering University of Connecticut Storrs CT 06269 USA Department Mechanical Engineering College of Engineering Computing and Applied Science Clemson University Clemson SC 29634 USA College of Textile Engineering Taiyuan University of Technology Jinzhong Shanxi 030600 China

Thermal comfort is essential for maintaining physiological well-being, with textile materials traditionally serving as the primary medium for regulating heat exchange between the body and its environment. However, conventional textiles often fall short of maintaining optimal thermal balance. So, there is an increasing demand for advanced thermoregulation systems that can effectively reduce heat loss and enhance warmth, ensuring consistent comfort. Recent research has highlighted the promise of advanced functional materials, especially graphene and its composites, for modifying textiles to improve thermal properties. This article comprehensively reviews recent advancements in graphene-functionalized textile composites, focusing on their applications in wearable Joule heaters designed for personalized thermal comfort or thermal therapy. Various graphene-functionalized textile composites are reviewed from the perspectives of material properties, processing strategies and device fabrication methods. Key challenges and future opportunities are summarized for graphene-functionalized textile-based Joule heaters as innovative solutions in wearable thermal regulation.

关键词： Graphene Textile Composite Wearable electronics Joule heater

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Online Robot Motion Planning Methodology Guided by Group Social Proxemics Feature

arXiv

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arXiv 2025年

作者： Mu, Xuan Liu, Xiaorui Guo, Shuai Chi, Wenzheng Wang, Wei Ge, Shuzhi Sam School of Automation Qingdao University Qingdao266000 China School of Automation Qingdao University Qingdao University Qingdao266000 China Robotics and Microsystems Center School of Mechanical and Electric Engineering Soochow University Suzhou215021 China School of Mechanical Engineering & Automation the Robotics Institute Beihang University Beijing100000 China Department of Electrical and Computer Engineering National University of Singapore Singapore117576 Singapore

Nowadays robot is supposed to demonstrate human-like perception, reasoning and behavior pattern in social or service application. However, most of the existing motion planning methods are incompatible with above requirement. A potential reason is that the existing navigation algorithms usually intend to treat people as another kind of obstacle, and hardly take the social principle or awareness into consideration. In this paper, we attempt to model the proxemics of group and blend it into the scenario perception and navigation of robot. For this purpose, a group clustering method considering both social relevance and spatial confidence is introduced. It can enable robot to identify individuals and divide them into groups. Next, we propose defining the individual proxemics within magnetic dipole model, and further established the group proxemics and scenario map through vector-field superposition. On the basis of the group clustering and proxemics modeling, we present the method to obtain the optimal observation positions (OOPs) of group. Once the OOPs grid and scenario map are established, a heuristic path is employed to generate path that guide robot cruising among the groups for interactive purpose. A series of experiments are conducted to validate the proposed methodology on the practical robot, the results have demonstrated that our methodology has achieved promising performance on group recognition accuracy and path-generation efficiency. This concludes that the group awareness evolved as an important module to make robot socially behave in the practical scenario. © 2025, CC BY-NC-ND.

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Large spin accumulation signals in ultrafast magneto-optical experiments.

arXiv

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arXiv 2025年

作者： Anadón, Alberto Singh, Harjinder Díaz, Eva Le-Guen, Yann Hohlfeld, Julius Wilson, Richard B. Malinowski, Gregory Hehn, Michel Gorchon, Jon Université de Lorraine CNRS IJL NancyF-54000 France Department of Mechanical Engineering and Materials Science and Engineering Program University of California RiversideCA United States

Magneto-optical techniques have become essential tools in spintronics, enabling the investigation of spin dynamics in the ultrafast regime. A key challenge in this field has been to accurately isolate the contributions to magneto-optical signals of spin transport phenomena from the local magnetization dynamics. The contribution of transported and accumulated spins was long believed to be orders of magnitude smaller than that of the magnetization and thus previous approaches to disentangle these signals have relied on specific experimental designs, usually including thick metal layers. Here, we present experimental evidence demonstrating that the magneto-optical signal from ultrafast spin accumulations can, under certain conditions, be comparable to or even exceed that of the magnetic layer in a standard ultrafast demagnetization experiment. Our findings provide a new framework for accessing and isolating these spin accumulations, allowing for time and depth dependent probing of transported spin and/or orbital angular momentum. © 2025, CC BY.

关键词： Spin dynamics

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Extracellular matrix repair and organization of chronic infected diabetic wounds treated with MACF hydrogels

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Acta Biomaterialia 2025年 199卷 166-177页

作者： Durr, Hannah A Abri, Shahrzad Salinas, Samuel D Adkins-Travis, Kayla Amini, Rouzbeh Shriver, Leah P Leipzig, Nic D Integrated Biosciences Program Department of Biology University of Akron AkronOH United States Department of Chemical Biomolecular and Corrosion Engineering University of Akron AkronOH United States Mechanical and Industrial Engineering Northeastern University BostonMA United States Department of Chemistry Washington University St. LouisMO United States Center for Mass Spectrometry and Isotope Tracing Washington University St. LouisMO United States Department of Medicine Washington University St. LouisMO United States

Diabetic foot ulcers (DFUs) are a multifactorial medical problem that require multifaceted approaches for effective healing. Most research on DFU healing has concentrated on promoting wound closure, with less emphasis on the quality of repaired tissue. This is problematic, however, since quality of the repaired tissues can have potential to improve wound healing outcomes and limit re-ulceration. If more functionally active dermis replaces the lost tissue, this can effectively maximize strength, organization, and overall structure of the plantar surface. Additionally, DFUs commonly show multi-strain infection, which further exacerbates the non-healing status of these wounds. Treatment of chronic wounds can be benefitted by application of oxygen and localized infection treatment, both can be achieved via our methacrylated chitosan-based (MACF) hydrogel. A non-healing diabetic infected wound model was used to explore extracellular matrix (ECM) organization, tensile strength, and metabolomic profiles at a 21-day endpoint as a marker for maturation and improved functionality of repaired tissues over normal scar formation. Effective remediation of infection was achieved with 14 days of polyhexamethylene biguanide (PHMB) application with improved wound repair compared to continuous treatment. Prolonged (21 day) application of PHMB showed resulting necrosis, although standard application times for patients with infected wounds can reach up to 28 continuous days. Biaxial mechanical analysis showed improved isotropic strength of infected tissues treated with MACF with PHMB stopped on D14, supported by collagen fiber orientation in second harmonics generation (SHG) imaging. Oxygenating MACF treatments also improved collagen deposition through the enhancement of the hydroxyproline fibrillary collagen synthesis pathway. These structural and mechanical results demonstrate a promising potential treatment for infected diabetic foot ulcers which shows improved dermal functionality.

关键词： Electroacupuncture

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Understanding Connection between PMP and HJB equations from the Perspective of Hamilton Dynamics

IEEE Transactions on Artificial Intelligence

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IEEE Transactions on Artificial Intelligence 2025年

作者： Zhang, Xiangteng Lyu, Yao Li, Shengbo Eben Duan, Jingliang Zhan, Guojian Liu, Chang Cheng, Bo Li, Keqiang Tsinghua University School of Vehicle and Mobility Beijing100084 China University of Science and Technology Beijing School of Mechanical Engineering China Peking University Department of Advanced Manufacturing and Robotics Beijing100871 China Peking University College of Engineering Beijing100871 China

Reinforcement learning (RL) is widely used to tackle optimal control problems, with optimality conditions as the principle of algorithm design. Two key optimality conditions are the Pontryagin Maximum Principle (PMP) and the Hamilton-Jacobi-Bellman (HJB) equation. The relationship between these conditions is vital for developing effective policy learning algorithms. Existing studies mainly focus on their relationship in the open-loop optimality, but this property cannot be directly extended to nonoptimal or closed-loop cases due to the absence of extreme condition and the existence of non-zero partial derivative term. This paper unifies the relationship between PMP and HJB equations in all cases by considering optimal control problems as nonholonomic Lagrange systems, and proves the intrinsic equivalence between value function and costate variable from the perspective of Hamilton dynamics. We redefine costate variable as Legendre transformation of state derivative in nonholonomic Lagrange systems, where the Weierstrass condition is selected as a constraint for optimal cases while fixed policy condition is chosen for nonoptimal cases. By utilizing the anti-symmetric property of canonical equations, we identify conservation properties in optimal control where symplectic form remains invariant across all cases. Additionally, we prove that the costate variable has the identical differential equation and boundary conditions as the partial derivative of value function with respect to state in both optimal and nonoptimal, open-loop and closed-loop cases. Numerical experiments are conducted to verify our theoretical results. This discovery can establish more readily available conservation conditions, thereby providing a high-level view angle on algorithm designs. © 2020 IEEE.

关键词： Lagrange multipliers

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A novel photovoltaic/thermal (PVT) system using nano-enhanced micro-encapsulated PCM slurry for steam production: A numerical study

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International Journal of Thermofluids 2025年 27卷

作者： Azmeer, Ahmed Sheikh, Yahya Kanjo, Hasan A. Sabouni, Hamzeh Physical Science and Engineering Department King Abdullah University of Science and Technology Thuwal Saudi Arabia Department of Mechanical Engineering American University of Sharjah Sharjah United Arab Emirates Department of Sustainable and Renewable Energy Engineering University of Sharjah Sharjah United Arab Emirates Materials Science and Engineering Program American University of Sharjah Sharjah United Arab Emirates

As industries reliant on steam-based processes strive to reduce fossil fuel consumption and carbon emissions, interest in renewable technologies, particularly photovoltaic/thermal (PVT) systems that generate both thermal and electrical energy, is increasing. However, the limited thermal performance of PVT systems remains a key barrier. Traditional working fluids, such as water, nanofluids, and phase change material (PCM) slurries, exhibit low thermal conductivity, poor temperature regulation, and inefficient heat storage. To address these issues, a novel working fluid incorporating graphene oxide (GO) nanoparticles into microencapsulated PCM (MPCM) slurry is proposed. The integration of GO nanoparticles not only enhances the dispersion stability of the MPCM slurry but also significantly increases its thermal conductivity, leading to improved heat dissipation from PV cells. A comprehensive CFD investigation is conducted using ANSYS Fluent 2021, employing an Eulerian–Eulerian multiphase model to simulate the three-phase flow. In this model, water serves as the primary phase, while GO nanoparticles and MPCM function as secondary dispersed phases. The results demonstrate that increasing the GO volume fraction from 0 to 0.005 reduces average PV cell temperatures by up to 5°C at 40°C. Additionally, the nano-enhanced MPCM slurry achieves a thermal efficiency of 88.1 % and an electrical efficiency of 10.3 %. It is also found that using MPCM slurry as the working fluid, a 15 % volume fraction of MPCM with a melting point of 40°C achieves the highest thermal efficiency of 90.1 %, outperforming water by 20.1 % and surpassing previous studies on MPCM slurry and nanofluids. © 2025 The Author(s)

关键词： Nanofluidics

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A Stable Lithium-ion Battery SOH Estimation Framework for Suppressing Measurement Noise with Unknown Distribution

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IEEE Transactions on Transportation Electrification 2025年

作者： Ma, Wentao Xue, Jingsong Li, Yang Guo, Peng Liu, Xinghua Wei, Zhongbao Wang, Yiwen Chen, Badong Xi’an University of Technology School of Electrical Engineering 710048 China Chalmers University of Technology Department of Electrical Engineering Gothenburg41296 Sweden Beijing Institute of Technology National Engineering Laboratory for Electric Vehicles School of Mechanical Engineering Beijing100081 China Hong Kong University of Science and Technology Department of Electronic and Computer Engineering Hong Kong Institute of artificial intelligence and robotics Xi’an Jiaotong University Xi’an710048 China

Existing methods for estimating the state of health (SOH) of lithium-ion battery (LIB) typically rely on the assumption that the distribution of noise (or outliers) in the measurement data is known. However, this assumption rarely holds true for LIB operating under real-word conditions. This article proposes a stable framework for accurate SOH estimation that accommodates noises with unknown distribution in both measurement data and label values. The framework combines generalized correntropy loss (GCL) with Savitzky-Golay (SG) filter and extreme learning machine (ELM) to obtain measurement data filter named SG-GCL and SOH estimator named generalized ELM (GELM), respectively. The SG-GCL filtering of the measurement data keeps the root mean square error (RMSE) within 0.0365%, and Pearson correlation between extracted feature and SOH improves by 0.4963, which in turn leads to the reduction of the RMSE metrics of the ELM for the estimation of the SOH by 43.69%. From the filtering results, feature extraction and estimation results proved its necessity and effectiveness. GELM effectively suppresses the influence of label value noise on the model in the training process, which reduces the SOH estimation RMSE index by more than 0.66%. The results from experiments with different distributional noise conditions show that the proposed SOH estimation framework has excellent and stable performance. © 2015 IEEE.

关键词： Mean square error

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Large eddy simulation of partially-premixed O2–H2 combustion with steam dilution in multi-cluster jet

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International Journal of Hydrogen Energy 2025年

作者： Siahaan, Gabriele Maruli Tondi Jiang, Shan Tanahashi, Mamoru Juangsa, Firman Bagja Mechanical Engineering Undergraduate Program Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Jl Ganesha 10 Bandung40132 Indonesia Thermal Science and Engineering Research Group Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Jl Ganesha 10 Bandung40132 Indonesia Research Center for New and Renewable Energy Institut Teknologi Bandung Jl Ganesha 10 Bandung40132 Indonesia Department of Mechanical Engineering Institute of Science Tokyo 2-12-1 Ookayama Meguro-ku Tokyo152-8550 Japan

Over the past 150 years, carbon dioxide levels in the atmosphere have risen significantly, causing a rise in temperatures due to disruptions in the natural carbon cycle. One proposed solution is transitioning to non-carbon fuels like hydrogen, which requires modifications to current gas turbine systems despite its higher flame temperature and flammability than carbon-based fuels. A suggested modification involves a non-premixed multi-cluster jet configuration with steam dilution to achieve a lifted flame. Steam dilution is utilized to lower the combustion temperature due to material limitations and to achieve a high systematical efficiency, which can be achieved through the Graz Cycle system. This study employs large eddy simulation (LES) to analyze oxy-hydrogen combustion with steam dilution, focusing on flow dynamics, flame structure, and combustion behavior. The study also examines the impact of oxidizer jet angles and fuel jet velocities. Three simulations with different oxidizer jet angles and four variations of fuel jet velocity reveal that narrower oxidizer jet angles produce richer combustion regions. Larger oxidizer jet angles yield less turbulent flow but a more stable flame. In contrast, higher fuel jet velocities intensify turbulence, resulting in a more stable flame. This can occur since the combustion shifts towards stoichiometric and rich combustion region as fuel jet velocity increases. A more pronounced recirculation flow and enhanced mixing process also allow the flame to hold on to the flame anchor, which helps reach a more stable flame. The maximum heat release rates within the simulation domain are approximately 270 W and 250 W for angle and fuel jet velocity cases, respectively. © 2025 Hydrogen Energy Publications LLC

关键词： Steam

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