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Heat transfer performance of serpentine mini-channel cold plate in various Reynolds numbers

AIP Conference Proceedings 2025年第1期3120卷

作者： Muhammad Aulia Rahman Yusuf Yunus Indro Pranoto Khasani Djati Wibowo Djamari Department of Mechanical and Industrial Engineering Faculty of Engineering Gadjah Mada University Jl. Grafika No. 2 Kampus UGM Yogyakarta 55281 Indonesia Mechanical Engineering State Vocational High School 2 Ternate Ternate 97727 Indonesia Mechanical Engineering Study Program Faculty of Engineering and Technology Sampoerna University Jakarta 12780 Indonesia

The electric vehicle showcases a promising development in the future. Recently, the most reliable power storage for such a system is a Li-ion battery. The performance of this battery, however, relies on the thermal management system implemented on the vehicle. Albeit having a sufficient performance for the current state of an electric vehicle, enhancement is necessary to make sure that the future requirement is within the remit of the cooling system. One of the simple but powerful enhancements is by employing a mini-channel cold plate. In this study, the performance of a serpentine mini-channel cold plate in various Reynolds numbers (Re) was investigated experimentally. The results illustrate a better mean of cooling of high Re flow, indicated by the lower surface temperature and higher heat transfer coefficient up to 2.1 W/m2·K. Additionally, the performance was then compared to the pressure drop to represent the efficiency of the pumping power requirement of such a system. The highest h/ΔP is observed at Re = 2130.33 which correspond to the mass flow rate of 0.5 LPM. It was found that although having a higher heat transfer coefficient, the efficiency is much lower due to pressure drop rise as the mass flow rate increases.

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Learning from failure - Development of a Culture of Failure Scale for Higher Education

Learning from failure - Development of a Culture of Failure ...

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World engineering Education Forum - Global engineering Deans Council (WEEF-GEDC)

作者： Michael M. Malschützky Ph.D. Jamie R. Gurganus Centre for Teaching Development and Innovation (ZIEL) & Department of Management Sciences Hochschule Bonn-Rhein-Sieg University of Applied Sciences Sankt Augustin Germany Engineering & Computing Education Program Mechanical Engineering & Graduate School University of Maryland Baltimore County Baltimore USA

ISBN: (数字)9781665475280

ISBN: (纸本)9781665475297

Benefits of a failure friendly culture, e.g., learning from failure, are widely known in occupational settings. Validated scales have been developed to measure organizational failure culture and individuals' mind-sets on failure. While research on learning from failure exists in secondary education, scales for higher education are lacking. To support both higher education engineering instructors and students, this contribution aims to develop a Culture of Failure Scale to assess students' and lecturers' handling of failures in engineering higher education settings. This data-driven approach helps inform instructors about aspects of educational settings that are safe and conducive to learning and supports their students to develop a mind-set where failures are seen as a source for improvements and learning. Exemplary application of the developed scale is shown by assessing the failure culture in different groupings, e.g., gender, between two participating German and US institutions.

关键词： Correlation Education Psychology Reliability History engineering students Principal component analysis

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Single-step precision programming of decoupled multiresponsive soft millirobots

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Proceedings of the National Academy of Sciences of the United States of America 2024年第13期121卷 e2320386121页

作者： Zheng, Zhiqiang Han, Jie Shi, Qing Demir, Sinan Ozgun Jiang, Weitao Sitti, Metin Physical Intelligence Department Max Planck Institute for Intelligent Systems Stuttgart 70569 Germany State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong University Xi’an 710054 China School of Mechanical Engineering Xi’an Jiaotong University Xi’an 710054 China Intelligent Robotics Institute School of Mechatronical Engineering Beijing Institute of Technology Beijing 100081 China Key Laboratory of Biomimetic Robots and Systems Beijing Institute of Technology) Ministry of Education Beijing 100081 China Institute for Biomedical Engineering ETH Zurich Zurich 8092 Switzerland School of Medicine College of Engineering Koç University Istanbul 34450 Turkey

Stimuli-responsive soft robots offer new capabilities for the fields of medical and rehabilitation robotics, artificial intelligence, and soft electronics. Precisely programming the shape morphing and decoupling the multiresponsiveness of such robots is crucial to enable them with ample degrees of freedom and multifunctionality, while ensuring high fabrication accuracy. However, current designs featuring coupled multiresponsiveness or intricate assembly processes face limitations in executing complex transformations and suffer from a lack of precision. Therefore, we propose a one-stepped strategy to program multistep shape-morphing soft millirobots (MSSMs) in response to decoupled environmental stimuli. Our approach involves employing a multilayered elastomer and laser scanning technology to selectively process the structure of MSSMs, achieving a minimum machining precision of 30 µm. The resulting MSSMs are capable of imitating the shape morphing of plants and hand gestures and resemble kirigami, pop-up, and bistable structures. The decoupled multistimuli responsiveness of the MSSMs allows them to conduct shape morphing during locomotion, perform logic circuit control, and remotely repair circuits in response to humidity, temperature, and magnetic field. This strategy presents a paradigm for the effective design and fabrication of untethered soft miniature robots with physical intelligence, advancing the decoupled multiresponsive materials through modular tailoring of robotic body structures and properties to suit specific applications. Copyright © 2024 the Author(s).

关键词： environmental response miniature robot soft electronics soft robotics

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Image Segmentation for High-Density Surface Electromyography Mappings of Pelvic Floor Muscle Activity of Women with Interstitial Cystitis/Bladder Pain Syndrome

Image Segmentation for High-Density Surface Electromyography...

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

作者： Michael Houston Nicholas Dias Theresa Spitznagle Marcie Harris-Hayes H. Henry Lai Yingchun Zhang Department of Biomedical Engineering University of Houston Houston TX USA Program in Physical Therapy at Washington School of Medicine St. Louis Missouri USA Departments of Surgery and Anesthesiology Division of Urologic Surgery Washington University School of Medicine St. Louis Missouri USA

Interstitial cystitis/bladder pain syndrome (IC/BPS) can result in pelvic floor muscle (PFM) overactivity. Current clinical assessment protocols include basic electromyographic assessment of PFM activation; however, they do not provide a comprehensive assessment localized to each region of the PFM. We examined the ability of high-definition features from intravaginal high-density surface electromyography (HD-sEMG) to assess the severity of PFM overactivity in female IC/BPS patients. HD-sEMG was collected from fifteen female IC/BPS patients and fifteen urologically healthy female controls. The 2D mappings of root mean squared amplitude (RMS) at rest normalized by maximal voluntary contraction (resting RMS ratios) were segmented via k-means to identify areas of peak activity and surrounding activity. Female IC/BPS patients exhibited significantly greater resting RMS ratios for peak activity (p=0.0096), surrounding activity (p=0.0003), and average activity (p=0.0016) compared to healthy female controls. Furthermore, the area of peak activity was significantly larger for female IC/BPS patients than for healthy female controls (p=0.0063). Image segmentation of intravaginal HD-sEMG provides a more robust biomarker of PFM as compared to current methods.

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Discrete Element Method to Model Tension and Bending for Single Layer 3-Dimension Systems with Bimodal and Pseudo-Full Particle Size Distributions of Spherical Particles

Discrete Element Method to Model Tension and Bending for Sin...

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TAPPICon LIVE 2021

作者： Varney, Dan Toivakka, Martti Bousfield, Doug OMYA Inc. ProctorVT05765 United States Laboratory of Paper Coating and Converting Åbo Akademi University Turku Finland Paper Surface Science Program Department of Chemical and Biomedical Engineering University of Maine OronoME04469 United States

ISBN: (纸本)9781713848370

The mechanical properties of paper coating layers are important in converting operations such as calendering, printing and, folding. While a number of experimental and theoretical studies have advanced our knowledge of these systems, a good particle level understanding of issues like crack-at-the-fold are lacking. In this paper, the three-dimensional version of the discrete element method (DEM) model of Varney et al. (2019) has been modified. The particles used in the model have been expanded from the standard monodisperse packing of spherical particles to bimodal distributions of spherical particles and also to pseudo-full particle size distributions of spherical particles. In making this upgrade to the model, the impact of particle size distribution on the mechanical properties of the coating layer could be studied. Simulations were run for both in-line tension and for three-point bending of single coating layer systems. As with past models, inputs to the 3D version include properties of the pure binder film and the binder concentration. The model predicts crack formation as a function of these parameters and can also calculate the modulus, the maximum stress, and the strain-at-failure. The simulation results were compared to the work of Zhu et al. (2014) and of Hashemi-Najafi et al. (2018). Reasonable predictions were obtained for both tensile and bending for a range of latex-starch ratios and at various pigment concentrations. In addition, the model predicted the correct trends and order of magnitude relative to the experimental data. Copyright© 2021 by the TAPPI Press, All rights reserved.

关键词： Particle size analysis

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Influence of Rainfall on Size-Resolved Bioaerosols Around a Livestock Farm

SSRN

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SSRN 2024年

作者： Kwak, Nohhyeon Tsameret, Shahar Gaire, Tara N. Mendoza, Kristelle M. Cortus, Erin L. Cardona, Carol Noyes, Noelle Li, Jiayu Mechanical and Aerospace Engineering University of Miami 1251 Memorial Dr. Coral GablesFL33146 United States Department of Veterinary Population Medicine University of Minnesota 1988 Fitch Ave. St. PaulMN55108 United States Department of Veterinary and Biomedical Sciences University of Minnesota 1971 Commonwealth Ave. St. PaulMN55108 United States Department of Bioproducts and Biosystems Engineering University of Minnesota 1390 Eckles Ave. St. PaulMN55108 United States

Bioaerosols, capable of transporting microorganisms, can impact human health and agriculture by spreading to nearby communities. Their transmissions are influenced by various factors, including weather conditions and human activities. However, the scarcity of detailed, taxon-specific data on bioaerosols’ sizes limits our ability to assess risks associated with bioaerosols’ generation and spread. This study examined the composition and size of bioaerosols at a livestock farm and a non-agricultural site, focusing on how bioaerosols evolve at different locations and meteorological conditions. The location had a straightforward impact on bioaerosol samples. We observed consistently higher concentrations of bioaerosols across all sizes at the livestock farm and livestock farm samples exhibited greater bacterial diversity, where we identified Staphylococcus and Corynebacterium as the most abundant species. The effects of rainfall on bioaerosol diversity are complex, suggesting a dynamic interplay between bioaerosol removal and generation. After rainfall, bioaerosol fraction of particles larger than 2.5 µm increased by nearly 400% compared to post-rain levels. Conversely, for bioaerosols below 1 µm size, the fraction decreased by 50%. Our analysis showed that Streptococcus and Prevotella were common during non-rainy periods. Our research reveals how size, location, and environmental conditions influence bioaerosol dynamics, enhancing our understanding of bioaerosol formation and transmission. © 2024, The Authors. All rights reserved.

关键词： Rain

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Wireless Wearable Monitoring of Human Motion Activities Using Polyvinylidene Fluoride/Liquid Exfoliated Nanographite-Based Flexible Piezoelectric Sensor

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SSRN 2023年

作者： Thirugnanam, Sarathi Krishnan, Venkataraman K. Rathinasamy, Senthil Kumar Bhattacharyya, Amitava Cyber Physical Laboratory PSG Institute of Advanced studies Coimbatore641 004 India Biomedical Instrumentation Lab PSG Institute of Advanced Studies Coimbatore641004 India Centre for Research and Development Department of Mechanical Engineering KPR Institute of Engineering and Technology Coimbatore641 407 India Advance textile polymer laboratory PSG Institute of Advanced studies Coimbatore641 004 India

In recent years, continuous healthcare monitoring devices are in high demand. In this context, the flexible piezoelectric sensors are widely used in the biomedical monitoring applications. Here, the combined piezoelectric effect of the liquid exfoliated nanographite (LENG) with polyvinylidene fluoride (PVDF) polymer has been investigated. The prepared PVDF-LENG nanocomposite films (0.1-0.6% (w/v)) have undergone electrical poling process to attain high β beta phase transition for enhancement of the piezoelectric effect. The samples characterized for morphological study, functional group, and electrical properties. Piezoelectric responses over 100 cycles of compression indicate the use of LENG improves the piezo response of PVDF as well as its structural robustness. Wireless wearable monitoring of human gait was studied using these sensors positioned at different loci of socks. The foot strike data was obtained using in-house developed microcontroller-based Bluetooth miniature device. In future, these piezoelectric sensors can be applicable for wearable devices to assess the human activities in detail. © 2023, The Authors. All rights reserved.

关键词： Wearable sensors

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Hierarchical Porous Carbon Spheres @Ce-Mno2 as Cathode for Energy-Dense and Long-Cycling Flexible Aqueous Zinc-Ion Batteries

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SSRN 2023年

作者： Yu, Baozhu Lu, Leilei He, Yuting Dai, Xin Wang, Yi Wang, Tian Chong, Shaokun Liu, Liting Liu, Yongning Tan, Qiang Department of Applied Chemistry Xi'an University of Technology Shaanxi Xi'An710048 China State Key Laboratory for Mechanical Behavior of Materials School of Material Science and Engineering Xi’an Jiaotong University Xi’an710049 China Analytical and Testing Center Northwestern Polytechnical University Xi’an710072 China Xi’an Institute of Biomedical Materials & Engineering Northwestern Polytechnical University Xi’an710072 China

Aqueous zinc-ion batteries (ZIBs) have been considered one of the most promising flexible chemical power sources, because of their low cost, high safety, and lightweight feature. However, the traditional manganese dioxide (MnO2) based cathode of ZIBs became a serious obstacle to the development of flexible aqueous ZIBs because of its relatively poor electrical conductivity, unstable structure, and unclear electrochemical energy storage process and mechanism. To address the above issues, a core-shell hybrid structure with hierarchical carbon spheres core and cerium-doped manganese dioxide nanosheets shell (CS@Ce-MnO2) was successfully prepared and assembled in the flexible aqueous ZIBs with improved specific capacity and stability. The ZIBs exhibited a high reversible specific capacity of 200 mAh g-1 and 120 mAh g-1 at current densities of 200 mA g-1 and 1000 mA g-1, respectively. The origin of the improved electrochemical performance and storage mechanism was monitored by various electrochemical methods and ex-site x-ray diffraction (XRD) and scanning electron microscopy (SEM). The co-insertion/extraction of Zn2+ and H+ provides a high reversible specific capacity for ZIBs, while the porous structure of the carbon spheres contributes to the improved electron conduction and ion transport in the MnO2 matrix. The improved MnO2 cathode has a reasonable synergistic deconstruction design, and excellent electrochemical properties, and This work provides a new approach to portable wearable electronic devices. © 2023, The Authors. All rights reserved.

关键词： Nanosheets

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On the Existence and Uniqueness of Steady State Solutions of a Class of Dynamic Hydraulic Networks via Actuator Placement

On the Existence and Uniqueness of Steady State Solutions of...

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IEEE Conference on Decision and Control

作者： Mark Jeeninga Juan E. Machado Michele Cucuzzella Giacomo Como Jacquelien Scherpen Department of Automatic Control Lund University Lund Sweden Chair of Control Systems and Network Control Technology Faculty 3 Mechanical Engineering Electrical and Energy Systems Brandenburg University of Technology Cottbus - Senftenberg Cottbus Germany Department of Electrical Computer Science and Biomedical Engineering Univeristy of Pavia Pavia Italy Department of Mathematical Science “G.L. Lagrange” Politecnico di Torino Torino Italy Department of Automatic Control Lund University Faculty of Science and Engineering Jan C. Willems Center for Systems and Control ENTEG University of Groningen Groningen the Netherlands

In this paper, using tools from graph theory we provide verifiable necessary and sufficient conditions for the existence of a unique hydraulic equilibrium in district heating systems of meshed topology and containing multiple heat sources. Even though numerous publications have addressed the design of efficient algorithms for numerically finding hydraulic equilibria in the general context of water distribution networks, this is not the case for the analysis of existence and uniqueness. Moreover, most of the existing work dealing with these aspects exploit the equivalence between the nonlinear algebraic equations describing the hydraulic equilibria and the KKT conditions of a suitably defined nonlinear convex optimization problem. Differently, this paper proposes necessary and sufficient graph-theoretic conditions on the actuator placement for the existence and uniqueness of a hydraulic equilibrium, independent of the actuators' control objective. An example based on a representative district heating network is considered to illustrate the key aspects of our contribution, and an explicit formulation of the steady state solution is given for the case in which pressure drops through pipes are linear with respect to the flow rate.

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A review of technological developments in modern farming: Intelligent greenhouse systems

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AIP Conference Proceedings 2023年第1期2631卷

作者： N. M. Nouri Hayder M. Abbood M. Riahi Seyed Hamed Alagheband School of Mechanical Engineering Iran University of Science and Technology Tehran Iran Collage of Engineering Biomedical Engineering Department University of Kerbala Karbala Iraq

Ongoing population growth, increasing environmental pollution, and a shortage of basic resources, especially water, have worsened the ongoing problem of food insecurity. Food security requires all people at all times to have access to sufficient, safe, and nutritious food that meets the needs of active, healthy lives, yet traditional farming methods are currently unable to meet these new demands in continuously growing markets. One of the most important current developments in the modern agriculture sector is thus greenhouse technology, and modern greenhouse agricultural production relies heavily on instrumentation and control system technologies that manage many automated tasks. Artificial intelligence technology, as one of the most important modern methods of managing complex systems, can thus be employed for real time monitoring of the microclimate environment as well as many basic tasks within such greenhouses, and this is the main driver of this review paper. In particular, however, the paper focuses on the potential abilities of artificial intelligence to monitor and control systems in the greenhouse microclimate environment, and to this end, a comprehensive study of the current field of greenhouse microclimate applications is offered.

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