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arXiv 2021年

作者： Tac, Vahidullah Sree, Vivek D. Rausch, Manuel K. Tepole, Adrian B. School of Mechanical Engineering Purdue University West LafayetteIN United States Department of Aerospace Engineering and Engineering Mechanics University of Texas at Austin AustinTX United States Weldon School of Biomedical Engineering Purdue University West LafayetteIN United States

Constitutive models that describe the mechanical behavior of soft tissues have advanced greatly over the past few decades. These expert models are generalizable and require the calibration of a number of parameters to fit experimental data. However, inherent pitfalls stemming from the restriction to a specific functional form include poor fits to the data, non-uniqueness of fit, and high sensitivity to parameters. In this study we design and train fully connected neural networks as material models to replace or augment expert models. To guarantee objectivity, the neural network takes isochoric strain invariants as inputs, and outputs the value of strain energy and its derivatives with respect to the invariants. Convexity of the material model is enforced through the loss function. Direct prediction of the derivative functions -rather than just predicting the energy- serves two purposes: it provides flexibility during training, and it enables the calculation of the elasticity tensor through back-propagation. We showcase the ability of the neural network to learn the mechanical behavior of porcine and murine skin from biaxial test data. Crucially, we show that a multi-fidelity scheme which combines high fidelity experimental data with low fidelity analytical data yields the best performance. The neural network material model can then be interpreted as the best extension of an expert model: it learns the features that an expert has encoded in the analytical model while fitting the experimental data better. Finally, we implemented a general user material subroutine (UMAT) for the finite element software Abaqus and thereby make our advances available to the broader computational community. We expect that the methods and software generated in this work will broaden the use of data-driven constitutive models in biomedical applications. Copyright © 2021, The Authors. All rights reserved.

关键词： Constitutive models

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Biomechanical behaviour and hyperelastic model parameters identification of sheep omasum

Research Square

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Research Square 2021年

作者： Lebea, Lebogang Ngwangwa, Harry Pandelani, Thanyani Nemavhola, Fulufhelo Unisa Biomedical Engineering Research Group Department of Mechanical Engineering School of Engineering College of Science Engineering and Technology University of South Africa Pretoria0001 South Africa Defence and Security Council for Scientific and Industrial and Research Pretoria001 South Africa

The function of the omasum is incompletely understood;however, the omasum plays an important role in the transport of appropriately sized feed particles from the reticulorumen to the abomasum, oesophageal groove closure, fermentation of ingesta, and absorption of water, volatile fatty acids, and minerals. The aim of this study is to evaluate the suitable hyperelastic anisotropic model based on biomechanical properties of sheep omasum. The results show that all five (5) hyperelastic models may be suitable for the evaluation of sheep omasum. The average coefficient of determination (R2) of Fung, Polynomial (Anisotropic), Holzapfel (2000), Holzapfel (2005) and Four-Fiber-Family hyperelastic models were found to be 0.79 ± 0.19, 0.95 ± 0.05, 0.92 ± 0.07, 0.93 ± 0.05 and 0.94 ± 0.03, respectively. Also, it was found that the best hyperelastic model for fitting uniaxial data of the sheep omasum was Polynomial (Anisotropic) with EI of 100.0 followed by the Four-Fiber-Family model with EI of 96.18. © 2021, CC BY.

关键词： Volatile fatty acids

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Microfluidic generation of water-in-water-in-water(-in-water) double and triple emulsions 24

Microfluidic generation of water-in-water-in-water(-in-water...

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24th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2020

作者： Jeyhani, Morteza Thevakumaran, Risavarshni Abbasi, Niki Hwang, Dae Kun Tsai, Scott S.H. Department of Mechanical and Industrial Engineering Ryerson University Toronto Canada Keenan Research Centre for Biomedical Science St. Michael's Hospital Toronto Canada -a Partnership Between Ryerson University St. Michael's Hospital Toronto Canada Department of Electrical Computer and Biomedical Engineering Ryerson University Toronto Canada Department of Chemical Engineering Ryerson University Toronto Canada

ISBN: (纸本)9781733419017

Microfluidically generated higher order emulsions are used in a wide range of applications in biomedicine and biology. Conventional droplet generation platforms use organic solvents to fabricate higher order emulsions, but they have biocompatibility issues due to the interaction between biological materials and organic solvents. To overcome these issues, some researchers propose using aqueous two-phase systems (ATPS) to generate biocompatible higher order emulsions in microfluidics [1]. © 2020 CBMS-0001

关键词： Solvent extraction

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Effects of additional hydrogen and biodiesel crude palm oil on performance and exhaust gas emissions of one cylinder diesel engine

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AIP Conference Proceedings 2023年第1期2630卷

作者： Kuntang Winangun Atok Setiyawan Bambang Sudarmanta Mechanical Engineering Department Institut Teknologi Sepuluh Nopember Surabaya Indonesia 60111 Mechanical Engineering Study Program Universitas Muhammadiyah Ponorogo Ponorogo Indonesia 63471

The scarcity of fuel oil is caused by the increasing demand for fuel oil, and production at the refineries begins to decrease. Making researchers look for solutions, one of which is new and renewable energy. New and renewable energy can be produced sustainably, such asbiodiesel Crude Palm Oil (CPO), and hydrogen gas. The use of CPO biodiesel is known to be low in emissions, high in oxygen content, and cetane number. However, the use of biodiesel without engine modification can lead to decreased thermal efficiency and increased smoke emissions in the engine. The addition of hydrogen gas in small amounts can improve the performance of diesel engines. This study aimsto determine the performance and emissions of diesel engines using CPO biodiesel and hydrogen gas as fuel. The engine used is a single-cylinderdiesel engine, direct injection, with a constant speed of 2000rpm. The load variation is 1kW to 4kW with 0.5kW increment interval, and the hydrogen flow variation is (2.5, 5, 7.5, 10) Liters per minute. At high load, the results obtained thermal efficiency of 78.75 percent without hydrogen flowand decreased to 24.09 percent with 10lpm hydrogen flow. Increased biodieselfuel consumption and soot emissions along with the addition of hydrogen flow, at full load.

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Enhancing Knee Contact Force Prediction Using Transformer Networks: A Comparative Study with Lstm and Mlp

SSRN

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SSRN 2025年

作者： Xu, Fashu Wang, Junqing Tong, Bingkui Fang, Xuyi Zhang, Hui Deng, Tao Wei, Qu Nie, Yong Li, Kang Department of Orthopedic Surgery West China Biomedical Big Data Center West China Hospital Sichuan University Sichuan Chengdu China Department of Orthopedic Surgery Orthopedic Research Institute West China Hospital Sichuan University Sichuan Chengdu China State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Liaoning Shenyang China College of Computer Science Sichuan University Sichuan Chengdu China College of Electrical Engineering Sichuan University Sichuan Chengdu China School of Mechanical Engineering Sichuan University Sichuan Chengdu China

Background and objectiveKnee contact force (KCF) is pivotal in both the study and degenerative pathologies like Knee Osteoarthritis. Traditionally, they are primarily estimated using musculoskeletal modeling and machine learning predictive algorithms. However, musculoskeletal modeling is limited by intricate experimental protocols, prohibitive equipment cost, and scalability challenges. While machine learning methods, though computationally efficient, exhibit suboptimal predictive accuracy. This study innovatively developed a Transformer model for predicting KCF, benchmarked against long short-term memory (LSTM) and multilayer perceptron (MLP) *** comprehensive database was constructed with gait data from 513 participants, incorporating three degrees of freedom of hip, knee flexion/extension, and ankle dorsiflexion/plantarflexion, constituting four input combinations for the models. Contact forces derived from OpenSim served as the ground truth. Root mean square error (RMSE) and coefficient of determination (R2) were used to evaluate the performance of *** results indicated that the Transformer model demonstrated superior performance, achieving a significantly lower mean root mean square error of 0.02 body weight (BW) compared to MLP (0.54 BW) and LSTM (0.45 BW). Furthermore, the mean R2 of the Transformer network (0.99) was markedly superior to that of MLP (0.45) and LSTM (0.58).ConclusionsThe application of Transformer networks significantly improved the accuracy of KCF prediction, addressing the limitations of traditional musculoskeletal modeling and existing machine learning approaches, which was of paramount importance in both clinical practice and biomechanical research. © 2025, The Authors. All rights reserved.

关键词： Mean square error

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Respiration and Maturity Assessment of Mango (Mangifera Indica Cv. Arumanis) for Long-Distance Transportation Planning in Indonesia

SSRN

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SSRN 2023年

作者： Kailaku, Sari Intan Arkeman, Yandra Purwanto, Y. Aris Udin, Faqih Agroindustrial Engineering Study Program Graduate School IPB University Bogor16680 Indonesia Research Center for Agroindustry National Research and Innovation Agency Jakarta10340 Indonesia Agroindustrial Technology Department Faculty of Agricultural Technology IPB University Bogor16680 Indonesia Department of Mechanical and Biosystem Engineering Faculty of Agricultural Technology IPB University Bogor16680 Indonesia Center for Tropical Horticulture Studies IPB University Bogor16680 Indonesia

Transportation of mango (Mangifera indica) is a significant challenge in a large archipelago country like Indonesia. This study addresses the quality assurance problem of long-distance transportation of mangoes from Java Island, Indonesia, and recommends the optimal harvest age for different transportation schemes in the Indonesian mango supply chain. The study investigated harvested mangoes at three different maturity levels and evaluated their quality characteristics, including climacteric peak and respiration rate, total soluble solids, acidity, firmness, dry matter concentration, and weight loss. Samples were kept in their respective packaging during storage to imitate transportation conditions, and an Internet of Things (IoT)-based system was used for real-time monitoring and remote access to the storage conditions information. Long-distance transportation cases of six destinations with different distances, modes of transportation, travel durations, and environmental conditions were studied. Mango harvested at 105 and 108 days after flowering is suitable for consumption, while the harvest age of 90-95 days after flowering is recommended for longer transportation durations involving non-refrigerated and refrigerated vehicles. The harvest age of 105 days after flowering is appropriate for long-distance transportation with non-refrigerated vehicles, while 108 days after flowering is only recommended for inter-province transportation with non-refrigerated vehicles with a short duration of transportation. The results emphasize the importance of determining the optimal harvest time based on the climacteric peak and quality changes during storage to ensure that mangoes meet consumer demands and maximize their quality and shelf life. © 2023, The Authors. All rights reserved.

关键词： Fruits

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Using sio2 hard mask for fabrication of micro fresnel focusing lens for ultrasonic ejectors

Using sio2 hard mask for fabrication of micro fresnel focusi...

引用

National Conference on mechanical engineering and Manufacturing, NCMME 2019

作者： Bui, Tuan-Anh Pan, Min-Chun Wu, Tzon-Han Le, Thanh-Long School of Mechanical Engineering Hanoi University of Science and Technology Viet Nam Department of Mechanical Engineering National Central University Taiwan Graduate Institute of Biomedical Engineering National Central University Taiwan Faculty of Mechnical Engineering Ho Chi Minh City University of Technology VNUHCM Viet Nam Vietnam National University Ho Chi Minh City Viet Nam

ISBN: (纸本)9783035717143

The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one. © 2020 Trans Tech Publications Ltd, Switzerland.

关键词： Silica

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Very high cycle fatigue behaviour of a structural steel for offshore applications under a biaxial stress state

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International Journal of Fatigue 2025年 199卷

作者： Rita Dantas Felipe Fiorentin José A. F. O. Correia Grzegorz Lesiuk Abílio de Jesus University of Porto Rua Dr. Roberto Fria 4200-465 Porto Portugal INEGI Department of Mechanical Engineering University of Porto Portugal CONSTRUCT Department of Civil Engineering University of Porto Portugal Department of Mechanics Materials Science and Biomedical Engineering Faculty of Mechanical Engineering Wroclaw University of Science and Technology Ul. Smoluchowskiego 25 PL-50370 Wrocław Poland

The characterisation of the very high cycle fatigue (VHCF) regime has become pertinent due to the interest of extending the service life of engineering structures. However, the fatigue testing of materials at the longer lives of VHCF regime (usually greater than 10 million of cycles) is by far most efficient with an ultrasonic fatigue testing system, which introduces new challenges such as the specimen’s design. As a consequence, the fatigue behaviour in the VHCF regime under the presence of stress states different from the uniaxial one is not well known. Thus, in this work, the fatigue behaviour of S690QL structural steel is analysed for the case of a biaxial stress state. A cruciform specimen was developed by finite element model analysis and, consequently, it was experimentally validated. Moreover, several specimens were tested and a mean stress-life curve estimated, considering the von Mises stresses. Additionally, the mechanism of fatigue crack initiation was assessed and the fracture surfaces were analysed.

关键词： Very high cycle fatigue S690 steel Biaxial stress state Cruciform specimen

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Statistical mechanics of a dielectric polymer chain in the force ensemble

arXiv

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arXiv 2021年

作者： Grasinger, Matthew Dayal, Kaushik deBotton, Gal Purohit, Prashant K. Materials and Manufacturing Directorate Air Force Research Laboratory UES Inc. Department of Civil and Environmental Engineering Carnegie Mellon University Department of Materials Science and Engineering Carnegie Mellon University Center for Nonlinear Analysis Department of Mathematical Sciences Carnegie Mellon University Department of Mechanical Engineering Ben-Gurion University Department of Biomedical Engineering Ben-Gurion University Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania United States

Constitutive modeling of dielectric elastomers has been of long standing interest in mechanics. Over the last two decades rigorous constitutive models have been developed that couple the electrical response of these polymers with large deformations characteristic of soft solids. A drawback of these models is that unlike classic models of rubber elasticity they do not consider the coupled electromechanical response of single polymer chains which must be treated using statistical mechanics. The objective of this paper is to compute the stretch and polarization of single polymer chains subject to a fixed force and fixed electric field using statistical mechanics. We assume that the dipoles induced by the applied electric field at each link do not interact with each other and compute the partition function using standard techniques. We then calculate the stretch and polarization by taking appropriate derivatives of the partition function and obtain analytical results in various limits. We also perform Markov chain Monte Carlo simulations using the Metropolis and umbrella sampling methods, as well as develop a new sampling method which improves convergence by exploiting a symmetry inherent in dielectric polymer chains. The analytical expressions are shown to agree with the Monte Carlo results over a range of forces and electric fields. Our results complement recent work on the statistical mechanics of electro-responsive chains which obtains analytical expressions in a different ensemble. © 2021, CC BY-NC-ND.

关键词： Statistical mechanics

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Experimental study using variations of cooling liquids for the utilization of thermoelectric generators applied in a charcoal production furnace

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AIP Conference Proceedings 2024年第1期3090卷

作者： Rinasa Agistya Anugrah Sugiyanto Department of Automotive Engineering Technology Vocational Program Universitas Muhammadiyah Yogyakarta Bantul 55183 Indonesia Department of Mechanical Engineering Vocational School Universitas Gadjah Mada Sleman 55281 Indonesia

A Thermoelectric generator is a small module that can convert heat energy into electricity directly. Utilization of these tools can be applied to charcoal furnaces using coolant to get an increase in temperature to produce optimal electricity. This study aims to determine the efficiency of using coolant in thermoelectric generators. Water, radiator coolant, and oil are some examples of coolants that can be used in water blocks. This study uses a Thermoelectric generator SP184827145SA with three fluids, namely Water, Ethylene Glycol radiator coolant, and Mpx1 Oil, and uses Arduino Uno as a monitoring system with an 8 W 6V lamp as load and 900 seconds of testing time. The results of the coolant found that the Mpx1 oil had the largest T of 64.5℃ and received 8.81 kJ of heat with an efficiency of 0.17%. Liquid water has the largest T of 71.5℃ and receives the heat of 48.6 kJ with an efficiency of 0.46%, and Ethylene Glycol radiator coolant has the largest T of 82.75℃ and receives heat of 50.53 kJ with an efficiency of 0.68%. This revealed that the Ethylene Glycol radiator coolant had the highest efficiency, and the oil coolant had the lowest efficiency.

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