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data driven prediction of fragment velocity distribution under explosive loading conditions

defence technology(防务技术) 2025年第1期43卷 109-119页

作者： donghwan Noh Piemaan Fazily Songwon Seo Jaekun Lee Seungjae Seo Hoon Huh Jeong Whan Yoon Department of Mechanical Engineering Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon 34141Republic of Korea Warhead System Team Precision Firepower Research DivisionPOONGSAN Defense R&D Institute2606-10 Hoguk-roAngang-OupKyung JuKyung-BukRepublic of Korea School of Engineering Deakin UniversityWauran PondsVIC 3216Australia

This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading *** fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation *** paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN *** results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and *** model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance.

关键词： data driven prediction dynamic fracture model dynamic hardening model Fragmentation Fragment velocity distribution High strain rate Machine learning

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AC BrEAKdOWN STrENGTH ANd EL INCEPTION FIELd OF TiO2/EPOXY NANOCOMPOSITES HAVING dIFFErENT PArTICLE dISPErSION 23

AC BREAKDOWN STRENGTH AND EL INCEPTION FIELD OF TiO2/EPOXY N...

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23rd International Symposium on High Voltage Engineering, ISH 2023

作者： Hirai, M. Kurimoto, M. Tohyama, K. Sawada, T. Yoshida, S. Umemoto, T. Muto, H. Department of Electrical Engineering Nagoya University Nagoya Japan National Institute of Technology Numazu College Numazu Japan Advanced Technology R&D Center Mitsubishi Electric Corporation Amagasaki Japan

ISBN: (纸本)9781839539954

We have revealed that AC breakdown strength of TiO2/epoxy nanocomposites having agglomerate sizes smaller than 0.5 μm is higher than that of the unfilled epoxy. This paper investigates AC breakdown strength and electroluminescence (EL) inception field of TiO2/epoxy nanocomposites having different particle dispersion as a basic study to clarify the mechanism of enhancing the breakdown strength. The particle dispersion of the TiO2/epoxy nanocomposites was controlled by using centrifugation. We prepared NC0H samples containing agglomerates and NC3H samples not containing the agglomerates larger than 0.05 μm. Compared to the unfilled epoxy, both the EL inception field and AC breakdown strength of NC3H were higher, while the EL inception field and AC breakdown strength of NC0H was lower. © The Institution of Engineering & technology 2023.

关键词： Titanium dioxide

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Mutual Self‑regulation of d‑Electrons of Single Atoms and Adjacent Nanoparticles for Bifunctional Oxygen Electrocatalysis and rechargeable Zinc‑Air Batteries

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Nano-Micro Letters 2023年第4期15卷 40-57页

作者： Sundaram Chandrasekaran rong Hu Lei Yao Lijun Sui Yongping Liu Amor Abdelkader Yongliang Li Xiangzhong ren Libo deng College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060People’s Republic of China College of Chemistry and Bioengineering Guilin University of TechnologyGuilin 541004People’s Republic of China Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advanced Technology of CeramicsCollege of Materials Science and EngineeringGuangdong Research Center for Interfacial Engineering of Functional MaterialsShenzhen UniversityShenzhen 518060People’s Republic of China Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials Institute of New Energy for VehiclesSchool of Materials Science and EngineeringTongji UniversityShanghai 201804People’s Republic of China Department of Design and Engineering Faculty of Science&TechnologyBournemouth UniversityPoole BH125BBDorsetUK

rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(Orr)and oxygen evolution reactions(OEr).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(Cd)based metal-organic framework as the *** the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline Orr activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional Orr/OEr overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to *** X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in Orr/OEr,resulting in an enhanced bifunctional electrocatalytic *** Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+ruO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))*** the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional Orr/OEr electrocatalytic activity.

关键词： Cyclodextrin Cd-MOF Single-atom catalyst Orr/OEr Zinc-air battery

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The transition from 2G to 3G-feedstocks enabled efﬁcient production of fuelsand chemicals

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Green Energy & Environment 2024年第11期9卷 1759-1770页

作者： Kai Wang Changsheng Su Haoran Bi Changwei Zhang di Cai Yanhui Liu Meng Wang Biqiang Chen Jens Nielsen Zihe Liu Tianwei Tan College of Life Science and Technology Beijing University of Chemical TechnologyBeijing Advanced Innovation Center for Soft Matter Science and EngineeringNo.15 North 3rd Ring Rd EastBeijing100029China National Energy R&D Center for Biorefnery Beijing Key Lab of BioprocessBeijing University of Chemical TechnologyNo.15 North 3rd Ring Rd EastBeijing100029China Department of Life Sciences Chalmers University of TechnologyGothenburgSE41296Sweden

For decades micoorganisms have been engineered for the utilization of lignocellulose-based second-generation (2G) feedstocks, but with theconcerns of increased levels of atmospheric CO_(2) causing global warming there is an emergent need to transition from the utilization of 2Gfeedstocks to third-generation (3G) feedstocks such as CO_(2) and its derivatives. Here, we established a yeast platform that is capable ofsimultaneously converting 2G and 3G feedstocks into bulk and value-added chemicals. We demonstrated that by adopting 3G substrates such asCO_(2) and formate, the conversion of 2G feedstocks could be substantially improved. Speciﬁcally, formate could provide reducing power andenergy for xylose conversion into valuable chemicals. Simultaneously, it can form a concentrated CO_(2) pool inside the cell, providing thermodynamically and kinetically favoured amounts of precursors for CO_(2) ﬁxation pathways, e.g., the Calvin–Benson–Bassham (CBB) ***, we demonstrated that formate could directly be utilized as a carbon source by yeast to synthesize endogenous amino acids. Theengineered strain achieved a one-carbon (C1) assimilation efﬁciency of 9.2%, which was the highest efﬁciency observed in the co-utilization of2G and 3G feedstocks. We applied this strategy for productions of both bulk and value-added chemicals, including ethanol, free fatty acids(FFAs), and longifolene, resulting in yield enhancements of 18.4%, 49.0%, and ~100%, respectively. The strategy demonstrated here for coutilization of 2G and 3G feedstocks sheds lights on both basic and applied research for the up-coming establishment of 3G bioreﬁneries.

关键词： transition utilized Benson

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Vertical graphene-decorated carbon nanofibers establishing robust conductive networks for fiber-based stretchable strain sensors

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Journal of Materials Science & technology 2024年第33期200卷 52-60页

作者： Hyeon-Jong Lee Seung Chan Na TaeGyeong Lim Jeongmin Yun Yonas Tsegaye Megra Ji-Hyun Oh Wonyoung Jeong daeyoung Lim Ji Won Suk School of Mechanical Engineering Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea Department of Smart Fab.Technology Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea Department of Clothing and Textiles Changwon National UniversityChangwonGyeongsangnam-do51140Republic of Korea Material and Component Convergence R&D Department Korea Institute of Industrial Technology(KITECH)AnsanGyeonggi-do 15588Republic of Korea SKKU Advanced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea

Stretchable strain sensors have great potential for diverse applications including human motion detection,soft robotics,and health ***,their practical implementation requires improved repeatability and stability along with high sensing ***,we utilized spiky vertical graphene(VG)sheets decorated on carbon nanofibers(VG@CNFs)to establish reliable conductive networks for resistive strain ***-dimensional(3d)VG@CNFs combined with reduced graphene oxide(rGO)sheets were simply coated on stretchable spandex fibers by *** of the spiky geometry of the VG sheets,VG@CNF and rGO exhibited enhanced interactions,which was confirmed by mode I fracture *** to the robust conductive networks formed by the VG@CNF and rGO hybrid,the fiber strain sensor exhibited a significantly improved strain range of up to 522%(with a high gauge factor of 1358)and stable resistance changes with minimal variation even after 5000 stretching–releasing cycles under a strain of 50%.In addition,the textile strain sensor based on the VG@CNF/rGO hybrid showed even improved repeatability for various strain levels of 10%to 200%,enabling its implementation on leggings for monitoring of squat *** study demonstrates the high potential of the 3d VG@CNF for high-performance and reliable stretchable strain sensors.

关键词： Stretchable strain sensor Vertical graphene reduced graphene oxide Carbon nanofiber Human motion detection

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real-time porosity reduction during metal directed energy deposition using a pulse laser

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Journal of Materials Science & technology 2022年第21期116卷 214-223页

作者： Hoon Sohn Peipei Liu Hansol Yoon Kiyoon Yi Liu Yang Sangjun Kim Department of Civil and Environmental Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Center for 3D Printing Nondestructive Testing Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Global R&D Center SQ EngineeringSeoul 05818Republic of Korea Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

Porosity is a challenging issue in additive manufacturing and is detrimental to the quality of the additively manufactured *** this study,a real-time porosity reduction technique was developed by incorporating a pulse laser into a laser metal powder directed energy deposition(dEd)*** incorporated pulse laser can accelerate fluid flow within the melt pool and facilitate the escape of pores before complete *** achieves this real-time porosity reduction by inducing accelerated and turbulent Marangoni flow,ultrasonic waves,and shock waves into the melt *** uniqueness and advantages of the proposed technique include the following:(1)For a laser metal powder dEd process,this study proposed a noncontact,nondestructive,and real-time porosity reduction technique at the melt pool level.(2)It was experimentally and numerically validated that the developed technique did not alter the geometry and the grain structure of the manufactured Ti-6Al-4V samples.(3)Because the porosity reduction is accomplished at the melt pool level,its application is not limited by the size,shape,or complexity of the printing target.(4)The developed technique can be readily incorporated into the existing dEd systems without any modification of the original tool-path *** experimental results showed that the pore volume fraction decreased from 0.132%to 0.005%,no pores larger than 6×10^(4)μm^(3) were observed,and a 91%reduction in the total pore number was achieved when the pulse laser energy reached 11.5 mJ.

关键词： real-time porosity reduction Pulse laser Melt pool directed energy deposition Ti-6Al-4V

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Conductor design Method considering AC resistance for High Efficiency of PMSM using High Fill Factor Winding

Conductor Design Method considering AC Resistance for High E...

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2023 IEEE International Magnetic Conference - Short Papers, INTErMAG Short Papers 2023

作者： Cha, Kyoung-Soo Lim, Myung-Seop Advanced R&D Research Group Korea Institute of Industrial Technology Daegu42994 Korea Republic of Hanyang University Department of Automotive Engineering Seoul04793 Korea Republic of

ISBN: (纸本)9798350338362

This paper proposes the design method of conductor considering AC resistance for high efficiency of PMSM using high fill factor winding. To achieve high power density of the motor, high fill factor winding such as hairpin winding is used. MSO coils were also developed for the same purpose. However, AC resistance is generated in the high fill factor winding used in the motor, which adversely affects the efficiency of the motor. For high efficiency of the motor using high fill factor windings, the AC resistance must be reduced. Therefore, in order to reduce the AC resistance, a design method in which the size of the respective conductor layers are different is proposed. In this paper, the method of reducing AC resistance is verified through analytical methods and FEA. Next, the validity of the proposed method is verified through performance evaluation of the prototype motor designed through the proposed method. © 2023 IEEE.

关键词： Synchronous motors

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Simultaneous achievement of large electrocaloric effect and ultrawide operating temperature range in BaTiO_(3)-based lead-free ceramic

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Journal of advanced Ceramics 2024年第8期13卷 1234-1241页

作者： Zhaojie Wang Yingzhi Meng Silin Tang Xiang Niu Hongfang Zhang dingyuan Wang Yisong Bai Bialin Peng Xue Chen Qingqing Ke Sheng-Guo Lu Laijun Liu Guangxi Key Lab of Optical and Electronic Functional Materials and Devices Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of ResourcesCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China School of Microelectronics Science and Technology Sun Yat-sen UniversityZhuhai 519082China Guangdong Provincial Research Center on Smart Materials and Energy Conversion Devices School of Materials and EnergyGuangdong University of TechnologyGuangzhou 510006China School of Physical Science and Technology&Key Laboratory of Advanced Electrode Materials for Novel Solar Cells for Petroleum and Chemical Industry of China Suzhou University of Science and TechnologySuzhou 215009China Qingdao Haier Smart Technology R&D Co. Ltd.Qingdao 266100China School of Advanced Materials and Nanotechnology Xidian UniversityXi'an 710071China Guangxi Key Laboratory of Manufacturing System&Advanced Manufacturing Technology Guilin University of Electronic TechnologyGuilin 541004China

The electrocaloric effect(ECE),known for its environmentally friendly characteristics,holds significant promise for advancing next-generation solid-state refrigeration *** a large ECE along with a wide working temperature range near room temperature remains a key developmental *** this study,we successfully obtained a substantial ECE of 1.78 K and an extensive working temperature range of 103 K(AT>1.52 K)near room temperature in CaZrO_(3)-modified BaTiO_(3) lead-free ferroelectric ***,this achievement was verified using direct *** piezoresponse force microscopy(PFM)results suggest that the broad temperature range is attributed to the formation of ferroelectric microdomains and polar nanoregions(PNrs).Furthermore,X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible(UV-Vis)spectroscopy reveal a decrease in the oxygen vacancy concentration and an increase in the bandgap for higher CaZrO_(3) doping *** changes synergistically enhance the maximum applied electric field,helping to achieve a high-performance EcE near room *** research presents a straightforward and effective approach for achieving high-performance ECEs in BaTiOg lead-free ceramics,offering promising prospects for application in next-generation solid-state refrigeration technologies.

关键词： BaTiO_(3) electrocaloric effect oxygen vacancy band-gap

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Mobile robot Tracking Method Based on Improved YOLOv8 Pedestrian detection Algorithm 2

Mobile Robot Tracking Method Based on Improved YOLOv8 Pedest...

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2nd International Conference on Machine Learning, Cloud Computing, and Intelligent Mining, MLCCIM 2023

作者： Zhu, Yuecong Zhong, Tianjie Wang, Yu Kan, Jing dong, Fangyan Chen, Kewei Ningbo University Faculty of Mechanical Engineering & Mechanics Ningbo China China Academy of Safety Science & Technology R&D Department Beijing China Advanced Institute of Information Technology Peking University Beijing China

ISBN: (纸本)9798350328530

Human following of mobile robot is a classical application field in the category of human-computer interaction. To address the problem of unstable following of the target in complex scenes, a method of moving robot target following (YOB-CF) based on YOLOv8CSM-tiny and BKPs-CF (Correlation Filtering of Body Key Points) algorithm is proposed. Firstly, based on the YOLOv8 Network, the backbone network is replaced by Multi-Head Attention under this framework, which focuses on improving the detection accuracy of human target recognition in complex scenes, while lightening the model, the model reasoning speed and parameters are reduced to meet the deployment requirements of mobile robot platform. Then the BKPs-CF algorithm based on kernel correlation filter (KCF) is used to fuse the features of body key points, and the key points are updated by optical flow method under the condition of target occlusion, to ensure that the robot can still track the target stably under the occluded condition. Finally, the quantitative experiments are carried out on the self-built test set and the public dataset, and the target-following test and performance evaluation of the mobile robot are completed in the real scene, experimental results show that the proposed method is robust and real-time. © 2023 IEEE.

关键词： Mobile robots

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Investigation of structural and thermal analysis of clutch facings with different friction materials

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Materials Today: Proceedings 2023年 92卷 98-105页

作者： Padmanabhan S. Vinod Kumar T. Sendil Kumar d. Velmurugan G. Akshay Kumar B. Hitesh Sri Subramanyam K. Department of Automobile Engineering Vel Tech Rangarajan Dr Sagunthala R&D Institute of Science and Technology Chennai India Department of Mechanical Engineering Vels Institute of Science Technology and Advanced Studies (VISTAS) Chennai India Director Senthil College of Education Puducherry India

Almost every part of an automobile has been upgraded due to technological progress over the previous century. The automobile industry is a significant contributor to environmental degradation. Automobile engineers have a responsibility to develop innovative approaches to safety and environmental protection. The importance of determining the influence of stress and heat wear on transmitted torque has grown as interest in studying clutches has grown. Composite materials that are safer for the environment make it easier for vehicle developers to provide greater alternatives. This article investigates the potential for replacing conventional clutch facing materials with composites and other suitable materials like sintered metal, Kevlar, and hard steel. Clutch facings composed of base material have been modelled and analysed in Solid Works and ANSYS Workbench, respectively, to achieve this goal. The mechanical characteristics of clutch facings made of three materials have been compared. © 2023

关键词： Analysis Clutch liner Hard steel Kevlar Sintered metal

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