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Temperature fluctuations and heat transport in partitioned supergravitational thermal turbulence

Acta Mechanica Sinica 2024年第6期40卷 20-30页

作者： Dongpu Wang Jing Liu Rushi Lai Chao Sun Beijing Key Laboratory of Space Thermal Control Technology Beijing Institute of Spacecraft System EngineeringBeijing100094China Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of MoEand Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China Department of Engineering Mechanics School ofAerospace EngineeringTsinghua UniversityBeijing100084China

We report an experimental study of the local temperature fluctuationsδT and heat transport in a partitioned supergravitational turbulent convection *** to the dynamics of zonal flow in the normal system without partition walls,the probability density function(PDF)at a position in the mixing zone exhibits a downward bending shape,suggesting that the multi-plume clustering effect plays an important *** partitioned system,zonal flow is suppressed and the PDFs indicate that the single-plume effect is ***,statistical analysis shows that the PDF ofδT is sensitive to ***,the thermal spectra follow P(f)∼f^(-5) in the normal system,which is relevant to the zonal *** absolute value of the scaling exponent of P(f)and the scaling range become small in the partitioned system,which provides another evidence for the influence of zonal flow on the energy ***,heat transfer enhancement is found in the partitioned system,which may result from zonal flow being restricted and then facilitating the radial movement of thermal plumes to the opposite conducting *** work may provide insights into the flow and heat transport control of some engineering and geophysical flows.

关键词： Partitioned turbulent convection Supergravity Probability density function Power spectra Heat transfer

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Key Issues for Modelling, Operation, Management and Diagnosis of Lithium Batteries: Current States and Prospects

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Energy engineering 2024年第8期121卷 2085-2091页

作者： Bo Yang Yucun Qian Jianzhong Xu Yaxing Ren Yixuan Chen Faculty of Electric Power Engineering Kunming University of Science and TechnologyKunming650500China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing102206China School of Engineering University of LincolnLincolnLN67TSUK Department of Electrical and Electronic Engineering The University of Hong KongHong Kong999077China

1 *** the continuous growth of the global population,the energy demand continues to ***,due to the dominance of fossil fuels in global energy and fossil fuels are non-renewable,it has led to the global energy crisis[1].Besides,the use of fossil fuels will generate a mass of air pollutants(e.g.,carbon dioxide,sulfur dioxide,etc.),which will cause serious environmental pollution,climate change[2],*** resolve the aforementioned issues,countries around the world have implemented a variety of measures hoping to fundamentally adjust the global energy structure and achieve sustainable ***,“Paris Agreement”reached in 2015 under the framework of“United Nations Framework Convention on Climate Change”aims to control the increase in the average temperature of the globe to within 2°C below preindustrial levels,and thereafter to peak global greenhouse gas emissions as soon as possible,continuously decreasing thereafter[3].United Kingdom plans to reduce the average exhaust emissions of“new cars”to approximately 50–70 g/km by 20230,which is roughly half of what it is now[4].In addition,China proposed a plan at“United Nations General Assembly”in 2020 to peak carbon dioxide emissions by 2030 and strive to achieve carbon neutrality by *** is a fact that the whole world is committed to changing the current energy structure,protecting the Earth’s ecology,and achieving global sustainable development[5].

关键词： Lithium batteries optimization operation modelling state estimation life prediction fault diagnosis

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Detection of False Data Injection Attacks in Smart Grids via Nonlinear Interval Observer: A Review 7

Detection of False Data Injection Attacks in Smart Grids via...

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7th International Conference on Energy Conservation and Efficiency, ICECE 2024

作者： Ali, Kashif Rana, Zuraiz Haseeb, Rashid Niaz, Ashfaq Zahid, Muhammad Liang, Dingkang Shanxi Key Laboratory of Power System Operation and Control Taiyuan University of Technology Taiyuan China College of Electrical and Power Engineering Taiyuan University of Technology Taiyuan China U.E. T. Lahore Department of Electrical Engineering Lahore Pakistan

ISBN: (纸本)9798350370898

Identify individual False Data Injection (FDI) attacks in different intelligent networks. FDI attacks can circumvent conventional means of identifying corrupt data and interfere with the health assessment process. The rise of FDI attacks has introduced significant security vulnerabilities to smart grids. To address these important issues, A technique for detecting FDI attacks in various SG systems have been proposed. The interval observer is designed to precisely predict the Temporal condition of the internal physical structure based on development of the physical properties of the smart grid system. A detection criterion has been proposed to activate an alert if the remaining interval fails to include zero, considering the inner state boundary and the outer interference boundary. A sensor isolation algorithm based on a logical matrix for assessing attack characteristics is additionally proposed for introducing FDI attacks into sub-areas. Finally, we hope this article complements a series of recent review articles and fosters further research in this rapidly evolving area. And discussed our opinions on remaining challenges and future research directions in this area. © 2024 IEEE.

关键词： Smart power grids

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Internet-mediated automation of a cascade control system-an engineering laboratory experiment

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International Journal of Electrical engineering and Education 2022年第2期59卷 112-129页

作者： Sangeetha, A Lakshmi Bharathi, N. Ganesh, A Balaji Kalaichitra, G. Department of Electronics and Instrumentation Velammal Engineering College Chennai India Department of Electronics and Instrumentation KCG College of Technology Chennai India Electronic System Design Laboratory TIFAC-CORE Velammal Engineering College Chennai India

The paper aims to enhance the controllability of a standalone cascade control system with Internet architecture and promote the system to be accessible by remote students. The user interactive web page is developed by using platform independent *** language and enabled with both monitoring and controlling functionalities. The Internet transmission time delays that are associated with both feed-forward and feedback channels are compensated by using model predictive controller. The performance of cascade control system with and without compensation is validated by measuring indices, such as rise time, peak time and settling time, and also integral square error and integral absolute error. Access privileges among web page users have been added to ensure simultaneous operations as well as security. The cascade control system is an engineering laboratory experiment interfaced with a dedicated computer by using MODBUS protocol and it is made available to the remote students. The user perception analysis is carried out by using a set of questionnaire that observes 85% of positive feedback. © The Author(s) 2019.

关键词： Time delay

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Granular flows over normally vibrated inclined bases

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Physical Review Fluids 2024年第12期9卷 124304-124304页

作者： Prasad Sonar Ashish Bhateja Ishan Sharma Department of Mechanical System Engineering Tokyo University of Agriculture and Technology 184-8588 Tokyo Japan and Department of Mechanical Engineering Indian Institute of Technology Kanpur 208016 Uttar Pradesh India

We investigate granular flows over an inclined rigid base, which is vibrated externally in a direction normal to itself, through the discrete element method. We vary the base's inclination angle θ, vibration frequency f, and amplitude A to study changes in the granular flow's profile and the mass flow rate Q. We find that the flow velocity profiles for the vibrated bases are nonlinear, unlike their fixed-base counterparts. Our study reveals that Q may be maintained nearly constant in flows over vibrated bases utilizing appropriate combinations of θ, A, and f. At the same time, by vibrating the base depending on the inclination angle, we may increase the mass flow rate by 25 to 100 times, compared to the values for the fixed base. Finally, we characterize Q in terms of a nondimensional number S, which is the ratio of vibrational and gravitational energies.

关键词： Granular flows

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Intelligent Aerospace Terminologies Recognition based on Spectrogram using Machine Learning

Intelligent Aerospace Terminologies Recognition based on Spe...

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2023 International Conference on Electrical and Information technology, IEIT 2023

作者： Sumari, Arwin Datumaya Wahyudi Sitorus, Zest Amborgang Abdie, Syafrudin Adisutjipto Institute of Aerospace Technology Aerospace Intelligent System and Data Engineering Research Group Yogyakarta Indonesia Politeknik Negeri Malang Cognitive Artificial Intelligence Research Group Malang Indonesia Adisutjipto Institute of Aerospace Technology Faculty of Industrial Technology Department of Electrical Engineering Yogyakarta Indonesia Adisutjipto Institute of Aerospace Technology Faculty of Industrial Technology Aerospace Avionics System Research Group Department of Electrical Engineering Yogyakarta Indonesia

ISBN: (纸本)9798350327298

A speech recognition system is an application to recognize spoken words through audio inputs. On the other hand, spectrograms are visual representations of audio signals and effectively represent words numerically. In this research, we developed a spectrogram-based speech recognition system using machine learning's K-Nearest Neighbors (KNN) method to recognize aerospace terminologies, some uncommon for ordinary people. We used 300 audio signal data consisting of two categories, namely 15 spectrogram data for aerospace terminologies and 15 spectrogram data for non-aerospace ones, each taken ten times. By conducting a 70:30 training and testing scheme, strengthened by k-fold cross-validation, the optimum K for KNN is 13. With such value of K, our developed Intelligent system for aerospace terminologies recognition based on spectrogram can achieve an accuracy of 75.56% with a precision of 75.56%, recall of 75.56%, and F-1 score of 75.56%. With that accuracy, our developed intelligent system is considered as a good system. © 2023 IEEE.

关键词： Terminology

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Ultra-thin light-weight laser-induced-graphene (LIG) diffractive optics

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Light(Science & Applications) 2023年第7期12卷 1268-1300页

作者： Younggeun Lee Mun Ji Low Dongwook Yang Han Ku Nam Truong-Son Dinh Le Seung Eon Lee Hyogeun Han Seunghwan Kim Quang Huy Vu Hongki Yoo Hyosang Yoon Joohyung Lee Suchand Sandeep Keunwoo Lee Seung-Woo Kim Young-Jin Kim Department of Mechanical Engineering Korea Advanced Institute of Science and Technology(KAIST)Daehak-roYuseong-guDaejeon 34141Republic of Korea School of Mechanical and Aerospace Engineering Nanyang Technological University(NTU)50 Nanyang Avenue639798 SingaporeSingapore Panasonic Factory Solutions Asia Pacific(PFSAP) 285 Jalan Ahmad Ibrahim639931 SingaporeSingapore Department of Aerospace Engineering Korea Advanced Institute of Science and Technology(KAlST)Daehak-roYuseong-guDaejeon 34141Republic of Korea Department of Mechanical System Design Engineering Seoul National University of Science and Technology(Seuoltech)232 Gongneung-roNowon-guSeoul 01811Republic of Korea LASER N GRAPN INC 193 Munj-roYuseong-guDaejeon 34051Republicof Korea

The realization of hybrid optics could be one of the best ways to fulfll the technological requirements of compact,light-weight,and multi-functional optical systems for modern *** diffractive lens(PDL)such as diffractive lenses,photonsieves,and metasurfaces can be patterned on ultra-thin flexible and stretchable substrates and be conformally attached on top of arbitrarily shaped *** this review,we introduce recent research works addressed to the design and manufacturing of ultra-thin graphene optics,which will open new markets in compact and light-weight optics for next-generation endoscopic brain imaging,space internet,real-time surface proflometry,and multi-functional mobile *** provide higher design flexibility,lower process complexity,and chemical-free process with reasonable investment cost,direct laser writing(DLW)of laser-induced-graphene(LIG)is actively being applied to the patterning of *** realizing the best optical performances in DLW,photon-material interactions have been studied in detail with respect to different laser parameters;the resulting optical characteristics have been evaluated in terms of amplitude and phase.A series of exemplary laser-written 1D and 2D PDL structures have been actively demonstrated with different base materials,and then,the cases are being expanded to plasmonic and holographic *** combination of these ultra-thin and light-weight PDL with conventional bulk refractive or reflective optical elements could bring together the advantages of each optical *** integrating these suggestions,we suggest a way to realize the hybrid PDL to be used in the future micro-electronics surface inspection,biomedical,outer space,and extended reality(XR)industries.

关键词： optics weight holographic

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Performance Comparison of Vector Based Forwarding and Depth Based Routing in Underwater Wireless Sensor Networks 9

Performance Comparison of Vector Based Forwarding and Depth ...

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9th IEEE International Conference on Big Data Computing Service and Applications, BigDataService 2023

作者： Kulla, Elis Elmazi, Donald Matsuo, Keita Fukuoka Institute of Technology Department of System Management Fukuoka Japan Canadian Institute of Technology Electronics and Telecommunication Department Tirana Albania Fukuoka Institute of Technology Department of Information and Communication Engineering Fukuoka Japan

ISBN: (纸本)9798350333794

In the emerging Underwater Wireless Sensor Networks (UWSN) applications, delays, disruptions and disconnections between nodes are expected and need to be addressed. Usage of acoustic waves is recommended in order to improve the propagation in water environment, but the communication becomes unstable when nodes are distant, so real-time communication faces a lot of challenges. The usage of Delay Tolerant Networks (DTN) protocols to forward data in UWSN might solve these problems. One characteristic of routing protocols for DTN is flooding of messages to increase the delivery probability. For instance, Epidemic Routing protocol floods the network with copies of generated messages, which creates a lot overhead in each node's buffer, and uses a lot of valuable energy from the relay *** this paper, in order to minimize the overhead of unnecessary message copies, we implemented Sender-based Depth-Based Routing and Sender-based Vector-Based Forwarding in The ONE simulator. We then evaluated their performance for different width of the forwarding area. The results suggest that narrow Sender-based Vector-Based Forwarding shows higher delivery ratio and lower overhead. © 2023 IEEE.

关键词： Floods

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Mechanism and Analysis of HCC to Suppress DC Commutation Failure 7

Mechanism and Analysis of HCC to Suppress DC Commutation Fai...

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7th IEEE Conference on Energy Internet and Energy system Integration, EI2 2023

作者： Lou, Yantao Wang, Song Zhang, Lei Qu, Lu Wang, Jiangping Zi, Zhenning Li, Liang Wang, Zongze Gao, Qi Yu, Zhanqing Yao, Shu Ma, Yuanshe Xu, Haibo Electric Power System and Power Electronic Technology Xi'an Xidian Power System Co. Ltd Xi'an China Tsinghua University Department of Electrical Engineering and Applied Electronics Technology Beijing China

ISBN: (纸本)9798350345094

This article addresses the issue of commutation failure in high-voltage direct current transmission systems based on the line-commutated converter (LCC) topology. It proposes a solution using a hybrid commutated converter (HCC) topology based on reverse-blocking integrated gate commutated thyristor (IGCT) devices to mitigate commutation failures. Firstly, it introduces the mechanism of commutation failure in LCC and discusses in detail the process and factors that contribute to commutation failure. Next, it analyzes the principles behind HCC's enhanced commutation capabilities, which are achieved by utilizing IGCTs with faster reverse recovery speeds, allowing for a smaller minimum extinction angle. Finally, the article conducts simulation analyses on two critical operating conditions: insufficient extinction time and grid undervoltage. The results demonstrate that HCC on the inverter side can increase the commutation margin and significantly reduce the risk of commutation failure, validating the effectiveness of HCC in suppressing DC commutation failures. © 2023 IEEE.

关键词： Electric commutation

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Analyzing Employee Retention Factors using Machine Learning 4

Analyzing Employee Retention Factors using Machine Learning

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4th International Conference on Advances in Electrical, Computing, Communication and Sustainable Technologies, ICAECT 2024

作者： Rahman, Moshiur Islam, Md Rashedul Bala, Partho Sattar, Abdus Daffodil International University Department of Management Information System Daffodil Smart City Dhaka Bangladesh Daffodil Institute of Information and Technology Department of Computer Science and Engineering Dhanmondi Dhaka Bangladesh Bangabandhu Sheikh Mujibur Rahman Science and Technology University Department of Computer Science and Engineering Dhaka8100 Bangladesh Daffodil International University Department of Computer Science and Engineering Daffodil Smart City Dhaka Bangladesh

ISBN: (纸本)9798350343670

This research proposal aims to employ machine learning techniques to analyze employee retention factors in Software Companies, recognizing its crucial role in organizational success and the potential costs of high turnover rates. Through Watson Analytics' advanced analytics capabilities, the study seeks to identify key factors contributing to employee attrition and retention, culminating in the development of a predictive model using machine learning algorithms. The outcomes are expected to include actionable recommendations to improve retention strategies, insights into the relative importance of different factors, and the creation of a data- driven, proactive talent management approach for Software Companies. By empowering organizations to retain top talent and fostering a positive work environment, this research envisions a transformative impact on long-term success and performance. © 2024 IEEE.

关键词： Artificial Intelligence Data Science Deep Learning Machine Learning Monitoring Smartphone Sensors

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