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Journal of Hydrodynamics 2020年第6期32卷 1212-1216页

作者： cheng-zao han Shun Xu Huai-yu cheng Bin Ji Zhi-yuan Zhang State Key Lab of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Marine Design and Research Institute of China Shanghai200011China

The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the cavitation-vortex interaction *** calculated cavitation structures around the blades are in a remarkable agreement with the experimental *** distributions of the tip clearance vortex under two cavitation conditions are obtained and *** results show that the cavitation development enhances the vorticity generation and the flow unsteadiness around the tip clearance of a propelling *** are basically located around the cavitation areas,particularly in the tip clearance region,during the *** relative vorticity transport equation is applied for the cavitating turbulent flows and it is further indicated that the vortex stretching term makes the main contribution in the vortex production,and the baroclinic torque and dilation terms are important source terms for the vorticity generation in the cavitating *** addition,the viscous diffusion term and the Coriolis force term are significant in modifying the vorticity field inside the blade tip clearance.

关键词： Tip-clearance cavitation propelling pump large eddy simulation(LES) vorticity transport equation

Metamaterial terahertz device with temperature regulation function that can achieve perfect absorption and complete reflection conversion of ultrawideband

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Communications in Theoretical Physics 2024年第07期76卷 125-135页

作者： Hao Sun zao Yi Can Ma Shubo cheng Bin Tang Qingdong Zeng Sohail Ahmad School of Mathematics and Science Joint Laboratory for Extreme Conditions Matter Properties State Key Laboratory of Environment-Friendly Energy Materials Tianfu Institute of Research and InnovationSouthwest University of Science and Technology Department of Oncology Sichuan Science City Hospital School of Chemistry and Chemical Engineering Jishou University School of Physics and Optoelectronic Engineering Yangtze University School of Microelectronics and Control Engineering Changzhou University School of Physics and Electronic Information Engineering Hubei Engineering University Institute of Physics Bahauddin Zakariya University

The field of terahertz devices is important in terahertz technology. However, most of the current devices have limited functionality and poor performance. To improve device performance and achieve multifunctionality, we designed a terahertz device based on a combination of VO2and metamaterials. This device can be tuned using the phase-transition characteristics of VO2, which is included in the triple-layer structure of the device, along with SiO2and Au. The terahertz device exhibits various advantageous features, including broadband coverage, high absorption capability, dynamic tunability, simple structural design, polarization insensitivity, and incidentangle insensitivity. The simulation results showed that by controlling the temperature, the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99. At 313 K, the device exhibited complete reflection of terahertz waves. As the temperature increased,the absorption rate also increased. When the temperature reached 353 K, the device absorption rate exceeded 97.7% in the range of 5–8.55 THz. This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO2. Simultaneously, the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures. Furthermore, the impact of various structural parameters on device performance was examined, offering valuable insights and suggestions for selecting suitable parameter values in real-world applications. These characteristics render the device highly promising for applications in stealth technology, energy harvesting, modulation, and other related fields, thus showcasing its significant potential.

关键词： complete reflection perfect absorption smart device temperature regulation terahertz ultrawideband

Prediction and Output Estimation of Pattern Moving in Non-Newtonian Mechanical Systems Based on Probability Density Evolution

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 515-536页

作者： cheng han Zhengguang Xu School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of Knowledge Automation for Industrial Processes University of Science and Technology BeijingBeijing100083China

A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz *** a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s *** this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic *** pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is ***,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output *** on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased ***,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction *** effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.

关键词： Non-newtonian mechanical systems prediction and estimation pattern moving probability density evolution pseudo partial derivative

Multiscale engineering of molecular electrocatalysts for the rapid hydrogen evolution reaction

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Nano Research 2024年第7期17卷 6026-6031页

作者： Huan Li Zhan Jiang Yubo Yuan Yirong Tang Jie zao Wentao Zhang Peiyi han Xun Zhang Bulin Chen Yongye Liang Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China South China Institute of Environmental Sciences Guangzhou 510655China

Molecular electrocatalysts have demonstrated potential for the hydrogen evolution reaction(HER)due to their well-defined structures and high intrinsic *** rapid production of hydrogen requires molecular electrocatalysts to operate at high current densities,which still presents a *** this work,we demonstrate that molecularly dispersed electrocatalysts of cobalt phthalocyanine anchored on carbon nanotubes(CoPc MDEs)are superior candidates due to the efficient charge transport between the substrate and the active *** intrinsic activity can be enhanced by introducing functional groups on *** facilitate mass transport,di(ethylene glycol)substituted CoPc molecules are further anchored on a threedimensional self-supported electrode(CoPc-DEG MDE@CC),enabling continuous operation for 25 h at−1000 mA/cm^(2)in 1.0 M *** study demonstrates the potential of molecular electrocatalysts for HER and emphasizes the importance of adjusting intrinsic activity,and charge and mass transport capacity for practical molecular electrocatalysts.

关键词： hydrogen evolution reaction cobalt phthalocyanine intrinsic activity mass transport

Multi-functional metasurface:ultra-wideband/multi-band absorption switching by adjusting guided-mode resonance and local surface plasmon resonance effects

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Communications in Theoretical Physics 2024年第6期76卷 174-184页

作者： Wenxin Li Shubo cheng Huafeng Zhang zao Yi Bin Tang Can Ma Pinghui Wu Qingdong Zeng Rizwan Raza School of Physics and Optoelectronic Engineering Yangtze UniversityJingzhouHubei 434023China Joint Laboratory for Extreme Conditions Matter Properties Southwest University of Science and TechnologyMianyang 621010China School of Chemistry and Chemical Engineering Jishou UniversityJishou 416000China School of Microelectronics and Control Engineering Changzhou UniversityChangzhou 213164China Department of Oncology Sichuan Science City HospitalMianyangSichuan Province 621000China Office of Science and Technology Quanzhou Normal UniversityQuanzhou 362000China School of Physics and Electronic-information Engineering Hubei Engineering UniversityXiaogan 432000China Department of Physics COMSATS Institute of Information Technology 54000 LahorePakistan

This study introduces an innovative dual-tunable absorption film with the capability to switch between ultra-wideband and narrowband *** manipulating the temperature,the film can achieve multi-band absorption within the 30-45 THz range or ultra-wideband absorption spanning 30-130 THz,with an absorption rate exceeding ***,the structural parameters of the absorption film are optimized using the particle swarm optimization(PSO)algorithm to ensure the optimal absorption *** absorption response of the film is primarily attributed to the coupling of guided-mode resonance and local surface plasmon resonance *** film's symmetric structure enables polarization incoherence and allows for tuning through various means such as doping/voltage,temperature and structural *** the case of a multi-band absorption response,the film exhibits good sensitivity to refractive index changes in multiple absorption ***,the absorption spectrum of the film remains effective even at large incidence angles,making it highly promising for applications in fields such as biosensing and infrared stealth.

关键词： PSO optimization ultra-wideband/narrowband absorption switching intelligent absorption film vanadium dioxide

Reactor field reconstruction from sparse and movable sensors using Voronoi tessellation-assisted convolutional neural networks

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Nuclear Science and Techniques 2024年第5期35卷 173-185页

作者： He-Lin Gong han Li Dunhui Xiao Sibo cheng Paris Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences Tongji UniversityShanghai 200092China Department of Computing Data Science InstituteImperial College LondonLondon SW72AZUK

The aging of operational reactors leads to increased mechanical vibrations in the reactor *** vibration of the incore sensors near their nominal locations is a new problem for neutronic field *** field-reconstruction methods fail to handle spatially moving *** this study,we propose a Voronoi tessellation technique in combination with convolutional neural networks to handle this *** from movable in-core sensors were projected onto the same global field structure using Voronoi tessellation,holding the magnitude and location information of the *** convolutional neural networks were used to learn maps from observations to the global *** proposed method reconstructed multi-physics fields(including fast flux,thermal flux,and power rate)using observations from a single field(such as thermal flux).Numerical tests based on the IAEA benchmark demonstrated the potential of the proposed method in practical engineering applications,particularly within an amplitude of 5 cm around the nominal locations,which led to average relative errors below 5% and 10% in the L_(2) and L_(∞)norms,respectively.

关键词： Voronoi tessellation Field reconstruction Nuclear reactors Reactor physics On-line monitoring

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Monocular Distance Estimated Based on PTZ Camera

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Computers, Materials & Continua 2024年第5期79卷 3417-3433页

作者： Qirui Zhong Xiaogang cheng Yuxin Song han Wang Bell Honors School Nanjing University of Posts and Telecommunications Nanjing210003China College of Telecommunications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing210003China College of Automation and College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing210003China

This paper introduces an intelligent computational approach for extracting salient objects fromimages and estimatingtheir distance information with PTZ (Pan-Tilt-Zoom) cameras. PTZ cameras have found wide applications innumerous public places, serving various purposes such as public securitymanagement, natural disastermonitoring,and crisis alarms, particularly with the rapid development of Artificial Intelligence and global infrastructuralprojects. In this paper, we combine Gauss optical principles with the PTZ camera’s capabilities of horizontal andpitch rotation, as well as optical zoom, to estimate the distance of the *** present a novel monocular objectdistance estimation model based on the Focal Length-Target Pixel Size (FLTPS) relationship, achieving an accuracyrate of over 95% for objects within a 5 km range. The salient object extraction is achieved through a simplifiedconvolution kernel and the utilization of the object’s RGB features, which offer significantly faster computingspeeds compared to Convolutional Neural Networks (CNNs). Additionally, we introduce the dark channel beforethe fog removal algorithm, resulting in a 20 dB increase in image definition, which significantly benefits distanceestimation. Our system offers the advantages of stability and low device load, making it an asset for public securityaffairs and providing a reference point for future developments in surveillance hardware.

关键词： Public security location information PTZ camera image processing

Spatio-Temporal Service Analysis in Multi-Layer Non-Terrestrial Networks

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Journal of Communications and Information Networks 2024年第1期9卷 43-55页

作者： Qian Chen Weixiao Meng Shuai han cheng Li School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China School of Engineering Science Simon Fraser UniversityBurnabyBC V5A 1S6Canada Department of Electrical and Computer Engineering Memorial UniversitySt.John’sNL A1B 3X5Canada

In the advent of the 6G era, non-terrestrial networks (NTN) with expansive coverage are being increasingly recognized as a vital supplement to cellular networks for facilitating seamless communication. The intricate interplay between network performance and service quality necessitates a thorough investigation into the modeling and analysis of services for efficient construction of *** studies on service analysis, predominantly focused on terrestrial networks,fall short in addressing the unique challenges posed by NTN,particularly those related to platform distribution and antenna gain modeling. This deficiency in research,coupled with the varying preferences of users for different network types, forms the basis of this study. This paper explores the spatio-temporal characteristics of services within a multi-layered NTN *** this context,the spatial distribution of the platforms is modeled using a binomial point process, and the antennas are characterized by a sectorized beam pattern. We derive the closed-form expressions for the association probability,the number of accessed users, and the arrival rate of services with certain delay requirements towards different types of NTN. Simulation results are provided to evaluate the influence of various parameters on the association probability, the number of accessed users, and the total arrival rate of services. The number of satellites can be determined to achieve the optimal system utility,balancing the accessed services, offloading effects, and launching costs. This initial investigation lays the groundwork for further theoretical progress in the service analysis and platform deployment of NTN.

关键词： association strategy non-terrestrial networks service analysis stochastic geometry system utility

不同工况下无轴泵喷推进器间隙流动损耗特性数值分析

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水动力学研究与进展（A辑） 2022年第1期37卷 1-9页

作者：韩承灶阮华洪方文季斌武汉大学水资源与水电工程科学国家重点实验室武汉430072 中国船舶科学研究中心船舶振动噪声重点实验室无锡214082

为研究无轴泵喷推进器间隙流动特性以及流动损耗机理,采用雷诺平均(RANS)方程对不同工况下无轴泵喷推进器周围流场进行数值模拟。该文首先进行了推进器水动力性能计算,通过与试验结果的比较,评估了湍流模型和网格数量对结果的影响。在... 详细信息

为研究无轴泵喷推进器间隙流动特性以及流动损耗机理,采用雷诺平均(RANS)方程对不同工况下无轴泵喷推进器周围流场进行数值模拟。该文首先进行了推进器水动力性能计算,通过与试验结果的比较,评估了湍流模型和网格数量对结果的影响。在此基础上,进一步采用柱坐标系下涡量输运方程和熵增理论,分析了不同工况下推进器间隙流动特征和能量损耗机理。结果表明,计算结果与试验吻合程度较高;进一步由涡量输运方程分析可得方程右侧其影响涡量输运的各项多集中于间隙及间隙进出口区域,其中黏性耗散项对间隙区涡量变化起到主要作用,加剧流动不稳定性;由熵增结果可知,间隙区域中由黏性耗散引起的功率损失占据主导地位,由湍流耗散产生的损失可以忽略不计;同时,间隙流出口区由于流体流动方向与主流方向垂直,二者相互碰撞的同时受到叶轮抽吸作用向下游运动,导致该区域流动较为复杂,流动损耗较大;且随着进速系数提高,由轮缘所引发的流动损耗对推进器水动力性能有一定影响。

关键词：无轴泵喷间隙流动涡量输运数值分析熵增理论

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Differential Operator Approach to■quantum Groups and Their Oscillator Representations

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1360-1374页

作者： Zhao Bing FAN Ji cheng GENG Shao Long han College of Mathematical Science Harbin Engineering UniversityHarbin 150001P.R.China

For a quasi-split Satake diagram,we define a modified q-Weyl algebra,and show that there is an algebra homomorphism between it and the corresponding■quantum *** other words,we provide a differential operator approach to■quantum ***,the oscillator representations of■quantum groups are *** crystal basis of the irreducible subrepresentations of these oscillator representations are constructed.

关键词： ■quantum group differential operator oscillator representation crystal basis

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