检索结果-南通市图书馆

Self-centering characteristics of a petal-shaped capsule robot

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2019年第4期62卷 619-627页

作者： ZHANG YongShun CHEN Jun ZHANG Yu meng kang Key Laboratory for Precision & Non-traditional Machining Technology of Ministry of Education Dalian University of Technology School of Computer Science and Technology Faculty of Electronic Information and Electrical Engineering Dalian University of Technology

Based on the multiple wedge effects, a petal-shaped capsule robot(PCR) is proposed, and the self-centering phenomenon of the PCR is discovered. For investigating the self-centering characteristics, an innovative concept of the instantaneous fluid membrane(FM) thickness, along with the dynamic FM thickness, is proposed; thus a dynamic FM thickness model and a hydrodynamic pressure(HP) model are derived when the PCR axis deviates from the pipe axis under the effect of gravity. A kinematics equation during suspending process in the vertical direction and a swimming kinematics equation in axial direction are derived respectively. Four capsule robots with different eccentricities of the tiles were manufactured and tested, the theoretical and experimental results show that the HP gradient is a fundamental reason for the self-centering phenomenon. The PCR with the self-centering ability can directly avoid the contact with the bottom of the gastrointestinal(GI) tract, achieving the excellent obstacle surmounting ability in the GI complex environment with the less twisted impact on the GI tract, which has a promising application prospect in the GI diagnosis.

关键词： petal-shaped capsule robot self-centering characteristics multiple wedge effects complete suspension phenomenon

Merging bound states in the continuum by harnessing higher-order topological charges

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2022年第9期11卷 2098-2106页

作者： meng kang Li Mao Shunping Zhang meng Xiao Hongxing Xu Che Ting Chan School of Physics and Technology and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of EducationWuhan UniversityWuhan 430072China Department of Physics The Hong Kong University of Science and TechnologyHong KongChina Wuhan Institute of Quantum Technology Wuhan 430206China School of Microelectronics Wuhan UniversityWuhan 430072China

Bound states in the continuum(BICs)can confine light with a theoretically infinite Q ***,in practical on-chip resonators,scattering loss caused by inevitable fabrication imperfection leads to finite Q factors due to the coupling of BICs with nearby radiative *** multiple BICs can improve the robustness of BICs against fabrication imperfection by improving the Q factors of nearby states over a broad wavevector *** date,the studies of merging BICs have been limited to fundamental BICs with topological charges±*** we show the unique advantages of higher-order BICs(those with higher-order topological charges)in constructing merging *** multiple BICs with a higher-order BIC can further improve the Q factors compared with those involving only fundamental *** addition,higher-order BICs offer great flexibility in realizing steerable off-T merging BICs.A higher-order BIC at F can split into a few off-T fundamental BICs by reducing the system *** split BICs can then be tuned to merge with another BIC,e.g.,an accidental BIC,at an off-Γ*** the in-plane mirror symmetry is further broken,merging BICs become steerable in the reciprocal *** BICs provide a paradigm to achieve robust ultrahigh-Q resonances,which are important in enhancing nonlinear and quantum effects and improving the performance of optoelectronic devices.

关键词： topological charges states

Interfacial Structures Governed Plastic Deformation Behaviors in Metallic Multilayers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2016年第2期29卷 199-204页

作者： Ming-Zhen Wei Zhen-Hua Cao Xiang-kang meng Institute of Materials Engineering National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Nanjing University Department of Physics School of Science Linyi University

In this work, we have investigated the mechanical properties of Cu/Ta, Ag/Cu and Ag/Nb multilayers with different heterogeneous interfaces. The results suggest that when individual layer thickness （h） is larger than 5-10 nm, the hardness/strength of three different multilayer systems has the similar length scale effect with decreasing layer thickness, while when h ≤ 5 nm, the three multilayer systems show remarkably different plastic deformation behaviors. The strength curves exhibit the variation trends of unchanging, softening and increasing corresponding to Cu/Ta, Ag/Cu and Ag/Nb multilayers, respectively. The microstructure analysis shows that three kinds of multilayers have totally different interfacial structures, which lead to the different strengthening or softening mechanisms.

关键词： Metallic multilayers Plastic deformation Interfacial structures Strengthening mechanism

Numerical simulation of gas-liquid two-phase flow impacting fixed structure by CLSVOF/IB method based on OpenFOAM

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2021年第6期33卷 1176-1189页

作者： Wen-kang meng Ching-hao Yu Jia Li Rui-dong An State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu 610065China

In this paper,a coupled level set and volume of fluid,immersed boundary(CLSVOF/IB)method is proposed and implemented into the interFoam solver of the OpenFOAM to simulate the gas-liquid two-phase flows,involving the gas-liquid and fluid-structure *** the volume of fluid(VOF)method,the multidimensional universal limiter with explicit solution(MULES)approach is used to restrain the volume *** approach for calculating the grid characteristic size for the level set(LS)initial function and the re-initialization equation is proposed in order to make it more applicable to non-uniform grids in the finite volume *** the proposed CLSVOF method,the continuous LS function is used to calculate the gas-liquid interface curvature so that the surface tension term can be calculated *** the immersed boundary(IB)method proposed in this paper,a virtual forcing term is introduced in the momentum equation to deal with the fluid-structure interface by defining a solid volume fraction,which is convenient for the three-dimensional numerical *** the present flow field solver,an improved scheme of the velocity predictor loop of the PIMPLE framework is also *** benchmark cases:the Zalesak’s notched disk and a circular bubble at equilibrium,are simulated first to examine the accuracy of the present CLSVOF ***,the effects of several gas-liquid two-phase flows on different fixed structures are *** simulation results are in good agreement with the published numerical and experimental results.

关键词： Volume of fluid(VOF)method level set(LS)method immersed boundary method gas-liquid interface fluid-structure interface

Adaptive Photon Mapping Based on Gradient

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2016年第1期31卷 217-224页

作者： Chun-meng kang Lu Wang Yan-Ning Xu Xiang-Xu meng Yuan- Jie Song School of Computer Science and Technology Shandong University Jinan 252000 China Engineering Research Center of Digital Media Technology Ministry of Education Jinan 252000 China

Photon mapping can simulate some special effects efficiently such as shadows and caustics. Photon mapping runs in two phases： the photon map generating phase and the radiance estimation phase. In this paper, we focus on the bandwidth selection process in the second phase, as it can affect the final quality significantly. Poor results with noise arise if few photons are collected, while bias appears if a large number of photons are collected. In order to solve this issue, we propose an adaptive radiance estimation solution to obtain trade-offs between noise and bias by changing the number of neighboring photons and the shape of the collected area according to the radiance gradient. Our approach can be applied in both the direct and the indirect illumination computation. Finally, experimental results show that our approach can produce smoother quality while keeping the high frequency features perfectly compared with the original photon mapping algorithm.

关键词： photo-realistic rendering global illumination photon mapping radiance estimation

Performance improvement of ultra-low Pt proton exchange membrane fuel cell by catalyst layer structure optimization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第1期35卷 473-479页

作者： Jinyan Xi kang meng Ying Li meng Wang Qiang Liao Zidong Wei Minhua Shao Jianchuan Wang School of Chemistry&Chemical Engineering Chongqing UniversityChongqing 400044China School of Energy and Power Engineering Chongqing UniversityChongqing 400044China School of Chemistry and Bioengineering HongKong University of Science and TechnologyHong KongChina

Reducing the loading of noble Pt-based catalyst is vital for the commercialization of proton exchange membrane fuel cell(PEMFC),However,severe mass transfer polarization loss resulting in fuel cell performance decline will be encountered in ultra-low Pt *** this work,mild oxidized multiwalled carbon nanotubes(mMWCNT)were adopted to construct the catalyst layer,and by varying the loading of carbon nanotubes,the catalyst layer structure was optimized.A high peak power density of 1.23 W·cm^(-2) for the MEA with mMWCNT was obtained at an ultra-low loading of 120μg·cm^(-2) Pt/PtRu(both cathode and anode),which was 44.7%higher than that of MEA without *** catalyst dispersion,low charge transfer resistance,more porous structure and high hydrophobicity of catalyst layer were ascribed for the reasons of the performance improvement.

关键词： Catalyst Mass transfer Optimization Fuel cell Ultra-low platinum Carbon nanotubes

Research on Distributed Data Sharing System based on Internet of Things and Blockchain

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Information 2021年第3期9卷 239-254页

作者： Enchang SUN kang meng Ruizhe YANG Yanhua ZHANG meng LI School of Information and Communications Engineering Faculty of InformationBeijing University of TechnologyBeijing 100124China

Aiming at the problems of the traditional centralized data sharing platform,such as poor data privacy protection ability,insufficient scalability of the system and poor interaction ability,this paper proposes a distributed data sharing system architecture based on the Internet of Things and blockchain *** this system,the distributed consensus mechanism of blockchain and the distributed storage technology are employed to manage the access and storage of Internet of Things data in a secure *** to the physical topology of the network,a hierarchical blockchain network architecture is proposed for local network data storage and global network data sharing,which reduces networking complexity and improves the scalability of the *** addition,smart contract and distributed machine learning are adopted to design automatic processing functions for different types of data(public or private)and supervise the data sharing process,improving both the security and interactive ability of the system.

关键词： blockchain smart contract Internet of Things data sharing

The unique magnetic damping enhancement in epitaxial Co2Fe1-xMnxAl films

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第9期28卷 332-337页

作者： Shu-Fa Li Chu-Yuan Cheng kang-kang meng Chun-Lei Chen College of Electronics and Information Engineering Guangdong Ocean UniversityZhanjiang 524000China State-Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-Sen UniversityGuangzhou 510275China State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Uniform precession dynamics and its magnetic damping are investigated in epitaxial Co2Fe1-xMnxAl films by using the time-resolved magneto-optical Kerr effect under out-of-plane *** decay time of uniform precession mode decreases, and thus the magnetic damping increases with the increase of external ***, the decay time decreases as x decreases, so that the enhancement of magnetic damping occurs in Fe-rich ***, the decay time decreases as the excitation fluence increases, which drops rapidly at low magnetic field comparing with the slow reduction at high magnetic *** unique magnetic damping enhancement is attributed to the enhancement of homogeneous magnetization.

关键词： ultrafast dynamics pump-probe magnetic damping Heusler alloy

Denoising Stochastic Progressive Photon Mapping Renderings Using a Multi-Residual Network

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2020年第3期35卷 506-521页

作者： Zheng Zeng Lu Wang Bei-Bei Wang Chun-meng kang Yan-Ning Xu School of Software Shandong UniversityJinan 250101China School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Information Science and Engineering Shandong Normal UniversityJinan 250358China

Stochastic progressive photon mapping(SPPM)is one of the important global illumination methods in computer *** can simulate caustics and specular-diffuse-specular lighting effects ***,as a biased method,it always suffers from both bias and variance with limited iterations,and the bias and the variance bring multi-scale noises into SPPM *** learning-based methods have shown great advantages on denoising unbiased Monte Carlo(MC)methods,but have not been leveraged for biased *** this paper,we present the first learning-based method specially designed for denoising-biased SPPM ***,to avoid conflicting denoising constraints,the radiance of final images is decomposed into two components:caustic and *** two components are then denoised separately via a two-network *** each network,we employ a novel multi-residual block with two sizes of filters,which significantly improves the model’s capabilities,and makes it more suitable for multi-scale noises on both low-frequency and high-frequency *** also present a series of photon-related auxiliary features,to better handle noises while preserving illumination details,especially *** with other state-of-the-art learning-based denoising methods that we apply to this problem,our method shows a higher denoising quality,which could efficiently denoise multi-scale noises while keeping sharp illuminations.

关键词： denoising stochastic progressive photon mapping(SPPM) deep learning residual neural network