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A Computational Synthesis Approach of Mechanical Conceptual Design Based on Graph Theory and Polynomial Operation

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 60-74页

作者： Lin han Geng Liu Xiaohui Yang Bing han Shaanxi Engineering Laboratory for Transmissions and Controls Northwestern Polytechnical UniversityXi’an 710072China

The design synthesis is the key issue in the mechanical conceptual design to generate the design candidates that meet the design *** paper devotes to propose a novel and computable synthesis approach of mechanisms based on graph theory and polynomial *** graph framework of the synthesis approach is built firstly,and it involves:(1)the kinematic function units extracted from mechanisms;(2)the kinematic link graph that transforms the synthesis problem from mechanical domain into graph domain;(3)two graph representations,i.e.,walk representation and path representation,of design candidates;(4)a weighted matrix theorem that transforms the synthesis process into polynomial ***,the formulas and algorithm to the polynomial operation are *** on them,the computational flowchart to the synthesis approach is summarized.A design example is used to validate and illustrate the synthesis approach in *** proposed synthesis approach is not only supportive to enumerate the design candidates to the conceptual design of a mechanical system exhaustively and automatically,but also helpful to make that enumeration process computable.

关键词： Design synthesis Conceptual design Graph theory Polynomial operation Kinematic link graph Weighted matrix theorem

The energy conversion rates from eddies and mean fl ow into internal lee waves in the global ocean

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Journal of Oceanology and Limnology 2022年第4期40卷 1304-1313页

作者： Bing han Laboratory for Coastal Ocean Variation and Disaster Prediction College of Ocean and MeteorologyGuangdong Ocean UniversityZhanjiang 524088China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Institut für Meereskunde Universität HamburgHamburg 20146Germany Key Laboratory of Climate Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong ProvinceGuangdong Ocean UniversityZhanjiang 524088China

Internal lee waves play an important role in transferring energy from eddies to small scale ***,the energy conversion from eddies into lee waves in the global ocean remains poorly *** rates from eddies and from mean fl ow in the global ocean were diff erentiated using single beam sounding data,stratifi cation from climatology,eddy velocity,and mean fl ow from a global ocean *** global integral energy conversion from eddies is estimated to be 0.083 TW and is almost twice as that from the mean fl ow.A new method was developed to study the uncertainties of energy conversion caused by dealing with the topographic *** show that diff erent data processing procedures,and the resolution and accuracy of topographic data have a signifi cant impact on the estimated global energy conversion.

关键词： internal lee waves eddies mean flow energy conversion topography

Preparation of ZIF-8@PEBAX/PVDF nanocomposite membrane by the combination of self-assembly and in-situ growth for removing thiophene from the model gasoline

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Chinese Journal of Chemical Engineering 2023年第12期64卷 177-187页

作者： Zhesai Zhao Qingwen han Wenwen He Xiaolong han School of Chemical Engineering Northwest UniversityXi’an 710069China Hubei Three Gorges Laboratory Yichang 443007China School of Chemistry and Life Science Advanced Institute of Materials ScienceChangchun University of TechnologyChangchun 130012China

Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for ***,the agglomeration of MOFs particles and interfacial defects limit its further *** this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ ***,a PVDF supporting membrane was modified to have a negative ***,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic ***,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 ***,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring *** results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX *** optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.

关键词： Nanocomposite membrane ZIF-8 nanoparticles PEBAX Thiophene

A high-resolution numerical investigation of unsteady wake vortices for coaxial rotors in hover

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Chinese Journal of Aeronautics 2024年第11期37卷 278-299页

作者： Shaoqiang han Wenping SONG Zhonghua han Jianhua XU Tianfu Engineering-oriented Numerical&Software Innovation Center College of Computer ScienceSichuan UniversityChengdu 610065China National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi’an 710072China

High-resolution numerical simulations for wake vortical flows have long been a challenge in rotor aerodynamics.A novel spectrum-optimized sixth-order Weighted Essentially NonOscillatory(WENO)scheme is proposed to discretize inviscid fluxes on moving overset grids,and the Improved Delayed Detached Eddy Simulation(IDDES)is employed to resolve turbulent *** integration of these methods facilitates a comprehensive numerical investigation into the unsteady vortical flows over coaxial rotors in *** results highlight the substantial improvement in numerical resolution,in terms of both spatial structure and temporal evolution of unsteady multiscale wake *** rotors in hover manifest three primary scales of wake vortex structures:(A)the helical evolution of primary blade tip vortices and the periodic occurrence of strong Blade-Vortex Interactions(BVI);(B)the continuous shedding of small-scale horseshoeshaped vortices from the trailing edges of rotor blades,forming the vortex sheets;(C)the emergence of small-scale secondary vortex braids induced by interactions between rotor tip vortices and the vortex *** vortex structures and their interactions cause high-frequency oscillations in rotor disk loads and induce unsteady perturbations in the local flow *** among these primary vortices,coupled with the generation of secondary vortices,result in the dissipation,distortion,and breakup of the rotor tip vortices,ultimately forming a vortex ***,a substantial quantity of seemingly weak small-scale secondary vortex braids significantly contribute to energy dissipation during the evolution of wake vortices for coaxial rotors in hover.ó2024 Chinese Society of Aeronautics and *** and hosting by Elsevier *** is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Coaxial rotor Blade tip vortex Secondary vortex High-order scheme IDDES Moving overset grid

FAST unveils a new era in the discovery of long-period pulsars in globular clusters

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 185-186页

作者： Zhanwen han International Centre of Supernovae Yunnan Key LaboratoryYunnan ObservatoriesChinese Academy of SciencesKunming 650011China

Globular clusters(GC)are among the oldest celestial bodies in the Milky *** possessing millions of stars and have been going through abundant stellar interactions,GCs are futile ground for hunting for compact objects,particularly,neutron stars.A significant number of fast-spinning millisecond pulsars(MSPs)have been discovered,comprising the majority of known GC pulsars.

关键词： stars pulsars abundant

Eff ects of climate change on the potential habitat distribution of swimming crab Portunus trituberculatus under the species distribution model

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Journal of Oceanology and Limnology 2022年第4期40卷 1556-1565页

作者： Xingyu LIU Xiaolu han Zhiqiang han Fishery College Zhejiang Ocean UniversityZhoushan 316002China

Over the last decades,the species distribution model(SDM)has become an essential tool for studying the potential eff ects of climate change on species *** this study,an ensemble SDM was developed to predict the changes in species distribution of swimming crab Portunus trituberculatus across diff erent seasons in the future(2050s and 2100s)under the climate scenarios of Representative Concentration Pathway(RCP)4.5 and *** of the ensemble SDM indicate that the distribution of this species will move northward and exhibit evident seasonal *** the four seasons,the suitable habitat for this species will be signifi cantly reduced in summer,with loss rates ranging from 45.23%(RCP4.5)to 88.26%(RCP.8.5)by the *** loss of habitat will mostly occur in the East China Sea and the southern part of the Yellow Sea,while a slight increase in habitat will occur in the northern part of the Bohai *** fi ndings provide an information forecast for this species in the *** forecast will be helpful in improving fi shery management under climate change.

关键词： Portunus trituberculatus climate change species distribution model suitable habitat

Soft-Control for Collective Opinion of Weighted DeGroot Model

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Journal of Systems Science & Complexity 2017年第3期30卷 550-567页

作者： han Huawei QIANG Chengcang WANG Caiyun han Jing Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China Sinopec Research Institute of Safety Engineering Qingdao 266000China.

The DeGroot model is a classic model to study consensus of opinion in a group of individuals(agents). Consensus can be achieved under some circumstances. But when the group reach consensus with a convergent opinion value which is not what we expect, how can we intervene the system and change the convergent value? In this paper a mechanism named soft control is first introduced in opinion dynamics to guide the group's opinion when the population are given and evolution rules are not allowed to change. According to the idea of soft control, one or several special agents,called shills, are added and connected to one or several normal agents in the original group. Shills act and are treated as normal agents. The authors prove that the change of convergent opinion value is decided by the initial opinion and influential value of the shill, as well as how the shill connects to normal agents. An interesting and counterintuitive phenomenon is discovered: Adding a shill with an initial opinion value which is smaller(or larger) than the original convergent opinion value dose not necessarily decrease(or increase) the convergent opinion value under some conditions. These conditions are given through mathematical analysis and they are verified by the numerical tests. The authors also find out that the convergence speed of the system varies when a shill is connected to different normal agents. Our simulations show that it is positively related to the degree of the connected normal agent in scale-free networks.

关键词： Consensus DeGroot model intervention strategy opinion dynamics soft control.

Electrochemical Properties of Tubular SOFC Based on a Porous Ceramic Support Fabricated by Phase-Inversion Method

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Journal of Materials Science & Technology 2016年第7期32卷 681-686页

作者： Zongying han Yuhao Wang Zhibin Yang Minfang han Union Research Center of Fuel Cell School of Chemical and Environmental Engineering China University of Mining and Technology State Key Laboratory of Power Systems Department of Thermal Engineering Tsinghua University

In this work, a tubular ceramic-supported solid oxide fuel cell （SOFC） was successfully fabricated by a low cost and simple process involving phase-inversion, brush coating and co-sintering. Properties in- cluding sintering behavior, microstructure of the tubular support as well as the electrochemical properties of single cell were investigated. The results show that a porous tubular support with finger-like pores and macrovoids was obtained after phase-inversion process. The tubular support is proved to be gaspermeable after sintering at 1400 ℃ with shrinkage of about 34%. The maximum power density of single tubular SOFC is 100 mW/cm2 and 122 mW/cm2 at 850 ℃ when fed with wet methane and hydrogen, respectively. The current collection, thickness of electrolyte and gas permeability of tubular support should account for the large total resistance. The present tubular design could be expected to deliver a higher voltage for longer support with several segmented-in-series cell stacks.

关键词： Phase-inversion method Ceramic support Tubular solid oxide fuel cell Segmented-in-series

Network Coding-Aware Routing Protocol in Wireless Mesh Networks

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Tsinghua Science and Technology 2015年第1期20卷 40-49页

作者： Yan Gu han han Xujie Li Jie Guo College of Computer and Information Hohai University

Network coding mechanisms, such as COPE, can improve network throughput effectively in Wireless Mesh Networks（WMN）. While the Hybrid Wireless Mesh Protocol（HWMP） is suitable for WMN, its extension with COPE does not provide any added benefits; specifically, HWMP cannot establish paths with more coding opportunities. As a result, the advantages of network coding cannot be exploited sufficiently. This paper proposes improvements upon HWMP with a new, network Coding-Aware routing protocol（CAHWMP） for WMN. In the CAHWMP protocol, we propose a coding criterion based on data streams to devise an algorithm for actively detecting coding opportunities during path discovery. CAHWMP subsequently establishes paths using the codingaware routing metric, which can balance channel resource consumption and the gain due to sharing resources introduced by network coding. Simulation results show that CAHWMP can establish paths with more coding opportunities; as a result, it improves network performance such as network throughput.

关键词： wireless mesh network network coding-aware Hybrid Wireless Mesh Protocol(HWMP) COPE mechanism coding criterion