检索结果-南通市图书馆

Integration of high-fidelity model of forward variable area bypass injector into zero-dimensional variable cycle engine model

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第8期34卷 1-15页

作者： Fu SONG Li zhou Zhanxue WANG Zhifu LIN Jingwei SHI Shaanxi Key Laboratory of Internal Aerodynamics in Aero-engine School of Power and EnergyNorthwestern Polytechnical UniversityXi'an 710129China

Forward Variable Area Bypass Injector(FVABI)is one of key components which contributes to modulate the cycle parameters of Variable Cycle Engine(VCE)under various operation *** modeling method of zero-dimensional FVABI was reviewed and its deficiency was analyzed based on FVABI flow *** order to improve the accuracy of VCE performance simulation,the high-fidelity modeling method of FVABI was developed based on its working *** it was coupled with the zero-dimensional VCE model and the multi-level VCE model was *** results indicate that the geometric and aerodynamic parameters can affect the interaction between the two airflows and the zero-dimensional FVABI model is too simple to predict the component performance accurately,especially when the FVABI inner bypass is *** on the performance curves for single bypass mode and the regression model of multi-scale support vector regression for double bypass mode,the high-fidelity model can predict FVABI performance accurately and *** integration of high-fidelity FVABI model into zerodimensional VCE model can be done by adjusting iterative variables and balance *** multi-level model has good convergence and it can predict VCE performance when the FVABI inner bypass is chocked.

关键词： Coupling method Forward variable area bypass injector High-fidelity model Multi-scale support vector regression Variable cycle engine

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2020年第3期14卷 113-128页

作者： Yun PENG Yitong XU Huawei ZHAO Zhizheng zhou Huimin HAN Research Center of Big Data Application Qilu University of TechnologyJinan 250353China Data Science Institute Columbia UniversityNew York 10027USA College of Mechanics and Materials Hohai UniversityNanjing 210098China

This paper studies the most similar maximal clique query(MSMCQ).Given a graph G and a set of nodes Q,MSMCQ is to find the maximal clique of G having the largest similarity with *** has many real applications including advertising industry,public security,task crowdsourcing and social network,*** can be studied as a special case of the general set similarity query(SSQ).However,the MCs of G has several specialties from the general *** on the specialties of MCs,we propose a novel index,namely *** outperforms the state-of-the-art SSQ method significantly in terms of the number of candidates and the query ***,we first construct an inverted indexⅠfor all the MCs of *** the MCs in a posting list often have a lot of overlaps,MCIndex selects some pivots to cluster the MCs with a small *** a query Q,we compute the distance from the pivots to *** clusters of the pivots assured not answer can be pruned by our distance based pruning *** it is NP-hard to construct a minimum MCIndex,we propose to construct a minimal MCIndex onⅠ(v)with an approximation ratio 1+ln|Ⅰ(v)|.Since the MCs have properties that are inherent of graph structure,we further propose a S Index within each cluster of a MCIndex and a structure based pruning rule.S Index can significantly reduce the number of *** the sizes of intersections between Q and many MCs need to be computed during the query evaluation,we also propose a binary representation of MCs to improve the efficiency of the intersection size *** extensive experiments confirm the effectiveness and efficiency of our proposed techniques on several real-world datasets.

关键词： most similar maximal clique similarity query graph data

Molten-LiCl induced thermochemical prelithiation of SiOx:Regulating the active Si/O ratio for high initial Coulombic efficiency

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第1期15卷 230-237页

作者： Yang Li Yong Qian Jie zhou Ning Lin Yitai Qian Department of Applied Chemistry University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China

The low initial Coulombic efficiency(ICE)of SiOx anode caused by the irreversible generation of LiySiOz and Li20 during lithiation process limits its application for high energy-density lithium-ion ***,we report a molten-salt-induced *** strategy for regulating the electrochemically active Si/O ratio of SiOx and thus enhancing ICE through thermal treatment of pre-synthesized LiNH2-coated SiOx in molten LiCl at 700℃.Bulk SiOx micro-particle was transformed into pomegranatelike prelithiated micro-cluster composite(M-Li-SiOx)with SiOx core and outer nano-sized agglomerates consisting of Li2Si20s,SiO2,and *** the analysis of the reaction intermediates,molten-UC!could initiate reactions and promote mass transfer by the continuous extraction of oxygen component from SiOx particle inner in the form of inert Li2Si20s and SiO2 nanotubes to realize *** degree of prelithiation can be regulated by adjusting the coating amount of LiNH2 layer,and the resulted M-Li-SiOx displays a prominent improvement of ICE from 58.73%to 88.2%.The graphite/M-Li-SiOx(8:2)composite electrode delivers *** capacity of 497.29 mAh·g^(-1) with an ICE of 91.79%.By pairing graphite/M-Li-SiOx anode and LiFeP04 cathode in a full-cell an enhancement of energy density of 37.25%is realized compared with the full-cell containing graphite/SiOx ***,,ex-situ X-ray photoelectron spectroscopy(XPS)/Raman/X-ray diffraction(XRD)and related electrochemical measurements reveal the SiOx core and Si of M-Li-SiOx participate in the lithiation,and pre-generated Li2Si20s with u+diffusivity and *** reduces the reaction resistance and interface impedance of the solid electrolyte interphase(SEI)film.

关键词： initial Coulombic efficiency thermochemical prelithiation liquid coating molten-salt mass transfer

Controllable nitridation of Ta_(2)_(O5) in molten salts for enhanced photocatalysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第12期27卷 1703-1710页

作者： Jing zhou Dan-dan Nie Xian-bo Jin Wei Xiao College of Chemistry and Molecular Sciences Hubei Key Laboratory of Eletrochermical Power SourexWuhan Lniversitwuhan 430072China Sschool of Resouwce and Einvironmental Sciences Hubei lnternational Scientifie and Teehnological Cooperation Base of Sustainable Rexource and EnergyWuhan UniversityWuhan 430072China

Pyrolysis of the Ta_(2)_(O5)/melamine mixture in molten chlorides is herein demonstrated as a facile and controllable method to nitridize and functionalize Ta_(2)_(O5).The influence of the stoichiometry and composition of Ta_(2)_(O5)/melamine in molten salts on the nitridation process is rationalized to ensure the controllable preparation of Ta_(3)N_(5) and Ta_(3)N_(5)/*** characterization results,including scanning electron microscopy,transmission electron microscopy,elemental mapping,X-ray photoelectron spectroscopy,and photoluminescence spectroscopy,all confirm the existence of the Ta_(3)N_(5)/TaON heterojunction,in which the TaON nanoparticles are closely anchored to the Ta_(3)N_(5) *** from its composition and structure,the Ta_(3)N_(5)/TaON composites show enhanced photocatalytic activity for the degradation of methylene *** present study highlights that the molten salt method using a solid nitrogen source can be a new technique for rationalizing the design of nitrides and oxynitrides.

关键词： molten salts photocatalysis Ta_(3)N_(5) TaON heterojunction

Numerical modeling and experimental study of microstamping process for fabricating microchannels using thin sheets of titanium

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第12期24卷 1079-1095页

作者： Wenze MAO Yancheng WANG Deqing MEI Lingfeng XUAN Caiying zhou State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversiyHangzhou 310058China Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province School of Mechanical EngineeringZhejiang UniversityHangzhou 310058China

Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.

关键词： Titanium sheets Microstamping Anisotropy Constitutive model Springback

Low-dimensional MXenes as noble metal-free co-catalyst for solar-to-fuel production:Progress and prospects

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 Materials Science & Technology 2022年第19期114卷 143-164页

作者： Wanying Lei Tong zhou Xin Pang Shixiang Xue Quanlong Xu College of Materials Science and Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Key laboratory of Carbon Materials of Zhejiang Province Wenzhou UniversityWenzhou 325027China

Direct conversion of solar energy into chemical fuels via semiconducting materials through photocatalytic technology is a sustainable way to tackle the global warming, environmental issue and energy crisis. Transition metal carbides and nitrides(MXenes), a newly emerging class of 2D layered materials, has gained tremendous attention as a noble metal-free co-catalyst for boosting photoreactivity due to its extraordinary characteristics like elemental abundance, excellent electrical conductivity, abundant surface functional groups, unique hydrophilic behavior and flexible modulation of chemical composition. The rational integration of low-dimensional MXenes in the form of 2D layered structures or 0D quantum dots with diverse semiconducting materials offer more versatile and robust heterostructured-photocatalysts that are applicable in solar fuel generation. Herein, we summarize the recent advances and achievements in the synthesis of low-dimensional MXenes and their application in hydrogen production from water splitting and CO_(2) photoreduction. A comprehensive discussion of the fundamentals for solar fuel production, synthesis strategies and theoretical calculations for MXenes-based photocatalysts are also given. Finally, the existing challenges and further perspectives of MXenes-based nanostructures for efficient solar fuel production are addressed.

关键词： MXenes Low-dimensional materials Co-catalyst Photocatalytic H_(2)evolution CO_(2)photoreduction

Film Cooling Effectiveness Superposition Calculation of Double-Row Injection Holes on Turbine Vane

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第6期31卷 2424-2437页

作者： XU Zhipeng ZHU Huiren LIU Cunliang YE Lin zhou Daoen School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of Thermal Sciences in Aero-engine System Xi'an 710129China

Film cooling effectiveness superposition of double-row injection holes on the turbine vane was studied by infrared temperature measurement experiment. The Sellers superposition method and a modified Sellers method were adopted for dustpan-shaped hole and cylindrical hole. Numerical simulations were implemented to analyze the film superposition mechanism. It is found that the Sellers method is more accurate on the suction side than the pressure side. Injection film of the two types of holes exhibits different superposition modes. Cylindrical hole are “blocky-like” superposition. Dustpan-shaped hole are “sheet-like” superposition. The counter-rotating vortex pairs and separation of the film are the main factors affecting the accuracy of Sellers film superposition method. The modified method can significantly improve the superposition prediction accuracy for almost all situations. The modified method reduces superposition errors from 28% to 3% for the cylindrical hole, and from 42% to 13% for the dustpan-shaped hole on the suction side. It reduces superposition errors from 30% to 8% for the cylindrical hole, and from 23% to 15% for the dustpan-shaped hole on the pressure side.

关键词： film cooling superposition calculation shaped hole infrared temperature measurement numerical simulation

GroupNet:Learning to group corner for object detection in remote sensing imagery

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第6期35卷 273-284页

作者： Lei NI Chunlei HUO Xin ZHANG Peng WANG Zhixin zhou Space Engineering University Beijing 101416China National Laboratory of Pattern Recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China Beijing Institute of Remote Sensing Beijing 100192China

Due to the attractive potential in avoiding the elaborate definition of anchor attributes,anchor-free-based deep learning approaches are promising for object detection in remote sensing *** Net is one of the most representative methods in anchor-free-based deep learning ***,it can be observed distinctly from the visual inspection that the Corner Net is limited in grouping keypoints,which significantly impacts the detection *** address the above problem,a novel and effective approach,called Group Net,is presented in this paper,which adaptively groups corner specific to the objects based on corner embedding vector and corner grouping *** with the Corner Net,the proposed approach is more effective in learning the semantic relationship between corners and improving remarkably the detection *** NWPU dataset,experiments demonstrate that our Group Net not only outperforms the Corner Net with an AP of 12.8%,but also achieves comparable performance to considerable approaches with 83.4%AP.

关键词： CornerNet Feature representation Multi-dimension embedding Object detection Remote sensing

Analysis of the Microstructure and Mechanical Properties during Inertia Friction Welding of the Near-α TA19 Titanium Alloy

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2020年第6期33卷 205-217页

作者： Yanquan Wu Chunbo Zhang Jun zhou Wu Liang Yunlei Li Research and Development Center Harbin Welding Institute Limited CompanyHarbin150028China China Academy of Machinery Science and Technology Group Co. LtdBeijing100044China

The current research of titanium alloy on friction welding process in the field of aero-engines mainly focuses on the linear friction *** to the linear friction welding,inertial friction welding of titanium alloy still has important application position in the welding of aero-engine rotating ***,up to now,few reports on inertial friction welding of titanium alloy are *** this paper,the near-alpha TA19 titanium alloy welded joint was successfully obtained by inertial friction welding(IFW)*** microstructures and mechanical properties were investigated *** showed that the refined grains within 15‒20μm and weak texture were found in the weld zone due to dynamic recrystallization caused by high temperature and plastic *** weld zone consisted of acicularα′martensite phase,αp phase and metastableβ*** lath-shapedαs andβphase in base metal were transformed into acicular martensiteα′phase and metastableβphase in thermo-mechanically affected zone and heat affected *** a result,the microhardness of welded joint gradually decreased from the weld zone to the base *** specimens in room temperature and high temperature of 480℃ were all fractured in base metal illustrating that the inertia friction welded TA19 titanium alloy joint owned higher tensile strength compared to the base metal.

关键词： Inertia friction welding TA19 Micostructure Mechanical property Texture