检索结果-南通市图书馆

Hadoop-based secure storage solution for big data in cloud computing environment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第1期10卷 227-236页

作者： Shaopeng Guan Conghui Zhang Yilin Wang wenqing Liu School of Information and Electronic Engineering Shandong Technology and Business UniversityYantai264003China

In order to address the problems of the single encryption algorithm,such as low encryption efficiency and unreliable metadata for static data storage of big data platforms in the cloud computing environment,we propose a Hadoop based big data secure storage ***,in order to disperse the NameNode service from a single server to multiple servers,we combine HDFS federation and HDFS high-availability mechanisms,and use the Zookeeper distributed coordination mechanism to coordinate each node to achieve dual-channel ***,we improve the ECC encryption algorithm for the encryption of ordinary data,and adopt a homomorphic encryption algorithm to encrypt data that needs to be *** accelerate the encryption,we adopt the dualthread encryption ***,the HDFS control module is designed to combine the encryption algorithm with the storage *** results show that the proposed solution solves the problem of a single point of failure of metadata,performs well in terms of metadata reliability,and can realize the fault tolerance of the *** improved encryption algorithm integrates the dual-channel storage mode,and the encryption storage efficiency improves by 27.6% on average.

关键词： Big data security Data encryption Hadoop Parallel encrypted storage Zookeeper

Resonance mechanism of flapping wing based on fluid structure interaction simulation

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 Aeronautics 2024年第5期37卷 243-262页

作者： Yueyang GUO wenqing YANG Yuanbo DONG Dong XUE National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Yangtze River Delta Research Institute of Northwestern Polytechnical University Taicang 215400China

Certain insect species have been observed to exploit the resonance mechanism of their *** order to achieve resonance and optimize aerodynamic performance,the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal(TSM)***,there exists controversy among researchers regarding the relationship between frequency and aerodynamic *** that the structural response of wings can be influenced by the surrounding air vibrations,an analysis known as Acoustic Structure Interaction Modal(ASIM)is introduced to calculate the resonant *** this study,Fluid Structure Interaction(FSI)simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM *** performance is evaluated for various mass ratios and frequency ratios,and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic ***,the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency,as does the frequency corresponding to maximum ***,the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible ***,it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure *** paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings(FFWs)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping Wing(FFW) Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance

Total Synthesis of Laurane and Guaiane Sesquiterpenoids via Oxidative Nazarov Reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第11期42卷 1267-1274页

作者： Yuye Chen wenqing Chen Zhiting Zhang Jing Xu Shenzhen Grubbs Institute and Department of Chemistry and Guangming Advanced Research Institute and Guangdong Provincial Key Laboratory of Catalysis and Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis Southern University of Science and TechnologyShenzhenGuangdong518055 China

As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as ***,straightforward method for transforming unfunctionalized TDCs to their corresponding cyclopentenones is currently ***,we wish to report the total syntheses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key *** work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.

关键词： Total synthesis Synthetic methods Sesquiterpenoids Oxidative Nazarov reaction Electrocyclization Oxoammonium salt Pericyclic reaction Annulation

Mastering air combat game with deep reinforcement learning

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第4期34卷 295-312页

作者： Jingyu Zhu Minchi Kuang wenqing Zhou Heng Shi Jihong Zhu Xu Han Department of Precision Instruments Tsinghua UniversityBeijing 100084China Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China Chengdu Aircraft Design&Research Institute Aviation Industry Corporation of ChinaChengdu 610000China

Reinforcement learning has been applied to air combat problems in recent years,and the idea of curriculum learning is often used for reinforcement learning,but traditional curriculum learning suffers from the problem of plasticity loss in neural *** loss is the difficulty of learning new knowledge after the network has *** this end,we propose a motivational curriculum learning distributed proximal policy optimization(MCLDPPO)algorithm,through which trained agents can significantly outperform the predictive game tree and mainstream reinforcement learning *** motivational curriculum learning is designed to help the agent gradually improve its combat ability by observing the agent's unsatisfactory performance and providing appropriate rewards as a ***,a complete tactical maneuver is encapsulated based on the existing air combat knowledge,and through the flexible use of these maneuvers,some tactics beyond human knowledge can be *** addition,we designed an interruption mechanism for the agent to increase the frequency of decisionmaking when the agent faces an *** the number of threats received by the agent changes,the current action is interrupted in order to reacquire observations and make decisions *** the interruption mechanism can significantly improve the performance of the *** simulate actual air combat better,we use digital twin technology to simulate real air battles and propose a parallel battlefield mechanism that can run multiple simulation environments simultaneously,effectively improving data *** experimental results demonstrate that the agent can fully utilize the situational information to make reasonable decisions and provide tactical adaptation in the air combat,verifying the effectiveness of the algorithmic framework proposed in this paper.

关键词： Air combat MCLDPPO Interruption mechanism Digital twin Distributed system

Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG Ang CHEN Zhihe WANG Dong XUE wenqing YANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft Research Center Chengdu Technological UniversityChengdu 610031China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3. respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

Simulation Analysis of DC Fault Interruption Characteristics of Superconducting Electric Aircraft Propulsion

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第4期10卷 1834-1842页

作者： Muhammad Junaid Xiaolong Yu Shuzhi Cao wenqing Yu Dongsheng Zuo Jianhua Wang School of Electrical Engineering Nanhu CampusChina University of Mining and TechnologyXuzhouJiangsu 221116China Shanghai Dianji University Shanghai 201306China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’anShaanxi 710049China

Environmental issues associated with the aviation industry are getting more attention as air traffic *** standards are imposed for fuel consumption and pollution emissions for next-generation *** electrical propulsion aircraft(SEPA)have been seen as an efficient way to achieve this ***-temperature superconducting(HTS)devices are extensively used in the power system to supply enormous *** is distributed to the different loads via a DC distribution ***,it will generate an inrush current over ten times higher than the rated current in short-circuit state,which is very harmful to the ***,it is essential to adopt an appropriate protection *** paper discusses one protection scheme that combines DC vacuum circuit breakers(DC VCB)and resistive superconducting current limiters(RSFCL)for superconducting aircraft *** problems of cost and loss,the auxiliary capacitor is pre-charged by system voltage,and mechanical elements extinguish the ***,combined with RSFCL,the interrupting environment is fully *** limits fault current,and then the VCB breaks this limited current based on creating an artificial current zero(ACZ).The prospective rated power is 8MW,rated voltage and current are 4 kV and 1 kA,*** this paper,we discuss and simulate switching devices that protect *** interrupting performance of the circuit breaker is analysed in the DC short-circuit fault that occurs on the transmission ***,the residual energy consumption of different situations is calculated.A comparison is made between using RSFCL with metal oxide varistor(MOV)and just using *** scheme with RSFCL shows a significant advantage in energy consumption.

关键词： Artificial current zero DC circuit breakers metal oxide varistor RSFCL superconducting electrical propulsion aircraft

G0 Pythagorean-Hodograph Curves Closest to Prescribed Planar Bézier Curves

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 Mathematical Research with Applications 2024年第3期44卷 408-426页

作者： wenqing FEI Yongxia HAO School of Mathematical Sciences Jiangsu University

The task of identifying the quintic PH curve G0“closest” to a given planar Bézier curve with or without prescribed arc length is discussed here using Gauss-Legendre polygon and Gauss-Lobatto polygon respectively. By expressing the sum of squared differences between the vertices of Gauss-Legendre or Gauss-Lobatto polygon of a given Bézier and those of a PH curve, it is shown that this problem can be formulated as a constrained polynomial optimization problem in certain real variables, subject to two or three quadratic constraints, which can be efficiently solved by Lagrange multiplier method and Newton-Raphson iteration. Several computed examples are used to illustrate implementations of the optimization methodology. The results demonstrate that compared with Bézier control polygon, the method with Gauss-Legendre and Gauss-Lobatto polygon can produce the G0PH curve closer to the given Bézier curve with close arc length. Moreover, good approximations with prescribed arc length can also be achieved.

关键词： Pythagorean-hodograph curves Gauss-Legendre polygon Gauss-Lobatto polygon constrained optimization Lagrange multiplier Newton-Raphson iteration

A Nonlinear Grey Bernoulli Model with Conformable Fractional-Order Accumulation and Its Application to the Gross Regional Product in the Cheng-Yu Area

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Information 2024年第2期12卷 245-273页

作者： wenqing WU Xin MA Bo ZENG Yuanyuan ZHANG School of Science Civil Aviation Flight University of ChinaDeyang 618307China School of Mathematics and Physics Southwest University of Science and TechnologyMianyang 621010China College of Business Planning Chongqing Technology and Business UniversityChongqing 400067China

This study considers a nonlinear grey Bernoulli forecasting model with conformable fractionalorder accumulation,abbreviated as CFNGBM(1,1,λ),to study the gross regional product in the ChengYu *** new model contains three nonlinear parameters,the power exponentγ,the conformable fractional-orderαand the background valueλ,which increase the adjustability and flexibility of the CFNGBM(1,1,λ)*** parameters are determined by the moth flame optimization algorithm,which minimizes the mean absolute prediction percentage *** CFNGBM(1,1,λ)model is applied to the gross regional product of 16 cities in the Cheng-Yu area,which are Chongqing,Chengdu,Mianyang,Leshan,Zigong,Deyang,Meishan,Luzhou,Suining,Neijiang,Nanchong,Guang’an,Yibin,Ya’an,Dazhou and *** data from 2013.to 2021,several grey models are established and results show that the new model has higher accuracy in most cases.

关键词： nonlinear grey Bernoulli model conformable fractional-order operator moth flame optimization algorithm gross regional product the Cheng-Yu area

Synthesis and Characterization of Phenyl Camellia oleifera Seed Oil Ester Plasticizing PVC

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2024年第3期12卷 615-628页

作者： wenqing Xiao Yuhang Liu Yuxin He Qiaoguang Li Yongquan Li College of Chemistry and Chemical Engineering Zhongkai University of Agriculture and EngineeringGuangzhou510225China College of Chemical Engineering Zhejiang University of TechnologyHangzhou310000China Key Laboratory of Germplasm Platform and Ornamental Plants College of Horticulture and Landscape ArchitectureZhongkai University of Agriculture and EngineeringGuangzhou510225China

Plasticizers are essential additives in the processing of polyvinyl chloride(PVC),with phthalate plasticizers being widely ***,these conventional plasticizers have been shown to be harmful to human health and environmentally unfriendly,necessitating the exploration of eco-friendly bio-based *** this study,Camellia oleifera seed oil,a specialty resource in China,was utilized as a raw material and reacted with 4,4′-Methylenebis(N,N-diglycidylaniline)(AG-80)to synthesize Phenyl Camellia seed Oil Ester(PCSOE).PCSOE was employed as a plasticizer to prepare modified PVC films with varying concentrations,with the conventional plasticizer dioctyl phthalate(DOP)serving as a *** results demonstrate that PSCOE-plasticized PVC films exhibit enhanced hydrophilicity,tensile strength,and thermal stability compared to DOP-modified PVC *** contact angle of PSCOE-plasticized PVC films ranges from 66.26°to 78.48°,which is generally lower than the contact angle of DOP-modified PVC films at 78.40°,indicating improved hydrophilicity due to the modification with *** tensile strength of PSCOE-plasticized PVC films ranges from 17.73.to 20.17 MPa,all surpassing the value of 16.41 MPa for DOP-modified PVC ***,the temperatures corresponding to 5%,10%,and 50%weight loss for PVC samples modified with PCSOE are higher than those for ***,PCSOE presents a viable alternative to DOP as a plasticizer for PVC materials.

关键词： Polyvinyl chloride(PVC) Camellia oleifera seed oil 4,4′-Methylenebis(N,N-diglycidylaniline) bio-based plasticizer