检索结果-南通市图书馆

Pitting corrosion resistance of a novel duplex alloy steel in alkali-activated slag extract in the presence of chloride ions

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2017年第10期24卷 1134-1144页

作者： Jin-jie Shi Jing Ming xin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and Engineering Southeast University Nanjing 211189 China

In this study, two types of reinforcing steels(conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions(ordinary Portland cement(OPC) extract and alkali-activated slag(AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various Na Cl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.

关键词： pitting corrosion resistance alloy steel alkali-activated slag chloride ions electrochemical impedance spectroscopy cyclic potentiodynamic polarization

Polarization characteristics and controllability mechanism of passive scattering elements

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2023年第2期34卷 342-349页

作者： GUO jie YIN Hongcheng MAN Liang LI xin Science and Technology on Electromagnetic Scattering Laboratory Beijing 100854China Beijing Institute of Environmental Features Beijing 100854China

Polarization feature is one of the important features of radar targets,which has been used in many *** this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and *** electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are *** typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and *** on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is *** solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.

关键词： polarization characteristic physical reproduction passive scattering element controllability mechanism radar feature simulation

Impacts of Dirty Data on Classification and Clustering Models:An Experimental Evaluation

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2021年第4期36卷 806-821页

作者： Zhi-xin Qi Hong-Zhi Wang An-jie Wang School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China

Data quality issues have attracted widespread attentions due to the negative impacts of dirty data on data mining and machine learning *** relationship between data quality and the accuracy of results could be applied on the selection of the appropriate model with the consideration of data quality and the determination of the data share to ***,rare research has focused on exploring such *** by this,this paper conducts an experimental comparison for the effects of missing,inconsistent,and conflicting data on classification and clustering *** the experimental results,we observe that dirty-data impacts are related to the error type,the error rate,and the data *** on the findings,we suggest users leverage our proposed metrics,sensibility and data quality inflection point,for model selection and data cleaning.

关键词： data quality classification clustering model selection data cleaning

A drag force formula for heterogeneous granular flow systems based on finite average statistical method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2021年第2期19卷 94-107页

作者： xin Li jie Ouyang Xiaodong Wang Panpan Chu School of Mathematics and Statistics Northwestern Polytechnical UniversityXi’an 710129China

The existing drag models are mostly based on the assumption of homogenous ***,the use of a homogeneous drag model to predict a heterogeneous granular flow system will cause a *** this study,we developed a drag force model based on the assumption of heterogeneous *** prevent weakening of the heterogeneous characteristics in the drag force formula,we propose a finite average statistical method to filter the information of the heterogeneous granular *** filtered information was used to fit the modified drag formula,which can reflect the heterogeneity of the granular cluster considering different configurations.A comparison shows that the new proposed drag formula filtered by the finite average statistical method fits well with energy minimization multi-scale simulation results.

关键词： Granular flow Drag force Heterogeneous Lattice Boltzmann method Finite average statistical method

Using BiLSTM with attention mechanism to automatically detect self-admitted technical debt

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2021年第4期15卷 49-60页

作者： Dongjin YU Lin WANG xin CHEN jie CHEN School of Computer Science and Technology Hangzhou Dianzi UniversityHangzhou 310018China

Technical debt is a metaphor for seeking short-term gains at expense of long-term code *** studies have shown that self-admitted technical debt,which is introduced intentionally,has strong negative impacts on software development and incurs high maintenance *** help developers identify self-admitted technical debt,researchers have proposed many state-of-the-art ***,there is still room for improvement about the effectiveness of the current methods,as self-admitted technical debt comments have the characteristics of length variability,low proportion and style ***,in this paper,we propose a novel approach based on the bidirectional long short-term memory(BiLSTM)networks with the attention mechanism to automatically detect self-admitted technical debt by leveraging source code *** BiLSTM,we utilize a balanced cross entropy loss function to overcome the class unbalance *** experimentally investigate the performance of our approach on a public dataset including 62,566 code comments from ten open source *** results show that our approach achieves 81.75%in terms of precision,72.24%in terms of recall and 75.86%in terms of F1-score on average and outperforms the state-of-the-art text mining-based method by 8.14%,5.49%and 6.64%,respectively.

关键词： technical debt self-admitted technical debt long short-term memory attention mechanism natural language processing

Thermodynamic analysis and kinetic optimization of high-energy batteries based on multi-electron reactions

在线全文

学校读者我要写书评

暂无评论

National Science Review 2020年第8期7卷 1367-1386页

作者： Yong-xin Huang Feng Wu Ren-jie Chen Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and Engineering Beijing Institute of Technology Advanced Technology Research Institute (Jinan) Beijing Institute of Technology Collaborative Innovation Center of Electric Vehicles in Beijing

Multi-electron reaction can be regarded as an effective way of building high-energy systems(>500 W h kg-1). However, some confusions hinder the development of multi-electron mechanisms, such as clear concept, complex reaction, material design and electrolyte optimization and full-cell ***, this review discusses the basic theories and application bottlenecks of multi-electron mechanisms from the view of thermodynamic and dynamic principles. In future, high-energy batteries,metal anodes and multi-electron cathodes are promising electrode materials with high theoretical capacity and high output voltage. While the primary issue for the multi-electron transfer process is sluggish kinetics,which may be caused by multiple ionic migration, large ionic radius, high reaction energy barrier, low electron conductivity, poor structural stability, etc., it is urgent that feasible and versatile modification methods are summarized and new inspiration proposed in order to break through kinetic ***, the remaining challenges and future research directions are revealed in detail, involving the search for high-energy systems, compatibility of full cells, cost control, etc.

关键词： multi-electron reactions thermodynamic kinetics high-energy density metal anodes

Contact vibration analysis of the functionally graded material coated half-space under a rigid spherical punch

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2022年第8期43卷 1187-1202页

作者： xin LYU Liaoliang KE Jiayong TIAN jie SU School of Mechanical Engineering Tianjin UniversityTianjin300350China National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing100085China

This paper studies the contact vibration problem of an elastic half-space coated with functionally graded materials(FGMs)subject to a rigid spherical punch.A static force superimposing a dynamic time-harmonic force acts on the rigid spherical ***,we give the static contact problem of FGMs by a least-square fitting ***,the dynamic contact pressure is solved by employing the perturbation ***,the dynamic contact stiffness with different dynamic contact displacement conditions is derived for the FGM coated *** effects of the gradient index,coating thickness,internal friction,and punch radius on the dynamic contact stiffness factor are discussed in detail.

关键词： contact vibration functionally graded material(FGM) spherical punch perturbation method

Numerical Study on the Unsteady Characteristics of the Propeller Cavitation in Uniform and Nonuniform Wake Flows

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第5期34卷 688-696页

作者： GONG Zhao-xin CHEN Ying LI jie CHEN xin LU Chuan-jing Key Laboratory of Hydrodynamics(Ministry of Education) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Propeller cavitation is a problematic issue because of its negative effects, such as performances losses, noise,vibration and erosion. Numerical methodology is an effective and efficient technical tool for the study of propeller cavitation, however, it is hard to capture tip-vortex cavitation in the previous work by using common turbulence models based on turbulent-viscosity hypothesis. In this work, the Reynolds-Averaged Naiver-Stokes(RANS)approach, adopting the Reynolds stress turbulence model(RSM), is taken to study the unsteady characteristics of the cavitation on the four-bladed INSEAN E779 A model propeller. The numerical simulation was carried out using the commercial CFD software ANSYS Fluent 14.0. One kind of uniform wake flow and two kinds of nonuniform wake flows are considered here. The results in the uniform flow show a good agreement with previous experimental results on both the sheet cavitation and the tip vortex cavitation and prove the ability of the RSM on capturing the tip vortex cavitation. Two kinds of nonuniform wake flows are designed based on the previous experimental researches and the unsteady characteristics of the propeller cavitation are analyzed by comparing the results in the uniform and two nonuniform wake flows together.

关键词： propeller cavitation wake flow Reynolds stress model

Research of stochastic weight strategy for extended particle swarm optimizer

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 122-124,134页

作者： XU Jun-jie YUE xin xin Zhan-hong Economics and Management College Anqing Teachers CollegeAnqing 246133 China School of Economics and Management Beijing University of Posts andTelecommunications Beijing 100876 China

To improve the performance of extended particle swarm optimizer, a novel means of stochastic weight deployment is proposed for the iterative equation of velocity updation. In this scheme, one of the weights is specified to a random number within the range of [0, 1] and the other two remain constant configurations. The simulations show that this weight strategy outperforms the previous deterministic approach with respect to success rate and convergence speed. The experiments also reveal that if the weight for global best neighbor is specified to a stochastic number, extended particle swarm optimizer achieves high and robust performance on the given multi-modal function.

关键词： particle swarm optimization evolutionary computation,stochastic weight function optimization