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Analysis of precipitation behavior of MnS in sulfur-bearing steel system with finite-difference segregation model

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Journal of Iron and Steel Research International 2018年第8期25卷 803-812页

作者： De-lin Hu Hui Liu jian-bo Xie Juan cheng jian Li jian-xun Fu State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy and School of Materials Science and Engineering Shanghai University Shanghai 200444 China

To further reveal the influence of micro-segregation on the precipitation behavior of MnS in sulfur-bearing steel system, a coupled model of micro-segregation and MnS precipitation was established by the finite-difference method based on various calculation domains and the solid diffusion degrees, and a new controlled diffusion equation with more stable convergence was also used. 49MnVS3 and 1215 steels were used to analyze the influence of calculation domain, segregation model and S content on the precipitation behavior of MnS. The calculation results were verified by a high- temperature confocal laser scanning microscope （HT-CLSM）. The results show that the domain has little effect on the precipitation temperature, precipitation solid fraction and precipitation amount of MnS, but affects the precipitation location and segregation of the solutes. For low- and medium-sulfur steels, the temperatures calculated by the diffusion control growth （DCG） model and the Lever model were nearly identical, whereas the temperature calculated by the Scheil model was lower. However, for high-sulfur steels, the precipitation temperatures calculated by three segregation models were nearly same. The precipitation solid fraction is more reasonable to describe the precipitation behavior of MnS. The precipitation behavior of MnS, observed by the HT-CLSM, matches well with that in the DCG model.

关键词： MnS precipitation Micro-segregation Mathematical model Solidification In situ observation

Internet QoS: Architectures, Strategies and Mechanisms

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High Technology Letters 2001年第1期7卷 13-21页

作者：隆克平 cheng Shiduan Ma jian National Laboratory of Switching Technology Telecommunication Networks Beiji ng University of Posts and Telecommunications Nokia China RD Center Nokia House 1

As an extensive study of Internet QoS, a framework for emerging Internet QoS strategies is presented. Integrated service (Intserv/RSVP), Differentiated service (Diffserv), MPLS, and QoS routing, are overviewed. The key issues and relationship of these QoS architectures are discussed. Some algorithms in IP QoS implementation and unsolved problems are also studied in this paper. Furthermore, a new strategies of incorporating Intserv with Diffserv to archive end-to-end QoS is proposed. It is also discussed why MPLS and QoS routing are introduced into this framework, how they differ from and relate to other schemes and where they fit into the Diffserv architecture. The timescales of different QoS strategies are also studied and some proposals for QoS routing deployment are given.

关键词： Internet QoS IntServ/RSVP DiffServ MPLS QoS routing

Preparation and Characterization of Mesophase Pitch via Co-Carbonization of Waste Polyethylene/Petroleum Pitch

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Journal of Materials Science & Technology 2015年第8期31卷 857-863页

作者： Youliang cheng Lu Yang Tao Luo Changqing Fang jian Su jian Hui School of Printing and Packaging Engineering Xi'an University of Technology Petrochina Liaoyang Petrochemical Company China National Petroleum Corporation

The low-cost petroleum pitch and waste polyethylene （WPE） were used as raw materials to prepare the mesophase pitch by co-carbonization method and the forming mechanization of mesophase pitch was also investigated. Polarized microscopy, softening point, Fourier transform infrared spectroscopy （FTIR） and thermogravimetric analysis （TGA） were used to characterize and analyze the properties and struc- ture of the mesophase pitch. The results showed that the carbonization yield of the modified pitch was high when 1-2 wt% WPE was added and the property of mesophase pitch （MP1-450-4 and MP2-450-4） prepared by thermal polymerization was excellent. Moreover, when the treatment temperature was above 420 ~C, the mesophase development of the modified pitch may be entire and 100% streamline texture mesophase can form. During the co-carbonization of WPEJpetroleum pitch, a large number of naphthenic structures and methylene bridges may be generated, which can improve the properties of the obtained mesophase pitch.

关键词： Polarized light microscopy Microstructure Property Thermogravimetric analysis (TGA) Formation mechanism

A New Inverse Method of Elastic Constants for a Fibre-Reinforced Composite Plate from Laser-Based Ultrasonic Lamb Waves

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Chinese Physics Letters 2001年第12期18卷 1620-1623页

作者： YANG Jing cheng jian-Chun State Key Laboratory of Modern Acoustics Nanjing UniversityNanjing 210093

A new inverse method based on the wavelet transform and artificial neural networks (ANN) is presented to recover elastic constants of a fibre-reinforced composite plate from laser-based ultrasonic Lamb waves. The transient waveforms obtained by numerical simulations under different elastic constants are taken as the input of the ANN for training and learning. The wavelet transform is employed for extracting the eigenvectors from the raw Lamb wave signals so as to simplify the structure of the ANN. Then these eigenvectors are input to a multi-layer internally recurrent neural network with a back-propagation algorithm. Finally, the experimental waveforms are used as the input in the whole system to inverse elastic constants of the experimental material.

关键词： material constants inverse

Supervised Penalty Matrix Decomposition for Tumor Differentially Expressed Genes Selection

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Chinese Journal of Electronics 2018年第4期27卷 845-851页

作者： LIU jian cheng Yuhu WANG Xuesong CUI Xiaoluo School of Information and Control Engineering China University of Mining and Technology Department of Information Engineering Weihai Ocean Vocational College

A reliable and precise recognition of the differentially expressed genes of tumor is crucial to treat the cancer effectively. The small number of differentially expressed genes in a huge gene expression dataset determines the important role of sparse methods, such as Penalty matrix decomposition(PMD), among the feature selection methods. The sparse methods always have the drawback: they do not take advantage of known class labels of gene expression data. A novel supervised-sparse method named as Supervised PMD(SPMD) is proposed by adding the class information into PMD via the total scatter matrix. The brief idea of our method used to select the differentially expressed genes is given as *** total scatter matrix is obtained according to the gene expression data with class label. The obtained total scatter matrix is decomposed by PMD to acquire the sparse vectors. The non-zero items in sparse vectors are selected as the differentially expressed genes. The Gene ontology(GO) enrichment of functional annotation of the selected genes is detected by Topp Fun. Experiments on synthetic data and two real tumor gene expression datasets show that the proposed SPMD is quite promising to select the differentially expressed genes.

关键词： Tumor gene expression data Differentially expressed genes Supervised methods Scatter matrix Penalized matrix decomposition(PMD)

A Cost-Efficient Approach to Storing Users'Data for Online Social Networks

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Journal of Computer Science & Technology 2019年第1期34卷 234-252页

作者： Jing-Ya Zhou jian-Xi Fan cheng-Kuan Lin Bao-Lei cheng School of Computer Science and Technology Soochow UniversitySuzhou 215006China Provzncial Key Laboratory for Computer Information Processing Technology Soochow UniversitySuzhou 215006China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing University Nanjing 210023China

As users increasingly befriend others and interact online via their social media accounts,online social networks (OSNs)are expanding *** with the big data generated by users,it is imperative that data storage be distributed,scalable,and *** one of the most significant challenges about this topic is determining how to minimize the cost without deteriorating system *** many storage systems use the distributed key value store,it cannot be directly applied to OSN storage *** because users'data are highly correlated,hash storage leads to frequent inter-server communications,and the high inter-server traffic costs decrease the OSN storage system's scalability. Previous studies proposed conducting network partitioning and data replication based on social ***,data replication increases storage costs and impacts traffic ***,we consider how to minimize costs from the perspective of data storage,by combining partitioning and *** cost-efficient data storage approach supports scalable OSN storage *** proposed approach co-locates frequently interactive users together by conducting partitioning and replication simultaneously while meeting load-balancing *** experiments are undertaken on two real- world traces,and the results show that our approach achieves lower cost compared with state-of-the-art *** we conclude that our approach enables economic and scalable OSN data storage.

关键词： online social network inter-server traffic cost storage cost network partitioning data replication

Optimal Replacement Policy for Cold Standby System

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 316-322页

作者： TAN Lin YANG jian cheng Zhijun GUO Bo College of Humanities and Social Sciences National University of Defense Technology Changsha 410073 China Guilin Airforce Academy Guilin 541003 China College of Information System andManagement National University of Defense Technology Changsha 410073 China

Investigators are attracted by the complexity and significance of preventive maintenance problem,and there are hundreds of maintenance models and methods to solve the maintenance problems of companies and army,going with a lot of investigative harvests. However,one-component system or series system is focused by most of the *** problem of preventive maintenance（PM） on cold standby repairable system does not attach importance despite the fact that the cold standby repairable system is ubiquitous in engineering *** this paper,an optimal replacement model for gamma deteriorating system is *** methodology presented uses a gamma distribution to model the material degradation,and the impact of imperfect maintenance actions on system reliability is *** an imperfect maintenance action,the state of a degrading system is assumed as a random variable and the maintenance time follows a geometric process.A maintenance policy（N）is applied by which the system will be repaired whenever it experiences the Nth PM,and an optimal policy（N~＊） could be determined numerically or analytically for minimizing the long-run average cost per unit time.A numerical example about how to confirm the optimal maintenance time by the inspecting information of liquid coupling device is given to demonstrate the use of this *** paper presents a condition-based replacement policy for cold standby repairable system under continuous *** contribution embody in two aspects,relaxing the restrictions of hypothesis and investigating the condition-based maintenance policy of the cold standby repairable system which is ignored by others.

关键词： cold standby system maintenance policy gamma process geometrical process imperfect maintenance

Influence of N/C ratio on microstructure and properties of new highstrength weathering steels

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Journal of Iron and Steel Research International 2019年第1期26卷 84-90页

作者： jian cheng Yue-hua Guo Hou-fa Shen The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Advanced Materials Processing Technology School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Pangang Group Research Institute Co. Ltd.State Key Laboratory of Vanadium and Titanium Comprehensive UtilizationPanzhihua 617000SichuanChina

Influence of the N/C ratio on the microstructure and properties of new-generation high-strength weathering steels was investigated using calculation of phase diagram(CALPHAD)and *** microstructures of weathering steels containing different N/C ratios were predicted by a CALPHAD approach,and only three phases were predicted in these steels within the rolling temperature range of 850-1050℃.The precipitation fraction of VN/V(C,N)in creases with increasing N/C *** of the four tested steels were all experimentally determined to contain bainite,ferrite,and VN precipitates after air cooling to room *** bainite fraction increases with in creasing N/C ratio,and it is 85%in the steel containing 0.038% N and 0.032% C,The results of the tensile tests and impact tests demonstrated that the yield strength and tensile strength of the steel containing 0.038%N and 0.032%C are greater than 550 and 650 MPa,respectively,and the elongation is greater than 24%,which satisfies the design objectives for mechanical *** impact toughness values of the four steels at 0,-20,and-40℃ are all greater than 24 *** increasing N/C ratio,the bainite fraction and the precipitation fraction of VN/V(C,N)increase,resulting in increasing yield strength and tensile strength.

关键词： CALPHAD Weathering steel Tensile test-Impact test Microstructure

Time-domain solution for transient dynamic response of a large-diameter thin-walled pipe pile

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 239-251页

作者： Ding Xuanming Liu Hanlong Chu jian cheng Ke Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University) Ministry of Education Department of Civil Construction & Environmental Engineering Iowa State University 328 Town Engineering Building School of Mechanical and Power Engineering Nanjing University of Technology

The propagation of stress waves in a large-diameter pipe pile for low strain dynamic testing cannot be explained properly by traditional 1D wave theories. A new computational model is established to obtain a wave equation that can describe the dynamic response of a large-diameter thin-walled pipe pile to a transient point load during a low strain integrity test. An analytical solution in the time domain is deduced using the separation of variables and variation of constant methods. The validity of this new solution is verifi ed by an existing analytical solution under free boundary conditions. The results of this time domain solution are also compared with the results of a frequency domain solution and fi eld test data. The comparisons indicate that the new solution agrees well with the results of previous solutions. Parametric studies using the new solution with reference to a case study are also carried out. The results show that the mode number affects the accuracy of the dynamic response. A mode number greater than 10 is required to enable the calculated dynamic responses to be independent of the mode number. The dynamic response is also greatly affected by soil properties. The larger the side resistance, the smaller the displacement response and the smaller the refl ected velocity wave crest. The displacement increases as the stress waves propagate along the pile when the pile shaft is free. The incident waves of displacement and velocity responses of the pile are not the same among different points in the circumferential direction on the pile top. However, the arrival time and peak value of the pile tip refl ected waves are almost the same among different points on the pile top.

关键词： pipe pile transient load analytical solution time