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Influence of Prior Austenite Deformation and Non-Metallic Inclusions on Ferrite Formation in Low-Carbon Steels

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Journal of Iron and Steel Research International 2010年第6期17卷 36-42页

作者： ZHANG chi XIA Zhi-xin YANG Zhi-gang LIU Zhi-hao Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

Effects of prior austenite deformation and non-metallic inclusions on the ferrite nucleation and grain refine- ment of two kinds of low-carbon steels have been studied. The ferrite nucleation on MnS and V（C, N） is observed. The combination of thermomeehanical processes with adequate amounts of non-metallic inclusions formed in low-car- bon steels could effectively refine the grain size and the microstructure. Ferrite nucleated on the single MnS or V（C, N） inclusions and complex MnS＋V（C,N） inclusion. The proper addition of elements S and V could effectively promote the formation of ferrite and further refinement of ferrite grains.

关键词： austenite deformation non-metallic inclusion ferrite nucleation low-carbon steel

Preparation of true solutions of monomeric amyloidogenic protein/peptide:A critical prerequisite for aggregation kinetic study

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Science china Chemistry 2012年第1期55卷 118-124页

作者： DIAO Shu ZHAO hong WANG WeiMao WU chi Department of Chemistry The Chinese University of Hong Kong Hong Kong China The Hefei National Laboratory of Physical Science at Microscale Department of Chemical physics The University of Science and Technology of China Hefei 230022 China

Our dynamic laser light scattering(LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution;namely,there always exist a trace amount of interchain aggregates,which greatly affect the association kinetics,partially explaining why different kinetics were reported even for a solution with identical protein and ***,using a combination of the conventional dissolution procedure and our newly developed ultra-filtration method,we have developed a novel protocol to prepare a true solution of amyloidogenic protein/peptide without any interchain *** resultant solutions remain in their monomeric state for at least one week,which is vitally important for further study of the very initial stage of the interchain association under the physiological conditions because more and more evidence suggests that it is those small oligomers rather than large fabric aggregates that are *** addition,this study shows that combining static and dynamic LLS can lead to more physical and microscopic information about the protein association instead of only the size distribution.

关键词： amyloidogenic protein/peptide laser light scattering monomer ultra-filtration

Mechanical properties and thermal deformation behavior of low-cost titanium matrix composites prepared by a structure-optimized Y_(2)O_(3) crucible

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Journal of Iron and Steel Research International 2024年第3期31卷 738-751页

作者： Qian Dang gang Huang Ye Wang chi Zhang Guo-huai Liu Zhao-dong Wang The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150004HeilongjiangChina School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870LiaoningChina

A porous yttrium oxide crucible with both thermal shock resistance and erosion resistance was developed by structural *** structure-optimized yttrium oxide crucible was proved to be suitable for melting highly reactive titanium ***-cost(TiB+Y2O_(3))-reinforced titanium matrix composites were prepared by vacuum induction melting using the prepared *** thermal deformation behavior and microstructure evolution of(TiB+Y2O_(3))-reinforced tita-nium matrix composites were investigated at deformation temperatures of 900-1100℃with strain rates of 0.001-1 *** results showed that the prepared yttrium oxide crucible had both thermal shock and erosion resistance,the low-cost titanium matrix composites could be prepared by the developed yttrium oxide crucibles which were homogeneous in composition and highly sensitive to strain rate and deformation temperature,and the peak and theological stresses decreased with increasing deformation temperature or decreasing strain *** addition,the average thermal deformation activation energy of the composites was calculated to be 574.6 kJ/mol by establishing the Arrhenius constitutive equation in consideration of the strain variables,and the fitting goodness between the predicted stress value and the measured value was 97.624%.The calculated analysis of the hot processing map showed that the best stable thermal deformation zone was located in the deformation temperature range of 1000-1100℃and strain rate range of 0.001-0.01 s^(-1),where the peak dissipation coefficient wasη=71%.In this zone,the deformation of the reinforcement and matrix was harmonious,the reinforcement was less likely to fracture,dynamic recrystallization occurred more fully and the alloy exhibited near steady rheological characteristics.

关键词： Yttrium oxide crucible Titanium matrix composite Thermal deformation behavior Constitutive equation Hot processing map Microstructure evolution

A chiral Phosphorous Derivatizing Agent for the Determination of the Enantiomeric Excess of chiral Alcohols, Amines by ^(31)P NMR

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chinese Chemical Letters 2001年第10期12卷 907-908页

作者： Kang Ying LI Zheng hong ZHOU chi Hung YEUNG Chu chi TANG State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071 Laboratory of chiral Technology and Department of Applied Biology and Chemical Technology The Hong Kong Polytcchnic UniversityHong Kong

A chiral phosphorous derivatizing agent prepared from PCl3 and (S)-BINOL was described. It is used to determine the enantiomeric excess of chiral alcohols and amines by 31P NMR.

关键词： chiral phosphorous derivation chiral alcohols chiral amines enantiomeric excess asymmetric induction.

A Simulation Model for Component Commonality

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Systems Science and Systems Engineering 2002年第4期11卷 479-493页

作者： ZHUXiao-chi ZHANGZi-gang School of Information Management Wuhan UniveristyWuhan 430074China College of Management Huazhong University of Science and TechnologyWuhan 430074China

Component commonality has been cited as a powerful approach for manufacturers to cope with increased component proliferation and to control inventory costs. To fully realize its potential benefits, one needs a clear understanding of its impacts on the system. In this paper, the feasibility of using a simulation model to provide a systematic perspective for manufacturing firms to implement a commonality strategy is demonstrated. Alternative commonality strategies including the stage of employing commonality and the allocation policies are simulated. Several interesting results on effects of commonality, allocation policies, and optimal solutions are obtained. We then summarize qualitative insights and managerial implications into the component commonality design and implementation, and inventory management in a general multi-stage assembly system.

关键词： component commonality simulation allocation policy multi-stage assembly systems

Defect detection method based on 2D entropy image segmentation

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china Welding 2020年第1期29卷 45-49页

作者： chi Dazhao gang Tie State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

In order to improve the work efficiency of non-destructive testing(NDT)and the reliability of NDT results,an automatic method to detect defects in the ultrasonic image was *** to the characterization of ultrasonic D-scan image,clutter wave suppression and de-noising were presented ***,the image is processed by binaryzation using KSW 2 D entropy based on image segmentation *** results showed that,the global threshold based segmentation method was somewhat ineffective for D-scan image because of ***,when the image is big in size,small targets which are composed by a small amount of pixels are often ***,local threshold based image segmentation method is effective in recognizing small defects because it takes local image character into account.

关键词： ultrasonic testing defect detection 2D entropy image segmentation

Feature Extraction of Sectorial Scan Image of Thick-Walled Electron Beam Welding Seam Based on Principal Component Analysis

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Journal of Harbin Institute of Technology(New Series) 2017年第6期24卷 45-51页

作者： Tie gang Yilin Luan chi Zhang State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology School of Materials Science and Engineering Heilongjiang University of Science and Technology

A feature extraction method was proposed to sectorial scan image of Ti-6Al-4V electron beam welding seam based on principal component analysis to solve problem of high-dimensional data resulting in timeconsuming in defect recognition. Seven features were extracted from the image and represented 87. 3% information of the original data. Both the extracted features and the original data were used to train support vector machine model to assess the feature extraction performance in two aspects: recognition accuracy and training time. The results show that using the extracted features the recognition accuracy of pore,crack,lack of fusion and lack of penetration are 93%,90.7%,94.7% and 89.3%,respectively,which is slightly higher than those using the original data. The training time of the models using the extracted features is extremely reduced comparing with those using the original data.

关键词： electron beam welding phased array ultrasonic sectorial scan image feature extraction principal component analysis

A comparison of approaches in fitting continuum SEDs

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Research in Astronomy and Astrophysics 2013年第4期13卷 420-434页

作者： Yao Liu David Madlener Sebastian Wolf hong-chi Wang Purple Mountain Observatory and Key Laboratory for Radio Astronomy Chinese Academy of Sciences Graduate University of chinese Academy of Sciences Institut fr Theoretische Physik und Astrophysik Universitt zu Kiel

We present a detailed comparison of two approaches, the use of a precalculated database and simulated annealing （SA）, for fitting the continuum spectral energy distribution （SED） of astrophysical objects whose appearance is dominated by surrounding dust. While pre-calculated databases are commonly used to model SED data, only a few studies to date employed SA due to its unclear accuracy and convergence time for this specific problem. From a methodological point of view, different approaches lead to different fitting quality, demand on computational resources and calculation time. We compare the fitting quality and computational costs of these two approaches for the task of SED fitting to provide a guide to the practitioner to find a compromise between desired accuracy and available resources. To reduce uncertainties inherent to real datasets, we introduce a reference model resembling a typical circumstellar system with 10 free parameters. We derive the SED of the reference model with our code MC3 D at 78 logarithmically distributed wavelengths in the range [0.3 μm, 1.3 mini and use this setup to simulate SEDs for the database and SA. Our result directly demonstrates the applicability of SA in the field of SED modeling, since the algorithm regularly finds better solutions to the optimization problem than a precalculated database. As both methods have advantages and shortcomings, a hybrid approach is preferable. While the database provides an approximate fit and overall probability distributions for all parameters deduced using Bayesian analysis, SA can be used to improve upon the results returned by the model grid.

关键词： methods numerical - radiative transfer - protoplanetary disks

Radiative transfer modeling of three T Tauri stars: selecting candidates for studying circumstellar disk evolution

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Research in Astronomy and Astrophysics 2013年第7期13卷 841-848页

作者： Yao Liu hong-chi Wang Sebastian Wolf David Madlener Purple Mountain Observatory&Key Laboratory for Radio Astronomy Chinese Academy of Sciences Graduate University of chinese Academy of Sciences Institut für Theoretische Physik und Astrophysik Universitt zu Kiel

We present modeling work on three young stellar objects that are promis-ing targets for future high-resolution observations to investigate circumstellar disk evolution. The currently available data comprise the spectral energy distribution from optical to millimeter wavelengths which allow constraining the structure of the cir-cumstellar disk using self-consistent radiative transfer models. The results suggest that the assumption of well-mixed dust and gas leads to overestimation of flux in the far-infrared. Observational and theoretical arguments suggest that an overall decrease in far-infrared excess can be explained by dust settling towards the midplane. A new disk model is hence employed to take the effect of dust sedimentation into account. The extended model satisfactorily reproduces all existing observations. The three tar-gets studied here therefore deserve follow-up observations to reveal the evolutionary state of their protoplanetary disks.

关键词： circumstellar matter - planetary systems: protoplanetary disks - ra-diative transfer