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Identification and spatial patterns of coastal water pollution sources based on GIS and chemometric approach

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Journal of Environmental Sciences 2007年第7期19卷 805-810页

作者： ZHOU Feng guo huai-cheng liu Yong HAO Ze-jia College of Environmental Sciences Peking University Beijing 100871 China.

Comprehensive and joint applications of GIS and chemometric approach were applied in identification and spatial patterns of coastal water pollution sources with a large data set （5 years （2000-2004）, 17 parameters） obtained through coastal water monitoring of Southern Water Control Zone in Hong Kong. According to cluster analysis the pollution degree was significantly different between September-next May （the 1st period） and June-August （the 2nd period）. Based on these results, four potential pollution sources, such as organic/eutrophication pollution, natural pollution, mineral/anthropic pollution and fecal pollution were identified by factor analysis/principal component analysis. Then the factor scores of each monitoring site were analyzed using inverse distance weighting method, and the results indicated degree of the influence by various potential pollution sources differed among the monitoring sites. This study indicated that hybrid approach was useful and effective for identification of coastal water pollution source and spatial patterns.

关键词： source identification spatial pattern cluster analysis (CA) principal component analysis (PCA) inverse distance weighting (IDW) Hong Kong

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

Optimization of investment casting process for K477 superalloy aero-engine turbine nozzle by simulation and experiment

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China Foundry 2022年第4期19卷 351-358页

作者： Xin Hao guo-huai liu Ye Wang Shi-ping Wu Zhao-dong Wang AECC South Industry Company Limited Zhuzhou 412002HunanChina State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

In order to reduce the shrinkage porosity of nickel-based superalloy castings in the investment casting process,the effects of different gating systems on mold filling,solidification process,and prediction of shrinkage porosity of aero-engine turbine nozzle castings were investigated by simulation and experimental *** show that the design of the vertical runner would cause greater turbulence of the melt in the riser during the mold filling process,and the outer runner is not *** the decrease in number of runners,the hot spot moves down towards the casting,and the shrinkage and porosity defects are formed in the casting below the *** the original designs,a certain tendency of shrinkage and porosity defect is found in the vanes,inner rings,and outer rings of the castings by both simulation prediction and ***,based on the processing optimization,the aero-engine turbine nozzle casting with no shrinkage and porosity defects is obtained.

关键词： nickel-based superalloy investment casting shrinkage porosity simulation optimization

FUZZY COMPREHENSIVE EVALUATION MODEL OF ECOLOGICAL DEMONSTRATION AREA

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Chinese Geographical Science 2005年第4期15卷 303-308页

作者： YU Ya-juan guo huai-cheng liu Yong WANG Shu-tong WANG Jin-feng College of Environmental Sciences Peking University Beijing 100871 P. R. China

Ecological demonstration area (EDA) is an authorized nomination, which should be assessed from several aspects, including ecological, social, environmental, economic ones and so on. It is difficult to advance an exact developing level index of EDA due to its indicator system’s complexity and disequilibrium. In this paper, a framework of indicators was set to evaluate, monitor and examine the comprehensive level of ecological demonstration area (EDA). Fuzzy logic method was used to develop the fuzzy comprehensive evaluation model (FCEM), which could quantitatively reveal the developing degree of EDA. Huiji District of Zhengzhou, Henan Province, one of the 9th group of national EDAs, was taken as a study case. The framework of FCEM for the integrated system included six subsystems, which were social, economic, ecological, rural, urban and accessorial description ones. The research would be valuable in the comprehensive quantitative evaluation of EDA and would work as a guide in the construction practices of Huiji ecological demonstration area.

关键词： fuzzy comprehensive evaluation model (FCEM) ecological demonstration area (EDA) fuzzy logic system dynamics Huiji District of Zhengzhou

Effect of competitive crystal growth on microstructural characteristics of directionally solidified nickel-based single crystal superalloy

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China Foundry 2022年第2期19卷 109-116页

作者： Mang Xu Xiao-qi Geng Xiang-long Zhang guo-huai liu Ye Wang Zhao-dong Wang Jing-jie guo State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Directionally solidified single crystal superalloy test bars were prepared by the spiral grain selection *** microstructural evolution and orientation characteristics of the starter block and spiral part were studied,and the influence of the competitive growth of crystals on the microstructural characteristics was *** results show that the divergent grain groups,with small size and randomly oriented grains,appear at the bottom of the start block due to the chilling effect,which is an important area for competitive *** the height of the starter block increases,the primary dendrite spacing increases,and the grain density decreases;furthermore,the proportion of grains with an orientation deflection angle less than 10°gradually ***texture gradually becomes stronger as the height of the starter block increases,which indicates that the competitive growth of crystals gradually *** the initial stage of the crystal selection in the spiral part,the obstacle of adjacent grains and spiral passage is the main working *** grains located at the inner side of the front edge of the spiral passage have the growth *** single crystal screening process is achieved at about two-thirds of the spiral height,and the single crystal with the orientation deviation angle of 6.7°from the casting axis is prepared.

关键词： directional solidification Ni-based superalloy microstructural evolution spiral grain selector single crystal

Hot Deformation Behavior and Microstructural Characteristics of Ti–46Al–8Nb Alloy

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Acta Metallurgica Sinica(English Letters) 2018年第9期31卷 933-944页

作者： Tian-Rui Li guo-huai liu Mang Xu Tian-Liang Fu Yong Tian Ra-Ja Devesh Kumar Misra Zhao-DongWang State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and BiomedicalEngineeringUniversity of Texas at E1 PasoE1 PasoTX 79968-0521USA

Hot deformation behavior, microstructural evolution and flow softening mechanism were investigated in Ti-46A1-8Nb alloy via isothermal compression approach. The true stress-strain curves exhibited typical work hardening and flow softening, in which the dependence of the peak stress on temperature and strain rate was obtained by hyperbolic sine equation with Zener-Hollomon （Z） parameter, and the activation energy was calculated to be 446.9 kJ/mol. The microstructural analysis shows that the alternate dark and light deformed ribbons of Al-rich and Nb-rich regions appeared and were associated with local flow involving solute segregation. The Al segregation promoted flow softening mainly arising from the recrystaUization of V phase with low stacking fault energy. The coarse recrystallized 7 and several massive phase were observed at grain boundaries. While in the case of Nb segregation, t/B2 phase harmonized bending of lamellae, combined with the growth of recrystallized γ grains and α ＋ β ＋ γ→α＋ γ transition under conditions of temperature and stress, leading to the breakdown of α2/γ lamellar colony. During the hot compression process, gliding and dissociation of dislocations occurred in γ phase that acted as the main softening mechanism, leading to extensive γ twins and cross twins in α/γ lamellae and at grain boundaries. In general, homogeneous microstructure during the hot defor- mation process can be obtained in TiAl alloy with high Nb addition and low Al segregation. The deformation substructures intrinsically promote the formability of Ti--46Al-8Nb alloy.

关键词： Titanium aluminides Deformation behavior Activation energy Dynamic recrystallization Local flow softening

Microstructure characteristics of Ti-43Al alloy during twin-roll strip casting and heat treatment

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Transactions of Nonferrous Metals Society of China 2019年第5期29卷 1017-1025页

作者： Mang XU guo-huai liu Tian-rui LI Bing-xing WANG Zhao-dong WANG State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

To shorten the fabrication process of difficult-to-form TiAl sheets, twin-roll strip casting and microstructural control were investigated in Ti-43Al alloy. A crack-free sheet with dimensions of 1000 mm × 110 mm × 2 mm was obtained. The microstructure of stip casting sheets and heat treatments was systematically studied. The macrostructure consisted of columnar crystals extending inward and centrally located equiaxed crystals with severe Al segregation were observed along the thickness direction, due to the symmetrical solidification process and decreasing cooling rates. The strip casting alloy was characterized by fine duplex microstructure with a grain spacing of 20-30 μm and a lamellar spacing of 10-20 nm. Furthermore, multiple microstructures of near gamma, nearly lamellar and fully lamellar were obtained through heat treatment process with significantly improved homogeneity of the microstructure.

关键词： strip casting TiAl alloy sheet fabrication microstructure characterization heat treatment

The complex effects of miR-146a in the pathogenesis of Alzheimer's disease

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Neural Regeneration Research 2025年第5期20卷 1309-1323页

作者： Yunfan Long Jiajia liu Yu Wang Haidong guo guohong Cui Department of Neurology Shanghai No.9 People’s HospitalShanghai Jiaotong University School of MedicineShanghaiChina Academy of Integrative Medicine Shanghai University of Traditional Chinese MedicineShanghaiChina School of Integrative Medicine Shanghai University of Traditional Chinese MedicineShanghaiChina Department of Neurology Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese MedicineShanghaiChina

Alzheimer's disease is a neurodegenerative disorder characterized by cognitive dysfunction and behavioral *** plaques formed through the extracellular deposition of amyloid-βproteins,as well as neurofibrillary tangles formed by the intracellular deposition of hyperphosphorylated tau proteins,comprise two typical pathological features of Alzheimer's *** symptomatic treatment,there are no effective therapies for delaying Alzheimer's disease ***(miR)are small,non-coding RNAs that negatively regulate gene expression at the transcriptional and translational levels and play important roles in multiple physiological and pathological ***,miR-146a,a NF-κB-regulated gene,has been extensively implicated in the development of Alzheimer's disease through several *** has demonstrated substantial dysregulation of miR-146a both during the initial phases and throughout the progression of this *** R-146a is believed to reduce amyloid-βdeposition and tau protein hyperphosphorylation through the TLR/IRAK1/TRAF6 pathway;however,there is also evidence supporting that it can promote these processes through many other pathways,thus exacerbating the pathological manifestations of Alzheimer's *** has been widely reported that miR-146a mediates synaptic dysfunction,mitochondrial dysfunction,and neuronal death by targeting m RNAs encoding synapticrelated proteins,mitochondrial-related proteins,and membrane proteins,as well as other *** the impact on glial cells,miR-146a also exhibits differential *** one hand,it causes widespread and sustained inflammation through certain pathways,while on the other hand,it can reverse the polarization of astrocytes and microglia,alleviate neuroinflammation,and promote oligodendrocyte progenitor cell differentiation,thus maintaining the normal function of the myelin sheath and exerting a protective effect on *** this review,we provide a

关键词： Alzheimer's disease amyloid-β glial cells microRNAs miR-146a neuroinflammatory

Effect of growth rate and diameter on microstructure and hardness of directionally solidified Ti-46Al-8Nb alloy

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Transactions of Nonferrous Metals Society of China 2014年第12期24卷 4044-4052页

作者：刘国怀李新中张元陈瑞润苏彦庆郭景杰傅恒志王昭东王国栋东北大学轧制技术与连轧自动化国家重点实验室沈阳110819 哈尔滨工业大学材料科学与工程学院哈尔滨150001

Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure （B2 phase,α2/γlamellar structure） respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies.

关键词： TiAl alloy directional solidification growth rate diameter phase transition