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Effect of surface nanocrystallization on the corrosion behavior of Zircaloy-4

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Science china(Technological Sciences) 2009年第8期52卷 2227-2231页

作者： ZHU YuTao1,2 & ZHANG XiYan1,2,3 1 College of Materials Science and engineering, Chongqing university, Chongqing 4.004., china 2 National engineering {4. center for Magnesium Alloys, Chongqing university, Chongqing 4.004., china 3 School of Physical Science and engineering Technology, Guangxi university, Nanning 530004. china 1. College of Materials Science and engineering Chongqing University Chongqing 400045 China 2. National engineering research center for Magnesium Alloys Chongqing University Chongqing 400044 China 3. School of Physical Science and engineering Technology Guangxi University Nanning 530004 China

The contrastive corrosion experiments between surface nanocrystallined Zircaloy-4.and coarse-grained Zircaloy-4.under the condition of 673 K/10.3 MPa in pure water are carried out, and the microstructure of oxide films has been studied. The results indicate that the growth rate of oxide films formed on the nanocrystalline Zircaloy-4.is lower than that of oxide films formed on the coarse-grained Zircaloy-4. Simultaneously, the oxide/metal interface of the former is more regular and glossy than that of the latter. For nanocrystalline Zircaloy-4. the low oxygen diffusion rate through the oxide/metal interface can hinder the reaction of oxygen ion with metal ion. Furthermore, more tetragonal ZrO2 are observed in the oxide films, which can delay the martensite phase transition from tetragonal to monoclinic phase in oxide films.

关键词： nanocrystalline Zircaloy oxide film microstructure

The impact of vegetation restoration on erosion-induced sediment yield in the middle Yellow River and management prospect

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Science china Earth Sciences 2005年第6期48卷 724-741页

作者： CHEN Hao1, ZHOU Jinxing2, CAI Qiangguo1, YUE Zhongqi3, LU Zhongchen4. LIANG Guanglin1& HUANG Jianguo5 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Re-search, Chinese Academy of Sciences, Beijing 100101, china 2. Institute of Forestry, Chinese Academy of Forestry Sciences, Beijing 100091, china 3. Department of Civil engineering, university of Hong Kong, Hong Kong, china 4. Eco-environmental research center, Chinese Academy of Sciences, Beijing 100085, china 5. College of Resources and Environment, Southwest Agricultural university, Chongqing 4.0716, china Correspondence should be addressed to Chen Hao 1. Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. Institute of Forestry Chinese Academy of Forestry Sciences 100091 Beijing China 3. Department of Civil engineering University of Hong Kong Hong Kong China 4. Eco-environmental research center Chinese Academy of Sciences 100085 Beijing China 5. College of Resources and Environment Southwest Agricultural University 400716 Chongqing China

According to the characteristics of water and erosion environments of different natural zones on the Loess Plateau, this paper studies changes of vegetation types, distribution boundaries of forest and grass as well as restoration capacity of vegetation in different natural zones in the middle Yellow River. The annual precipitation of 530 mm is the critical annual pre-cipitation for forest and grass distribution in the middle Yellow River. Among the zonal and azonal environmental factors affecting watershed sediment yield, the intermediate diameter D50 (mm) of suspended load and forest coverage (V, %) play the leading role. Of them the effect weight of forest coverage (V, %) on catchments sediment yield is only 3.4. less than the role of the intermediate diameter (D50, mm), they are almost the same. To effectively control soil erosion in semiarid, especially in hilly-gullied areas and make sediment transport modulus reduce to less than 6000 t/km2, it is rather difficult by merely relying on natural restoration of forest. In the process of cultivated land conversion into forest land and grassland, measures suiting local conditions should be adopted in tree species selection and artificial afforestation (grass planting) based on management with biological measures for slopeland and engineering measures for hilly-gullied areas, so that watershed forest coverage in key counties can reach at least over 30%.Compared with the standard period of precipitation prior to the 1960s, with the decrease of an-nual precipitation at various periods, plant productivities decline to different degrees under natural conditions. The main reason accountable for the low survival rate of new seedlings and grass over years is due to precipitation decrease. In light with regression models of annual pre-cipitation and natural vegetation productivities, it is possible to obtain estimated values of wa-tershed natural vegetation productivity and eco-water consumption needed for the restoration to

关键词： vegetation restoration, eco-water requirement, watershed sediment yield, the middle Yellow River.

Study on NDVI-T_s space by combining LAI and evapotranspiration

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Science china Earth Sciences 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2,3, WANG Pengxin4. YANG Hua1,2,3, LIU Shaomin1,2,3 & WANG Jindi1,2,3 1. research center for Remote Sensing and GIS, School of Geography, Beijing Normal university, Beijing 100875, china 2. State Key Laboratory of Remote Sensing Science, Beijing 100875, china 3. Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing 100875, china 4. Department of Information Management, College of Information and Electronic engineering, china Agricultural university, Beijing 100083, china 1. research center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing 100875 China 2. State Key Laboratory of Remote Sensing Science Beijing 100875 China 3. Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing 100875 China 4. Department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing 100083 China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

Tanshinone prevents cancellous bone loss induced by ovariectomy in rats

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Acta Pharmacologica Sinica 2004年第05期25卷 136-142页

作者： Liao CUI2,3, Tie WU3, Yu-yu LIU3, Yi-feng DENG4. Chun-mei AI4. Huai-qing CHEN22Institue of biomedical engineering, West china Medical center, Sichuan {4., Chengdu 61004., china 3Department of Pharmacology, 4.uangdong Key Laboratory for research and Development of Natural Drugs,Guangdong Medical College, Zhanjiang 524.23 china Institue of biomedical engineering West China Medical Center Sichuan University Department of Pharmacology Guangdong Key Laboratory for Research and Development of Natural Drugs Guangdong Medical College

AIM: To investigate the skeletal effects of total tanshinone in ovariectomized rats by analyzing cancellous bonehistomorphometry of fourth lumbar vertebrae (LV4. and proximal tibial metaphyses (PTM). METHODS: Four-month-old Sprague-Dawley female rats were sham-operated and treated with vehicle or ovariectomized and treatedwith either vehicle, total tanshinone (200 mgkg-1d-1, equivalent to 35 gkg-1d-1 of tanshinone II A and 16 mgkg -1d-1 ofcryptotanshinone), or 17a-ethynylestradiol (30 gkg-1d-1 as positive treatment group) starting one day post-sur-gery for 10 weeks. Double in vivo fluorochrome labeling was administered to all rats. The undecalcified longitu-dinal LV4.and PTM sections were cut and stained with Goldners Trichrome (4.m thickness) or unstained (8-mthickness) for the bone histomorphometric analysis. RESULTS: A significant decrease in trabecular bone volume(BV/TV) and trabecular number (Tb.N) and a significant increase in osteoclast surface (OCS/BS) and mineralizingsurface (MS/BS) were found in both LV and PTM of vehicle-treated OVX rats compared with sham *** completely prevented the decreases in BV/TV and Tb.N and the increase in OCS/BS in the LV4. andpartially prevented the decreases in BV/TV and Tb.N in the PTM of OVX rats. In addition, tanshinone increasedtrabecular thickness (***) whereas it did not alter MS/BS. Moreover, tanshinone had no effect on uterine weightand body weight of OVX rats. Estrogen treatment increased BV/TV and Tb.N and decreased OCS/BS, but, alsomarkedly decreased MS/BS and increased uterine weight in OVX rats. CONCLUSION: The current study demon-strated that the adequate supply of tanshinone prevented OVX-induced cancellous bone loss in rats through inhibi-tion of elevated bone resorption.

关键词： tanshinone cryptotanshinone 2-fluoro-17alpha-ethynylestradiol ovariectomy bone and bones osteoclasts osteoporosis histocytochemistry morphology

STUDY ON SELECTIVE DISSOLUTION OF GOLD IN ALKALINE THIOUREA MEDIA

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Journal of Central South university 1997年第2期9卷 79-83页

作者： Chai Liyuan Zhong Haiyun Zhang Chuanfu (Department of Nonferrous Metallurgy, Central South university of Technology, changsha 4.0083, china)Masazumi kido Ryouichi Ichino(center for Integrated {4.in Science and engineering Nagoya university,Nagoya 4 Department of Nonferrous Metallurgy Central South University of Technology Changsha 410083 China center for Integrated research in Science and engineering Nagoya University Nagoya 464 Japan

Gold dissolves easily in an alkaline thiourea solution with Na2SO3 and Na2S2O8, where the accompanied elements of Au, such as Ag, Cu, Ni and Fe can hardly dissolve. It was considered that electrochemical reduction and catalytic action of SO32- prevent thiourea from decomposing irreversibly and accelerates dissolution of *** S2O82- as an oxidant can control the potential so that formamidine disulfide may form efficiently. The dissolution of gold is mainly through oxidation of Au by formamidine disulfide and complexation of thiourea with An+,and not direct oxidation of S2O82-. Thus,sufficient formamidine disulfide is necessary to accelerate the dissolution of gold. The reason for Ag, Cu hardly being dissoluble is that the black layers of Ag2S and Cu1.92S form on the surface of Ag and Cu. The metal Ni and Fe do not dissolve in the alkaline media due to their sulfide films passivation samely.

关键词： mechanism selective dissolution of gold alkaline thiourea electrochemical reduction and catalytic action formamidine disulfide mix potential

Modified vegetation-erosion dynamics model and its application in typical watersheds in the Loess Plateau

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International Journal of Sediment research 2011年第01期26卷 78-86页

作者： CHEN Yuehong~1,WANG Feixin~2,LIU Guangquan~3,YU Xinxiao~4. JIA Guodong~5,and GAN Ping~6 china Institute of Water Resources and Hydropower research,Beijing 10004. International research and Training center on Erosion and Sediment research,Beijing 10004.,china Beijing Forestry university,Beijing 100083,china. Key Lab of Dredging Technology of CCGRP,Shanghai Waterway engineering Design and Consulting Co., Ltd,Shanghai 200120,china. International research and Training center on Erosion and Sedimentation china Institute of Water Resources and Hydropower research,Beijing 10004. Northwest A&F university,Yangling 712100,china, Beijing Forestry university,Beijing 100083,china, Beijing Forestry university,Beijing 100083,china. china Institute of Water Resources and Hydropower research,Beijing 10004.,and International research and Training center on Erosion and Sediment research,Beijing 10004.,china [a] Assoc. Prof. Dr. china Institute of Water Resources and Hydropower research Beijing 10004. International research and Training center on Erosion and Sediment research Beijing 10004. china Beijing Forestry university Beijing 100083 china [b] Dr. Key Lab of Dredging Technology of CCGRP Shanghai Waterway engineering Design and Consulting Co. Ltd Shanghai 200120 china [c] Prof. Dr. International research and Training center on Erosion and Sedimentation china Institute of Water Resources and Hydropower research Beijing 10004. Northwest A&F university Yangling 712100 china [d] Prof. Dr. Beijing Forestry university Beijing 100083 china [e] Dr. Beijing Forestry university Beijing 100083 china [f] Engineer china Institute of Water Resources and Hydropower research Beijing 10004. and International research and Training center on Erosion and Sediment research Beijing 10004. china

The vegetation-erosion model was applied in three typical watersheds of hilly and gully area in the Loess Plateau in northwestern china to study the dynamic relations between vegetation coverage and soil erosion rate and various *** model was improved by introducing rainfall and runoff *** the modified model was applied in the Luergou and Luoyugou *** calculation results with the modified model were compared with the results of the original *** precisions of simulated vegetation coverage and soil erosion rate with the modified model were greatly improved compared with the original *** erosion rate reduced with increasing vegetation coverage and the human disturbance caused high soil erosion.

关键词： Soil erosion Vegetation coverage Vegetation-erosion dynamics model Loess Plateau Modified model

Torque model of hydro turbine with inner energy loss characteristics

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Science china(Technological Sciences) 2010年第10期53卷 2826-2832页

作者： ZENG Yun1,2, GUO YaKun2, ZHANG LiXiang1, XU TianMao3 & DONG HongKui4.1 Construction engineering College, Kunming university of Science and Technology, Kunming 650051, china 2 School of engineering, university of Aberdeen, Aberdeen AB24.3UE, UK 3 Computing center, Kunming university of Science and Technology, Kunming 650051, china 4.Hydraulic Energy Department, Yunnan Electric Power Test and research Institute, Kunming 650217, china 1. Construction engineering College Kunming University of Science and Technology Kunming 650051 China2. School of Engineering University of Aberdeen Aberdeen AB24 3UE UK3. Computing Center Kunming University of Science and Technology Kunming 650051 China4. Hydraulic Energy Department Yunnan Electric Power Test and Research Institute Kunming 650217 China

This paper presents the result and analysis of the composition of energy loss occurring in the hydro turbine. Two new types of energy losses,namely the hydraulic loss in the flow channel and the impact loss,are defined. All losses within the hydro turbine are divided into four types and the loss coefficients are defined accordingly. Expressions or characteristic descriptions of these losses as well as the calibration method of the loss coefficients are presented. Furthermore,the torque model of the hydro turbine where the inner energy loss takes place is established. The developed model has been used to calculate the power loss due to the mechanical friction generated by the units’ rotation to solve the difficulty of measurements of the mechanical friction loss in the hydro turbine. The definition of the impact loss explains the phenomenon that the loss of no-load is greater than that of the rated operation. A set of conversion coefficients are defined using the characteristic parameters at the rated operation,which are used to transform the parameters in the torque model into those that are easily measured. Therefore,the expression of the hydro turbine power is converted into a function that has the main servomotor displacement as its single variable. This makes the proposed model be convenient to use. Finally,the proposed model and methods are calibrated and verified using the measured data of a hydropower plant. Good agreement between the modeled results and the measurements indicates that the proposed model can represent the inner energy loss characteristics of the hydro turbine.

关键词： hydraulic loss in flow channel impact loss loss coefficients conversion coefficients

无压渗透法制备SiC颗粒增强铝基复合材料的研究

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天津大学学报（自然科学与工程技术版） 2003年第4期36卷 418-423页

作者：石锋钱端芬吴顺华天津大学电子信息工程学院天津300072 湖南大学材料科学与工程学院长沙410082

利用无压渗透法制备出SiCp/Al复合材料,研究了SiCp/Al系统的界面微观结构及复合材料的机械性能.研究表明:SiCp/Al系统的界面处存在着界面反应,生成Si、Al2O3和Al3C4.产物,在界面处存在着Si和Mg元素的富集;复合材料的机械性能受界面反应... 详细信息

利用无压渗透法制备出SiCp/Al复合材料,研究了SiCp/Al系统的界面微观结构及复合材料的机械性能.研究表明:SiCp/Al系统的界面处存在着界面反应,生成Si、Al2O3和Al3C4.产物,在界面处存在着Si和Mg元素的富集;复合材料的机械性能受界面反应和Si元素富集的影响,其中界面反应是最重要的影响因素.当界面反应控制在一定程度时,在基体与增强相的界面处形成比较充分的"机械绞合",才会使复合材料的机械性能有较大提高.界面上Si元素的富集对机械性能的影响较为复杂,一方面它可以控制界面反应的过度发生,另一方面又会产生晶格畴变,这两方面效应的叠加,使之对复合材料机械性能的影响减弱,远小于界面反应对机械性能的影响.

关键词： SiC颗粒增强铝基复合材料无压渗透法微观结构机械性能界面反应 Si元素富集

Vertical Dynamic Stability Analysis of EDS Levitation Systems Based on Halbach Magnet Arrays

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Vertical Dynamic Stability Analysis of EDS Levitation System...