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HIGH-TEMPERATURE TENSILE FRACTURE BEHAVIOR OF DIRECTIONALLY SOLIDIFIED Ni,Cr,Al-TaC EUTECTIC SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 455-459页

作者： j.Zhang j.j.Yu H.Z.Fu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072ChinaInstitute of Metal Research Chinese Academy of Sciences Shenyang 110016 ChinaState Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072China

The high-temperature tensile fracture behavior of the Ni, Cr, Al-TaC eutectic superal-loy directionally solidified under high temperature gradient is investigated. The high-temperature tensile fracture of this in situ composite has ductile character with lots of ductile nests whose diameters decrease with the increasing solidification rates. The maximum σb and δ are respectively 668.5MPa and 19.6%. There is α TaC whisker in the center of each nest, and the deformation of γ' and TaC is uneven. The high-temperature tensile behavior cannot be explained by the rule of mixtures but is decided by the formation of the plastic deformation band. The crack extension model is given.

关键词： Ni Cr Al-TaC eutectic superalloy directional solidification,in situ composite high-temperature tenslie fracture

An Integrated Approach to Crop Genetic Improvement

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journal of Integrative Plant Biology 2012年第4期54卷 250-259页

作者： Martin A.j.Parry Malcolm j.Hawkesford Rothamsted Research Plant Science Department

The balance between the supply and demand of the major food crops is fragile, fueling concerns for long-term global food security. The rising population, increasing wealth and a proliferation of non- food uses （e.g. bioenergy） has led to growing demands on agricul- ture, while increased production is limited by greater urbanization, and the degradation of land. Furthermore, global climate change with increasing temperatures and lower, more erratic rainfall is projected to decrease agricultural yields. There is a predicted need to increase food production by at least 70% by 2050 and there- fore an urgent need to develop novel and integrated approaches, incorporating high-throughput phenotyping that will both increaseproduction per unit area and simultaneously improve the resource use efficiency of crops. Yield potential, yield stability, nutrient and water use are all complex multigenic traits and while there is genetic variability, their complexity makes such traits difficult to breed for directly. Nevertheless molecular plant breeding has the potential to deliver substantial improvements, once the component traits and the genes underlying these traits have been identified. In addition, interactions between the individual traits must also be taken into account, a demand that is difficult to fulfill with traditional screening approaches. Identified traits will be incorporated into new cultivars using conventional or biotechnological tools. In order to better understand the relationship between genotype, component traits, and environment over time, a multidisciplinary approach must be adopted to both understand the underlying processes and identify candidate genes, QTLs and traits that can be used to develop improved crops.

关键词： Germpiasm variation nitrogen TILLING transformation trait water wheat yield.

High Efficient Laser Operation of the Nd:KGd(WO_(4))_(2) Crystal Grown by Flux Method

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Chinese Physics Letters 2000年第12期17卷 888-889页

作者： LUO Zun-Du CHEN Xue-Yuan TU Chao-Yang j.j.Romero j.Garcia Sole Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002 Departamento de Fisica de Materiales Universidad Autonoma de MadridCantoblanco28049 MadridSpain

The laser performance of Neodymium-doped potassium gadolinium tungstate(Nd:KGd(WO4)2)crystal was studied by using Ti:Sapphire laser as the pump *** maximum optical-to-optical efficiencies for the 1.067 and 1.3μm laser outputs were measured to be 60%and 32.3%,*** internal loss coefficient of the crystal for 1.067μm laser was estimated to be as low as 0.004 *** oscillation thresholds at 1.067 and 1.3μm for different output transmittances are also given.

关键词： Nd: laser pump

Experimental Studies of Electrostatic Fluctuations and Turbulent Transport in the Boundary of j-TEXT Tokamak Using Reciprocating Probe

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Plasma Science and Technology 2012年第12期14卷 1041-1047页

作者： CHEN Zhipeng SUN Yue WANG Zhijiang YANG Zhoujun DING Yonghua ZHUANG Ge j-TEXT team State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China Key Laboratory of Geospace Environment Chinese Academy of Sciences University of Science & Technology of China Hefei 230026 China

As the basic of a deeper investigation on the turbulent transport, the fluctuation property in the boundary of the newly-reconstructed joint Texas Experimental Tokamak （j- TEXT） is studied experimentally using the reciprocating Langmuir four-tip probe, which has been built and operated as the primary diagnostic tool in the boundary of j-TEXT tokamak. In this paper, spatial profiles of the plasma-edge parameters are obtained, such as electron temperature, plasma density, plasma potential, poloidal electric field and their fluctuations. The results indicate the existence of a Er ×BT shear layer at the vicinity of last closed flux surface （LCFS）, with the fluctuations suppressed in varying degrees. The turbulence-induced particle and energy fluxes can be calculated by the local plasma parameters above. Convection dominates the cross-field turbulent transport in boundary plasma. Electrostatic fluctuations properties are also studied in detail with the help of numerical analysis. Statistical analysis on density fluctuation shows that, the intermittency can affect the turbulence in the scrape-off layer （SOL）.

关键词： electrostatic fluctuations anomalous transport j-TEXT reciprocating Lang- muir probe

Overcoming obstacles to implementation: addressing political,institutional and behavioral problems in earthquake hazard mitigation policies

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Earthquake Engineering and Engineering Vibration 2002年第1期1卷 152-158页

作者： Daniel j.Alesch William j.Petak Department of Public and Environmental Affairs University of Wisconsin-Green BayGreen BayWisconsin54311USA Professor School of Policy Planning and DevelopmentUniversity of Southern California650 Childs WayRoom 201eLos AngelesCalifornia90089-0626USA Professor

This project is aimed at bridging the three planes,from basic research,through enabling processes,to engineered *** the basic research plane,we have been working to improve our collective understanding about obstacles to implementing mitigation practices,owner decision processes (in connection with other MCEER projects),and public policy *** the level of enabling processes,we have been seeking to develop an understanding of how obstacles to greater mitigation can be overcome by improved policy design and *** the engineered systems plane, our work is intended to result in practical guidelines for devising policies and programs with appropriate motivation and incentives for implementing policies and programs once *** phase of the research has been aimed,first,at a thorough,multidisciplinary review of the literature concerning obstacles to ***,the research has focused on advancing the state of the art by developing means for integrating the insights offered by diverse perspectives on the implementation process from the several social,behavioral,and decision *** research establishes a basis for testing our understanding of these processes in the case of hospital retrofit decisions.

关键词： earthquake mitigation earthquake mitigation policies earthquake losses

Comeld^TM joints: A Novel Technique for Bonding Composites and Metal

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稀有金属材料与工程 2009年第A03期38卷 134-141页

作者： Tu W Guild F j Hogg P j Queen Mary University of London Imperial College London South Kensington Campus University of Manchester PO Box 88

Current and future structural applications for composite laminates frequently involve design solutions combining composite laminates and metal; the materials must be joined. Two conventional means of joining are available mechanical joining and adhesive bonding. Both methods have critical disadvantages. A novel surface treatment for metals developed at TWI, Surfi-Sculpt, leads to the formation of surface protrusions on metal surfaces. These protrusions are typically 1.0 mm high and 0.6 mm in diameter. The surface modified metal can be bonded with composite laminates to form a Comeld～TM joint. These joints can be described as a combination of mechanical fastening and adhesive bonding. This paper describes our current work using finite element modelling to optimize the protrusions in respect to their geometry and distribution. The simulations require multi-scale modelling techniques to transfer results between the global model of the whole joint and the unit cell models containing a protrusion. Results from the simulations show critical effects on stress distributions arising from changing protrusion geometry. These joints show significant advantages over conventional adhesive joining technologies and their application would allow improved performance for combinations of metal and composite laminates.

关键词：复合材料金属表面处理技术物理性能

Estimation of j—R Curves for Small-Sized COEC Specimens and Its Application Considering Crack-Tip Cons tr aints

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Acta Mechanica Solida Sinica 2019年第3期32卷 261-276页

作者： G.W.He C.Bao L.X.Cai Y.j.Wu Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

The normalization method has been employed to estimate the j-resistance (j—R) curves for C-shaped outside edge-notched compression (COEC) specimens of SA-508 steel. The COEC specimens present the lowest j—R curves in comparison with other three types of specimens. Based on the j—Q—M met hod, the constraint parame ter Q determined at the mid-plane in the through-thickness direction of the specimen is used to approximately quantify the threedimensional crack-tip constraint for COEC specimens. Combining with the previous experiments on j—R curves, the constraint-coirected j—R curves for SA-508 steel specimens are given, which may be used to predict the fracture toughness of actual cracked components in structural integrity assessment.

关键词： Ductile fracture toughness COEC specimen Dimensionless load separation principle Normalization method Crack-tip constraint j-Q-M method

Contribution of national bioassessment approaches for assessing ecological water security： an AUSRIVAS case study

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Frontiers of Environmental Science & Engineering 2013年第5期7卷 669-687页

作者： Susan j. NICHOLS Fiona j. DYER Institute for Applied Ecology and MDBfutures CRN University of Canberra Canberra ACT 2601 Australia

River managers in Australia are managing in the face of extremes to provide security of water supply for people, production and the environment. Balancing the water requirements of people, environments and econo- mies requires that water security is viewed holistically, not just in terms of the water available for human consump- tion. Common definitions of water security focus on the needs of both humans and ecosystems for purposes such as drinking, agriculture and industrial use, and to maintain ecological values. Information about achieving water security for the environment or ecological purposes can be a challenge to interpret because the watering require- ments of key ecological processes or assets are not well understood, and the links between ecological and human values are often not obvious to water users. Yet the concepts surrounding river health are inherently linked to holistic concepts of water security. The measurement of aquatic biota provides a valuable tool for managers to understand progress toward achieving ecological water security objectives. This paper provides a comprehensive review of the reference condition approach to river health assessment, using the development of the Australian River Assessment System （AUSRIVAS） as a case study. We make the link between the biological assessment of river health and assessment of ecological water security, and suggest that such an approach provides a way of reporting that is relevant to the contribution made by ecosystems to water security. The reference condition approach, which is the condition representative of minimally disturbed sites organized by selected physical, chemical, and biological characteristics, is most important for assessing ecological water security objectives.

关键词： ecological water security biological assessment river health

Implementation of a Roughness Element to Trip Transition in Large-eddy Simulation

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journal of Thermal Science 2015年第1期24卷 30-36页

作者： j.Boudet j.-F.Monier F.Gao LMFA Ecole Centrale de Lyon Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France PhD.Candidate Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France

In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer con- figuration, with Reynolds number Rex=l.3x 106. First, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. Finally, two subgrid-scale models are tested： the WALE model of Nic0ud and Ducros （Flow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of Ldv^que et al. （j. Fluid Mech., vol. 570, 2007）. Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.

关键词： large-eddy simulation boundary layer roughness element transition tripping