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A NOVEl METHOD FOR EVAlUATING PlANE STRESS DYNAMIC FRACTURE TOUGHNESS OF 0Cr18Ni10Ti STAINlESS STEEl WElDED jOINTS

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Acta Metallurgica Sinica(English letters) 2008年第4期21卷 303-312页

作者： Z.j. Xu Y.l. li School of Aeronautics Northwestern Polytechnical University Xi＇an 710072 China

A novel method was proposed for the evaluation of Mode I dynamic fracture toughness （DFT） under plane stress and small scale yielding conditions for welded joints of stainless steel （SS）, 0Cr18Ni10Ti. In a hybrid experimental-numerical approach, the experiments were carried out on the Hopkinson pressure bar apparatus, and three dimensional （3D） transient numerical simulations were performed by a finite element （FE） computer program. Macroscopical plastic deformation was observed at the loading and supporting points, on the specimens, after the test, which could cause a large error if omitted in the numerical simulation. Therefore, elustic-viscoplustic analysis was performed on the specimen by adopting the johnson-Cook （j-C） model to describe the rate-dependent plastic flow behavior of the material. The material heterogeneity in the mismatched welded joints, induced by the difference in the base metal （BM） and the weld metal （WM） in yield stress, has also been taken into consideration by using the j-C models separately. Good accordance was obtained between the experimental and the computational results by the present approach. The relationship between plane stress DFT and loading rate was also obtained on the order of 108 MPa.m^1/2.s^-1.

关键词： 0Cr18Ni10Ti Welded joint High strain rate Dynamic fracture Plane stress

An ensemble method for gene discovery based on DNA microarray data

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Science China(life Sciences) 2004年第5期47卷 396-405页

作者： Kathy l. MOSER Eric j. TOPOl Department of Medicine Institute of Human Genetics University of Minnesota Minnesota 55455 USA Center for Cardiovascular Genetics Department of Cardiovascular Medicine the Cleveland Clinic Foundation 9500 Euclid Avenue Cleveland Ohio 44195 USADepartment of Molecular Cardiology the Cleveland Clinic Foundation 9500 Euclid Avenue Cleveland Ohio 44195 USA

The advent of DNA microarray technology has offered the promise of casting new insights onto deciphering secrets of life by monitoring activities of thousands of genes simulta-neously. Current analyses of microarray data focus on precise classification of biological types, for example, tumor versus normal tissues. A further scientific challenging task is to extract dis-ease-relevant genes from the bewildering amounts of raw data, which is one of the most critical themes in the post-genomic era, but it is generally ignored due to lack of an efficient approach. In this paper, we present a novel ensemble method for gene extraction that can be tailored to fulfill multiple biological tasks including (i) precise classification of biological types; (ii) disease gene mining; and (iii) target-driven gene networking. We also give a numerical application for (i) and (ii) using a public microarrary data set and set aside a separate paper to address (iii).

关键词： microarrays,ensemble decision,recursive partition tree,feature gene selection.

Existence and Uniqueness of Fixed Point in Partially Ordered Sets and Applications to Ordinary Differential Equations

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Acta Mathematica Sinica,English Series 2007年第12期23卷 2205-2212页

作者： juan j.NIETO RosanaRODRGUEZ-lPEZ Departamento de Análisis Matemático Facultad de MatemáticasUniversidad de Santiago de Compostela

We prove some fixed point theorems in partially ordered sets, providing an extension of the Banach contractive mapping theorem. Having studied previously the nondecreasing case, we consider in this paper nonincreasing mappings as well as non monotone mappings. We also present some applications to first-order ordinary differential equations with periodic boundary conditions, proving the existence of a unique solution admitting the existence of a lower solution.

关键词： fixed point partially ordered set first-order differential equation lower and upper solutions

Potential influence of wildfire in modulating climate-induced forest redistribution in a central Rocky Mountain landscape

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Ecological Processes 2017年第1期6卷 52-68页

作者： john l.Campbell Douglas j.Shinneman Department of Forest Ecosystems and Society Oregon State UniversityCorvallisORUSA U.S.Geological Survey Forest and Rangeland Ecosystem Science CenterBoiseIDUSA.

Introduction:Climate change is expected to impose significant tension on the geographic distribution of tree ***,tree species range shifts may be delayed by their long life spans,capacity to withstand long periods of physiological stress,and dispersal *** could theoretically break this biological inertia by killing forest canopies and facilitating species redistribution under changing *** investigated the capacity of wildfire to modulate climate-induced tree redistribution across a montane landscape in the central Rocky Mountains under three climate scenarios(contemporary and two warmer future climates)and three wildfire scenarios(representing historical,suppressed,and future fire regimes).Methods:Distributions of four common tree species were projected over 90 years by pairing a climate niche model with a forest landscape simulation model that simulates species dispersal,establishment,and mortality under alternative disturbance regimes and climate ***:Three species(Douglas-fir,lodgepole pine,subalpine fir)declined in abundance over time,due to climate-driven contraction in area suitable for establishment,while one species(ponderosa pine)was unable to exploit climate-driven expansion of area suitable for *** fire frequency accelerated declines in area occupied by Douglas-fir,lodgepole pine,and subalpine fir,and it maintained local abundance but not range expansion of ponderosa ***:Wildfire may play a larger role in eliminating these conifer species along trailing edges of their distributions than facilitating establishment along leading edges,in part due to dispersal limitations and interspecific competition,and future populations may increasingly depend on persistence in locations unfavorable for their establishment.

关键词： Forest disturbance Wildfire Climate change Central Rocky Mountains Climate niche Species migration Species distribution

An Improved Experiment to Determine the‘Past of a Particle’in the Nested Mach-Zehnder Interferometer

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Chinese Physics letters 2017年第2期34卷 4-6页

作者： A.Ben-Israel l.Knips j.Dziewior j.Meinecke A.Danan H.Weinfurter l.Vaidman Raymond and Beverly Sackler School of Physics and Astronomy Tel-A viv UniversityTel-A viv 69978Israel Max-Planck-Institut für Quantenoptik Hans-Kopfermann-Straβe 1Garching 85748Germany Department für Physik Ludwig-Maxirnilians-UniversitatMunchen 80797Germany

We argue that the modification proposed by li et al. [Chin. Phys. lett. 32 （2015）050303] to the experiment of Danan et al. [Phys. Rev. lett. 111 （2013） 240402] does not test the past of the photon as characterized by local weak traces. Instead of answering the questions：（i） were the photons in A？（ii） were the photons in B？ and （iii） were the photons in C？ the proposed experiment measures a degenerate operator answering the questions：（i） were the photons in A？ and （ii） were the photons in B and C together？ A negative answer to the last question does not tell us if photons were present in B or C. On the other hand, a simple variation of the proposal by li et al. does provide conceptually better evidence for the past of the pre- and post-selected photon, but this evidence will be in agreement with the results of Danan et al.

关键词： li In in the Nested Mach-Zehnder Interferometer An Improved Experiment to Determine the

Preliminary Mapping and Characterisation of Soils in the Pirin Mountains (Bulgaria)

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journal of Mountain Science 2008年第2期5卷 122-129页

作者： Maika lβiger jrg Scheithauer Karsten Grunewald University of Technology Dresden D-01062 Dresden Germany landscape Research Centre Dresden Am Ende 14 D-01277 Dresden Germany

Soil types, humus types and vegetation as well as their hypsometric variation were analysed in terms of sequences in the northern part of the high mountains of the Pirin National Park at altitudes between looo and 2400 m a.s.1. The study area is characterised by a large variety of natural parameters like petrology （mainly marble and granite）, morphology （different slope deposits, exposition） and the orographic climate gradient. Statistical analyses using these parameters provided a basis for the soil group classification of the sites. Based on a Digital Terrain Model （DTM） and a geological map of the Pirin National Park, the results of these statistical analyses were used to generate a ＂map of potential soil groups＂（regionalisation using GIS）. Six potential soil groups could be determined. The resulting map exhibits a confidence level of 68 % on 74.4 % of the covered area. Rendzic leptosols, in combination with Folic Histosols and Histi-lithic leptosols occur in the alpine and subalpine regions on calcareous substrates. With decreasing altitude they are replaced by a mosaic of Rendzic leptosols, Phaeozems and an increasing occurrence of Cambic Umbrisols. Umbrisols found on silicatic substrates in the alpine region are replaced by Cambic Umbrisols with decreasing altitude as well. Hence, pedogenesis is characterised by increasing browning and depth of the soil profiles with decreasing altitude. The pH-level is slightly acidic to neutral in lower zones and on calcareous rocky bases. Acidification increases in the subalpine zone. Soil pH decreases down to 4 on silicate subtrates. Typical humic values in mineral topsoils are 10 to 12 %, and in organic layers of the soils above 2000 m a.s.1, they are even more. The C：N ratio closely ranges around 20 （median）.

关键词： Cluster analysis soil mapping hypsometric soil differentiation Southeast Europe

Fish embryo and juvenile size under hypoxia in the mouth- brooding African cichlid Pseudocrenilabrus multicolor

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Current Zoology 2012年第3期58卷 401-412页

作者： E.E. REARDON l.j. CHAPMAN Department of Biology McGill University 1205 Dr. Penfield Ave Montreal Quebec H3A 1B 1 Canada Wildlife Conservation Society 2300 Southern Boulevard Bronx NY 10460 USA

We used a field survey and a laboratory rearing experiment to （a） examine response （size and survival） to life-long hypoxia in offspring of the African maternal mouth-brooding cichlid Pseudocrenilabrus multicolor victoriae （Seegers） and （b） explore the degree to which developmental response can be environmentaUy-induced. Embryo size metrics were quantified in 9 field populations across a range of dissolved oxygen （DO） concentrations. In the laboratory, first generation （F1） broods of low-DO origin were reared under high or low DO. Brooding period was quantified for the mothers; and egg size, egg metabolic rate and juvenile size-at-release were quantified in their （F2） offspring. The F2 offspring were split and grown for 3 months post-release under high or low DO, and juvenile size and survival were quantified. In the field survey, across stages, embryos from low-DO field populations were shorter and weighed less than embryos from high-DO populations. In the laboratory experi- ment, F2 eggs and juveniles-at-release from mother＇s mouth did not differ in mass, length, survival regardless of development DO environment. However, juveniles diverged in size after leaving mother＇s mouth, exhibiting smaller size when grown under low DO. Size differences in embryo size across field populations and divergence in embryo size after release from the mother＇s mouth support predictions for smaller body size under hypoxia. There was no evidence for negative effects on survival of juveniles after 3 months. Brooding period was 16% shorter in females reared under low DO suggesting that hypoxia may accelerate embryo de- velopment. This work provides insights into how bearer fishes respond to hypoxic stress relative to fishes with no post-spawning parental care; a shorter brooding interval and smaller body size may provide an optimal solution to parent and embryo survival under hypoxia in brooding fishes [Current Zoology 58 （3）： 401-412, 2012].

关键词： African cichlid lake Victoria life-history Parental care Dissolved oxygen

Effect of Composts,lime and Diammonium Phosphate on the Phytoavailability of Heavy Metals in a Copper Mine Tailing Soil

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Pedosphere 2009年第5期19卷 631-641页

作者： M.j.KHAN D.l.jONES Department of Soil and Environmental Sciences NWFP Agricultural UniversityPeshawar(Pakistan) School of Agricultural and Forest Sciences University of WalesBangorGwynedd LL57 2UW(UK)

Soil samples from a historic copper mine tailing site at the Parys Mountain,North Wales(UK) were amended with green waste compost(GC),GC+30% sewage sludge(GCS),lime and diammonium phosphate(DAP),to determine the effect of amendments on DTPA-and Ca(NO3)2-extractable metals in the mine tailing and on the phytoavailability of heavy metals by a lettuce(lactuca sativa l.).Both compost were added at the rate of 10% by weight,lime was added as calcium carbonate equivalent(pH = 7) and DAP at a 2300 mg kg-1 soil *** experiment was arranged in randomised complete design with three replicates in pots under control *** of lime resulted in the largest reduction in metal extractability with DTPA and Ca(NO3)2 and phytoavailability of Cu,Fe and Zn while DAP was effective in lowering Pb extractability and *** exception of Zn,all other metals extracted decreased with time after amendment *** distribution of heavy metals between and within the four procedures of potentially bioavailable sequential extraction(PBASE) varied significantly(P lationships were noted between the metals extracted with PBASE SE1 and Cu,Pb(P lts indicate that addition of lime is sufficient to restore the vegetative cover to a high metal mine waste while DAP is good for stabilizing Pb,but its detrimental role on plant growth and the risk associated with presence of N in DAP(through N leaching) may restrict its chances for remediation of contaminated sites.

关键词： lettuce metal uptake potentially bioavailable sequential extraction

EFFECT OF TESTING ENVIRONMENT ON FRACTURING BEHAVIOR OF Fe_3Si BASED AllOY

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Acta Metallurgica Sinica(English letters) 2003年第2期16卷 104-109页

作者： j.H.Peng G.l.Chen National Key laboratory for Nuclear Fuel&Materials China Nuclear Power InstituteChengdu 610041ChinaState Key Laboratory for Advanced Metal MaterialsUniversity of Science&Technology BeijingBeijing 100083China

The mechanical behavior of Fes Si based alloy with B2 structure was studied by tension and fracture toughness test in various testing media. The fracture strength σb of Fe3Si alloy decreased in the following order: oxygen, air and hydrogen respectively. The fracture toughness in different testing environment showed that KIC in oxygen is 11.5±0.3MPa·m1/2, and is 8.6±0.4MPa·ml/2 in distilled water. The reduction of fracture toughness is contributed to the environmental reaction of Si with water. Addition of Al element in Fe3Si is not beneficial to improve the intrinsic ductility of Fe-14Si-3Al alloy. The scattering phenomenon of fracture strength was found, and explained by fracture mechanics. It was found by means of SEM that the fracture mode changed from transgranular in oxygen to intergranular in hydrogen gas and distilled water.

关键词： Fe3Si intermetallic mechanical behavior environmental em- brittlement