检索结果-南通市图书馆

A CLASS OF TESTS USING L STATISTIC FOR CONSTANT RELATIVE FAILURE RATE AGAINST MONOTONE RELATIVE FAILURE RATE

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Systems Science and Mathematical Sciences 1992年第1期5卷 19-26页

作者： K.w.chen University of North Carolina Charlotte NC 28223USA

In this paper we develop tests using L-statistic for constant relativefailure rate against monotone relative failure *** invariance,monotonepower and locally asymptotic power results are *** examples arepresented.

关键词： Relative failure rate L-statistic scale invariance monotone power asymptotic power Pitman efficacy

Precipitation on stacking faults in Mg–9.8wt%Sn alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第10期42卷 230-240页

作者： C.Q.Liu C.He H.w.chen J.F.Nie International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China Department of Materials Science and Engineering Monash UniversityVictoria3800Australia Electron Microscopy Center Chongqing UniversityChongqing400044PR China

In this work,we have systematically investigated precipitation ofβ’-Mg3Sn phase on intrinsic stacking faults I1 and I2 in a Mg-9.8 wt%Sn alloy using aberration-corrected scanning transmission electron *** observed I1 faults are generated by the dissociation of c+a perfect dislocations and bounded by Frank partial dislocations having a Shockley *** ofβ’on I1 involves a shear of 1/3α,similar to its formation directly from theα-Mg ***β’phase often nucleates at one end of an I1 fault due to the interaction between shear strain fields ofβ’and the Shockley component of the Frank partial at that end,and subsequently grows towards the other end of the *** theβ’reaches to the other end,the Shockley partial bounding the lengthening end of theβ’reacts with the Frank partial bounding the fault,generating an a perfect dislocation that can glide away from the precipitate and the *** observed I2 faults are generated by the dissociation of a perfect dislocations and bounded by Shockley *** ofβ’on I2 does not need a shear of 1/3α,since the pre-existing I2 fault already provides an ABCA four-layer structure ofβ’.Thickening of theβ’that has already formed on the I2 involves the successive occurrence of three crystallographically equivalent shears of 1/3αon every second(0002)αplane of theα-Mg *** this thickening mechanism is similar to that of theβ’formed directly from theα-Mg matrix,an a perfect dislocation will be produced when theβ’is thickened to eight layers,and it can again glide away from the precipitate and the fault.

关键词： Heterogeneous precipitation HAADF-STEM Shockley partial dislocation Frank partial dislocation Dislocation reaction

Active{1121}and{1012}extension twinning in a wE43 Mg alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第13期144卷 93-101页

作者： w.Q.chen S.Deng X.J.Zhao S.N.Luo Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China The Peac Institute of Multiscale Sciences Chengdu 610031China

Deformation twinning in a wE43 alloy subjected to uniaxial compression at room temperature is ***{1121}and{1012}extension twinning is *** activation of{1121}twinning in a certain grain is influenced not only by its own Schmid factor,but also by that of the basal ***-twin interactions of the co-zone{1121}twin variants are commonly observed and systematically studied,including the crystallographic characteristics of the four typically observed twin-twin junctions(TTJs)and the associated twin-twin *** the quilted-looking TTJs formed by the interaction of co-zone{1012}twin variants,crossing-like TTJs of co-zone{1121}twin variants are observed and their formation mechanisms are ***-like TTJs are also formed by the interaction of{1121}and{10¯12}*** morphology and thickening rate of{1121}and{1012}twins vary markedly due to the difference in twinning *** needle-like{1121}twins thicken more slowly than the lenticular{1012}*** nucleation is observed on the previously formed{1121}twin boundary due to the relatively large strain concentration on such interface,while twin nucleation on{1012}twin boundary is rarely observed.

关键词： Mg alloy Plastic deformation Twinning Twin-twin interaction Twin-twin junction

Partial melting and re-solidification in partially melted zone during gas tungsten arc welding of AZ91 cast alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2007年第A1期17卷 342-346页

作者： T. P. ZHU Z. w. chen w. GAO Department of Chemical and Materials Engineering University of Auckland NZ Department of Mechanical and Production Engineering Auckland University of Technology New Zealand

During the welding of AZ91 cast alloy,the presence of eutectic β-Mg17Al12 phase results in constitutional liquation in the original interdendritic regions and in the formation of a partially melted zone(PMZ). In this study,gas tungsten arc welding(GTAw) and partial melting(simulated using furnace,salt bath and Gleeble) experiments were conducted. The results show that practically there would not be a critical heating rate during the welding to prevent constitutional liquation. The gradual change of the re-solidification microstructure within PMZ from base metal side to weld metal side was characterized. A sharp transition from base metal to PMZ has been observed. It is found that the original partially divorced eutectic has become a more regular eutectic in most of the PMZ,although close to the fusion boundary the re-solidified eutectic is again a more divorced one. Proceeding the eutectic re-solidification,α-Mg re-solidified with a cellular growth resulting in a serrated interface. The morphological change affected by the peak temperature and cooling rate will be presented and explained.

关键词：镁合金凝固技术金属材料制造方法

Maneuvering Modeling and Simulation of AUV Dynamic Systems with Euler-Rodriguez Quaternion Method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2013年第3期27卷 403-416页

作者： C.w.chen J.S.Kouh J.F.Tsai Department of Science Engineering and Ocean Engineering National Taiwan University

The purpose of this study is to develop maneuvering models and systems of a simulator to improve the motion performance of autonomous underwater vehicles （AUVs） at the preliminary design stages in advance. The AUVs simulation systems based on the standard submarine equations of motion in six-degree-of-freedom （6-DOF） integrated with the Euler-Rodriguez quaternion method for representing singularity-free AUV attitude and time-saving calculation, and with a nonlinear control model for maneuvering and depth control simulations, time-marching in the fourth-order Runge-Kutta scheme. For validation of the simulation codes, results of the ISiMI AUV open-loop tests including turning test and zigzag test as well as an AUV simulator on the basis of Euler-angle method were used to compare with the quaternion-based AUV simulator. The computational results from the proposed simulator agree well with those from both the ISiMI AUV experiments and the Euler-angle based simulations. Additionally, a new maneuvering procedure, namely ＂put-out＂ was implemented to test directional stability for a large-scale AUV in the proposed AUV simulator that can be considered for vehicles in space as well as in constrained planes.

关键词： autonomous underwater vehicle (.4 UV) Euler-Rodriguez quaternion hydrodynamics maneuvering systemdynamics

Comparative cytotoxicity of fourteen trivalent and pentavalent arsenic species determined using real-time cell sensing

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2016年第11期28卷 113-124页

作者： Birget Moe Hanyong Peng Xiufen Lu Baowei chen Lydia w.L.chen Stephan Gabos Xing-Fang Li X.Chris Le Division of Analytical and Environmental Toxicology Department of Laboratory Medicine and Pathology Faculty of Medicine and DentistryUniversity of Alberta Alberta Centre for Toxicology Department of Physiology and Pharmacology Faculty of Medicine University of Calgary MOE Key Laboratory of Aquatic Product Safety School of Marine Sciences Sun Yat-Sen University Department of Chemistry Brock University Department of Chemistry and Chemical Biology McMaster University

The occurrence of a large number of diverse arsenic species in the environment and in biological systems makes it important to compare their relative toxicity. The toxicity of arsenic species has been examined in various cell lines using different assays, making comparison difficult. we report real-time cell sensing of two human cell lines to examine the cytotoxicity of fourteen arsenic species： arsenite（As~Ⅲ）, monomethylarsonous acid（MMA~Ⅲ） originating from the oxide and iodide forms, dimethylarsinous acid（DMA~Ⅲ）, dimethylarsinic glutathione（DMAG~Ⅲ）, phenylarsine oxide（PAO~Ⅲ）, arsenate（AsV）, monomethylarsonic acid（MMA~Ⅴ）, dimethylarsinic acid（DMA~Ⅴ）,monomethyltrithioarsonate（MMTTA~Ⅴ）, dimethylmonothioarsinate（DMMTA~Ⅴ）,dimethyldithioarsinate（DMDTA~Ⅴ）, 3-nitro-4-hydroxyphenylarsonic acid（Roxarsone, Rox）,and 4-aminobenzenearsenic acid（p-arsanilic acid, p-ASA）. Cellular responses were measured in real time for 72 hr in human lung（A549） and bladder（T24） cells. IC50 values for the arsenicals were determined continuously over the exposure time, giving rise to IC50 histograms and unique cell response profiles. Arsenic accumulation and speciation were analyzed using inductively coupled plasma-mass spectrometry（ICP-MS）. On the basis of the 24-hr IC50 values, the relative cytotoxicity of the tested arsenicals was in the following decreasing order： PAO~Ⅲ？ MMA~Ⅲ≥ DMA~Ⅲ≥ DMAG~Ⅲ≈ DMMTA~Ⅴ≥ As~Ⅲ？ MMTTA~Ⅴ〉 AsV〉 DMDTA~Ⅴ〉DMA~Ⅴ〉 MMA~Ⅴ≥ Rox ≥ p-ASA. Stepwise shapes of cell response profiles for DMA~Ⅲ, DMAG~Ⅲ,and DMMTA~Ⅴcoincided with the conversion of these arsenicals to the less toxic pentavalent DMA~Ⅴ. Dynamic monitoring of real-time cellular responses to fourteen arsenicals provided useful information for comparison of their relative cytotoxicity.

关键词： Arsenic species Thio-arsenicals Methylarsenicals Phenylarsenicals Toxicity Real-time sensing

Influence of Heat Treatment on the Bond Coat Cyclic Oxidation Behaviour in an Air-plasma-sprayed Thermal Barrier Coating System

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第5B期25卷 923-929页

作者： w.R.chen X.wu B.R.Marple P.C.Patnaik Structures MaterialsandPropulsionLaboratoryInstituteforAerospaceResearchNationalResearchCouncilCanadaOttawaOntarioCanadaK1AOR6 IndustrialMaterialsInstitute NationalResearchCouncilCanadaBouchervilleQuebecCanadaJ4B6Y4

It is generally believed that a thermally grown oxide (TOO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air-plasma-sprayed (APS) TBC system with Co-32Ni-21Cr-8Al-0.5Y (wt%) bond coat, the TGO layer formed upon thermal exposure in air was predominantly chromia and spinels, which would not effectively protect the bond coat at above 1000°C. In addition, mixed oxides of chromia, spinel and nickel oxide formed heterogeneously between the ceramic coating and CoNiCrAlY bond coat, which would promote crack initiation and lead to premature TBC failure. A heat treatment in a low-pressure condition was applied to the as-sprayed TBC system, with the aim to produce an alumina layer as well as reduce the amount of detrimental oxides. The influence of this low-pressure oxidation treatment (LPOT) on the bond coat cyclic oxidation behaviour of the TBC system was also investigated.

关键词：热处理 TGO TBC 低压氧化周期性氧化 CoNiCrAlY合金

Thinning intensity affects microbial functional diversity and enzymatic activities associated with litter decomposition in a Chinese fir plantation

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2018年第5期29卷 1337-1350页

作者： wenya Xiao Fei Fei Jiaojiao Diao Bin J.w.chen Qingwei Guan Department of Ecology College of Biology and the EnvironmentNanjing Forestry University Collaborative Innovation Center for Sustainable Forestry in Southern China of Jiangsu Province Nanjing Forestry University

Microbial functional diversity and enzymatic activities are critical to maintaining material circulation during litter decomposition in ***,an important and widely used silvicultural treatment,changes the microclimate and promotes forest ***,how thinning affects microbial functional diversity and enzymatic activities during litter decomposition remains poorly *** conducted thinning treatments in a Chinese fir plantation in a subtropical region of China with four levels of tree stem removal（0,30,50,and 70%）,each with three replicates,and the effects of thinning on microbial functional diversity and enzymatic activities were studied 7 years after treatment by collecting litter samples four times over a 1-year *** functional diversity and enzymatic activities were analyzed using Biolog Ecoplates（Biolog Inc.,Hayward,CA,USA）based on the utilization of 31 carbon *** microbial abundance during litter decomposition was lower after the thinning treatments than without *** functional diversity did not differ significantly during litter decomposition,but the types of microbial carbon-source utilization did differ significantly with the thinning *** cellulase and invertase activities during litter decomposition were significantly higher under the thinning treatments due to changes in the litter carbon concentration and the ratios of carbon and lignin to *** present study demonstrated the important influence of thinning on microbial activities during litter ***-intensity thinning may maximize vegetation diversity and,in turn,increase the available substrate sources for microbial organisms in litter and promote nutrient cycling in forest ecosystems.

关键词： Biology technology Litter decomposition Microbial enzymatic activities Shannon diversity index

Extension/Compression-Controlled Complete Band Gaps in 2D Chiral Square-Lattice-Like Structures

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2018年第1期31卷 51-65页

作者： Y. L. Huang N. Gao w.Q. chen R.H. Bao Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China State Key Lab of CAD & CG Zhejiang University Hangzhou 310058 China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou 310027 China Soft Matter Research Center Zhejiang University Hangzhou 310027 China

Achieving tunable band gaps in a structure by external stimuli is of great importance in acoustic applications. This paper aims to investigate the tunability of band gaps in square-lattice-like elastic periodic structures that are usually not featured with notable band gaps. Endowed with chirality, the periodic structures here are able to undergo imperfection-insensitive large deformation under extension or compression. The influences of geometric parameters on band gaps are discussed via the nonlinear finite element method. It is shown that the band gaps in such structures with curved beams can be very rich and, more importantly, can be efficiently and robustly tuned by applying appropriate mechanical loadings without inducing buckling. As expected, geometry plays a more significant role than material nonlinearity does in the evolution of band gaps. The dynamic tunability of band gaps through mechanical loading is further studied. Results show that closing, opening, and shifting of band gaps can be realized by exerting real-time global extension or compression on the structure. The proposed periodic structure with well-designed chiral symmetry can be useful in the design of particular acoustic devices.

关键词： Band gap Tunability Square-lattice-like periodic structure Chiral symmetry,Large deformation