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71.
In this paper, a new approach for extracting stress intensity factors (SIFs) by the extended element-free Galerkin method, through a crack closure integral (CCI) scheme, is proposed. The CCI calculation is used in conjunction with a local smoothing technique to improve the accuracy of the computed SIFs in a number of case studies of linear elastic fracture mechanics. The cases involve problems of mixed-mode, curved crack and thermo-mechanical loading. The SIFs by CCI, displacement and stress methods are compared with those based on the M-integral technique reported in the literature. The proposed CCI method involves very simple relations, and still gives good accuracy. The convergence of the results is also examined. 相似文献
72.
Sarvesh Pal R. K. Singh Raman R. N. Ibrahim 《Metallurgical and Materials Transactions A》2012,43(6):1944-1955
Stress corrosion cracking tests were conducted using Bayer solutions of different chemistry at different temperatures for
extraction of alumina from bauxite ores. The validity of the commonly used caustic cracking susceptibility (CS) diagram for
steels exposed to plain caustic solutions was assessed by testing the notched and precracked specimens. This study presents
first results toward the development of a model susceptibility diagram for actual Bayer solutions, and for improved applicability
of the traditional plain caustic diagram. For mechanistic understanding of caustic cracking, tests were also carried out under
imposed electrochemical conditions. 相似文献
73.
Jagadeeswari Sivanadanam Ramesh Mukkamala Sudip Mandal Raman Vedarajan Noriyoshi Matsumi Indrapal Singh Aidhen Kothandaraman Ramanujam 《International Journal of Hydrogen Energy》2018,43(9):4691-4705
Six triphenylamine-based dyes were explored for their application in dye-sensitized solar cells (DSSCs). Dyes 1–3 and dyes 4–6 possess cyanoacrylic acid (C-acceptor) and rhodanine-3-acetic acid (R-acceptor), respectively. Stilbene (in dyes 2 and 5) and bis(styryl)benzene (in dyes 3 and 6) were used as π-spacers. There is no π-spacer in the dye 1 and 4. To elucidate the role of π-spacers, optical, electrochemical, and photovoltaic properties of the dyes were studied. Among C-acceptor dyes, dye 2 exhibits the highest light-to-electricity conversion efficiency of 4.45%, followed by dye 3 (4.16%). Similarly, among R-acceptor dyes, dye 5 is the best. These results indicate that stilbene is a better π-spacer over bis(styryl)benzene. Although bis(styryl)benzene could extend the light absorption range (in dye-adsorbed TiO2 film), its tendency to promote intermolecular π-π stacking is possibly the reason for its poor performance in DSSCs. Furthermore, the conjugation break in the R-acceptor moiety attached to the TiO2 surface limits the electron injection of R-acceptor dyes poorer than C-acceptor dyes. Density functional theory calculations were performed for the dye-(TiO2)8 cluster, assuming a bidentate chelation of a carboxylic acid group with Ti4+ of TiO2 anatase. The natural bond orbital (NBO) analysis indicated relatively more electron-accepting ability of cyanoacrylic acid over rhodanine-3-acetic acid. 相似文献
74.
75.
S. Ghosh A. Guha K. M. Krishna A. K. Mukhopadhyay H. S. Maiti 《Materials and Manufacturing Processes》2006,21(7):662-668
During the last decade, worldwide attention of researchers has focused on nano-ceramic composites with superior mechanical behavior and improved reliability for structural applications. Here we report the development of a multi-layer composite (MLC) of tape cast nano zirconia with high failure energy. The MLC samples were fabricated by thermocompression of green tapes prepared from 3 mole % yttria stabilized zirconia (3-YSZ) powder with a primary crystallite size of 27 nm. Depending on the number of layers, the MLC samples exhibited failure energy (238.97 KJm-3) more than two times higher than that of the single tape (≈107 KJm-3) with a reasonably high bi-axial flexural strength (≈630 MPa), high hardness (≈ 13 GPa at 49 N), and indentation fracture toughness nearly four times as high as that of the single tape. In addition, these MLC materials showed the presence of a R-curve behavior. 相似文献
76.
77.
We demonstrate sensitive spatially resolved detection of physiological chromophores that emit in the ultraviolet (<330 nm). An atypical laser source (a visible wavelength femtosecond optical parametric oscillator), and an unconventional collection geometry (a lensless detector that detects the forward-emitted fluorescence) enable this detection. We report the excitation spectra of the catecholamines dopamine and norepinephrine, together with near-UV emitters serotonin and tryptophan, in the range of 550-595 nm. We estimate the molecular two-photon action cross section of dopamine, norepinephrine, and serotonin to be 1.2 mGM (1 GM, or Goppert Mayor, is equal to 10(-58) m4 s(-1) photon(-1)), 2 mGM, and 43 mGM, respectively, at 560 nm. The sensitivity achieved by this method holds promise for the microscopic imaging of vesicular catecholamines in live cells. 相似文献
78.
Journal of Materials Science - 相似文献
79.
A. Seal S. K. Dalui A. K. Mukhopadhyay K. K. Phani H. S. Maiti 《Journal of Materials Science》2003,38(5):1063-1071
To identify the best reinforcement condition for development of tough glass polymer multi-layer composites (GPMLC) with high failure strain, two such model composite structures were developed. Soda–lime–silica glasses of two different thicknesses viz (A—1.01 mm and B—1.17 mm) were used as the matrix layers. The A-glass and B-glass based GPMLC samples were prepared by a novel, low pressure lamination technique applied to the alternating planar structure of the matrix and reinforcing phases. These GPMLC materials were fabricated with and without a thin sprayed layer of kerosene, between the glass layer and the reinforcing layer in the interface where; the interface was either epoxy (a thermosetting resin) or polyvinyl butyral (PVB, a thermoplastic resin). The GPMLC samples which exhibited stepped load—displacement behaviour in the most pronounced fashion, had the thermoplastic resin at the interface. Most of these GPMLC samples had a thin layer of kerosene intentionally introduced between the glass layer and the reinforcing polymer layer such that a weak interface is obtained. Fractographic evidence suggested that more of controlled delaminaton cracking occurs in such samples. Apart from the chemical nature of the reinforcing polymer phase, the interfacial layer thickness (h
i
) and the interfacial shear stress (
xy
) were found out to have significant influence on the specific failure load and the failure stress of the current glass polymer multi-layer composites. 相似文献
80.
Hilary Alto Rangaraj M. Rangayyan Raman B. Paranjape J. E. Leo Desautels Heather Bryant 《电信纪事》2003,58(5-6):820-835
Computer-aided diagnosis (cad) systems are being developed to assist radiologists in the interpretation of ambiguous mammographic features corresponding to possible signs of early breast cancer. Databases of digital mammograms are needed for testing such systems; we present an overview of a few such databases. Most databases are limited to single-exam sets of two or four mammograms on which the diagnosis was made, some ground-truth information related to the position of diagnostically significant mammographic features, and the diagnosis. We propose the design of a comprehensive, indexed atlas of digital mammograms. The design of an appropriate indexing scheme facilitates the implementation of content-based retrieval techniques needed for efficient access to and retrieval of relevant cases from the atlas. We also propose the use of mobile software agents for facilitating remote consultation of the atlas. Mobile agents can move between data sources such as the atlas and hospital repositories, perform computational tasks at each site, and return only relevant data to the user. These features reduce the computational requirements of the local computer system, bandwidth requirements, and overall network traffic. Proposed applications of the atlas include research, remote consultation, teaching, evaluation ofcad systems, and self-evaluation by radiologists. 相似文献