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21.
根据电镜断面考察结果,以Gurson模型为本构方程的有限单元
法对包体模型及三维非均匀模型进行了详细分析. 为了评价应力-应变
关系及损伤的主要因素,考虑了基体中SiC粒子的体积率和径比的非均
匀分布. 其结果表明,用这种非均匀模型能很好地仿真铝基体在大量塑
性变形之后所发生的韧窝破坏过程. SiC粒子体积率、径比及其位置的
非均匀性,对局部和整体损伤过程与应力-应变关系的影响相当大. 当
Sic粒子径比为1.0,并在基体中均匀分布时,断裂应变会大幅度增大. 相似文献
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24.
Hassan Keypour Musa AhmadiMajid Rezaeivala Abdolkarim ChehreganiReza Golbedaghi Allan G. Blackman 《Polyhedron》2011,30(11):1865-1870
Two new branched pentadentate amines (N5), 3,7-bis(2-pyridylmethyl)-5,5-dimethyl-3,7-diazaheptane-1-amine (1) and 4,8-bis(2-pyridylmethyl)-6,6-dimethyl-4,8-diaza octane-1-amine (2) have been prepared. These have been used to synthesis two new Schiff base complexes containing a pyridine and 2-pyridylmethyl pendant arm, by template [1+1] condensation of pyridine-2-carbaldehyde with the amines in the presence of Mn(II) in methanol. Elemental and spectral results are used to characterize the complexes and their structures are confirmed by single crystal X-ray diffraction studies. The structure of MnL1(ClO4)2 indicates that in the solid state the Mn(II) ion adopts a slightly distorted octahedral geometry. The crystal structure of [Ni(1)(MeCN)](ClO4)2 is also reported and exhibits a slightly distorted octahedral geometry. Also the synthesized complexes were screened for their antibacterial activity against Escherichia coli (Lio), Serratia marcescens (PTCC 1330), Staphylococcous aureus (ATCC 6633), and Proteus vulgaris (Lio) and results showed that the all complexes have antibacterial effects and [NiL1](ClO4)2, [MnL2](ClO4) and [MnL1](ClO4)2 have more effective ones against E. coli. 相似文献
25.
Seventeen compounds, including a new lanostane triterpenoid, 24(Z)-1β-3β-dihydroxyeupha-7,24-dien-26-oic acid, have been isolated from the methanolic extracts of two samples of Jordanian propolis collected from two different places with different dominant flora. The structures of the isolated compounds were elucidated by spectral methods including IR, UV, MS and 1- and 2-D NMR. 相似文献
26.
Davenport JR Musa OM Paterson MJ Piepenbrock MO Fucke K Steed JW 《Chemical communications (Cambridge, England)》2011,47(35):9891-9893
A dimeric model compound gives structural insight into the mode of interaction of low dosage hydrate inhibitors with water. 相似文献
27.
New coumarin derivatives, namely 7-[(5-amino-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one, 5-[(2-oxo-2H-chromen-7-yloxy)methyl]-1,3,4-thiadiazol-2(3H)-one, 2-[2-(2-oxo-2H-chromen-7-yloxy)acetyl]-N-phenylhydrazinecarbothioamide, 7-[(5-(phenylamino)-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one and 7-[(5-mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methoxy]-2H-chromen-2-one were prepared starting from the natural compound umbelliferone. The newly synthesized compounds were characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR). 相似文献
28.
Alexey Kuznetsov Musa Mammadov Ibrahim Sultan Eldar Hajilarov 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(10):1427-1437
In this paper, we analyze an improved suspension system with the incorporated inerter device of the quarter-car model to obtain
optimal design parameters for maximum comfort level for a driver and passengers. That is achieved by finding the analytical
solution for the system of ordinary differential equations, which enables us to generate an optimization problem whose objective
function is based on the international standards of admissible acceleration levels (ISO 2631-1, Mechanical Vibration and Shock—Evaluation
of Human Exposure to Whole-Body Vibration–Part 1, 1997). The considered approach ensures the highest level of comfort for the driver and passengers due to a favorable reduction
in body vibrations. Numerical examples, based on actually measured road profiles, are presented at the end of the paper to
prove the validity of the proposed approach and its suitability for the problem at hand. 相似文献
29.
The possibility to build a high power copper laser using a new type of discharge – heated cathode discharge in the copper vapours continuously evaporated from a melted spot on the anode surface is analysed. From the experimental data on this new discharge type, the equivalent pressure of the copper atoms in the discharge space has been obtained. This pressure can be as high as 1 torr. The density of the power in the discharge volume is evaluated to be more than 1 kW/cm3. 相似文献
30.
Disposal of untreated industrial effluents is drastically deteriorating the quality of underground water. Research work has been conducted to analyze the effect of disposal of urea plant effluent on the quality of ground water of the District Mianwali Daudkhail, Pakistan. For this purpose the effluent and ground water samples were analyzed for pH, TDS, TSS, Cl, F, COD, BOD, Fe, Zn, Pb, Cu, Cr, Cd, Mn, and As. Results obtained were compared with WHO and NEQS standards for drinking and effluent emission limits, respectively. Moreover, effluent samples were also evaluated for irrigation purposes and results compared with criteria recommended for irrigation water. Results showed though the effluents were according to the standards given by National Environmental Quality Standards (NEQS) for liquid emission and fit for irrigation purposes, the quality of underground water was below standard due to having a higher quantity of total dissolved solids than permissible. 相似文献