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51.
D. Hanifeh Toubestani M. Ghoranneviss A. Mahmoodi M. Rahbar Zareh 《Macromolecular Symposia》2010,287(1):143-147
Summary: We report mass production of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) with relatively high length and aspect ratio. We synthesized carbon nanomaterials by chemical vapor deposition (CVD) of methane as the feeding gas on Fe/Mo nanoparticles that use alumina-aerogel support. Alumina-aerogel-supported Fe/Mo catalyst was prepared using sol-gel. Drying step performed using rotary evaporation and freeze-drying. CVD was performed using a quartz tube furnace. Samples were analyzed using scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Raman spectroscopy. 相似文献
52.
Aidin Delnavaz S. Nima Mahmoodi Nader Jalili Hassan Zohoor 《International Journal of Non》2010,45(2):176-185
Despite their simple structure and design, microcantilevers are receiving increased attention due to their unique sensing and actuation features in many MEMS and NEMS. Along this line, a non-linear distributed-parameters modeling of a microcantilever beam under the influence of a nanoparticle sample is studied in this paper. A long-range Van der Waals force model is utilized to describe the microcantilever-particle interaction along with an inextensibility condition for the microcantilever in order to derive the equations of motion in terms of only one generalized coordinate. Both of these considerations impose strong nonlinearities on the resultant integro-partial equations of motion. In order to provide an understanding of non-linear characteristics of combined microcantilever-particle system, a geometrical function is wisely chosen in such a way that natural frequency of the linear model exactly equates with that of non-linear model. It is shown that both approaches are reasonably comparable for the system considered here. Linear and non-linear equations of motion are then investigated extensively in both frequency and time domains. The simulation results demonstrate that the particle attraction region can be obtained through studying natural frequency of the system consisting of microcantilever and particle. The frequency analysis also proves that the influence of nonlinearities is amplified inside the particle attraction region through bending or shifting the frequency response curves. This is accompanied by sudden changes in the vibration amplitude estimated very closely by the non-linear model, while it cannot be predicted by the best linear model at all. 相似文献
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54.
Alinezhad Heshmatollah Vafaeezadeh Majid Mahmoodi Hashemi Mohammad 《Research on Chemical Intermediates》2017,43(4):2615-2625
Research on Chemical Intermediates - A metal-free method for activation of hydrogen peroxide (H2O2) is introduced using piperidinium trifluoroacetate (PPHTFA) ionic liquid as catalyst. The catalyst... 相似文献
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57.
Hossein Mahmoodi Darian Vahid Esfahanian Kazem Hejranfar 《Journal of computational physics》2011,230(3):494-514
A new shock-detecting sensor for properly switching between a second-order and a higher-order filter is developed and assessed. The sensor is designed based on an order analysis. The nonlinear filter with the proposed sensor ensures damping of the high-frequency waves in smooth regions and at the same time removes the Gibbs oscillations around the discontinuities when using high-order compact finite difference schemes. In addition, a suitable scaling is proposed to have dissipation proportional to the shock strength and also to minimize the effects of the second-order filter on the very small scales. Several numerical experiments are carried out and the accuracy of the nonlinear filter with the proposed sensor is examined. In addition, some comparisons with other filters and sensors are made. 相似文献
58.
Mahmoodi Nosrat O. Zeydi Masoud Mohammadi Mamaghani Manouchehr Montazeri Naser 《Research on Chemical Intermediates》2017,43(4):2641-2651
Research on Chemical Intermediates - A series of new thiocarbamoyl tris-pyrazoline (tripod pyrazoline with triazine core) compounds was obtained by tris-cyclization of chalcone with... 相似文献
59.
S.N. Mahmoodi S.E. Khadem N. Jalili 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,75(2-3):153-163
The nonlinear equations of motion of planar bending vibration of an inextensible viscoelastic carbon nanotube (CNT)-reinforced
cantilevered beam are derived. The viscoelastic model in this analysis is taken to be the Kelvin–Voigt model. The Hamilton
principle is employed to derive the nonlinear equations of motion of the cantilever beam vibrations. The nonlinear part of
the equations of motion consists of cubic nonlinearity in inertia, damping, and stiffness terms. In order to study the response
of the system, the method of multiple scales is applied to the nonlinear equations of motion. The solution of the equations
of motion is derived for the case of primary resonance, considering that the beam is vibrating due to a direct excitation.
Using the properties of a CNT-reinforced composite beam prototype, the results for the vibrations of the system are theoretically
and experimentally obtained and compared. 相似文献
60.
In this paper, electron beam (e-beam) reduction method is applied for the catalyst layer preparation in the growth of carbon nanotubes (CNTs). A hot cathodic electron beam facility was employed to electron bombarding of catalyst layer before stage of CNTs growth. This new method leads to reducing the diameter of particles via sputtering and evaporating the surface of catalyst. The growth of CNTs was performed on the Fe catalyst layer with SiO2 substrate in an environment of different mixed gases (H2, NH3 and C2H2) by thermal chemical vapor deposition (TCVD) system. The morphology of the electron beam reduced catalyst particles were probed by atomic force microscopy (AFM). All samples were analyzed by scanning electron microscopy (SEM) before and after growth of CNTs. SEM analyses clarified that the catalyst grains have been smaller under effect of electron beam bombardment. 相似文献