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排序方式: 共有272条查询结果,搜索用时 78 毫秒
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Fariba Zerafati Shoja Hudsa Majidian Leila Nikzad 《International Journal of Applied Ceramic Technology》2021,18(4):1174-1182
In the present work, particle arrangement and their packing in the sediment layer of zirconia suspension were studied. To evaluate the particle settling, aqueous suspensions of zirconia nanoparticles were prepared in different dispersion states. In one state, Dolapix CE64 was used as a dispersant to provide electrosteric mechanism. In another state, pH of the suspension was adjusted at 4 to provide electrostatic mechanism. The other state was the combination of dispersant and pH adjustment which resulted in the most stable suspension. First of all, the stability of all dispersion states was evaluated by zeta potential, sediment volume (SV) and height, viscosity, and packing density (PD). Then, the sediment layers of all suspensions were characterized. Incorporation of electrostatic mechanism was resulted in a main decrease in viscosity with high surface charges, while electrosteric mechanism caused lower sedimentation of particles. Fall velocities of particles/agglomerates were estimated, and the influences of dispersion states on the particles fall velocities were characterized. The microstructural observation revealed homogeneous packing of particles in the sediment layer of the stable suspension demonstrating the proper dispersion of particles. Dolapix CE64 and pH adjustment resulted in a uniform arrangement of particles without agglomeration and spherical and regular granules with a uniform shape. 相似文献
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M. Sheikholeslami F. Bani Sheykholeslami S. Khoshhal H. Mola-Abasia D. D. Ganji Houman B. Rokni 《Neural computing & applications》2014,25(1):171-178
Heat transfer of Cu–water nanofluid over a stretching cylinder in the presence of magnetic field has been investigated. The group method of data handling (GMDH) type neural networks (NNs) is used to calculate Nusselt number formulation. Results indicate that GMDH-type NN in comparison with fourth-order Runge–Kutta integration scheme provides an effective means of efficiently recognizing the patterns in data and accurately predicting a performance. The effects of nanoparticle volume fraction, magnetic parameter and Reynolds number on Nusselt number are studied by sensitivity analyses. The results show that Nusselt number is an increasing function of Reynolds number and volume fraction of nanoparticles while it is a decreasing function of magnetic parameter. As volume fraction of nanoparticles increases, the effect of this parameter on Nusselt number also increases, but opposite behavior is obtained for magnetic parameter and Reynolds number. 相似文献
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In this paper a novel MEMS tunable CPW antenna with wide tuning range of frequency is presented. The antenna’s frequency tuning range increment is achieved by loading three novel large tuning range capacitors at radiation edge of antenna patch. Two techniques are employed for increasing the capacitors tuning range. First, dual gap technique is used to overcome the pull-in limitation and then two lateral beams are added in order to parallel movement of capacitive plate which increases the capacitance value. The simulation result shows that the resonance frequency tuning range of antenna increased from 1.96 GHz loaded by traditional capacitor to 6.89 GHz using the new capacitor structure. Also in resonance frequency, the antenna has a good impedance matching with transmission line even in high capacitance values. 相似文献
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Fariba Takhtabnoos 《Inverse Problems in Science & Engineering》2018,26(11):1676-1694
In this paper, we consider coefficient inverse problems, which are associated with the identification of unknown time dependent control parameter and unknown solution of two-dimensional parabolic inverse problem with overspecialization at a point in the spatial domain. After suitable finite difference approximation of time variable, an MLPG method is used for spatial discretization. To improve the efficiency of the MLPG method, a greedy algorithm is used. In fact, using the greedy algorithm, we avoid using more points from the data site than absolutely necessary and therefore, the method becomes more efficient. Comparison of the different kind of point selection and the effect of noisy data are performed for four test problems while our last test problem considers a problem with unknown solution. The results reveal that the method is efficient. 相似文献
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In this paper, we have fabricated a new microphone using aluminum (Al) slotted perforated diaphragm and back plate electrode,
and photoresist (AZ1500) sacrificial layer on silicon wafer. The novelty of this method relies on aluminum diaphragm includes
some slots to reduce the effect of residual stress and stiffness of diaphragm for increasing the microphone sensitivity. The
acoustic holes are made on diaphragm to reduce the air damping, and avoid the disadvantages of non standard silicon processing
for making back chamber and holes in back plate, which are more complex and expensive. Photoresist sacrificial layer is easy
to deposition by spin coater and also easy to release by acetone. Moreover, acetone has a high selectivity to resist compared
to silicon oxide and Al, thus it completely removes sacrificial resist without incurring significant damage silicon oxide
and Al. The measured zero bias capacitance is 17.5 pF, and its pull-in voltage is 25 V. The microphone has been tested with
external amplifier and speaker, the external amplifier was able to detect the sound waves from microphone on speaker and oscilloscope.
The maximum amplitude of output speech signal of amplifier is 45 mV, and the maximum output of MEMS microphone is 1.125 μV. 相似文献
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M. Jalaal M.G. Nejad P. Jalili M. Esmaeilpour H. Bararnia E. Ghasemi Soheil Soleimani D.D. Ganji S.M. Moghimi 《Computers & Mathematics with Applications》2011,61(8):2267-2270
He’s homotopy perturbation method is applied to obtain exact analytical solutions for the motion of a spherical particle in a plane couette flow. It is demonstrated that the applied analytical method is very straightforward in comparison with existing techniques. Furthermore, it is decidedly effectual in terms of accuracy and rapid convergence. The formulation of the problem is presented in the text as well as the analytical and numerical procedures. The current results can be used in different areas of particulate flows. 相似文献