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2014  (Vol. 4, No. 2)

Beam-Like Instability of Carbon Nanotubes Conveying Fluid Based On Molecular Structural Mechanics Approach


H.R. Ali-Akbari, H. Haddadpour, R.D. Firouz-Abadi

Corresponding Author: H.R. Ali-Akbari

Vol. 4 (2), 21-37


In this paper, the instability analysis of single-walled carbon nanotubes (SWCNTs) conveying fluid is investigated based on the molecular structural mechanics (MSM). The structural displacements of SWCNTs are modeled via modal expansion technique. The lowest beam-like mode shapes and their corresponding natural frequencies are used in the modal expansion series. The MSM approach is applied to model the atomistic configuration of SWCNTs and this model is taken part in modal analysis to drive the mode shapes and natural frequencies. In this model, the effect of chirality on flow-induced instability of SWCNTs is taken into account. The results show that the dynamic behavior of SWCNTs conveying fluid is significantly depended on the small-scale effect, but, the effect of chirality is negligible. Besides, the results are compared with nonlocal beam theory represented in the literature and the suitable values for the nonlocal parameter e0a are obtained to adopt this model with the MSM model of SWCNTs. [[PASTING TABLES IS NOT SUPPORTED]]

10 Apr 2014
 08 Jul 2014

High Frequency Thermosonic Wire Bonding 

V. L. Lanin, I. B. Petuchov

Corresponding Author: V. L. Lanin

Vol. 4 (2), 39-45


Processes of thermosonic wire bonding of gold and copper wire at low temperature with using high frequency ultrasonic system are discussed. The vibration characteristics of ultrasonic system are modeling by finite element method and analyzed using laser beam. It was found there is robust bond copper wire to Au and Ni pads at temperature 80-100 ºC by increasing bond time and decreasing ultrasonic power without cover gas. Reliability of bonds gold and copper wire to samples with different micro hardness was investigated. Improved Au and Cu wire bonding process was achieved by concurrent measurement of wire deformation and contact resistance dynamic. Use of the raised US frequency in comparison with standard frequency (66 kHz) allows joining of conductors at temperature of heating of a product 100–180°С. The maximum durability of microconnections 10–12 H is reached on frequency 94 kHz for 20 msec at heating temperature 120ºС. 

10 Jun 2014
  11 Jul 2014

Fabrication of Dye-sensitized Solar Cells By Using Raspberry Extract

Hamidreza Akbarzadegan, Arezoo Jamshidi Rad

Corresponding Author: H. Akbarzadegan

Vol. 4 (2), 47-51


Throughout the world, people are increasingly realizing that the era of cheap fossil fuel is ending soon; yet, the need for energy is growing. So, looking for new energy sources that are sustainable and biocompatible to replace fossil fuel is of utmost urgency. Among the possible sources solar energy has a special place because of its low cost and lack of pollution. Today, dye-sensitized solar cells have attracted much attention because of their low cost. In this project solar cells based on titania and in the size of 2.5 × 2.5 cms were made by using natural dye. XRD machine and SEM microscopy were used to analyze samples. Accordingly, the average particle size was 18 nm and the deposited titanium dioxide nanoparticles were in anatase phase. The open circuit voltage was 17.23 mA, and the short-circuit current was o.67 V and efficiency was almost 7 %.

21 Jun 2014
3 Aug 2014