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SOME NEW RESULTS ON IRREGULARITY OF GRAPHS
Tavakoli, M.,Rahbarnia, F.,Ashra, A.R. The Korean Society for Computational and Applied M 2014 Journal of applied mathematics & informatics Vol.32 No.5
Suppose G is a simple graph. The irregularity of G, irr(G), is the summation of imb(e) over all edges $uv=e{\in}G$, where imb(e) = |deg(u)-deg(v)|. In this paper, we investigate the behavior of this graph parameter under some old and new graph operations.
A. Shadlaghani,M. R. Tavakoli,M. Farzaneh,M. R. Salimpour 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
This study aimed at determining a suitable pattern to allow for a better design of the fins used in heat sinks. Flow was considered laminar and steady, and the studied heat transfer mechanism was forced convection. Considering a fixed fin volume, the shape of fin cross section and its dimensions were optimized to maximize the heat transfer rate in a given physical condition. Numerical results showed that at a constant fin base area, heat transfer rate was higher in a fin with a triangular cross section compared to the fins with rectangular or trapezoidal cross sections. Investigation of optimum dimensional ratio in triangular fins showed that an increased height/thickness ratio enhanced the heat transfer rate. The effect of vertical position of the longitudinal perforations with different cross sections but similar volume ratios on the thermal performance of triangular fins was also examined. Results showed that perforation enhanced the thermal performance of the fins. Perforations with square and circular cross sections had almost identical thermal performances and dissipated more heat compared to those with triangular perforations.
Site effect microzonation of Babol, Iran
Tavakoli, H.R.,Amiri, M. Talebzade,Abdollahzade, G.,Janalizade, A. Techno-Press 2016 Geomechanics & engineering Vol.11 No.6
Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.
Development of the Performance Based Plastic Design for Steel Moment Resistant Frame
M. Reza Banihashemi,A. R Mirzagoltabar,H. R Tavakoli 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.1
This paper presents the development of performance based plastic design (PBPD) method for steel moment frames withconsidering the gravity loads and P-Δ effects. In this method the design lateral forces are obtained from energy-work balanceequation by using pre-selected target drift and yield mechanism. For further improvement of PBPD method, some solutions arerepresented to precisely obtain the required moment of columns in order to prevent their yielding that leads to form undesirablemechanisms in the structure. In order to show more validity of PBPD method, two model frames, 5 and 10story, are designedbased on PBPD as well as elastic design method. The mentioned frames are evaluated by extensive nonlinear static pushoveranalysis and dynamic analysis. The results show that the frames designed by PBPD method reach the intended performanceobjectives in terms of yield mechanism and target drift levels. In contrast, the frame designed by Ed method experience largestory drifts due to flexural yielding of the columns. Since PBPD method is a direct design method, little or no evaluation areneeded after the initial design because the nonlinear behavior is built into the design process from the start.
REMARKS ON THE INNER POWER OF GRAPHS
S. JAFARI,A.R. ASHRAFI,G.H. FATH-TABAR,M. TAVAKOLI 한국전산응용수학회 2017 Journal of applied mathematics & informatics Vol.35 No.1
Let G be a graph and k is a positive integer. Hammack and Livesay in [The inner power of a graph, Ars Math. Contemp., 3 (2010), no. 2, 193{199] introduced a new graph operation G(k), called the kth inner power of G. In this paper, it is proved that if G is bipartite then G(2) has exactly three components such that one of them is bipartite and two others are isomorphic. As a consequence the edge frustration index of G(2) is computed based on the same values as for the original graph G. We also compute the rst and second Zagreb indices and coindices of G(2).