• Journal of applied mathematics & informatics
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• v.14 no.1_2
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• pp.289-303
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• 2004

The non-rigid molecule group theory (NRG) in which the dynamical symmetry operations are defined as physical operations is a new field of chemistry. Smeyers in a series of papers applied this notion to determine the character table of restricted NRG of some molecules. In this work, a simple method is described, by means of which it is possible to calculate character tables for the symmetry group of molecules consisting of a number of NH3 groups attached to a rigid framework. We study the full non-rigid group (f-NRG) of tetraammineplatinum(II) with two separate symmetry groups C2v and C4v. We prove that they are groups of order 216 and 5184 with 27 and 45 conjugacy classes, respectively. Also, we will compute the character tables of these groups.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1167-1182
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• 2015

In this study, the stresses and electric potential redistributions of a cylinder made from functionally graded piezoelectric material (FGPM) are investigated. All the mechanical, thermal and piezoelectric properties are modeled as power-law distribution of volume fraction. Using the coupled electro-thermo-mechanical relations, strain-displacement relations, Maxwell and equilibrium equations are obtained including the time dependent creep strains. Creep strains are time, temperature and stress dependent, the closed form solution cannot be found for this constitutive differential equation. A semi-analytical method in conjunction with the Mendelson method of successive approximation is therefore proposed for this analysis. Similar to the radial stress histories, electric potentials increase with time, because the latter is induced by the former during creep deformation of the cylinder, justifying industrial application of such a material as efficient actuators and sensors.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.398-404
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• 2008

A new solvent polymeric membrane electrode, based on N,N'-bis(salicylidene)-2,2-dimethylpropane-1,3-diamine Ni(II) as the ionophore, was designed. The oxalate-selective electrode has the dynamic range between 1.0 10-6 M and 1.0 10-1 M with a Nernstian slope of -28.7 1.0 mV per decade. The detection limit was 6.3 10-7 M. The proposed electrode revealed good selectivities for oxalate over a variety of other anions and could be used in a pH range of 2.0-7.8. The electrode can be used for at least two months without any considerable divergence in potential. The designed electrode was applied as an indicator electrode in the potentiometric determination of oxalate in real samples.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1715-1718
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• 2009

A series of sitting-atop (SAT) complexes, [(ZrO)$H_2t(X)pp(NO_3)_2$], have been prepared via the reactions of free base meso-tetraarylporphyrins, $H_2$t(X)pp, with zirconyl nitrate hydrate, ZrO(N$O_3)_2{\cdot}xH_2$O. The products have been characterized by a variety of methods including $^1H\;NMR,\;^{13}C$ NMR, IR and UV-Vis spectroscopies, elemental analysis and conductance measurements. The data indicate that the meso-tetraarylporphyrins coordinate with two pyrrolenine nitrogen atoms to the zirconyl cation located above the distorted porphyrin plane and two protons remain on the pyrrole nitrogens. Such half sandwich-type sitting-atop complexes may be considered as models for the initial steps of the metallation of the macrocycles.

• Kyungpook Mathematical Journal
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• v.60 no.3
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• pp.467-475
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• 2020

Let G be a chemical graph with vertex set {v₁, v₁, …, v_n} and degree sequence d(G) = (deg_G(v₁), deg_G(v₂), …, deg_G(v_n)). The inverse degree, R(G) of G is defined as $R(G)={\sum{_{i=1}^{n}}}\;{\frac{1}{deg_G(v_i)}}$. The cyclomatic number of G is defined as γ = m - n + k, where m, n and k are the number of edges, vertices and components of G, respectively. In this paper, some upper bounds on the diameter of a chemical graph in terms of its inverse degree are given. We also obtain an ordering of connected chemical graphs with respect to the inverse degree.

• Computers and Concrete
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• v.22 no.2
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• pp.239-248
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• 2018

TBM penetration rate is a function of intact rock properties, rock mass conditions and TBM operational parameters. Machine rate of penetrationcan be predicted by knowledge of the ground conditions and its effects on machine performance. The variation of TBM operational parameters such as penetration rate and thrust plays an important role in its performance. This study presents the results of the analysis on the TBM penetration rates in schistose rock types present along the alignment of Golab tunnel based on the analysis of a TBM performance database established for every stroke through different schistose rock types. The results of the analysis are compared to the results of some empirical and theoretical predictive models such as NTH and QTBM. Additional analysis was performed to find the optimum thrust and revolution per minute values for different schistose rock types.

• Steel and Composite Structures
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• v.28 no.2
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• pp.149-165
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• 2018

Using the modified couple stress theory and Euler-Bernoulli beam theory, this paper studies nonlinear vibration analysis of microbeams resting on the nonlinear orthotropic visco-Pasternak foundation. Using the Hamilton's principle, the set of the governing equations are derived and solved numerically using differential quadrature method (DQM), Newark beta method and arc-length technique for all kind of the boundary conditions. First convergence and accuracy of the presented solution are demonstrated and then effects of radius of gyration, Poisson's ratio, small scale parameters, temperature changes and coefficients of the foundation on the linear and nonlinear natural frequencies and dynamic response of the microbeam are investigated.

• Computers and Concrete
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• v.24 no.6
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• pp.499-511
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• 2019

In this paper, wave propagation of double-bonded Cooper-Naghdi micro sandwich cylindrical shells with porous core and carbon nanotube reinforced composite (CNTRC) face sheets are investigated subjected to multi-physical loadings with temperature dependent material properties. The governing equations of motion are derived by Hamilton's principle. Then, the influences of various parameters such as wave number, CNT volume fraction, temperature change, Skempton coefficient, material length scale parameter, porosity coefficient on the phase velocity of double-bonded micro sandwich shell are taken into account. It is seen that by increasing of Skempton coefficient, the phase velocity decreases for higher wave number and the results become approximately the constant. Also, by increasing of the material length scale parameter, the cut of frequency increases, because the stiffness of micro structure increases. The obtained results for this article can be used to detect, locate and quantify crack.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.212-220
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• 2012

In the current paper, the optimization shape of a polysilicon variable-capacitance micromotor (VCM) was determined using the seeker optimization algorithm (SOA). The optimum goal of the algorithm was to find the maximum torque value and minimum ripple torque by varying the geometrical parameters. The optimization process was performed using a combination of SOA and the finite-element method (FEM). The fitness value was calculated via FEM analysis using COMSOL3.4, and SOA was realized by MATLAB7.4. The proposed method was applied to a VCM with eight and six poles at the stator and rotor, respectively. For comparison, this optimization was also performed using the genetic algorithm. The results show that the optimized micromotor using SOA had a higher torque value and lower torque ripple, indicating the validity of this methodology for VCM design.

• Structural Engineering and Mechanics
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• v.71 no.5
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• pp.459-467
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• 2019

In this paper, hyperbolic shear deformation theory is used for free vibration analysis of piezoelectric rectangular plate made of porous core. Various types of porosity distributions for the porous material is used. To obtain governing equations of motion, Hamilton's principle is used. The Navier's method is used to obtain numerical results of the problem in terms of significant parameters. One can conclude that free vibration responses are changed significantly with change of important parameters such as various porosities and dimensionless geometric parameters such as thickness to side length ratio and ratio of side lengths.