Sharif Digital Repository

In this paper, the influence of the excitation angle on the Endurance Time (TCT) analysis of skewed slab-on-girdcr bridges is studied. The excitation of the structure due to the critical angle produces maximum seismic responses that are sometimes significantly higher than the average. The modeled bridges are of slab-on-girder type that are typically used as highway bridges. The bridge models have skew angles of 0, 15, 30, 45, and CO degrees. The ET excitations exerted on structures cover a broad range of hazard levels. The results provide some insight with regard to choosing multiple excitation angles so as to balance computational costs and retain acceptable accuracy for practical design... 

We study the metal-insulator transition of the one-dimensional diagonal Anderson ternary model with long range correlated disorder. The starting point of the model corresponds to a ternary alloy (i.e. with three possible on-site energies), and shows a metal-insulator transition when the random distribution of site energies is assumed to have a power spectrum S(k) ∝ 1/k (2α-1). In this paper, we define a purity parameter for the ternary alloy which adjusts the occupancy probability of site potentials, and for any given α we calculate the critical purity parameter for which extended states are obtained. In this way, we show that the ternary alloy requires weaker correlations than the binary... 

Molybdenum(VI)–oxodiperoxo complex containing an oxazine ligand, ([MoO(O2)2(phox)], phox: 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine) was conveniently synthesized and immobilized onto chloro-functionalized mesoporous silica SBA-15 by covalent bonding between the chloropropyl group on the internal surface of the pores and the nitrogen atom of oxazine ligand yielding [MoO(O2)2(phox)]/SBA-15. The resulting material was characterized by FT-IR, TGA, XRD, SEM, TEM, EDX, ICP-AES, BET and UV–vis spectroscopy. The heterogeneous catalyst [MoO(O2)2(phox)]/SBA-15 was employed in the epoxidation of alkenes, exhibiting high catalytic performance and selectivity for epoxide similar to that of homogeneous... 

We study the metal–insulator transition in one-dimensional Anderson binary alloy with long-range disordered hopping integrals and on-site energies using the transfer matrix method. In this model, the on-site energies and hopping integrals are distributed randomly with long-range correlations characterized by power spectrum of the type (Formula presented.), with different exponents (Formula presented.) and (Formula presented.), respectively. We determine the critical value of long-range correlation exponent of hopping integral (Formula presented.) in the presence of only off-diagonal disorder in which the transition from localized to extended states occurs in thermodynamic limit. When both of... 

We study the electronic properties of superlattice with rough interfaces in two and three dimensions using the transfer-matrix method and direct diagonalization of the Anderson Hamiltonian. The system consists of layers with an average constant width, but with stochastic roughness added to the interfaces between the layers. The numerical results indicate that, in the thermodynamic limit, the two-dimensional superlattice is an insulator in the presence of even small roughness. In three-dimensional systems, however, the superlattice exhibits a metal-insulator transition with a well-defined mobility edge located at an energy E c that we compute numerically. For three-dimensional superlattice,... 

We study the metal-insulator transition in one-dimensional Anderson binary alloy with long-range disordered hopping integrals and on-site energies using the transfer matrix method. In this model, the on-site energies and hopping integrals are distributed randomly with long-range correlations characterized by power spectrum of the type S(k)∝1/k(2α-1), with different exponents αε and αt, respectively. We determine the critical value of long-range correlation exponent of hopping integral in the presence of only off-diagonal disorder in which the transition from localized to extended states occurs in thermodynamic limit. When both of the on-site energies and hopping... 

The electronic transmission and conductance of a gapped graphene superlattice were calculated by means of the transfer-matrix method. The system that we study consists of a sequence of electron-doped graphene as wells and hole-doped graphene as barriers. We show that the transmission probability approaches unity at some critical value of the gap. We also find that there is a domain around the critical gap value for which the conductance of the system attains its maximum value  

We study the electronic properties of disordered GaAs- Alx Ga1-x As semiconductor superlattices with structural long-range correlations. The system consists of quantum barriers and wells with different thicknesses and heights which fluctuate around their mean values randomly, following a long-range correlated pattern of fractal type characterized by a power spectrum of the type S (k) 1 k (2α-1), where the exponent α quantifies the strength of the long-range correlations. For a given system size, we find a critical value of the exponent α (αc) for which a metal-insulator transition appears: for α< αc all the states are localized, and for α> αc, we find a continuous band of extended states. We... 

Propagation of acoustic waves in the one-dimensional (1D) random-dimer (RD) medium is studied by three distinct methods. First, using the transfer-matrix method, we calculate numerically the localization length ξ of acoustic waves in a binary chain (one in which the elastic constants take on one of two values). We show that when there exists short-range correlation in the medium-which corresponds to the RD model-the localization-delocalization transition occurs at a resonance frequency ωc. The divergence of ξ near ωc is studied, and the critical exponents that characterize the power-law behavior of ξ near ωc are estimated for the regimes ω> ωc and ω< ωc. Second, an exact analytical analysis... 

Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network... 

This book focuses on a central question in the field of complex systems: Given a fluctuating (in time or space), uni- or multi-variant sequentially measured set of experimental data (even noisy data), how should one analyse non-parametrically the data, assess underlying trends, uncover characteristics of the fluctuations (including diffusion and jump contributions), and construct a stochastic evolution equation?
Here, the term "non-parametrically" exemplifies that all the functions and parameters of the constructed stochastic evolution equation can be determined directly from the measured data.
The book provides an overview of methods that have been developed for the analysis of... 

Consider the parameter Λ(G) = |E(G)| - |V(G)|(k - 1) + (k2) for a k-chromatic graph G, on the set of vertices V(G) and with the set of edges E(G). It is known that Λ(G)≥0 for any k-chromatic uniquely vertex-colourable graph G (k-UCG), and, S.J. Xu has conjectured that for any k-UCG, G, Λ(G) = 0 implies that cl(G) = k; in which cl(G) is the clique number of G. In this paper, first, we introduce the concept of the core of a k-UCG as an induced subgraph without any colour-class of size one, and without any vertex of degree k - 1. Considering (k, n)-cores as k-UCGs on n vertices, we show that edge-minimal (k, 2k)-cores do not exist when k ≥ 3, which shows that for any edge-minimal k-UCG on 2k...