Sharif Digital Repository

Shape memory polymers (SMPs) are a class of smart materials which can recover their shape even after many shape changes in application of an external stimulus. In this paper, flexural behavior of a composite beam, constructed of a corrugated part filled with SMPs, is studied. This composite beam is applicable in sensor and actuator applications. Since the corrugated profiles display higher stiffness-to-mass ratio in the transverse to the corrugation direction, the beams with a corrugated part along the transverse direction are stiffer than ones with a corrugated part along the length. Employing a developed constitutive model for SMPs and the Euler–Bernoulli beam theory, the behavior of the... 

Let G = {g1,...,gn} be a finite abelian group. Consider the complete graph with the vertex set {g1.....,.....g n}. The G-coloring of Kn is a proper edge coloring in which the color of edge {gi,gj} gi g i + gj, 1 ≤ i < 3 ≤ n. We prove that in the G-coloring of the complete graph Kn, there exists a multicolored Hamilton path if G is not an elementary abelian 2-group. Furthermore, we show that if n is odd, then the G-coloring of Kn can be decomposed into multicolored 2-factors and there are exactly lr/2 multicolored r-uniform 2-factors in this decomposition where lr is the number of elements of order r in G, 3 ≤ r ≤ n. This provides a generalization of a recent result due to Constantine which... 

On-chip interconnections play an important role in multi/many-processor systems-on-chip (MPSoCs). In order to achieve efficient optimization, each specific application must utilize a specific architecture, and consequently a specific interconnection network. For design space exploration and finding the best NoC solution for each specific application, a fast and flexible NoC simulator is necessary, especially for large design spaces. In this paper, we present an FPGA-based NoC co-simulator, which is able to be configured via software. In our proposed NoC simulator, entitled DuCNoC, we implement a Dual-Clock router micro-architecture, which demonstrates 75x-350x speed-up against BOOKSIM.... 

Freezing of gait (FOG) is a debilitating symptom in patients with Parkinson's disease (PD), which may be associated with motor control impairments in tasks other than gait. This study aimed to examine whether symmetric and asymmetric bimanual coordination is impaired in PD with FOG (PD +FOG) patients and whether dual-task and drug phases may affect bimanual coordination in these patients. Twenty PD +FOG patients, 20 PD patients without FOG (PD –FOG) performed symmetric and asymmetric functional bimanual tasks (reach to and pick up a box and open a drawer to press a pushbutton inside it, respectively) under single-task and dual-task conditions. PD patients were evaluated during on- and... 

For every natural number h, a graph G is said to be h-magic if there exists a labelling l:E(G)→Zh{0} such that the induced vertex set labelling l+:V(G)→Zh defined byl+(v)=∑uv∈E(G)l(uv), is a constant map. When this constant is zero, it is said that G admits a zero-sum h-magic labelling. The null set of a graph G, denoted by N(G), is the set of all natural numbers h∈N such that G admits an h-zero-sum magic labelling. In 2007, E. Salehi determined the null set of complete bipartite graphs. In this paper we generalize this result by obtaining the null set of complete multipartite graphs  

Let R be a commutative ring with unity. The cozero-divisor graph of R, denoted by Γ′(R), is a graph with vertex set W*(R), where W*(R) is the set of all nonzero and nonunit elements of R, and two distinct vertices a and b are adjacent if and only if a ∉ Rb and b ∉ Ra, where Rc is the ideal generated by the element c in R. Recently, it has been proved that for every nonlocal finite ring R, Γ′(R) is a unicyclic graph if and only if R ≅ ℤ2 × ℤ4, ℤ3 × ℤ3, ℤ2 × ℤ2[x]/(x 2). We generalize the aforementioned result by showing that for every commutative ring R, Γ′(R) is a unicyclic graph if and only if R ≅ ℤ2 × ℤ4, ℤ3 × ℤ3, ℤ2 × ℤ2[x]/(x 2), ℤ2[x, y]/(x, y)2, ℤ4[x]/(2x, x 2). We prove that for every... 

Let R be a commutative ring with unity. The cozero-divisor graph of R denoted by Γ'(R) is a graph with the vertex set W*(R), where W*(R) is the set of all nonzero and non-unit elements of R, and two distinct vertices a and b are adjacent if and only if a ∉ Rb and b ∉ Ra, where Rc is the ideal generated by the element c in R. Let α(Γ'(R)) and γ(Γ'(R)) denote the independence number and the domination number of Γ'(R), respectively. In this paper, we prove that if α(Γ'(R)) is finite, then R is Artinian if and only if R is Noetherian. Also, we prove that if α(Γ'(R)) is finite, then R/P is finite, for every prime ideal P. Moreover, we prove that if R is a Noetherian ring, γ(Γ'(R)) is finite and... 

Let R be a commutative ring with unity. The cozero-divisor graph of R denoted by Γ′(R) is a graph with the vertex set W*-(R), where W*-(R) is the set of all nonzero and non-unit elements of R, and two distinct vertices a and b are adjacent if and only if a*‰Rb and b*‰Ra. Let ω(Γ′(R)) and χ(Γ′(R)) denote the clique number and the chromatic number of Γ′(R), respectively. In this paper, we prove that if R is a finite commutative ring, then Γ′(R) is perfect. Also, we prove that if R is a commutative Artinian non-local ring and ω(Γ′(R)) is finite, then χ(Γ′(R)) = ω(Γ′(R)). For Artinian local ring, we obtain an upper bound for the chromatic number of cozero-divisor graph. Among other results, we... 

Let 1 < ti < t2 < ••• < th < n. A Toeplitz graph G = (V,E) denoted by Tn(tiy ..., f) is a graph where V = {1,. .. ,n} and E = {(m) I i-JI. • • >}}•this paper, we classify all regular Toeplitz graphs. Here, we present some conditions under which a Toeplitz graph has no cut-edge and cut-vertex  

The α-FAPbI3 perovskite nanocrystals exhibit interesting optical properties, which make them attractive for versatile optoelectronic applications; however, the spontaneous phase transformation to the non-perovskite phase (δ-FAPbI3) in humid conditions requires a new strategy to improve the phase stability of the material. We employed 3-Aminopropyl triethoxysilane (APTES)-assisted reprecipitation and sol-gel methods at ambient temperature to prepare stable α-FAPbI3 nanocrystals embedded in a silica matrix. Transmission electron microscopy (TEM) and X-ray diffraction analysis determined that ultrafine perovskite nanocrystals (11.5 ± 3 nm) were uniformly distributed in a silica matrix.... 

The energy of a graph G, denoted by E(G), is defined as the sum of absolute values of all eigenvalues of G. A graph of order n, whose energy is less than n, i.e., E(G) < n, is said to be hypoenergetic. Graphs for which E(G) ≥ n are called non-hypoenergetic. A graph of order n is said to be orderenergetic, if its energy and its order are equal, i.e., E(G) = n. In this paper, we characterize non-hypoenergetic graphs with nullity 2. It is proved that except two graphs, every connected graph with nullity 2 is non-hypoenergetic. © 2021 University of Kragujevac, Faculty of Science. All rights reserved  

We study graphs whose adjacency matrices have determinant equal to 1 or -1, and characterize certain subclasses of these graphs. Graphs whose adjacency matrices are totally unimodular are also characterized. For bipartite graphs having a unique perfect matching, we provide a formula for the inverse of the corresponding adjacency matrix, and address the problem of when that inverse is diagonally similar to a nonnegative matrix. Special attention is paid to the case that such a graph is unicyclic. © 2006 Elsevier Inc. All rights reserved  

The energy of a graph G, denoted by E(G), is defined as the sum of absolute values of all eigenvalues of G. A graph of order n, whose energy is less than n, i.e., E(G) < n, is said to be hypoenergetic. Graphs for which E(G) ≥ n are called non-hypoenergetic. A graph of order n is said to be orderenergetic, if its energy and its order are equal, i.e., E(G) = n. In this paper, we characterize non-hypoenergetic graphs with nullity 2. It is proved that except two graphs, every connected graph with nullity 2 is non-hypoenergetic. © 2021 University of Kragujevac, Faculty of Science. All rights reserved  

Wireless networks with the shared media require Medium Access Control (MAC) protocol that provides contention resolution mechanism. The design of MAC protocol in underwater sensor networks is a challenging issue because of limited energy source and high propagation delay. The most important goal of the MAC design for underwater sensor networks is to resolve data packet collision efficiently with respect to energy consumption. So, selection of MAC protocol is an important task because it has significant impact on the system efficiency. A suitable MAC protocol must consider some factors such as fairness, energy consumption, latency and throughput based on various applications. The bandwidth in... 

Clay liners are widely used as porous membrane barriers to control solute transport and to prevent the leakage of leachate both in horizontal and vertical flow scenarios, such as the isolated base and ramps of sanitary landfills. Despite the primary importance of saturated hydraulic conductivity in a reliable simulation of fluid flow through clay barriers, there is no model to predict hydraulic conductivity of clayey soils permeated with saline aqueous solutions because most of the current models were developed for pure water. Therefore, the main motivation behind this study is to derive semi-empirical models for simulating the hydraulic conductivity of clayey soils in the presence of... 

Solid waste is often buried in landfills isolated with a bentonite-based clay barrier to guarantee the high quality of groundwater. As the efficiency of clay barriers is highly dependent on solute concentration, this study aims to modify membrane efficiency, effective diffusion, and hydraulic conductivity of bentonite-based clayey barriers exposed to saline environments for numerical investigation of solute transport in such barriers. Therefore, the theoretical equations were modified as a function of solute concentration instead of constant values. First, a model was extended for membrane efficiency as a function of void ratio and solute concentration. Second, an apparent tortuosity model... 

Let G = (V,E) be a simple undirected graph. For a given set L ⊂ ℝ, a function ω: E → L is called an L-flow. Given a vector γ ∈ ℝv, ω is a γ-L-flow if for each υ ∈ V, the sum of the values on the edges incident to υ is γ(υ). If γ(υ) = c, for all υ ∈ V, then the γ-L-flow is called a c-sum L-flow. In this paper, the existence of γ-L-flows for various choices of sets L of real numbers is studied, with an emphasis on 1-sum flows. Let L be a subset of real numbers containing 0 and denote L*:= L {0}. Answering a question from [S. Akbari, M. Kano, and S. Zare. A generalization of 0-sum flows in graphs. Linear Algebra Appl., 438:3629-3634, 2013.], the bipartite graphs which admit a 1-sum ℝ*-flow or... 

Let G be a graph with no isolated vertex. A total dominating set of G is a set S of vertices of G such that every vertex is adjacent to at least one vertex in S. The total domatic number of a graph is the maximum number of total dominating sets which partition the vertex set of G. In this paper we provide a criterion under which a cubic graph has total domatic number at least two  

Let G be a graph with n vertices and m edges and assume that f : V ( G ) → N is a function with ∑v ∈ V ( G ) f ( v ) = m + n. We show that, if we can assign to any vertex v of G a list Lv of size f ( v ) such that G has a unique vertex coloring with these lists, then G is f-choosable. This implies that, if ∑v ∈ V ( G ) f ( v ) > m + n, then there is no list assignment L such that | Lv | = f ( v ) for any v ∈ V ( G ) and G is uniquely L-colorable. Finally, we prove that if G is a connected non-regular multigraph with a list assignment L of edges such that for each edge e = u v, | Le | = max { d ( u ), d ( v ) }, then G is not uniquely L-colorable and we conjecture that this result holds for...