Fracture resistance of upper central incisors restored with different posts and cores

Saeid Tavanafar,,Kamran Amirian Chaijan,Saeid Tavanafar 대한치과보존학회 2015 Restorative Dentistry & Endodontics Vol.40 No.3

Objectives: To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores. Materials and Methods: Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at 135° vertical angle, subjected to thermomechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data. Results: Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable. Conclusions: Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.

Power Factor Improvement of Distribution System with EV Chargers based on SMC Method for SVC

Saeid Gholami Farkoush,Chang-Hwan Kim,Ho-Chul Jung,Sanghyuk Lee,Nipon Theera-Umpon,Sang-Bong Rhee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4

Utilization of Electric Vehicles (EVs) have been growing popularity in recent years due to increment in fuel price and lack of natural resources. Random unexpected charging by home EV charger in distribution is predicted in the future. The power quality problems such as fluctuation of power factor in a residential distribution network was explored with random EV chargers. This paper proposes a high-performance nonlinear sliding mode controller (SMC) for an EV charging system to compensate voltage distortions and to enhance the power factor against the unbalanced EV chargers. For the verification of the proposed scheme, MATLAB-Simulink simulations are performed on 22.9-㎸ grid. The results show that the proposed scheme can improve the power factor of a smart grid due to the EV chargers on the grid.

Formulation for Free-standing Staircase

Saeid Zahedi Vahid,Mohammad Ali Sadeghian,Siti Aminah Bt. Osman,Abdul Khalim Bin Abdul Rashid 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

In the analysis of a free-standing staircase with slab elements, approximate analytical methods are sometimes used because of the absence of specific code provisions due to their inherent limitations. These approaches, however, cannot predict the actual threedimensional (3D) behavior of the stair slab system. In addition, analytical methods cannot predict the stress resultant distribution in any section. These drawbacks highlight the need for the development of more rational but simple analysis methods for design purposes. Thus, in this study, an extensive numerical study on the behavior of free-standing staircases was performed using the finite element package SAP2000. A sensitivity study on the different geometric parameters and material properties that affect the design force and moments was also conducted. As a result of this study, semi-empirical equations are proposed from which the design forces and moments can be calculated in a single step. The accuracy of the equations within an acceptable limit is established by comparison with the results of rigorous FE analyses. Finally, the proposed design equations lead to a simple, straightforward and safe design while simultaneously representing the true behavior of 3D free-standing stair slabs.

Evaluation of Maturity Method for Steel Fiber Reinforced Concrete

Saeid Kamkar,Özgür Eren 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.1

The evaluation of steel-fiber reinforced concrete using the maturity method was investigated in this study. There were four different volume fractions of fibers (0, 0.5, 1 and 1.5 by volume of concrete) and three different curing temperatures (8°C, 22°C and 32°C) considered. The compressive strength and flexural strength were tested at 1, 3, 7, 10, 14 and 28 days for all of the volume fractions of fibers and at the different curing temperatures. The results show that as the volume fraction of fiber increased from 0 to 1.5%, the compressive and flexural strengths increased by 14% and 35%, respectively, compared to plain concrete. The maturity method was used to predict the compressive and flexural strengths. Four different equations (linear hyperbolic, parabolic hyperbolic, logarithmic and exponential) were used to predict the compressive and flexural strengths. All of the predicted models have good correlations with the experimental results for both compressive and flexural strengths. Moreover, to predict the compressive and flexural strengths using the maturity method, the apparent activation energies were calculated.

cDNA cloning and expression analysis of a putative alternative oxidase HsAOX1 from wild barley (Hordeum spontaneum)

Saeid Abu-Romman,Mohamad Shatnawi,Maen Hasan,Issam Qrunfleh,Sharaf Omar,Nida Salem 한국유전학회 2012 Genes & Genomics Vol.34 No.1

A novel alternative oxidase (AOX1) gene, designated HsAOX1(GenBank accession number JF440341) was cloned by RT-PCR from wild barley (Hordeum spontaneum). The full length of HsAOX1 is 1115 bp with an open reading frame of 987 bp, encoding a protein of 328 amino acids with molecular weight of 36.89 kDa and a theoretical isoelectric point of 6.81. As found in other plant AOX1 proteins, sequence alignment showed that HsAOX1 had conserved metal binding and hydrophobic α-helix regions and had high homology to other AOX1 in plants. The expression analysis by semi-quantitative RT-PCR revealed that HsAOX1 was induced in response to cold stress, H2O2 treatment, SA, antimycin A and KCN. These results showed that HsAOX1 functions not only during inhibition of cytochrome electron transport but also during oxidative stresses, thus suggesting a role of HsAOX1 in preventing the generation of free radicals by the mitochondrial electron transport chain. The cloning and characterization of the HsAOX1 gene will be useful for further studies of biological roles of HsAOX1 in plants.

UNIFORM TOPOLOGY ON DIFFERENCE ALGEBRAS

SAEID, ARSHAM BORUMAND Korean Mathematical Society 2005 대한수학회보 Vol.42 No.2

In this paper, we consider a collection of ideals of a difference algebra X. We use the concept of congruence relation with respect to ideals to construct a uniformity that induces a topology on X which makes this to a topological difference algebras. We study the properties of this topology regarding different ideals.

T-NEIGHBORHOODS IN VARIOUS CLASSES OF ANALYTIC FUNCTIONS

Saeid Shams,Ali Ebadian,Mahta Sayadiazar,Janusz Sokol 대한수학회 2014 대한수학회보 Vol.51 No.3

Let A be the class of analytic functions f in the open unit disk U = {z : |z| < 1} with the normalization conditions f(0) = f′(0)−1 = 0. If f(z) = z + P∞ n=2 anzn and > 0 are given, then the T-neighborhood of the function f is defined as TN(f) = ( g(z) = z + ∞X n=2 bnzn 2 A : ∞X n=2 Tn|an − bn| ) , where T = {Tn}∞n=2 is a sequence of positive numbers. In the present paper we investigate some problems concerning T-neighborhoods of functions in various classes of analytic functions with T = { 2−n/n2} ∞ n=2. We also find bounds for ∗ T (A,B) defined by ∗ T (A,B) = inf { > 0 : B TN(f) for all f ∈ A} , where A, B are given subsets of A.

DISTINGUISHING NUMBER AND DISTINGUISHING INDEX OF STRONG PRODUCT OF TWO GRAPHS

( Saeid Alikhani ),( Samaneh Soltani ) 호남수학회 2020 호남수학학술지 Vol.42 No.4

The distinguishing number (index) D(G) (D’(G)) of a graph G is the least integer d such that G has an vertex label- ing (edge labeling) with d labels that is preserved only by a triv- ial automorphism. The strong product G □ H of two graphs G and H is the graph with vertex set V (G) × V (H) and edge set {{(x₁, x₂); (y₁, y₂)}|x_iy_i ∈ E(G_i) or x_i = y_i for each 1 ≤ i ≤ 2:}. In this paper we study the distinguishing number and the distin- guishing index of strong product of two graphs. We prove that for every k ≥ 2, the k-th strong power of a connected S-thin graph G has distinguishing index equal two.

The Non-gradient-based Reliability Method in Equivalent Linear Systems for Nonlinear Random Vibration

Saeid Pourzeynali,Hossein Abbaszadeh 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

A conventional approach for nonlinear random vibration analysis is using equivalent linearization method. Tail-Equivalent Linearization Method (TELM) is one the best proposed methods in the recent decade for determination of equivalent linear model. In TELM, the design point is obtained using first-order reliability method. In the current research, a non-gradient-based method is applied for determination of the design point. One of the main advantages of this method is non-application of limit-state function gradient for calculation of the design point. In the implemented method, n arbitrary points in n-dimension standard normal space are selected and limit-state function in these points is estimated. Then, these points converge to the design point using a convergent algorithm. Since many random variables are produced in TELM for discretization of seismic excitation, iterative algorithms for determination of design point numerical instability would be encountered. By modification of step length for each iteration and application of a magnification coefficient for each step, an appropriate non-gradient method is proposed for analysis of the problems with many random variables. The efficiency of this method was investigated by solving numerical examples. Moreover, the convergence of this method for finding the design point was presented. It was also indicated that results obtained using this method are in good agreement with results obtained by gradient methods.

SMARANDACHE WEAK BE-ALGEBRAS

Saeid, Arsham Borumand Korean Mathematical Society 2012 대한수학회논문집 Vol.27 No.3

In this paper, we introduce the notions of Smarandache weak BE-algebra, Q-Smarandache filters and Q-Smarandache ideals. We show that a nonempty subset F of a BE-algebra X is a Q-Smarandache filter if and only if $A(x,y){\subseteq}F$, which A($x,y$) is a Q-Smarandache upper set The relationship between these notions are stated and proved.