Bond strength characterization and estimation of steel fibre reinforced polymer - concrete composites

Hashem Jahangir,Danial Rezazadeh Eidgahee,Mohammad Reza Esfahani 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.6

Composite materials are effective in forming externally bonded reinforcements which find applications related to existing structures repair, attributed to their high strength-to-weight ratio and ease of installation. Among various composites, fibre reinforced polymers (FRP) have somewhat been largely accepted as a commonly utilized composite for such purposes. It is only recently that steel fibres have been considered as additional members of the FRP fibre family, intuitively termed as steel reinforced polymer (SRP). Owing to its low cost and permissibility of fibre bending at sharp corners, SRP is rapidly becoming a viable contender to other FRP systems. This paper investigates the bond behaviour of SRP-concrete joints with different bonded lengths (50, 75, 100, 150 and 300 mm) and widths (15, 30, 40, 50, and 75 mm) using single-lap shear tests. The experimental specimens contain SRP strips with a fixed density of steel fibres (0.472 cords/mm) bonded to the face of concrete prisms. The load responses were obtained and compared in terms of corresponding load and slip boundaries of the constant region and the peak loads. The failure modes of SRP composites are discussed, and the range of effective bonded length is evaluated herein. In the end, a new analytical model was proposed to estimate the SRP-concrete bond strength using a genetic algorithm, which outperforms 22 existing FRP-concrete bond strength models.

Measuring functional polycentricity developments using the flow of goods in Iran: a novel method at a regional scale

Hashem Dadashpoor,Sadegh Saeidi Shirvan 서울시립대학교 도시과학연구원 2019 도시과학국제저널 Vol.23 No.4

The debate concerning the polycentricity concept and its related methods has led to numerous studies. However, these studies have focused less on the analysis of polycentricity in developing countries, such as Iran, which is peculiar because of its various socioeconomic and political features. Also, while most of the current studies have measured the polycentricity at one time, only a limited number of them have paid attention to the longitudinal perspective. Thus, this paper intends to examine functional polycentricity developments by exploring a novel method on a regional scale. To do this, we have applied a dynamic method in the case of Iran to measure the polycentricity by using data concerning the flow of goods. Our findings indicate that the polycentricity index of the system raised from 0.24 to 0.81 over a 15-year period. Therefore, theoretically, the spatial system moved towards more polycentricity. The outcome of the socioeconomic flows in Iran was such that they continuously reduced the distance between centres and reproduced moves towards a more polycentric pattern.

Effect of Essential and Nonessential Amino Acids in North Carolina State University (NCSU)-23 Medium on Development of Porcine In vitro Fertilized Embryos

Hashem, Md. Abul,Bhandari, Dilip P.,Hossein, Mohammad Shamim,Jeong, Yeon Woo,Kim, Sue,Kim, Ji-Hye,Koo, Ok-Jae,Park, Seon Mi,Lee, Eu Gine,Park, Sun Woo,Kang, Sung Keun,Lee, Byeong Chun Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.5

The present study was conducted to examine the effect of different levels of essential and nonessential amino acid in NCSU-23 medium on the in vitro-produced porcine embryo as it develops from the zygote to the blastocyst stage. Four experiments were performed, each with a completely randomized design involving 5 to 8 replications of treatments. In order to know the effect of nonessential amino acids in NCSU-23 medium, 0, 5, 10 and $20{\mu}/ml$ MEM were supplemented there to, (Exp. 1) and the medium was supplemented with same level of essential amino acids (Exp. 2). The combined effect of nonessential (0, 5, 10 and $20{\mu}/ml$ MEM) and essential amino acids (0, 5, 10 and $10{\mu}/ml$ MEM) in NCSU-23 medium (Exp. 3), first 72 h with non-essential amino acids (at 0, 5, 10 and $20{\mu}/ml$ MEM), and last 4 d with essential amino acids with the same level as NEAA (Exp. 4) were examined. The embryo development was monitored and the quality of blastocysts was evaluated by counting the number of total cells and determining the ratio of inner cell mass (ICM) to trophoectoderm (TE) cells. When Eagle's nonessential amino acids (MEM) added to NCSU-23 medium, it significantly increased the likelihood of development to the 2- to 4-cell stage and subsequent blastocyst development. Supplementation of different levels of essential amino acids in the NCSU-23 medium decreased cleavage rate, rate of morula and blastocyst development and the number of ICMs. In the case of the combined effect of essential and nonessential amino acids, better and significant results were found for blastocysts, hatching blastocysts and for ICM numbers which were also dose dependent. With respect to the biphasic effect of nonessential and essential amino acids, nonessential amino acids increased cleavage whereas essential amino acids increased the total cell number. Neither the nonessential nor the essential group of amino acids, on their own, affected blastocyst cell number or the differentiation of cells in the blastocyst. In conclusion, this study determined the role of nonessential and essential amino acids in the culture of the porcine embryo and showed that the embryo requires different levels of amino acids as it develops from the zygote to the blastocyst stage.

Predicting Audit Reports Using Meta-Heuristic Algorithms

Hashem Valipour,Fatemeh Salehi,Mostafa Bahrami 한국유통과학회 2013 유통과학연구 Vol.11 No.6

Purpose - This study aims to predict the audit reports of listed companies on the Tehran Stock Exchange by using meta-heuristic algorithms. Research design, data, methodology - This applied research aims to predict auditors reports’ using meta-heuristic methods (i.e., neural networks,the ANFIS, and a genetic algorithm). The sample includes all firms listed on the Tehran Stock Exchange. The research covers the seven years between 2005 and 2011. Results - The results show that the ANFIS model using fuzzy clustering and a least-squares back propagation algorithm has the best performance among the tested models, with an error rate of 4% for incorrect predictions and 96% for correct predictions. Conclusion - A decision tree was used with ten independent variables and one dependent variable the less important variables were removed,leaving only those variables with the greatest effect on auditor opinion (i.e., net-profit-to-sales ratio, current ratio, quick ratio, inventory turnover, collection period, and debt coverage ratio).

Investigating loading rate and fibre densities influence on SRG - concrete bond behaviour

Hashem Jahangir,Mohammad Reza Esfahani 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.6

This work features the outcomes of an empirical investigation into the characteristics of steel reinforced grout (SRG) composite - concrete interfaces. The parameters varied were loading rate, densities of steel fibres and types of load displacement responses or measurements (slip and machine grips). The following observations and results were derived from standard single-lap shear tests. Interfacial debonding of SRG - concrete joints is a function of both fracture of matrix along the bond interface and slippage of fibre. A change in the loading rate results in a variation in peak load (Pmax) and the correlative stress (σmax), slip and machine grips readings at measured peak load. Further analysis of load responses revealed that the behaviour of load responses is shaped by loading rate, fibre density as well as load response measurement variable. Notably, the out-of-plane displacement at peak load increased with increments in load rates and were independent of specimen fibre densities.

Seismic control response of structures using an ATMD with fuzzy logic controller and PSO method

Hashem Shariatmadar,Hessamoddin Meshkat Razavi 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.4

This study focuses on the application of an active tuned mass damper (ATMD) for controlling the seismic response of an 11-story building. The control action is achieved by combination of a fuzzy logic controller (FLC) and Particle Swarm Optimization (PSO) method. FLC is used to handle the uncertain and nonlinear phenomena while PSO is used for optimization of FLC parameters. The FLC system optimized by PSO is called PSFLC. The optimization process of the FLC system has been performed for an 11-story building under the earthquake excitations recommended by International Association of Structural Control (IASC) committee. Minimization of the top floor displacement has been used as the optimization criteria. The results obtained by the PSFLC method are compared with those obtained from ATMD with GFLC system which is proposed by Pourzeynali et al. and non-optimum FLC system. Based on the parameters obtained from PSFLC system, a global controller as PSFLCG is introduced. Performance of the designed PSFLCG has been checked for different disturbances of far-field and near-field ground motions. It is found that the ATMD system, driven by FLC with the help of PSO significantly reduces the peak displacement of the example building. The results show that the PSFLCG decreases the peak displacement of the top floor by about 10%-30% more than that of the FLC system. To show the efficiency and superiority of the adopted optimization method (PSO), a comparison is also made between PSO and GA algorithms in terms of success rate and computational processing time. GA is used by Pourzeynali et al for optimization of the similar system.

Conservative management against arthroscopic Bankart repair for first-time anterior shoulder instability

Hashem Bukhary,Jae Chul Yoo,Jong Hun Park,Su Cheol Kim 대한견주관절의학회 2022 대한견주관절학회 학술대회논문집 Vol.2022 No.4

Effect of gas detonation on response of circular plate- experimental and theoretical

Hashem Babaei,Tohid Mirzababaie Mostofi,Seyed Hamidreza Sadraei 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.4

A series of experimental results on thin mild steel plates clamped at the boundary subjected to gas detonation shock loading are presented. Detonation occurred by mixing Acetylene (C2H2)-Oxygen (O2) in various volume ratio and different initial pressure. The applied impulse is varied to give deformation in the range from 6 mm to 35 mm. Analytical modeling using energy method was also performed. Dependent material properties, as well as strain rate sensitivity, are included in the theoretical modeling. Prediction values for midpoint deflections are compared with experimental data. The analytical predictions have good agreement with experimental values. Moreover, it has been shown that the obtained model has much less error compared with those previously proposed in the literature.

ON THE STABILITY OF A WET-LAND MODEL

Hashem, Ali A. 한국전산응용수학회 2001 The Korean journal of computational & applied math Vol.8 No.3

Mathematical models for studying the effect of ecological changes caused by the excessive growth of wild changes on the existence of various species in wet-land are investigated. Local stability criteria is also discussed. AMS Mathematics Subject Classification : 92D40, 34D20

A new layered manufacturing machine with cutting force analysis in tapered end milling

Hashem Ghariblu,Shahed Abedi 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

We introduce a new layered manufacturing machine with its associated geometric cutting force model. This machine is designed to build metal parts and is a modified type of commercial layered object manufacturing (LOM) machine. This apparatus uses tapered end mills with different angles instead of laser to cut the layer edges. The proposed machine needs higher stiffness, because cutting action would regularly create more inaccuracy. Consequently, a new force model is considered that takes into account cutting conditions, cutter geometry and combination of tool-workpiece materials. Then, by force and stress analysis cutting-force induced inaccuracy has been evaluated for different components of the machine. Finally, the effectiveness of the machine and its capability to build functional metal parts with different geometries is clearly shown.