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RISS 인기검색어
- 검색키워드
- 저자 : Fedakar, Halil ibrahim (검색결과 4 건)
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Gullu, Hamza,Fedakar, Halil ibrahim Techno-Press 2017 Geomechanics & engineering Vol.12 No.3
The determination of the mixture parameters of stabilization has become a great concern in geotechnical applications. This paper presents an effort about the application of artificial intelligence (AI) techniques including radial basis neural network (RBNN), multi-layer perceptrons (MLP), generalized regression neural network (GRNN) and adaptive neuro-fuzzy inference system (ANFIS) in order to predict the unconfined compressive strength (UCS) of silty soil stabilized with bottom ash (BA), jute fiber (JF) and steel fiber (SF) under different freeze-thaw cycles (FTC). The dosages of the stabilizers and number of freeze-thaw cycles were employed as input (predictor) variables and the UCS values as output variable. For understanding the dominant parameter of the predictor variables on the UCS of stabilized soil, a sensitivity analysis has also been performed. The performance measures of root mean square error (RMSE), mean absolute error (MAE) and determination coefficient ($R^2$) were used for the evaluations of the prediction accuracy and applicability of the employed models. The results indicate that the predictions due to all AI techniques employed are significantly correlated with the measured UCS ($p{\leq}0.05$). They also perform better predictions than nonlinear regression (NLR) in terms of the performance measures. It is found from the model performances that RBNN approach within AI techniques yields the highest satisfactory results (RMSE = 55.4 kPa, MAE = 45.1 kPa, and $R^2=0.988$). The sensitivity analysis demonstrates that the JF inclusion within the input predictors is the most effective parameter on the UCS responses, followed by FTC.
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Gullu, Hamza,Fedakar, Halil I. Techno-Press 2017 Geomechanics & engineering Vol.13 No.1
In recent years, the amount of sludge ash (SA) has considerably increased due to rapid urbanization and population growth. In addition, its storage in landfills induces environmental pollution and health problems. Therefore, its disposal in an environmentally friendly way has become more important. The main goal of this study is to investigate the reusability of sludge ash as an additive with polypropylene fiber (PF) to stabilize marginal sand based on the compressive strength performances from UCS tests. For this purpose, a series of UCS tests was conducted. Throughout the experimental study, the used inclusion rates were 10, 15, 20 and 30% for sludge ash and 0, 0.5 and 1% for polypropylene fiber by total dry weight of the sand+sludge ash mixture and the prepared samples were cured for 7 and 14 days prior to the testing. Freezing and thawing resistance of the mixture including 10% sludge ash and 0, 0.5 and 1% polypropylene fiber was also examined. On the basis of UCS testing results, it is said that sludge ash inclusion remarkably enhances UCS performance of sand. Moreover, the addition of polypropylene fiber to the admixtures including sand and sludge ash significantly improves their stress-strain characteristics and post-peak strength loss as well as UCS. As a result of this paper, it is suggested that sludge ash be successfully reused with polypropylene fiber for stabilizing sand in soil stabilization applications. It is also believed that the findings of this study will contribute to some environmental concerns such as the disposal problem of sludge ash, recycling, sustainability, environmental pollution, etc. as well as the cost of an engineering project.
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Hamza Güllü,Halil brahim Fedakar 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5
Optimization of the stabilization materials in terms of their dosage rates specifically used for stabilization applications have become a great interest by the experimenters due to the concerns of strength performance, time and economy for the construction projects. Using a relatively recent optimization technique, Response Surface Methodology (RSM), this paper is mainly focused on investigation of the optimum amounts of stabilizers (Sewage Sludge Ash (SSA) and Polypropylene Fiber (PF)) and Curing Time (CT) that yield to maximum unconfined compressive strength (UCS) for stabilization of a marginal sand (poorly-graded sand). For this purpose, an experimental study has been carried out conducting UCS tests, where the stabilizer proportions are 0-30% for SSA and 0-1% for PF, by total dry weight of sand+SSA. Also, the curing times considered prior to testing are 0, 7 and 14 days. All UCS tests have been performed following the experimental program by central composite design that used the ranges of stabilizer proportions and curing times. On the basis of experimental data, a full quadratic model with natural log transformation and backward analysis has been built through RSM considering the factors of SSA, PF, CT, and the response of UCS. The results indicate that the mathematical model built in this study is statistically significant (p ≤ 0.05) through the analysis of variance (ANOVA), thus it is applicable for optimization process. The findings from the optimization effort demonstrate that the most potential values for SSA, PF and CT are 19.95%, 0.57% and 12.15-day, respectively. The proposed values could be beneficial for the experimenters in practice specifically for preliminary evaluations prior testings of stabilizations.
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Nursel Turkmen,Bulent Eren,Recep Fedakar,Semra Akgoz 대한의학회 2008 Journal of Korean medical science Vol.23 No.6
Hemosiderin deposition is not often recognized on routine examination with hematoxylin and eosin staining; however, iron stains may be helpful in the evaluation of hemosiderin deposition in infant autopsies. This report describes the data obtained from autopsy of 86 infants and children whose deaths were investigated at the Forensic Medicine Council Bursa Morgue Department from January 2000 to January 2003. A histochemical technique was used to identify hemosiderin in lung, liver and spleen specimens, which was correlated with other descriptive variables such as the reported cause of death, postmortem interval, trauma history, gender, and age. There was a weakly positive but significant correlation between lung and liver hemosiderin scores (Spearman’s rank correlation coefficient, rho=0.348, p=0.001); i.e., given an increase in lung hemosiderin scores, an increase in liver hemosiderin scores was also observed. Similarly, a marked positive correlation between spleen and liver hemosiderin scores (Spearman’s rank correlation coefficient, rho=0.335, p=0.002) was observed. The probability of spleen hemosiderin-positive cases belonging to the age group under 6 months was found to be 4.3 times greater than those who were hemosiderin-negative (95% confidence interval, 1.6-11.8). After the major differential diagnoses were ruled out, this study demonstrated, that depending on the statistically assessed morphometric grounds, the presence of hemosiderin deposits in the liver and spleen were significantly higher in the age group under 6 months.
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