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Dadashzadeh N.,Kingston University | Duzgun H.S.B.,Middle East Technical University | Yesiloglu-Gultekin N.,General Maritime
Rock Mechanics and Rock Engineering | Year: 2017

While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The first-order reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%. © 2017 Springer-Verlag Wien

Hong F.-Y.,General Maritime | Huang D.-H.,Da - Yeh University | Lin H.-Y.,I - Shou University | Chiu S.-L.,General Maritime
Telematics and Informatics | Year: 2014

The purposes of this study are to (1) identify the role of the psychological traits of university students in Facebook addiction and Facebook usage; and (2) explore the correlation between Facebook usage and Facebook addiction. This study treated 241 university students in Taiwan as the research subjects, and adopted the Rosenberg's self-esteem scale, Lai's personality test, a Facebook usage scale, and a Facebook addiction scale (FAS). The structured equation modeling (SEM) was used for data analysis. The results showed that: (1) self-inferiority can significantly predict Facebook usage; and (2) having a depressive character and Facebook usage can significantly predict Facebook addiction. Finally, discussion was conducted on the findings, and relevant suggestions were proposed for schools, students, and future studies. © 2014 Elsevier Ltd. All rights reserved.

Hong F.-Y.,General Maritime | Chiu S.-I.,General Maritime | Huang D.-H.,Da - Yeh University
Computers in Human Behavior | Year: 2012

While many researches have analyzed the psychological antecedents of mobile phone addiction and mobile phone usage behavior, their relationship with psychological characteristics remains mixed. We investigated the relationship between psychological characteristics, mobile phone addiction and use of mobile phones for 269 Taiwanese female university students who were administered Rosenberg's self-esteem scale, Lai's personality inventory, and a mobile phone usage questionnaire and mobile phone addiction scale. The result showing that: (1) social extraversion and anxiety have positive effects on mobile phone addiction, and self-esteem has negative effects on mobile phone addiction. (2) Mobile phone addiction has a positive predictive effect on mobile phone usage behavior. The results of this study identify personal psychological characteristics of Taiwanese female university students which can significantly predict mobile phone addiction; female university students with mobile phone addiction will make more phone calls and send more text messages. These results are discussed and suggestions for future research for school and university students are provided. © 2012 Elsevier Ltd. All rights reserved.

Tobita M.,Nippon Medical School | Tobita M.,General Maritime | Mizuno H.,Nippon Medical School
Current Stem Cell Research and Therapy | Year: 2010

Periodontal disease leads to destruction of the periodontium such as alveolar bone, cementum, the periodontal ligament, and gingiva. Effective treatment for periodontal tissue regeneration is important, because periodontal disease is related to several systemic diseases. However, various conventional therapies for periodontal tissue regeneration have shown limited and variable clinical outcomes. Thus, there are ongoing efforts to identify an alternative cell source, such as stem cells, for the development of new tissue engineering therapies. In this review, periodontal disease and the application of tissue engineering for periodontal tissue regeneration are discussed. In particular, adipose-derived stem cells are presented as an agent for restoring periodontal tissue defects. © 2010 Bentham Science Publishers Ltd.

Gercekciolu H.,General Maritime | Baykal Y.,Cankaya University
IEEE Journal on Selected Areas in Communications | Year: 2015

On-axis intensity fluctuations of laser array beams are evaluated when they are used in a weakly turbulent non-Kolmogorov atmosphere. Our formulation of the scintillation index is based on the Rytov method, which in the limiting case, correctly reduces to the known Gaussian beam scintillation index in weak Kolmogorov turbulence. When the radius of the ring (on which the array beamlets are placed), number of beamlets forming the laser array, source size of the beamlets, propagation distance or the wavelength is fixed, a decrease in the power law exponent of the non-Kolmogorov spectrum is found to decrease the scintillation index. Examining for any realization of the non-Kolmogorov spectrum, it is observed that an increase in the ring radius, number of beamlets, wavelength, and decrease in the source size of the beamlet, propagation distance reduces the intensity fluctuations. © 2015 IEEE.

Although numerous studies have examined factors that influence smartphone addiction, few have analyzed the potential protective factors inherent in individuals that may benefit future intervention programs for smartphone addiction. Thus, this study established a model for analyzing the mediating effect that learning self-efficacy and social self-efficacy have on the relationship between university students' perceived life stress and smartphone addiction. Sampling 387 Taiwanese university students, we distributed scales surveying for university students' life stress, learning self-efficacy, social self-efficacy, and smartphone addiction. Data retrieved from the scales were analyzed using structural equation modeling (SEM). The SEM path analysis yielded the following results: (1) Academic stress had negative predictive power for social and learning self-efficacies, and interpersonal relationship stress had negative predictive power for social self-efficacy. (2) Social self-efficacy had positive predictive power for smartphone addiction. (3) Family and emotional stresses had positive predictive power for smartphone addiction. Generally, the results of this study could be used to significantly predict the life stresses that influenced university students' smartphone addiction. In addition, social self-efficacy can be considered a cognitive mechanism that mediates the relationships between academic stress and smartphone addiction and between interpersonal relationship stress and smartphone addiction. Finally, we discussed the research results and offered relevant suggestions for schools, university students, and future studies. © 2014 Elsevier Ltd. All rights reserved.

Gercekcioglu H.,General Maritime | Baykal Y.,Cankaya University
Optics Communications | Year: 2013

The average bit error rate () of annular and flat-topped beams are evaluated in strong turbulence. In this respect, our earlier results on the scintillation indices obtained by the unified Rytov method are employed and the intensity is taken to be gamma-gamma distributed. For comparison purposes, for the log-normal intensity distribution is also evaluated. It is found that for the annular beams, the ones that are thinner, possessing smaller ratio of primary to secondary beam size, and smaller focal lengths will have smaller average BER in strong turbulence. For the flat-topped beams, the ones that are flatter and possessing large source sizes have smaller average BER in strong turbulence. Large average SNR substantially reduces the average BER in weak and moderate turbulence, whereas in strong turbulence, the average BER stays at the same value no matter what the average SNR is. Comparison of the log-normal and the gamma-gamma statistics for the intensity shows that the average BER will be higher for the log-normal case when the average SNR is small and the reverse relationship holds at large average SNR. For both the gamma-gamma and the log-normal intensity distributions, obtained for the annular and the flat-topped beams in strong turbulence is advantageous over the Gaussian beam values. © 2013 Elsevier B.V. All rights reserved.

Gercekcioglu H.,General Maritime | Baykal Y.,Cankaya University
Optics Communications | Year: 2014

The scintillation index and the average bit error rate (BER) are evaluated for the optimum sinusoidal Gaussian beams in weak non-Kolmogorov turbulence. The beam parameters that minimize the scintillation index and the average BER are stated and such beams are denoted as the optimum beams. For the collimated Gaussian, cos- and cosh-Gaussian beams, the scintillations increase as the power law exponent, α increases. Cos- and cosh-Gaussian beams that have larger absolute displacement parameters are found to exhibit larger scintillations especially at small α. Larger focal length and larger source size of cos-Gaussian beams induce reduction in the scintillations. When the propagation distance is large, the power law exponent is small and the source size is large, the scintillations of the optimum beams tend to decrease. Small power law exponent and large source size reduce the average BER. The optimum beam is shown to exhibit the smallest average BER for any α. © 2014 Elsevier B.V.

Baykal Y.,Cankaya University | Gercekcioglu H.,General Maritime
Optics Communications | Year: 2014

The evaluation of system parameters in the non-Kolmogorov turbulent atmosphere involves the structure constant valid at the relevant non-Kolmogorov power law exponent. In some of the existing results, the comparisons of system parameters found under the Kolmogorov and non-Kolmogorov turbulences were made by using the same structure constant for all the power law exponents of the non-Kolmogorov spectrum. In this paper, we evaluate the scintillations and the average Bit Error Rate (〉BER〉) for the flat-topped and the annular beams in non-Kolmogorov turbulence, this time using the equivalent structure constant which is now different for all the power law exponents. It is observed that the scintillations and the (〉BER〉) show completely different behaviour when evaluated with the equivalent structure constant as compared to evaluations with constant structure constant. © 2013 Elsevier B.V.

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