Endüstri Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/279
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Article Control of trichloroethylene emissions from sparging systems by horizontal bio- and chemo- barriers(2005) Tezel, U.; Demirer, G.N.; Uludag, Demirer S.The scope of this study was to develop a continuous system to clean-up a trichloroethylene (TCE) contaminated gas stream, where biotic and abiotic removal mechanisms are undertaken sequentially simulating the horizontal bio- and chemo-barriers proposed for the in-situ remediation of the contaminated sites. The bio- and chemo-barriers were simulated by using glass columns packed with granular anaerobic mixed culture and Fe(0) filings, respectively. The effect of gas residence time, which is adjusted by the gas flowrate, on the TCE removal efficiency of the reactor system was investigated. TCE removal efficiency of over 90% was achieved at gas residence times above 1hr. Furthermore, the effluent of reactor system contained only ethane and ethylene, which are non-toxic by-products of TCE reduction reactions, along with trace amounts of TCE.Article Control of Trichloroethylene Emissions From Sparging Systems by Horizontal Bio- and Chemo-Barriers(Selper Ltd, Publications Div, 2005) Tezel, U; Demirer, GN; Uludag-Demirer, SThe scope of this study was to develop a continuous system to clean-up a trichloroethylene (TCE) contaminated gas stream, where biotic and abiotic removal mechanisms are undertaken sequentially simulating the horizontal bio- and chemo-barriers proposed for the in-situ remediation of the contaminated sites. The bio- and chemo-barriers were simulated by using glass columns packed with granular anaerobic mixed culture and Fe(0) filings, respectively. The effect of gas residence time, which is adjusted by the gas flowrate, on the TCE removal efficiency of the reactor system was investigated. TCE removal efficiency of over 90% was achieved at gas residence times above 1hr. Furthermore, the effluent of reactor system contained only ethane and ethylene, which are non-toxic by-products of TCE reduction reactions, along with trace amounts of TCE.Article Citation - WoS: 1Citation - Scopus: 1The Effect of Different Inflation Risks on Interest Rates of the Us(Routledge Journals, Taylor & Francis Ltd, 2009) Yuksel, E.; Akdi, Y.This article examines the effect of different inflation uncertainty measures on interest rates of the US in a Fisher hypothesis framework. Generalized Autoregressive Conditional Heteroskedasticity (GARCH) specification with a time-dependent parameter model is used to obtain three types of inflation uncertainties, namely, impulse uncertainty, structural uncertainty and steady-state uncertainty. It has been observed that the impulse uncertainty has negative but the structural uncertainty has positive impact on both short-term and long-term interest rates. Both of these effects are statistically significant. The influence of steady-state uncertainty on interest rates is positive, but the level of significance depends on the inclusion of output gap. Without the inclusion of output gap, the effect is insignificant, whereas the effect becomes significant when output gap is introduced.Article Citation - WoS: 4Citation - Scopus: 4Inference in Multivariate Linear Regression Models With Elliptically Distributed Errors(Taylor & Francis Ltd, 2014) Yazici, Mehmet; Islam, M. Qamarul; Yildirim, FetihIn this study we investigate the problem of estimation and testing of hypotheses in multivariate linear regression models when the errors involved are assumed to be non-normally distributed. We consider the class of heavy-tailed distributions for this purpose. Although our method is applicable for any distribution in this class, we take the multivariate t-distribution for illustration. This distribution has applications in many fields of applied research such as Economics, Business, and Finance. For estimation purpose, we use the modified maximum likelihood method in order to get the so-called modified maximum likelihood estimates that are obtained in a closed form. We show that these estimates are substantially more efficient than least-square estimates. They are also found to be robust to reasonable deviations from the assumed distribution and also many data anomalies such as the presence of outliers in the sample, etc. We further provide test statistics for testing the relevant hypothesis regarding the regression coefficients.