Endüstri Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/279
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Article Citation - WoS: 12Analysis of Dengue Transmission Dynamic Model by Stability and Hopf Bifurcation With Two-Time Delays(Imr Press, 2023) Ambalarajan, Venkatesh; Sivakumar, Vinoth; Dhandapani, Prasantha Bharathi; Baleanu, Dumitru; Murugadoss, Prakash RajBackground: Mathematical models reflecting the epidemiological dynamics of dengue infection have been discovered dating back to 1970. The four serotypes (DENV-1 to DENV-4) that cause dengue fever are antigenically related but different viruses that are transmitted by mosquitoes. It is a significant global public health issue since 2.5 billion individuals are at risk of contracting the virus. Methods: The purpose of this study is to carefully examine the transmission of dengue with a time delay. A dengue transmission dynamic model with two delays, the standard incidence, loss of immunity, recovery from infectiousness, and partial protection of the human population was developed. Results: Both endemic equilibrium and illness-free equilibrium were examined in terms of the stability theory of delay differential equations. As long as the basic reproduction number (R0) is less than unity, the illness-free equilibrium is locally asymptotically stable; however, when R0 exceeds unity, the equilibrium becomes unstable. The existence of Hopf bifurcation with delay as a bifurcation parameter and the conditions for endemic equilibrium stability were examined. To validate the theoretical results, numerical simulations were done. Conclusions: The length of the time delay in the dengue transmission epidemic model has no effect on the stability of the illness-free equilibrium. Regardless, Hopf bifurcation may occur depending on how much the delay impacts the stability of the underlying equilibrium. This mathematical modelling is effective for providing qualitative evaluations for the recovery of a huge population of afflicted community members with a time delay.Article Citation - WoS: 3Citation - Scopus: 4Comparison of Classroom Furniture To Anthropometric Measures of Turkish Middle School Students(Ios Press, 2021) Erdogan, Filiz Celikci; Satir, BenhurBACKGROUND: The match between classroom furniture and students' anthropometry is an important factor in students' academic performance. OBJECTIVE: Our aim was to investigate the ergonomic suitability of the classroom furniture to the students, and to propose design suggestions for both desks and chairs. METHODS: We analyzed the ergonomics of classroom furniture that students aged 10-14 years old in Turkey currently use. To this end, we selected Maltepe Primary Education School, one of the largest schools in the cankaya district of Turkey's capital city, Ankara, in which to conduct the study. A sample of 119 students was selected, and seven anthropometric measurements were taken for each of these students. We then calculated five relationships between the dimensions of the furniture and the students' anthropometric measures. RESULTS: We observed high levels of mismatch rates, with an average of 66.6% and high values of over 95% for the relations of two furniture measures, seat depth (related with buttock-popliteal length) and seat-to-desk height (related with elbow height, sitting). Each anthropometric measure was applied a fit probability distribution, and based on those distributions; we suggested the most appropriate classroom furniture dimensions in order to maximize suitability of the furniture to the anthropometric measures in terms of fixed-size (i.e., non-adjustable) classroom furniture. CONCLUSIONS: High mismatch rates can be reduced by 52.0% on average based on the classroom furniture dimensions suggested in this study.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.