IJET Vol. 7, Issue 1, March 2021
Bu koleksiyon için kalıcı URI
Güncel Gönderiler
Öğe Quantitative Estimation of Railway Vehicle Regenerative Energy Saving: “A Case of Addis Ababa Light Rail Transit (AALRT)”(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2021) Nkurunziza, Jean Marie Vianney; Nizeyimana, Jean d’Amour; Turabimana, PacifiqueA rapidly growing demand and shortage of electric energy require mankind to efficiently use it, recuperate and store it from the existing system, when possible, for further applications whenever the need arises. Electric trains figure among big energy consumers and among different railway transportation services; light rail transit trains are characterized by frequent stoppings to entrain and detrain passengers. In their operation, traction drives are made to keep on braking in order to meet their service requirements between closely spaced passenger stations. The modern service braking system used is regenerative braking, which acts as an electric energy generator during the braking period. The objective of this paper is to estimate the magnitude of regenerative energy that can be recuperated as a percentage of train energy consumption on East-West (Ayat to Tolhailoch) and West-East (Tolhailoch-Ayat) directions of Addis Ababa Light Rail Transit. Mathematical equations have been used to calculate the energy consumed between stations followed by the quantification of regenerative energy at each passenger station. Considering the current average running speed (24km/h) of the line, it resulted that 26.31% and 28.18% of energy consumption for East-West and West-East directions respectively are saved through regenerative braking energy recuperation. From the above results, it was observed that the magnitude of regenerative energy strongly depends on the speed at which the train is running and the efficiencies of inverter and traction induction motor.Öğe Testing of Maturity Methods for Concrete Quality Cured Using Various Temperatures(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2021) Pehlivan, Ahmet Onur; Yazgan, Ahmet UtkuMaturity of concrete is a subject of utmost essence in all phases of a construction project that has to be dealt with care and accordingly important advantages may be gained with optimum predictions. In this study, concrete specimens at various strength classes were prepared to investigate on the effect of concrete class on two different maturity function given in literature. Procedures were handled in accordance with the prescriptions given in ASTM C 1074. Recommendations given in the same standard for standard cement type was discussed and convenience of two different maturity functions were analyzed. Important values obtained from mortar specimens tests were applied to maturity calculations of concrete mixtures and applicability of the methods were discussed. It is found that with the increasing concrete quality, for two extreme temperatures (8 and 25 ?C) in this study, important deviations in the results are observed. Results obtained from specimens cured at 36 ?C were found to be significantly higher than specimens cured at 8 ?C at higher maturity levels. Datum temperature and Q-values data obtained from mortar mixtures were applied to concrete specimens and it may be asserted that concrete specimens demonstrated good correlation with the findings of both maturity functions. Generally, it may be expressed that maturity functions behave well under normal temperatures however applicability at extreme temperatures should be limited.
