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Full-Text Articles in Engineering
Performance Of Ballast Influenced By Deformation And Degradation: Laboratory Testing And Numerical Modeling, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Performance Of Ballast Influenced By Deformation And Degradation: Laboratory Testing And Numerical Modeling, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Faculty of Engineering and Information Sciences - Papers: Part B
This paper presents a study on the deformation and degradation responses of railway ballast using large-scale laboratory testing and computational modeling approaches. A series of large-scale triaxial tests were carried out to investigate the ballast breakage responses under cyclic train loading subjected to varying frequencies, f=10-40 Hz. The role of recycled rubber energy-absorbing mats (REAMs) on reducing ballast breakage was also examined. Laboratory test results show that the ballast experiences significant degradation (breakage) and deformation, while the inclusion of REAMs can reduce the ballast breakage up to about 35%. Numerical modeling using the coupled discrete-continuum approach [coupled discrete-element method-finite-difference method …
Power Loss And Thermal Impedance Modeling Of Multilevel Power Converter With Discontinuous Modulation, Md Mazharul Islam, Md. Ashib Rahman, Md Rabiul Islam
Power Loss And Thermal Impedance Modeling Of Multilevel Power Converter With Discontinuous Modulation, Md Mazharul Islam, Md. Ashib Rahman, Md Rabiul Islam
Faculty of Engineering and Information Sciences - Papers: Part B
The hard switching operation of the insulated gate bipolar transistor (IGBT)-based multilevel converters (MLCs) in the transformer less direct integration of renewable power plants produces a considerable amount of switching and conduction power loss. This eventually causes higher junction temperature and lower thermal stability. The third harmonic sixty-degree bus-clamped pulse width modulation (BCPWM) technique demonstrates reduced switching losses and better harmonic spectra. In this paper, an analytical model for calculating the average and the rms currents for the hard switching operation of IGBTs and antiparallel diodes (APDs) is proposed. Furthermore, to calculate the device turn-on and turn-off losses, a discrete …