Civil & Architectural Engineering
http://hdl.handle.net/10576/3332
20240518T07:37:45Z

Energy harvesting from railway slabtracks with continuous slabs
http://hdl.handle.net/10576/54921
Energy harvesting from railway slabtracks with continuous slabs
Hussein, Mohammed F. M.; Renno, Jamil M.; Muthalif, Asan G. A.
This paper contributes to the literature and development of knowledge in the topic of energy harvesting by presenting the modelling and calculations of energy from vibration of railway tracks due to moving trains on floatingslab tracks with continuous slabs, considering both the quasistatic and dynamic effects. The floatingslab track is modelled as a double EulerBernoulli beam connected by continuous spring and damper elements. The dynamic excitation is accounted for by considering the unsprung axles of a passing train with a number of coaches. The dynamic excitation is simulated using randomly generated unevenness from standard functions of power spectral density. The responses of rails' beam and slab are calculated for different unevenness realizations, and then used as inputs for a baseexcited singledegreeoffreedom system that models the harvester. The change in the harvested energy is investigated due to the change of natural frequency of the harvester, the change of condition of track and change of train's velocity. The parameters used in this paper correspond to tracks and trains for Doha metro and unevenness information from the literature. The results show that more energy can be harvested by tuning the harvester's natural frequency to the frequency of axletrack resonance. It is found that a maximum meanenergy can be harvested from the rails of 0.35 J/kg for a train moving at 100 km/h for a track with poor condition and this is obtained at the axletrack resonance frequency. For the same track condition, a reduction of about 55% and 61% is observed for train's velocities of 70 km/h and 40 km/h, respectively. Using a track with medium and good conditions resulted in reduction of the mean harvested energy at the axletrack resonance by 73.5% and 99.9%, respectively.
20230101T00:00:00Z

Geosyntheticreinforced soils above voids: Observation and prediction of soil arching
http://hdl.handle.net/10576/54568
Geosyntheticreinforced soils above voids: Observation and prediction of soil arching
da Silva Burke, T.S.; Elshafie, M.Z.E.B.
The assumption with the biggest impact on the design of geosyntheticreinforced soils above voids is the presence and degree of soil arching, which affects the predicted applied stress on the geosynthetic. A series of centrifuge tests were conducted to investigate the soil arching in geosyntheticreinforced soils with measurements of the soil stresses and observation of soil and geosynthetic deformation used to infer the arching behaviour. Detailed analysis of the results showed that arching significantly reduces the stress at the base of the soil when a void forms; this mechanism is due to stress redistributions and not the formation of a physical arch as suggested in some models. A new method to reliably predict this reduction is proposed by calculating the coefficient of lateral stress on vertical failure planes based on the observations of a continuous convex arc of major principal strains above the void, and the assumption that this is indicative of the stress behaviour.
20210101T00:00:00Z

Pure random orthogonal search (PROS): A plain and elegant parameterless algorithm for global optimization
http://hdl.handle.net/10576/54559
Pure random orthogonal search (PROS): A plain and elegant parameterless algorithm for global optimization
Plevris, Vagelis; Bakas, Nikolaos P.; Solorzano, German
A new, fast, elegant, and simple stochastic optimization search method is proposed, which exhibits surprisingly good performance and robustness considering its simplicity. We name the algorithm pure random orthogonal search (PROS). The method does not use any assumptions, does not have any parameters to adjust, and uses basic calculations to evolve a single candidate solution. The idea is that a single decision variable is randomly changed at every iteration and the candidate solution is updated only when an improvement is observed; therefore, moving orthogonally towards the optimal solution. Due to its simplicity, PROS can be easily implemented with basic programming skills and any nonexpert in optimization can use it to solve problems and start exploring the fascinating optimization world. In the present work, PROS is explained in detail and is used to optimize 12 multidimensional test functions with various levels of complexity. The performance is compared with the pure random search strategy and other three wellestablished algorithms: genetic algorithms (GA), particle swarm optimization (PSO), and differential evolution (DE). The results indicate that, despite its simplicity, the proposed PROS method exhibits very good performance with fast convergence rates and quick execution time. The method can serve as a simple alternative to established and more complex optimizers. Additionally, it could also be used as a benchmark for other metaheuristic optimization algorithms as one of the simplest, yet powerful, optimizers. The algorithm is provided with its full source code in MATLAB for anybody interested to use, test or explore.
20210101T00:00:00Z

Integration of Captivate and JOOMLA: Online demonstration and assessment elearning resources
http://hdl.handle.net/10576/54171
Integration of Captivate and JOOMLA: Online demonstration and assessment elearning resources
Aw, Swee Liang; Aye, Koko; Ayari, Arslan; Laban, Firas
The system uses Adobe Captivate [1] to create and generate the learning and assessments materials in PDF format to allow students to access the learning materials and to do the assessment interactively. Each assessment is based on the demonstration video which covers all the concepts included in the assessment. Joomla [2] platform is employed in this web application to distribute all the video materials online as well as to keep tracking the hits used on these materials by the students. The system also allows the user to do offline assessment. Like other assessment, the system can immediate feedback as to how many questions were answered correctly and what are the correct answers, as well as providing worked solutions indicating how the correct answers could be deduced. The highest quality of typesetting is employed in the system by using the Adobe Captivate software, via the Joomla, to produce a webbased written in PHP [3].Other software, such as Flash[4], can be embedded to control the interaction between users and the materials. © 2010 IEEE.
20100801T00:00:00Z