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Mahdi Mahdikhani,Melika Naderi,Mehdi Zekavati 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.1
Since the preservation of monuments is very important to human societies, different methods are required to preserve historic structures. In this paper, 3D model of arch stone bridge at Pont Saint Martin, Aosta, Italy, was simulated by 1660 integrated separate stones using ABAQUS® software to investigate the seismic susceptibility of the bridge. The main objective of this research was to study a method of preservation of the historical stone bridge against possible earthquakes using FRP techniques. The nonlinear behavior model of materials used theory of plasticity based on Drucker-Prager yield criterion. Then, contact behavior between the block and mortar was modeled. Also, Seismosignal software was used to collect data related to 1976 Friuli Earthquake Italy, which constitutes a real seismic loading. The results show that, retrofitting of the arch stone bridge using FRP techniques decreased displacement of stones of spandrel walls, which prevents the collapse of stones.
An Introduction to Energy-Based Blind Separating Algorithm for Speech Signals
Mahdi Mahdikhani,Mohammad Hossein Kahaei 한국전자통신연구원 2014 ETRI Journal Vol.36 No.1
We introduce the Energy-Based Blind Separating (EBS)algorithm for extremely fast separation of mixed speech signalswithout loss of quality, which is performed in two stages:iterative-form separation and closed-form separation. Thisalgorithm significantly improves the separation speed simplydue to incorporating only some specific frequency bins intocomputations. Simulation results show that, on average, theproposed algorithm is 43 times faster than the independentcomponent analysis (ICA) for speech signals, while preservingthe separation quality. Also, it outperforms the fast independentcomponent analysis (FastICA), the joint approximatediagonalization of eigenmatrices (JADE), and the secondorderblind identifica tion (SOBI) algorithm in terms ofseparation quality.
Ali Akbar Ramezanianpour,Mahdi Mahdikhani 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.2
In recent years, the emergence of nanotechnology and nanomaterial has created hopes to improve various properties of concrete. Nano silica as one of these materials has been introduced as a cement replacement material for concrete mixture in construction applications. It can modify the properties of concrete, due to high pozzolanic reactions and also making a denser microstructure. On the other hand, it is well recognized that the use of mineral admixtures such as silica fume affects the mechanical properties and durability of cementitious materials. In addition, the superior performance of self-consolidating concrete (SCC) and self-consolidating mortars (SCM) over conventional concrete is generally related to their ingredients. This study investigates the effect of nano silica and silica fume on the compressive strength and chloride permeability of self-consolidating mortars. Tests include compressive strength, rapid chloride permeability test, water permeability, capillary water absorption, and surface electrical resistance, which carried out on twenty mortar mixtures containing zero to 6 percent of nano silica and silica fume. Results show that SCMs incorporating nano silica had higher compressive strength at various ages. In addition, results show that nano silica has enhanced the durability SCMs and reduced the chloride permeability.