Sharif Digital Repository

This paper presents the results of a vulnerability assessment of the damaged Al-Askari shrine located in Samarra, Iraq by finite element analysis. Reliable material characteristics are derived using limited experimental data on this historical building in order to be utilized in the numerical models. It is concluded that the cracked piers are not vulnerable under the weight of the newly added dome. However, the cracks in the piers widen under design seismic loads, which results in unbalanced settlements in the piers and torsional cracks in the dome. The vulnerability of the minarets is more severe, necessitating heavy reinforcement at their bases and adequate anchorage to the masonry... 

The Al-Askari shrine, located in Samarra, Iraq, is a remarkable example of a building with ancient Islamic architecture and construction that was heavily damaged by massive bombings. The bombings were carried out by two separate terrorist attacks in 2006 and 2007. This paper summarizes the important undertakings in the identification of shrine buildings in terms of structural and architectural background and characteristics, damage classification and monitoring, site conditions and material properties. Moreover, the shortcomings of a series of previously performed partial restorations are elaborated upon. The results and findings of this study can be utilized as database in other numerical... 

One of important subjects in power system restoration that already is not addressed is frequency control. Operators are often concerned with the size of load and generation, which can be safely increased. With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming increasingly important. This requires information with higher accuracy and update rates faster than those usually provided by traditional SCADA systems. In addition, it must be synchronized over a wider geographical area than that provided by traditional protection systems. Nowadays, the introduction of Phasor Measurement Units (PMU) and Wide Area Monitoring Systems (WAMS) as well as advances in... 

The first control action in power system restoration concerns the generation restart. In the initial phase of restoration, operators are often concerned with load pickup problems. One of the important problems during load pickup is keeping frequency response in allowable range. The aim of this paper is to determine the best sequence of load pickup by hydro and steam units during power system restoration based on frequency response of prime movers. Hydro power plants and combustion turbine units have the capability of black start operation and can be used for early stages of power system restoration. This paper considers hydro power plants for evaluating the stability and frequency response... 

Optical coherence tomography (OCT) is a noninvasive imaging modality that provides cross-sectional images from microstructures of tissues. This optical imaging system works based on Michelson interferometry principle and has intermediate resolution and penetration depth which makes it appropriate for imaging thin tissues such as skin and eye. OCT images suffer from three main artifacts that make images difficult to be analyzed. The first one is small grainy structures called speckle which degrade image quality and decreases axial and lateral resolution. The second one is light intensity attenuation which is a function of depth. It happens because of absorbing and scattering nature of tissue... 

This paper presents an efficient scheme for blind watermark attacking using the concept of matching of the long-range data. The main idea of the proposed attack is to add plenty of noise to the watermarked image and then try to restore an unwatermarked copy of the noisy image. The aim is to destroy the watermark information without accessing the parameters used during the watermark embedding process. So, it allows our approach to be completely free from any pre-assumption on the watermarking algorithm or any other parameters that is used during the watermark embedding procedure. Experimental results show the proposed algorithm's superiority over several other traditional watermarking... 

Over the past decades, there has been a dramatic increase in the frequency of natural disasters, which are the leading causes of large-scale power outages. This paper, therefore, assesses the significance and role of optimal tie-line construction in improving the service restoration performance of unbalanced power distribution systems in the aftermath of high-impact low-probability incidents. In doing so, a restoration process aware stochastic mixed-integer linear programming model is developed to find the optimal locations for new tie-line construction in unbalanced three-phase distribution systems. In particular, the restoration process of distribution systems, including the fault... 

Over the past decades, there has been a dramatic increase in the frequency of natural disasters, which are the leading causes of large-scale power outages. This paper, therefore, assesses the significance and role of optimal tie-line construction in improving the service restoration performance of unbalanced power distribution systems in the aftermath of high-impact low-probability incidents. In doing so, a restoration process aware stochastic mixed-integer linear programming model is developed to find the optimal locations for new tie-line construction in unbalanced three-phase distribution systems. In particular, the restoration process of distribution systems, including the fault...