Sharif Digital Repository

In this study a Monte Carlo simulation was used to investigate the effect of cell reactivities and particle diffusivities in the cells and matrix on the diffusion and reaction rate constants in gel-immobilized cell systems with different spatial cell configurations. A variety of conditions were examined ranging from instantaneous to very slow reactions with reaction probabilities equal to or less than one, and diffusivity ratios bigger or smaller than one in a spherical domain. In the case of high reactivity (diffusion-limited), the simulation results indicated a decrease in the reaction rate constants when heterogeneity in the cell distribution was increased. In the case of low reactivity... 

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... 

In addition to meeting the real-time constraint, power/energy efficiency and high reliability are two vital objectives for real-time embedded systems. Recently, heterogeneous multicore systems have been considered an appropriate solution for achieving joint power/energy efficiency and high reliability. However, power/energy and reliability are two conflict requirements due to the inherent redundancy of fault-tolerance techniques. Also, because of the heterogeneity of the system, the execution of the tasks, especially real-time tasks, in the heterogeneous system is more complicated than the homogeneous system. The proposed method in this paper employs a passive primary/backup technique to... 

In addition to meeting the real-time constraint, power/energy efficiency and high reliability are two vital objectives for real-time embedded systems. Recently, heterogeneous multicore systems have been considered an appropriate solution for achieving joint power/energy efficiency and high reliability. However, power/energy and reliability are two conflict requirements due to the inherent redundancy of fault-tolerance techniques. Also, because of the heterogeneity of the system, the execution of the tasks, especially real-time tasks, in the heterogeneous system is more complicated than the homogeneous system. The proposed method in this article employs a passive primary/backup technique to... 

In this study the effect of deposition temperature and thickness on the physical properties of carbon films deposited by magnetron sputtering PVD was investigated. The results of Raman spectra and grazing incidence XRD (GIXRD) patterns show that the graphitization increases by increasing the deposition temperature. There is a change in deposition mechanism at 400 °C from amorphous carbon deposition to nano-structured graphite deposition. Also by increasing substrate temperature the electrical resistance of carbon films reduces significantly up to 300 °C and then remains largely constant. High intrinsic compressive stress in low temperature deposited carbon films causes cracks and... 

Dynamic Voltage and Frequency Scaling (DVFS) is one of the most popular and exploited techniques to reduce power consumption in multicore embedded systems. However, this technique might lead to a task-reliability degradation because scaling the voltage and frequency increases the fault rate and the worst-case execution time of the tasks. In order to preserve taskreliability at an acceptable level as well as achieving power saving, in this letter, we have proposed an enhanced DVFS method based on reinforcement learning to reduce the power consumption of sporadic tasks at runtime in multicore embedded systems without task-reliability degradation. The reinforcement learner takes decisions based... 

Human parvovirus B19 (B19) is a small, non-enveloped virus and belongs to Parvoviridae family. B19 persists in many tissues such as thyroid tissue and even thyroid cancer. The main aim of this study was to determine the presence of B19, its association with increased inflammation in thyroid tissue, and thus its possible role in thyroid cancer progression. Studies have shown that virus replication in non-permissive tissue leads to overexpression of non-structural protein and results in upregulation of proinflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha. A total of 36 paraffin-embedded thyroid specimens and serum were collected from patients and 12 samples were used...