Sharif Digital Repository

Sensors are one of the most vital instruments in Nuclear Power Plants (NPP), and operators and safety systems monitor various parts of the NPP and control transients by analyzing the values reported by the sensors. Failure to detect malfunctions or anomalies in them would lead to catastrophic consequences. A new approach based on thermo-hydraulic simulation by RELAP5 code and Feed-Forward Neural Networks (FFNN) is given to detect faulty sensors and estimate their correct value which are two main objectives of the current study. This approach consists of two main parts; The first part, Fault Detection Hyper Block (FDHB), responsible for detecting faulty sensors, and the second part,... 

One of the major challenges in construction of rubber modified asphalt mixtures is determination of mixing and compaction temperature (MCT). In order to estimate MCT according to Superpave volumetric mix design procedure, a temperature-viscosity relationship for the binder should be developed using ASTM D2493. This approach provides reasonable temperatures for unmodified binders which are Newtonian fluids at high temperatures and their viscosity is independent of shear rate. However, this method often yields excessively high temperatures for modified binders which exhibit non-Newtonian pseudoplastic behavior. The reason is that viscosity of modified binders depend on not only temperature but... 

One of the applications of signal digitization is its use in nuclear spectroscopy and in particular gamma ray spectroscopy. Parameters such as pulse amplitude and formation, pulse shrinkage correction or reduction, and pulse sampling are performed by the amplifier circuit and MCA. Such algorithms have advantages such as real-time pulse height analysis, high flexibility and significant cost reduction.Therefore, in this project, an attempt has been made to design a pulse analyzer system using electronic circuits and a computer ADC sound card. Optimal system will detect, amplify and shape the detector input signal, reduce the effect of pulse accumulation, count the number of pulses, and so... 

Today, lots of vulnerabilities are discovered by researchers who are analyzing the software. Some researchers study these discovered vulnerabilities and find new ones that are similar to them. So they need to first characterize each previously discovered vulnerability and extract the vulnerable context of the program, then extract new vulnerabilities based on that. Some vulnerabilities are emerging because of developer mistakes in the implementation phase. Software developers use different function calls to do the goal of the program. Incorrect invocation for functions can lead to critical vulnerabilities. Our investigation shows that the root cause for some vulnerabilities is incorrect... 

High performance concrete has a compressive strength of more than one hundred and twenty MPa. The effect of steel fibers on the flexural fracture of this type of concrete has been studied, but the mechanical behavior of fracture of this material has not been fully studied yet. In this research, the effect of different percentages of propylene fibers on the mechanical properties of reinforced concrete will be investigated experimentaly. For this purpose, beam samples with dimensions of 40*10*10 cm, which had an initial notch with a depth of 3 cm in the lower middle of it, have been tested to investigate the effect of fiber percentage on how the crack propegate and the sample breaks. It is... 

Change detection involves comparing images of a specific area taken at different times to identify the key changes that have occurred over time. It is critically important in the field of remote sensing, with applications spanning urban planning, disaster monitoring, and environmental conservation. However, challenges such as varying weather conditions and lighting in satellite images taken at different times, as well as the presence of non-target changes, can make this task challenging. In this research, we will focus on changes in land-use, particularly in building infrastructure, which is crucial for urban development planning. Moreover, since change detection does not specify the type of... 

Supply chain consists of many important processes that are critical to be analyzed in order to enhance effectiveness and efficiency of the whole organization. This survey presents a state-of-the-art approach for evaluating the health of supply chain processes by conducting a structure based diagnostic methodology. The proposed method is conducted in an Iranian automotive manufacturer and results are validated based on internal documents. The results of assessment can be used to improve supply chain performance by suggesting various projects. Finally different analysis like theme analysis is performed on extracted diagnosis and on suggested projects  

Permeability is an essential parameter used for reservoir evaluation, simulation and management to optimize oil recovery. The conventional approach to estimate reservoir connectivity, conductivity, sweep efficiency and other critical information for decision-making is to build detailed geological models, which are then upscaled to a coarser grid where flow simulations are run. However, this takes many hours to be carried out even for a single realization practically. In practice, a very small number of realizations are considered and consequently the true uncertainty in the results is very poorly estimated. In this study, a statistical model of isotropic overlying sandbodies is used to... 

One of the major reasons causing cracks in external surfaces of concrete arch dams are thermal loads. Therofore, in order to avoid instabilities due to function of thermal loads in association with hydrostatic and hydrodynamic pressures, a precise evaluation of temperature distribution through dam body is indispensable. In this study, effects of thermal loads mostly on upstream surface of Karun-3 concrete arch dam in Iran were examined using a 3-D finite element method considering water level fluctuations. Also the influence of operatvie boundry conditions in our problem which are water temperature, air temperature and solar radiation was precisely taken into account. Moreover, nonlinear...