Sharif Digital Repository

The numerical solution of the parabolized Navier-Stokes (PNS) equations for accurate computation of hypersonic axisymmetric flowfield with real gas effects is obtained by using the fourth-order compact finite-difference method. The PNS equations in the general curvilinear coordinates are solved by using the implicit finite-difference algorithm of Beam and Warming type with a high-order compact accuracy. A shock fitting procedure is utilized in the compact PNS scheme to obtain accurate solutions in the vicinity of the shock. To stabilize the numerical solution, numerical dissipation term and filters are used. The main advantage of the present formulation is that the basic flow variables... 

Our main goal in this project is to calculate the cell survival fraction (SF) in unhealthy tissue after carbon ion beams are emitted and hit the target tissue. At present, in the stages of carbon therapy, it usually takes a long time to make the necessary calculations for that particular person, and this makes the treatment process progress slowly, but in this project, we intend to address this problem with Eliminating the use of neural network. The main reason is the use of carbon ions to increase efficiency in the treatment of tumors and deep cancerous tissues. To do this project, we first convert the carbon ion energy to the dose absorbed at the desired point. For this phase of the... 

Solvatochromic parameters (ETN: normalized polarity parameter, π*: dipolarity/polarizability, β: hydrogen-bond acceptor basicity, α: hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (2-hydroxyethylammonium formate) at 25 ◦C. The applicability of nearly ideal combined binary solvent/Redlich-Kister equation was proved for the correlation of various solvatochromic parameters with solvent composition. Solute-solvent and solvent-solvent interactions were applied to interpret the results. Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/Al2O3, was carried out in... 

In this investigation, silica-based iron-metal catalyst was synthesized by the Atomic layer deposited (ALD) method with iron-acetylate (Fe(acac)3) as a precursor in different loading dosages. The synthesized catalyst were characterized by nitrogen absorption and excretion (BET), by Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), and Temperature-Programmed Reduction (TPR), Fourier-transform infrared spectroscopy (FTIR), Atomic Emission Spectroscopy (ICP) etc.
The temperature range of 180 to 200 °C was determined for the self-limited chemisorption of Fe(acac)3 on the silica surface as the first and the most important step in a single atomic cycle. Also the... 

Nowadays integrated circuits are extremely vulnerable to hardware trojans (HT). Hardware trojans can be injected into the ICs in design or fabricate phase, and damage system’s functionality or security. In this thesis, we first describe hardware trojan definition, classification and types of HTs, negative effects, detection ways and analysis of them. Then we propose a new solution in order to solve the negative points of previous methods  

Inequality and the feeling of injustice governing in the work environment place is one of the important and influential factors on employees'affecting productivity. If Should the employees believe that they are getting lower wages despite having the same productivity as their colleagues, they receive less wage than those co-workers, they might find the firm's behavior unfair and thus, they would loweradjust their performance accordingly. This problem is of great importance, hence the numerous related studies in the literature. This study investigates the effect of inequal unequal payment and promotion on the productivity of the employees by designing and implementing a natural work... 

MIMO radar is a next generation radar which transmits arbitrary waveforms at each one of its apertures. It has been shown that design of waveforms for MIMO radars in order to synthesize a desired spatial beampattern, is mapped into a waveform correlation matrix (R) design in the narrowband case. Therefore, waveform design in MIMO radar for beamforming could be broken into two steps, namely correlation matrix design and waveform synthesis for achieving given R. As of now, given a desired beampattern or estimated location information of targets, calculating R has been modeled as an optimization problem like SDP. Also, in some special cases like rectangular beampattern, close form solutions for... 

In this project, two bidirectional loadcell are designed and fabricated to be installed on a walker. Then upper extremities’ forces and moments have been obtained. Results can be used for rehabilitation purposes in Spinal Cord Injuries and Cerebral Palsy cases. The method used in this project is as follows: First, since the commercial multidirectional loadcells are too expensive, the loadcell (and an appropriate electronic board) are fabricated. Ultimately, a complete gait analysis by means of VICON motion analysis and using inverse dynamic method has been held to measure upper extremities’ forces and moments in the wrist, elbow and shoulder. The results for a person with Spinal Cord Injury... 

After proteins, one of the important biological macromolecules, are synthesized by ribosomes,they automatically reach their own special 3-D structure. This native structur or better known as folded state is what determines the function of a protein. In some situations, the proteins become misfolded leading to its lack of biological function through aggregation or fibril formation known as "amyloid". The amyloid fibrils have been shown to be a causative factor in nerve decay such as Alzheimer's. Therefore, inhibition of amyloid formation using different approaches such as synthetic organic and natural compounds has, recently, been under spotlight. A pyridazine basedcompound (RS-0406) has... 

Various contaminants and their leachate, when they penetrate into the soil, cause changes in soil microstructure, this change in microstructure leads to changes in soil permeability and volume. In this study, first, the effects of soil microstructure change on the hydraulic conductivity of saturated soil were investigated using the change in initial saturation degree during compaction for compacted samples and the change in sample construction in reconstituted samples. Also, the simultaneous effect of changing the initial microstructure and salt solution on the hydraulic conductivity of saturated silty clay soils using a three-axial permeability device with the ability to measure volume... 

Nearly 1.2 million people die in road crashes each year, and as many as 50 million are injured in the world. In Iran, approximately 800 thousand crashes occur annually killing up to 43 people per day. Given that over 90% of accidents are related to human factors, using models that incorporate driver’s attitudes and behavior can be highly predictive of crashes. The main objective of the current research is to examine the impact of drivers’ attitudes on road crashes along with other factors such as socio-demographic characteristics and vehicle type. This study uses data from a self-completed questionnaire among a representative sample of Iranian drivers living in Tehran. The Questionnaire... 

Many studies has been focused on extracting structural and behavioral properties of complex networks in recent decade. Online Social Networks (OSNs) are one example of complex networks. Nowadays with rapid growth of OSNs such as Facebook and Twitter, the study of OSNs has become an interesting research area. Many of recent OSN studies studied friendship networks. Friendship network is a binary unweighted network, and all of its links have the same importance. But, in reality not only all friendship links are not representative of social interactions, but also the social links have a variety of intimacy, intensity, and etc. So, all links should not be considered equal. Recently researchers... 

The aim of this project was to upgrade and reduce viscosity of heavy oils by adsorbing of asphaltene on Ni-Mo/CB and converting it into lighter and more valuable gas and liquid compounds. Asphaltene has been extracted from a heavy crude oil sample of Soroush oil field in Iran. After adsorption, Asphaltene conversion to lighter components (gas/liquid) was studied through hydrocracking process. To prepare the support of catalyst, Carbon Black, initially a thermal treatment step under the argon gas atmosphere followed by acid-washing process was performed. Afterward, the catalysts was prepared through dry impregnation method. In order to activate catalyst for hydrocracking, the catalysts has... 

Nowadays many of us spend a big part of our daily times on social media.One of the most important research problems in social media analysis is how to engage users. The trace of user activity over these websites is a valuable resource for user understanding and engagement, but this data is very huge and unstructured. An approach to deal with this problem is user behavior modeling. In this process, first a behavioral model is considered for users, then using the activity data and the behavioral model, some parameters are learned. Finally, using the learned parameters, a user profile is constructed for each user. This profile can be used for user engagement and many other applications.... 

This thesis was conducted both numerically and experimentally. In the experimental investigations aqueous solutions of high molecular weight Carboxymethylcellulose (CMC) was used. The experimental set-up was composed of a glass syringe, and a piston which can easily move through the syringe. Different die with aspect ratio ranging from 5.25 to 28.8 can be attached to the syringe. The syringe then is filled with the CMC solution with different weight fractions. Then using a force exerting on the piston, the solution comes out of the die and exiting velocity was calculated from weight of CMC solution that exit from die in a definite time. High quality photographs were taken from extrudate... 

One of the critical challenges in droplet based micro- and nanofluidic devices is handling the droplet breakup such that a controllable droplet size is produced. The experimental and numerical investigations at the microscale indicate that the droplet size can be well controlled by T junction geometries. In the present study we use non-equilibrium molecular dynamics (NEMD) simulations to investigate this phenomenon at the nanoscale. In order to generalize the study the Lennard-Jones type potential between the fluids and the walls have been considered and the strength and the effective range of the potential are changed to consider a wide variety of materials. Our results reveal that the... 

In this project, production of nano and micro particles with laser ablation of zinc, silver and copper sheet metals in the liquid medium has been experimentally studied. For this aim, homemade Nd:YAG pulsed laser at 1064nm wavelength, 60μs pulses with excellent stability with energies up to 700mj is used. By changing the pulse intensity on the target surface, the parameters such as size, shape and optical properties of nano and micro particles are studied by UV-visible spectroscopy, DLS, and SEM techniques. In this work, by microsecond pulses of Nd:YAG and using measuring devices such as Coherent power /energy meter, the appropriate optical table, the related experiments are implemented.... 

In this study, the possibility of detecting known and unknown anomalies in a micro jet engine is evaluated. the proposed method is neural network and clustering analysis. The process consists of two main parts, first part is experimental abnormal behavior simulation and second part is validation of proposed detection method. In the first part a micro jet engine (Olympuse HP) were used and we created pre-designed errors in engine normal behavior to record significant changes in its performance. Recorded outputs consist of six different variables: RPM, Exhaust gas temperature, Throttle command, Fuel pump voltage, Thrust and Fuel weight. In the second part, for analyzing data, we used...