Sharif Digital Repository

Mathematical modeling and computer simulation are powerful tools to help cancer research because they provide a good insight of cancer progression and an efficient framework to test biological hypothesis. Most of the previous studies ignored many intracellular communication between tumor cells. Gap junction is one of the interaction ways between tumor cells which plays a crucial role in cancer progression. In the first phase of this thesis, a model of intracellular communication through gap junction using evolutionary game theory scoring is proposed. In the second phase of this thesis, cancer is modeled by Markov decision process (MDP). Given that considering nutrient level constant is one... 

X-ray radiation is an ionizing radiation that can be produced under some conditions in an ion implanter and can have significant effects on equipment and personnel health. In this dissertation, we first examine the properties of ionizing radiations and their effects of electronic devices and discuss the general properties of common detectors. Next, Using Silvaco TCAD and GEANT4 we will simulate the interaction of ionzing radiation with energies up to 300 keV with electronic devices including a commercial off the shelf photo diode and a specialized x-ray detector and show that these devices can efficiently reveal informations of a radiation source to the user. Also, it has been shown that... 

Suppose that A is a large subset of N. It is interesting to think about the arithmetic progressions in A.In 1936, Erdos and Turan conjectured that for > 0 and k 2 N, there exists N = N(k; ) that for all subsets A {1; 2; : : : ;N}, if lAl N, A has a nontrivial arithmetic progression of length k. Roth proved the conjecture for k = 3 in 1953. In 1969, Szemeredi proved the case k = 4 and in 1975, he gave a combinatorial proof for the general case. In 1977, using ergodic theory, Furstenberg gave a different proof for the Erdos-Turan conjecture (or Szemeredi Theorem!) and finally Gowers found another proof for the Szemeredi theorem, which was an elegant generalization of the Roth’s proof for k =... 

Smart materials are able to change their physical properties under various environmental conditions. Shape memory alloys (SMA) are relatively new smart materials that can respond to environmental stimuli e.g., heat, electricity, etc. Unique behaviors of SMAs, called shape memory effect and superelasticity, have motivated many applications in various fields of study (aerospace, medical, civil engineering, etc.). Although the behavior of SMAs is complicated, modeling and utilizing these materials have been receiving much attention in the past 20 years. Since a cable tolerate more tension than a wire or rod, the shape memory alloy cables could have a broad range of potential applications.... 

The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have... 

Out of several ground improvement techniques available, stone columns have been widely used. This technique has been successfully applied to increase the bearing capacity and to reduce the settlement for foundation of structures like liquid storage tanks, earthen embankments, raft foundations, etc., where a relatively large settlement is permissible. This technique has, generally, been proven successful in increasing the stiffness of weak soils, upgrading their safe bearing capacity, and reducing their total and differential settlements, as well as speeding up their consolidation process. The beneficial effects of stone column installation in weak deposits is manifested in the form of... 

Laminar forced convection flow through a channel partially filled with a porous material was numerically studied in this thesis. The Navier-Stokes and Brinkman-Forchheimer equations were used to model the fluid flow in the free and porous regions, respectively. Coupling of the pressure and velocity fields was resolved using the SIMPLEC algorithm. The local thermal equilibrium was adopted in the energy equation. The effects of the thermal conductivity ratio, Darcy number, porosity, Reynolds number and height of the porous insert on velocity and temperature field were investigated. The results show that the flow behavior and its associated heat transfer are susceptible to the variation of the... 

In the present study, a new version of haptic devices is presented in which user’s hand is in contact with the device just while collision with virtual surface. In this system, the position of user’s finger can be traced by using a camera and the haptic device follows user’s finger at the distance of about two centimeters. While the haptic device approaches to the virtual surface, gradually reduces its speed and stops about two centimeters distant of virtual plane. Then user’s hand collides with the haptic device which is static. Greater fidelity, transparency, more stability and also no need to large actuators are of the advantages of this system. In this project, first we present a new... 

In this thesis we try to find optimized parameters for imaging and manipulation of a biosample with AFM. For this we have prepared a numerous Molecular Dynamics simulation and find some reliable result. So, first we have focused on imaging process in Non contact mode (the less harmful mode). Then we headed into the manipulation process. The main problem about manipulating a biosample is the environment. In imaging section, the process of imaging a biomolecule by AFM is modeled using molecular dynamics simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the non-contact...