Sharif Digital Repository

We study a class of optimization network problems on pairs of structures. In particular, given n pairs of points P = f(p1; q1); (p2; q2); : : : ; (pn; qn)g, in the plane or in general metric space, the goal is to color points of each pair, one red and the other blue, so as a given cost function on the red points and blue points is optimized. The cost functions studied previously are MST, TSP, and matching. In this work, we consider a new cost function; i.e., the diameter of each colored point set, and present efficient algorithms to solve the problem according to some objective functions  

Friction stir welding (FSW) is considered a significant manufacturing process for joining of different metals and alloys and usage of this process has been developed in different industries. Accordingly, extensive works have been done on FSW of different engineering materials. However many ambiguous problems related to thermo-mechanical behavior of this process have not been solved yet. This research investigates FSW behavior of a hardenable aluminum alloy, AA2017. Firstly, thermo-mechanical response of the material has been predicted using a three-dimensional finite element analysis performed in ABAQUS software. Then, microstructural events such as grain size, distribution of second phase... 

Access to the data of Tap30, a ride-hailing company in Iran, has allowed us to estimate the demand elasticity of online taxis. As Tap30 divides Tehran into 256 regions for pricing from Jan to June 2018, we assumed that unobservable consumer characteristics near borders are the same for adjacent regions. We used the Regression Discontinuity method to compare ride requests of people who live on two sides of borders and estimated the demand elasticity of Tap30. This research concludes that by 10 percent increase in price, the demand decreases about 3.5 percent on average in 1 hour time period. On the other hand, in 6 hours time period, the demand decreases about 7.5 percent on average by 10... 

The main purpose of this research is to investigate geotechnical parameters of surrounding rock mass of Taloun tunnels (Tehran-Shomal freeway, Iran), with application of back analysis technique and consideration of monitoring data, in order to analyzing stability of tunnel at particular monitoring station 10 (NPI10). First, the geo mechanical parameters were investigated by sensitivity analysis preceded back analysis due to determine significant geotechnical parameters of rock mass contributed to tunnel excavation with respect of displacement and stress level. Following this section sensitivity analysis of different parameters were conducted. In this section it has been found that, the most... 

In the present work, one dimensional ZnO nanostructures were grown by seed-assisted hydrothermal method. Hydrothermal processing parameters were controlled to obtain ZnO nanorods with diameter lower than 120 nm. The products were characterized by FE-SEM, EDAX, XRD, PL, and ATR-FTIR analyses. ZnO nanoparticles were also synthesized via a simple solvothermal method and their photo peropeties were compared with onedimensional nanostructures. Thereafter dye-sensitized solar cells based on TiO2-ZnO double layer nanostructured film were fabricated. It was observed that DSSC efficiency increased with decreasing the thickness of the film. The highest efficiency of 2.41% was obtained  

Graphene is a semiconductor with zero band gap. Due to electron ballistic transportation and having a single atom thickness of graphene, it is counted as an ideal material in Nano-electronic industry and essential candidate for fabrication of next generation of transistors. The Fermi level in graphene is located between Conduction and valance bands in a Dirac point. Due to low resistance, graphene has a substantial sensitivity near the Dirac point to local carrier density changes. This feature makes delicate detection of electromagnetic waves and gas sensing by graphene field effect transistors (GFETs). In this thesis, fabrication and characterization of graphene field effect transistor on... 

This paper presents five origin-destination (OD) flow estimation models using traffic sensors. The first model uses counting sensors data, the second model uses automated vehicle identification (AVI) sensors data and the third, fourth and fifth use combined data of counter and AVI sensors simultaneously. The first to fourth models are bi-level problems that the upper-level minimizes some objective functions where is the distance between estimated flows and observed flows. On the other hand, the lower-level problem finds user equilibrium (UE) flows pattern for estimated origin-destination matrix (ODM). The fifth model is a multi-objective problem, where a bi-level problem is solved for each...