Sharif Digital Repository

In this thesis, we try to design and implement a low noise, low power consumption CMOS direct conversion mixer with LO-2LO topology. Direct conversion mixers have two differential I,Q outputs. Because of zero intermediate frequency, flicker noise is critical. This mixer is designed for UHF band in TSMC CMOS 0.18µm technology. Total current consumption of I,Q mixer is less than 3mA .Voltage conversion gain is about 23 dB and DSB noise figure is less than 3.5 dB. Some conventional thermal and flicker noise cancellation has been used simultaneously to reduce noise figure. New noise cancellation techniques are proposed to get further improvement in noise figure with negligible extra current... 

In this thesis, we first define the pseudo-distance p on the group of Hamiltonian diffeomorphisms.Using the concept of displacement energy, we show that the pseudo-distance p is degenerate and if the manifold is closed, p will be zero for each p = 1; 2; 3; : : : Then, we introduce Lagrangian submanifolds and prove that if L R2n is a rational Lagrangian submanifold, we have the following inequality e(L) ≥ 1γ(L). : Finally, using the above inequality and the concept of displacement energy, for M = R2n we prove that 1 is non-degenerate. Therefore, the hypothesis for 1 to be a metric, are satisfied. This metric is called Hofer’s metric  

This research concerns investigating the behavior of two-phase flow in the inlet and outlet of the microchannels.Both the droplet based and the continuous microfluidics are considered. For the continuous system whenthe minor fluid enters the microchannel, due to ratio of viscosity of two fluids, viscous folding occurs.Viscous folding phenomena is similar to the buckling phenomena in solids.This means that the viscosity of the fluid, which is applied to two sides of the fluid layer, causes folding the fluid layer and changing the shape of it. For the study we employ a VOF based numerical routine. In order to verify numerical results, the grid and the time step independenciesare checked. In... 

This researⅽh investigates the perforⅿanⅽe of epiⅾeⅿiⅽ routing، in ⅿobiⅼe soⅽiaⅼ net−works (ⅯSNs)، whiⅽh ⅿakes use of the store−ⅽarry−forwarⅾ paraⅾigⅿ for ⅽoⅿⅿuni−ⅽation. Reaⅼ−ⅼife ⅿobiⅼity traⅽes show that peopⅼe have skeweⅾ ⅼoⅽation visiting pref−erenⅽes، with soⅿe pⅼaⅽes visiteⅾfrequentⅼy anⅾ soⅿe others infrequentⅼy. In orⅾer to ⅿoⅾeⅼ epiⅾeⅿiⅽ routing in ⅯSNs، we first anaⅼyze the tiⅿe taken for a noⅾe to ⅿeet the first noⅾe beⅼonging to a set of noⅾes restriⅽteⅾ to ⅿove in a speⅽifiⅽ subarea. Af−terwarⅾs، two networks are ⅽonsiⅾereⅾ. For eaⅽh network، a ⅿonoⅼithiⅽ stoⅽhastiⅽ re−warⅾ net (SRN) is proposeⅾ to evaⅼuate the ⅾeⅼivery ⅾeⅼay anⅾ the average nuⅿber of transⅿissions unⅾer... 

This paper examines the effect of the initial public offering (IPO) of banks in the Tehran Stock Exchange on their lending practices to firms. To this end, panel data from the financial statements of 93 listed firms, along with a database of loan balances of listed companies in the Tehran Stock Exchange, categorized by their respective banks, between 1386 and 1397, were utilized. The main question of this paper is whether the IPO of banks in the stock market affects their decision-making in granting loans and applying essential filters in selecting firms. To answer this question, the ordered logit method was employed. The results of the research show that publicly listed banks are more... 

This research program is built up from understanding the dominant leadership style in the Iranian prosperous and propounded organizations according to Robert Blake and Jane Mouton Seventh Dominant Patterns of Behavior. According to the main purpose of this research, which includes defining the dominant leadership style and consequently studying its effects on organizational performance, apprehending how staff are led in successful organizations provides immediate insights into how the employed style can bring the organization forward and make it closer to its final objectives. Moreover, the research provides an opportunity for managers to critically assess, evaluate, and analyze their own... 

Successful formulation development for poor water soluble drugs is a critical, long-standing and challengeable problem in cancer treatment. One of the methods for transporting low-soluble drugs is using nanoparticles which are able to pass through capillary walls of tumor tissues due to their small size. An example of the nanoparticles is micelle systems. Functionalized β-cyclodextrin (β-CD) by hyper branched polyglycerol (HPG) can dissolve low-soluble compounds. This polymer can be used in preparing micelles. In this project, β-cyclodextrin (β-CD) by anionic reactions is initiator for polymerization of glycidol monomer. Hydrophobic cavity of the β-cyclodextrin (β-CD) in placing the phenyl... 

Axial compressors are utilized to increase compressible flow pressure in an efficient manner where mass flow rate is high, such as aviation engines and power generation gas turbines. The flow is compressed within this machine through several stages. Each stage consists of a rotor blade row followed by a stator blade row. Energy transfer to the air is performed on the rotor by changing its velocity vector. Then, pressure is recovered from velocity by diffusion, meanwhile turning the flow direction through stator blades. These blades have been designed and optimized with various methods evolved with developing computational and manufacturing facilities. In this thesis the aerodynamic design of... 

In recent years, there have been huge advancements in fabrication of micron-sized devices such that they enabled engineers to create a wide range of miniaturized systems, each of which is utilized in mechanical, electrical, and thermal applications. Micromixers are one of these devices with the role of mixing various micro flows. These devices are broadly used for chemical, biological, and biomedical assays. Among variety of micromixers, one that employs electrokinetic transport phenomenon is of great popularity. For instance, mixing under electroosmotic flow enables accurate process control and eliminates the need for moving components inside micromixer. The very complex nature of electric... 

In this research it has been attempted to suggest a modified retrogression and re- aging heat treatment on the sheet of AA7075 alloy with a thickness of 2 mm. The main aim of the research is to reduce the required duration of RRA process while maintaining the value of the conventional tensile strength achieving by the RRA process. This was performed by adding an intermediate warm rolling deformation during the RRA process. The rolling temperature was 180 °C and the rolling reductions were 30%, 40%, 50%. Moreover, the temperature of 170°C was selected as the re-aging temperature, for which the aging time of 0.5, 1, 1.5, 2, and 2.5 hours were examined. This temperature and times were chosen to... 

Trip demand analysis is among the most important parts in comprehensive transportation studies. Developing four stage models including trip generation, trip distribution, mode choice, and assignment are so common in demand analyzing. In this study, trip generation models have been studied and to analyze data, two different methods including OLR and GWR are utilized. This study aims to examine relationship between aggregate zones in order to forecast future trips. Moreover, results of modeling trip generation with two different methods, OLR and GWR, are compared. Comparing different levels of aggregation reveals that as the number of zones decreases, the results get better. Decreasing number... 

Iran has the third largest reservoirs of oil and the second largest reservoirs of gas and has the greatest hydrocarbon reservoirs worldwide. Considering the fact that production of oil is highly dependent on gas injection, Iran is facing a great challenge in determining proper strategy for consuming natural gas. Due to the lack of proper strategy form the point of view of economical as well as scientific evaluation in political and social aspects, it has resulted in weakening Iran’s place in international markets and also reduction of oil wells’ productions.In this study, after a review of relevant literature, characteristics of oil and gas projects effective on modeling them were...