Sharif Digital Repository

DNA is big protein molecule consisting of two strands intertwining each others. Recently DNA molecule has drawn attention of researchers to be used in electronic circuits and molecule electronic field. Therefore, many experiments have been carried out to measure DNA conductivity in different temperature in single molecule or bundle mode with varying size and shape. In this thesis, metallic bundle DNA at normal room temperature is studied and their resistance characteristic is obtained and compared. In order to improve DNA conductivity Metal Ions like zinc are adulterated to each of its structure period. DNAs with these metallic impurities are called metallic DNAs.
Thus, golden electrodes... 

The employment of strategies with low operational and capital investment to reduce ship's voyage costs is gaining considerable attention. With rising fuel prices, shipping companies are concerned with the increase of fuel costs of the ships. In this research, the smart steaming strategy, including the simultaneous optimization of ship's sailing route and speed, is proposed as an efficient alternative for the slow steaming to minimize ships' fuel consumption and voyage costs. By implementing the smart steaming strategy, ships owners can ensure that the ship sails at the optimal and safe sailing route and reaches the destination port on time. In addition, the proposed shipping strategy can... 

Liquefaction of gases is one of the applications of cryogenic science. Among the gases, Helium has the lowest boiling point, which at a pressure of 1atm is approximately 4.2K. Liquid helium can be used to cool superconductors in transportation equipment, military radars, and medical imaging equipment. For helium liquefaction, various cycles are used; these cycles have different parameters in their structure such as of input mass fraction to expanders, heat exchanger effectiveness, expander arrangement and ... which their analysis for improving the performance of the cycle is important. In this research, the aim is to study 2, 3 and 4 expander cycle with various parameters and structure. For... 

Natural gas power plant installed in power system as rapid start unit. In the recent decades, with increasing in the number of gas generating units in the world, consideration of natural gas transmission network in optimal solution of security-constrained unit commitment (SCUC) become a non-negligible problem. The gas transmission grid constraints integrated into the scheduling of thermal units in the proposed model for minimizes power system operating cost. In a power plant transmission of natural gas to power plant is very important because congestion in natural gas pipeline increases. This model could consider natural gas storage tank in gas transmission network as decision variable.... 

Formulating of general relativity and the assumption that gravity is only effective interaction in large-scale universe, has been a beginning for surveying the whole universe , its start and its end as a physical phenomenon. According to the Friedmann's answer to the Einstein's equation , Hubble observations and CMB radiation observations , the Big Bang model was accepted as the standard model of cosmology.
According to this model , the universe which is assumed homogeneous and isotropic , starts from a singularity (Bang) and is currently expanding. In 1970s after some tentative researches like observation of homogeneity and isotropy of CMB and visionary researches some problems like... 

The cosmic inflation paradigmwas first introduced as a possible solution to the standardBig Bang cosmology problems. [1]. The inflationary models not only provide a solutionfor so the called flatness and horizon problems, but also they predict perturbations asprimordial seeds of large scale structures of Universe. Inflationary models can connecthigh-energy physics to the experiments. There is a mutual relation between inflationand high energy physics. It is necessary to find a fundamental description of inflationarymechanism and on the other hand the observational predictions of inflationary modelscan put bound on free parameters of associated fundamental theories. Thanks to vastdata... 

We know the matter can curve the space-time according to the general theory of relativity. On the other hand Quantum Field Theory has been formulated in a flat space-time and we cannot use most of its techniques within a curved space-time. Formulating the Quantum Field Theory in curved space-time is important for various subjects in physics like early universe or black hole physics. We will review the formulating QFT in cosmological background and will look for observable consequences on Cosmological Microwave Background in this thesis  

Today with respect to the particle physics experiments and astrophysical observations we know that Neutrinos are massive. Free streaming of light Neutrinos supresses the density field of matter and opposes gravitational growth, so that clusters formed at fixed mass are fewer and hence more biased than for a pure CDM density field. One way to study the effects of Neutrinos on the formation of large-scale structures is to examine the matter power-spectrum and corellation function in the presence of massive Neutrinos.In the presence of massive Neutrinos, the matter power-spectrum is suppressed in small scales and also correlation function and clustering bias are changed in comparison to the CDM... 

Millimeter waves provide an effective opportunity to improve vision and imaging in addition to systems based on visible light, X-rays, and infrared, and researchers have paid special attention to the field of millimeter waves to develop imaging. The spectrum of millimeter waves is in the frequency between 30GHz and 300GHz, which is equivalent to the wavelength in free space, between 1 and 10mm. The advantage of millimeter waves is that it works well in different weather conditions. Also, these millimeter waves have the ability to pass through clothing and provide a suitable level of resolution in reconstructed images and provide a suitable ability to separate different materials from each... 

Methods that has been used for articular defects are faced with many limitations, so new therapies based on tissue engineering were taken into consideration in recent years. However, tissue engineering also encounters challenges regarding optimal scaffold construction and suitable cell source selection. Mature harvested chondrocytes are limited in number and may lose their chondrogenic potential in several cultures, leading to dedifferentiation. In addition, using stem cells also presents unique challenges associated with them, among which hypertrophic differentiation is the most substantial problem. Choosing the appropriate biomaterial similar to the cartilage structure with sufficient... 

Due to the replacement of fossil fuel with cleaner products, the reduction of fuel consumption in transportation until 2045, the excessive production of fuel oil in refineries and the growth of feed demand from downstream chemical units, have made countries to upgrade their refineries or construct Petro-refineries. The Petro-refinery is a new generation of refinery and its main purpose is to supply chemicals to downstream units. The products of these units will have more valuable than fuel refineries. Steam cracking unit, aromatic unit and propane dehydrogenation unit are important units that are in Petro-refineries. In this research, all refinery units were technically and economically... 

Using Aspen Hysys to simulate burners and furnaces has been the focus of several studies in recent years. According to the studies and investigations carried out in the field of optimal design of the furnace, heating the air is one of the possible tasks to improve the performance and increase the efficiency. According to the obtained results, by adding air preheat, the efficiency increases from 92% to 96%. Also, to validate the simulation, two furnaces from Sepahan Oil Refinery furnaces were simulated in the field of oil production, which were simulated with an error of less than 1% in duty calculation, and according to the general results obtained, adding air preheat can increase the... 

One of the Advanced Oxidation Process (AOP) is Photocatalyst method. Structure of this method is according to three foundation: 1. Catalyst, 2. Source of energy, 3. Wastewater. Progress of human activity around variety of fields such as pharmaceutical, plastic industry, and medical science has produced some micro pollutants such as Bisphenol A (BPA) that has aroused the public concerns in recent years. The half-life of this components in water, air and soil is too long, so typical methods such as biological method, activated sludge and carbon adsorption are inefficient in removing BPA. This work describes a visible light responsive Carbon Quantum Dots(CQDs) embedded on TiO_2 nanoparticles... 

Quantum bits, also known as Qubits are the smallest building blocks of quantum computers, their correct operation has a great impact on quantum computing fidelity. For this purpose, Qubits need to have the necessary properties. Many properties have been defined for Josephson junction-based Qubits in order to implement better qubits. In this master thesis, the main characteristics of superconducting quantum bits including resonant frequency, anharmonicity factor, output readability signal, and quantum decoherence time including relaxation time and dephasing time have been calculated for cooper pair box topology in different operational regimes from cooper pair box regime to quantronium and... 

The top quark is the heaviest of elementary particles. It gives the dominant contribution to the radiative correction to the Higgs self coupling constant which itself determines the structure of the electroweak vacuum. Therefore, it is extremely important to have a precise measurement of the top quark mass. On the other hand, whereas the lifetime of top quark is short and rapidly decays to lighter particles, it is not easy to compute and measure its mass with a desired precision. In this work, we propose a measurement method to determine the top quark mass in the t▁t→leptons +jets channel by analyzing the decay of the b-hadron in the top quark decay chain. Through the reconstruction of the... 

This research uses the Comovement between electronic payment data with GDP growth rate and private consumption growth rate to nowcast these two important macroeconomics variables. We use point of sale data set from the beginning of 1392 to the end of autumn of 1395 in monthly frequency in mixed data sampling model to use the Comovement for Nowcasting. Besides, we use two other data set, sale of industrial electricity and sale of agricultural electricity. All of this data set gives a real time sense of macroeconomics. They are also free of mistake. We show that using of this data set in the frame of MIDAS can decrease the root mean square forecast error (RMSFE) relative to auto regressive... 

Pragmatic assessment and consistency in rating are among the subject matters which are still in need of more in-depth investigations. The significance of the issue is highlighted when remembering that inconsistency in ratings would surely damage the test fairness issue in assessment and lead to much diversity in ratings. The purpose of this study was investigating the criteria that native (American) and non-native (Iranian) English speaking teachers considered while rating the pragmatic productions of Iranian EFL learners regarding the two speech acts of compliment and compliment response. Overall, a hundred and twenty teachers (sixty native and sixty non-native raters) participated in this... 

Suspension system is one of the most influential components of vehicle in the area of stability and comfort. The suspension system is designed based on the use of the vehicle and stable characteristics. Obviously, being distant from the designed spots and applying various gates, its optimized performance is lost. Semi-active suspensions by changing their features get floating designed spots to be created and suspension system is always in optimum conditions through a suitable control. This research covers the efficacy of using damper Magneto Rheological which is called damper (MR) on the performance of seat suspension system in reducing vibrations. This damper is considered as a device in... 

Most companies, especially small and new ones, operational decisions effect internal capital and the ability to earn capital. However, most articles have been focused on dynamic inventory control, ignored financing and fiscal policy. An important question can be raised is how internal capital constraints and partial trade credit can be affected company optimal inventory and fiscal policy. In this study tried to develop a model for internal cash flow and inventory management and define ordering policy with cash flow constraint and partial trade credit. The retailer can use its own capital or a loan to buy products. Also, he can invest his extra cash in a bank. The retailer’s ultimate goal... 

major challenges in field of blood supply chain has made it to an important field of study in these era. Due to specific holding environment and limited lifetime, inventory management and inventory planning of blood banks are interesting fields for research. On the other hand, various process in a blood bank make this field very complicated. In this thesis an integer programming model is presented to minimize wastage and shortages in a hospital blood bank (HBB). Elective demands are considered in a finite horizon. This model considers blood compatibility (in case of shortage of same blood group) and crossmathcing a single unit of blood package for more than one patient (demand). Inventory...