Sharif Digital Repository

Auction is one of the most important and oldest institutions in economics, enabling resource allocation and trade of goods in the economy. Investigating the effects of changes in reservation price in auctions is an important question in auction theory research. In this study, focusing on a policy implemented by Yektanet, which involved altering the reservation price in auctions for advertising slots, we assessed its impact on advertiser costs. The implemented policy led to the activation of two distinct mechanisms, resulting in conflicting effects on the company's revenue. The first mechanism involved an increase in bid and intensified competition for ad placements on average, while the... 

With the rise of the concept of “Big Data”, both data volumes and data processing time increased, imposing the need for new methods of processing and computation of said data.Analytical and computational methods in Machine Learning are some of the most important applications of Big Data processing. There exist many methods of data analysis in the Machine Learning field, each requiring extensive processing on Big Data. One of the methods for working with Big Data is Distributed Systems. MapReduce is one of the most popular methods distributed computation by increasing the ease and speed of distributed processing of big data. But a number of bottlenecks have been discovered in MapReduce which... 

The usage of plugin hybrid electric vehicles has environmental benefits. However, the penetration of these components raises important concerns for grid planning. Thus, it is necessary to model the load change due to their charge to investigate the impact of these vehicles on distribution networks. For this reason, it is necessary to determine the specifications of these vehicles, such as battery charge and energy consumption on daily trips. In addition, the study of some behavioral patterns of these vehicles and some experts are necessary to complete the model.In this thesis, an active distribution network is planned using dynamic programming formulation. In this model, some buses are added... 

The integration of radar and communication functionalities into a unified Joint Radar-Communication (JRC) system offers enhanced spectral efficiency and reduced hardware complexity. Recognized as a key enabler for next-generation wireless networks, JRC systems require a careful balance between radar and communication demands, where waveform design plays a pivotal role in achieving this equilibrium. Although waveform design has been extensively studied separately in radar and communication domains, the requirements of modern networks necessitate a unified approach that simultaneously addresses the needs of both systems. This thesis advances waveform design methodologies for JRC systems,... 

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... 

TPPB are characterized by a cell-containing aqueous phase, and an immiscible and biocompatible organic phase that partitions toxic/insoluble substrates to the cells base on their metabolic demand and the thermodynamic equilibrium of the system. Surface areas, Mass transfer coefficient, Hydrophobicity of polycyclic aromatic hydrocarbons (PAH) are considered as limitation in two phase partition bioreactors (TPPB). For solving of this challenge, in this project used solid particle for increment of mss transfer and surface area, and also solid particles can eliminate limitation of initial concentration of polycyclic aromatic hydrocarbon and ratio of aqueous/organic phases. Naphthalene is used as... 

In this dissertation, the application of frequency and space diversities in radar target parameter estimation are investigated. On this basis, multi-frequency signal is used to improve the range resolution, array structure is used to increase the angle estimation accuracy and the merger of the multi-frequency signal and array structure are used to increase the maximum number of targets that can be uniquely identified.Considering the desirable properties of multi-frequency signals such as high bandwidth efficiency, high range resolution achievement without chip length decrease and …, there has been increased interest in the vast area of research on the design of such signals that has... 

Target recognition techniques based on micro Doppler phenomenon are popular because they are applicable even on low resolution radars, in contrast to other techniques such as High Resolution Range Profile (HRRP) which need high resolution in range or angle. Usually, main purpose of such techniques is generating robust features against target initial state, velocity, aspect angle, etc. rather than features which exactly identify a target. Main approaches in the literature are based on time-frequency transforms (TFT) such as spectrogram in order to generate features to classify targets, but in this thesis, we propose a totally different method using Recurrence Plot for generating features... 

In this research with Finite Element Methods in ABAQUS, numerical modeling has done in three-dimensions, which can be used to determine the effect of different factors on the surface settlement. Also, various factors such as geotechnical conditions, tunnel diameter,tunnel depth, the impact of the thickness of the segments and the amount of eccentricity of the structure relative to the longitudinal axis of the tunnel considered in this study. Face Pressure Supports, and Grout Injection Pressures are taken into account, too.Tunnel drilling causes a change in the displacement area and creates a changing zone around the tunnel. In this regard, not only adjacent buildings will be affected by... 

Proton precession magnetometers are one of the most sensitive scalar magnetic sensors. Their function is based on Zeeman effect and also nuclear magnetic resonance phenomena. In this project we have designed and implemented needed coils, swithching and signal detection circuits. Because of extremely high sensitivity of this sensor to induced noises and also gradient of earth’s magnetic fileld, detection of precession signal needs design of low noise electronic circuits with special EMC considerations. The implemented system in this project contains different blocks, such as switching circuit and its related control unit, amplifier, filter and frequency meter. Using this system, the obtained... 

Effective field theory is a practical method for model building and explaining experimental/observational data. These theories are constructed based on knowing low energy degrees of freedom and symmetries (accidental or fundamental). By construction, these theories are applicable up to a cut-off scale and their predictions beyond that are not reliable. For applications to higher energies a UV completion is needed through which modifications are applied or new heavy degrees of freedom are introduced. In order to complete a theory in a Wilsonian approach, scattering amplitudes must satisfy some constraints. These constraints are derived from basic assumptions like Lorentz invariance,... 

Experimental investigation of drillstring dynamics is essential to complete the theoretical studies and to alleviate complexity of such dynamic models. Vibration is one of the most effective parameter affecting drilling operation. Most of the experimental setups are looking for drilling mud tests, operational characteristics of bit under several bad condition and bit mud stone interaction in drilling operation and there are few setups to study vibration of the drilling setups. In this project a test rig has been introduce which is a scale of a real industrial drilling rig by the factor of 10300. Then based on the field studies of drilling failures in Iranian oil drilling rig , a crack has... 

The determinants of business cycles and how to deal with them are amongst the most important issues in macroeconomics. Using the annual data between 1980 to 2012, available for six oil producing members of Gulf cooperation council, we draw a connection between trade structure and business cycle synchronization. In fact, we try to answer whether the same trade structure in these countries with very similar characteristics has led to synchronized booms and recessions among them. Assuming cross correlation, different estimation methods, including common correlated effects, confirm the positive significant effect of trades tructure on business... 

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... 

Numerous structures which are involved in seismic soil-pile-structure interaction have been destroyed. Considering complexities which exist in soil-pile interaction problems and lack of precise methods without imperfect bases, it is necessary to use numerical methods for analyzing soil-pile interaction problems. In this research, three-dimensional modeling and studying the effect of changing soil and pile parameters on the behavior of pile under earthquake loading is performed using finite difference software, FLAC3D. The soil in this model has a softening behavior. Real earthquake spectrum has been applied into the model as the acceleration time history at the bedrock level. The results of... 

In this thesis, we provide a comprehensive overview of the efforts made towards achieving the goals of Hilbert’s program, and evaluate how successful They are. We begin by discussing Gödel’s incompleteness theorems, and then as a first attempt we present a brief presentation of Gentzen’s consistency theorem. Subsequently, various research fields that branched out from these initial efforts are explored, encompassing the application of the Omega-Rule, reverse mathematics, and self-verifying systems. Furthermore, we present the concept of “Almost Finitistic Consistency” as an alternative approach within Hilbert’s program. In conclusion, a thorough assessment of the success of Hilbert’s program... 

The current global economy challenges and the importance of maintaining a sustainable development strategy has increasingly bolded the importance of construction productivity measures. This research describes the results of a running research that is to find the most critical factors affecting the productivity of high rise concrete building projects in developing countries. To achieve that, we have conducted Delphi method in two phases. In the first phase we had a brainstorming program with construction experts from owner organizations, construction contractors and designing engineers to identify factors that have influenced productivity in recent concrete building construction projects.50... 

Multi-period Value-at-Risk (VaR) forecasting is important for risk management. Financial institutions especially commercial banks according to Basel Committee regulations for capital adequacy in “Internal Approach”, should forecast their VaR for multi-period horizons (longer than one day). The most conventional approach for forecasting multi-period VaR is scaling one-day forecasted VaR that is called “square root of time rule”; therefore most works in this area have been focused on forecasting one-day VaR. In this study, we review performance of a wide range of different methods in forecasting multi-period VaR. The results of our study show that historical simulation performs weakly in... 

Modern communication and space systems such as satellite communication devices, radars, SAR and radio astronomy interferometers are realized with large antenna arrays since this kind of radiating systems are able to generate radiation patterns with high directivity and resolution. In such a framework, conventional arrays with uniform inter-element spacing could be not satisfactory in terms of costs and dimensions. An interesting alternative is to reduce the array elements obtaining the so called ‘ thinned arrays’. Large thinned arrays have been exploited because of their advantages in terms of weight,consumption, hardware complexity, and cost over the... 

A large number of structures subjected to the seismic loading have been damaged or have experienced failure in different parts such as the pile structure or even in the entire structure due to unanticipated effects of the soil-pile-structure interaction.The complexity of problems regarding the soil-pile-structure interaction is an influencing factor in prediction of the behavior of structure during the earthquakes. In this study, the effect of the interaction on the dynamic response of bridges was investigated using the finite element software ABAQUS. The primary purpose of this study, as previously described, is to study the effects of the soil-structure interaction on a bridge located on a...