Sharif Digital Repository

High speed data converter are very often used in telecommunication systems. Since these systems are increasingly used in mobile foem reducing the power consumption in these circuits is of great importance. The goal of this project was to design a pipeline 10 bit converter for a sample rate 200MS/s with a power consumption of 35 mW for the input level of 1Vp-p and a 1.8V power supply in 0.18um CMOS technology.
To reach these goals, a number of low power techniqes are proposed in various levels of abstraction. In system level, the sampling and feedback capacitors is optimized analytically which leads to simple back-envelope formulas to calculate the optimum values. In circuit level, a... 

Forecasting demand for fast-moving consumer goods (FMCG) is a fundamental yet challenging issue in retail management due to highly volatile demand, short product life cycles, low profit margins, and limited customer loyalty. Customer purchase behavior reflects their response to a set of concurrent product attributes in the retail environment; price, discounts, product placement, and other stimuli influence the final purchase decision not independently, but in combination and in interaction with related products. Therefore, modeling this behavior realistically requires considering the dynamic interactions among products, and relying solely on univariate time series analysis is insufficient.... 

Today, hydrogels have various biomedical applications as three-dimensional networks with the ability to absorb and retain water and biological fluids. This study aimed to prepare nanocomposite hydrogels from polyvinyl pyrrolidone, polyethylene glycol, and barium titanate nanoparticles. Gamma radiation at irradiation doses of 25 and 35 kGy was used as the hydrogel's crosslinking agent. The effects of gamma irradiation dose, percentage of polyethylene glycol, and barium titanate composition on the swelling ratio and gel content were investigated. It was observed that the amount of gel content with the addition of polyethylene glycol and barium titanate nanoparticles reduces the gel content and... 

Due to safety critical applications of the embedded systems, reliability is one of the most important properties of these systems. Wireless networks also have error prone data transmission channels and limited power consumption. Therefore reliability and power conservation are two vital characteristics of the wireless network especially in embedded applications. Since achieving to a desirable level of data reliability is power consuming, we must consider a trade-off between power consumption and data reliability. In wireless networks power consumption can be categorized into: power consumption in wireless devices and power consumption in data transmission. For decrement of wireless devices... 

In recent years, there has been a trend toward outsourcing data to the cloud provider. These companies must tackle the data security challenges. Generally these parties are assumed to be honest but curious. In past years, the research communities have been investigating different solution to ensure confidentiality.
In addition to data confidentiality access and pattern confidentiality is a high-priority issue in some cases so. potential adversary should be unable to drive information from the observed access pattern to the outsourced data. Despite the fact that there are more investigation in the field of data confidentiality, concern over data security are the rise in outsourcing data,... 

Hydroxyurea is an anticancer drug that is commonly used to treat chronic myeloid leukemia (white blood cell cancer in bone marrow), polycythemia vera (red blood cell cancer), sickle cell anemia, solid tumors, and in particular leukemia. In this research, in addition to analyzing all available methods for synthesis of hydroxyurea, the most economical method for synthesis of hydroxyurea which is Hantzsch method was chosen; then we synthesized hydroxyurea crystals using a precipitation or crystallization process. To do so, two hydroxylamine hydrochloride and potassium cyanate reactants have been used in the semi batch reactor. Since the reaction efficiency and purity of the synthesized... 

An interesting theoretical and practical set of problems in computer science is concerned with the study of spatial relations among objects in a geometric space. Examples of such problems for a set of points P are finding the closest pair of the points P, partitioning space into regions such that all points of a region have minimum distance to the same point in P, and computing the Euclidean minimum spanning tree on P. Moreover, we need mechanisms to efficiently update these properties when the points P are allowed to move or may be inserted or deleted. This is to avoid re-computation of these properties from scratch. Here, we consider the Euclidean minimum spanning tree (EMST) of a set of... 

Individuals have been regarded as independent decision makers in the majority of transportation analysis. However, individual behaviors are usually affected by the interactions between the members in group decisions; and consequently, individual decision making paradigm could result in less-accurate predictions. Besides, as the data used for travel demand modeling typically comes from household level surveys, the idea of random sampling holds at household level and not the individual; and therefore, individual information would not be consistent with the theory of the discrete choice models when the household is the actual sampling unit. The present paper aims at modeling the way that... 

In robotic, Underactuated systems are interesting subject to study. Underactuated system, is a system that have fewer actuator than degrees of freedom. Underactuated systems are composed of active and passive joints. passive joints are existed, in order to decrease the weight, cost, and energy consumption. Usually, control of these systems are difficult. Underactuated systems have acceleration constraint. This property make the control method have fundamental constraint. So that controller dynamic could not be a smooth function of states of system. So most of standard method in control, such as feedback linearization, are not applicable. Local linearizing methods, because of... 

The behavior of construction materials at high temperatures has been an important aspect of researches in recent years. The first part of the current research aims to non-destructively monitor the formation and growth of damage at geopolymer concrete (GPC) after being exposed to high temperatures using linear and nonlinear ultrasonic techniques. Ultrasonic waveform and pulse velocity (UPV) tests were conducted on the specimens before and after exposure to the temperatures. Nonlinear wave signals were processed in phase-space domain for qualitative health monitoring of GPC. Furthermore, feature extraction was applied to phase-plane attractors using fractal dimension for quantitative...