Sharif Digital Repository

Nowadays, due to the need of high performance systems, embedded systems have been redirected to multicore architectures. As energy consumption is one of the most important issues in embedded systems, careful considerations must be taken during the design of embedded systems to achieve low energy consumption. In this thesis, we propose the use of hybrid scratchpad memories to achieve low energy consumption. The hybrid memory uses both SRAM and STT-RAM memory. While STT-RAM has very low static energy consumption it suffers from high latency and energy consumption during write activities. In order to tackle this problem, we have devised a genetic algorithm that exploits architecture information... 

Most propulsion systems use nozzles to increase the velocity of exhaust gas. Therefore, the efficiency of nozzles is important. Losses due to geometry and physical phenomena inside the nozzle define this efficiency. The length and divergence angle of the nozzle, the throat diameter, the Reynolds number, and the specifications and the combinations of fuel have a direct impact on these losses. Solid propellant rockets are widely used and today optimization of rockets is most noticeable. On the other hand, in different phases of design and optimization, empirical experiments are necessary, which are costly in real dimensions. The use of laboratory motors with specific considerations decrease... 

In this study, a three dimensional molybdenum oxide based coordination polymer of{(M¬o2O6)(4,4'–bpy)}n was synthesized by solvothermal process. Excellent properties of the fabricated metal–organic framework such as crystallinity, porosity, sufficient thermal stability and possession of different interactions encouraged us to employ it as a novel extraction phase in sample preparation. Extraction efficiency of the MOF–based sorbent was evaluated in needle trap extraction of some chlorobenzenes as volatile aromatic organic compounds in conjugation with gas chromatography–mass spectrometry. To achieve maximum efficiency and sensitivity, influential parameters including desorption time and... 

Communications is considered as a large part of project managers’ activities. Communications is one of success factors in the projects. A project manager in addition to have a good sight on project knowledge areas needs to know how to use them in order to reach a suitable point with integrating them by using communications. A survey on communications can predispose lots of dissertations in this field & subsequently causes improvement & continues development.
In this thesis, different areas of project body of knowledge have been explained & effect of communication on them has been described. In next step, this study depicts how to manage communications in projects & project-oriented... 

In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent... 

The microstructures of stainless steels consist of an austenitic matrix with almost continuous network of primery carbides.This class of steel had replaced the traditional super alloys with a reduction in costs and has similar properties under conditions of creep, which is one of the principal degradation mechanisms leading to failure in service at elevated temperaturs , therefore, their mechanical properties such as tensile strength and creep resistance are particularly important in hot deformation. Recently the effects of temperature and aging time on static strain aging in worked stainless steel have been investigated. In this study the deformation behavior of HP-series austenitic... 

Design of optimal controllers for nonlinear systems and even for linear systems is one of the most important parts of the control science. In optimal controller design, our aim is to maximize or minimize some kind of cost function associated with that particular problem. Such cost functions are usually combining the overall control effort, system’s energy, or some other important specifications of the system. Explicit solution for linear quadratic controllers exists under some mild conditions such as stabilizability of the system. The solution is in the form of a full state-feedback law. But in practical problems, we may not have access to all of the system state variables. The problem can... 

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s... 

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and... 

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework... 

A control strategy for islanded (autonomous) operation of a microgrid consisting of two Distributed Generation (DG) units is proposed in this thesis. The DG units are connected together in a radial configuration. Each DG unit utilizes a voltage-sourced converter (VSC) to interface to its dedicated load. The DG units and the loads are to operate in the islanded mode of operation. To provide autonomous operation for the microgrid, voltage and frequency of the loads should be regulated. The proposed control strategy utilizes (i) an internal oscillator for frequency control in an open loop manner and (ii) a decentralized servomechanism controller to regulate the load voltage. The microgrid is... 

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve...