Sharif Digital Repository

As petroleum resources are not steadily distributed in the world and all industries and manufacturing sections are dependent on these resources, petroleum transportation is very important to the extent that availability of these resources occurs in the fastest time and costing the least possible. The objective of this study is to study the petroleum distribution through time in the world and assess its transportation efficacy during 1965-2005 in 173 countries. Collecting information about petroleum distribution between exporting countries to importing ones helped to complete the study data base. Also in this study two transportation networks, sea and land multimodal transportation network... 

An Ad-Hoc wireless network consists of a collection of geographically distributed nodes that communicate with each other over a wireless medium. These networks don’t use any infrastructure or base station to channel allocation. The important difference between wireless networks and wired networks is the broadcast nature of wireless communications. In these networks, each node transmits data to all of the nodes in the transmission range which may cause an increase in interference and data loss. On the other hand, due to mobility of users, fading the channel between them and change of routing, the probability of data loss increases. The extensive and successful employment of TCP variants in... 

Network coding, as a novel technique, suggests that the intermediate nodes of a network can combine independent flows to optimize the usage of a shared communication channel. Also, distributed source coding, exploits the joint statistics of correlated information sources to reduce the volume of transmitted information. Surprisingly, it has been shown that linear network codes are able to compress correlated sources. In this project, we have focused on this problem, i.e. joint distributed source and network coding. We have two important contributions with different directions. First we give a practical design for joint coding. Second, we use an evolutionary approach to find the best placement... 

Analysis and design of power systems are challenging due to ever increasing dimension of the system and also the nonlinearities involved in the system. The conventional approach is to use linear analysis tools and then investigate the nonlinear impacts by the means of computer simulations. This requires great deal of trial and error and it is not always a timely approach. In this project, we initiate a comprehensive nonlinear analysis for a single-machine infinite-bus system by studying a Hopf bifurcation in its dynamics. We use results of our nonlinear analysis to study how a capacitive compensation such as TCSC works. Subsequently, we design a nonlinear controller for a PSS to have... 

The increasing trend of Green House gases’ emission, after the Industrial Revolution, has changed the balance of these gases in the atmosphere. Aggregation of these gases in the atmosphere has caused the temperature increase at the Earth’s surface. This temperature increase has altered the stationary trend of climatic variables. This change has been entitled, Climate Change. One of the important impacts and challenges of Climate Change is Sea Level Fluctuation, which has so many factors. Due the last researches, changes in Land Water Storage are one of the probable factors that change the sea level. Land water storage consists of all of the waters in lakes, ponds, ground waters, snow and... 

We deal with primal-dual interior point methods for solving the linear programming problem.Taken from recent literature on interior point methods, we discuss a short-step and a long-step path-following primal-dual method and show how to have polynomial-time bounds for both methods. The iteration bounds are for the short-step variant and for the long-step variant. In the analysis of both variants, a new proximity measure is used, which is closely related to the Euclidean norm of the scaled search direction vectors. The analysis of the long-step method depends strongly on the fact that the usual search directions form a descent direction for the so-called primal-dual logarithmic barrier... 

The heavy ion collision experiments are in progress in order to investigate how the Universe has evolved after the Big Bang. The recent observations show that a nearly perfect fluid is produced after heavy ion collisions. An appropriate incorporation of the relativistic hydrodynamics and the field theory would help us to describe the dynamics of QCD (Quantum Chromodynamics) matter under extreme conditions, and to survey the expected phase transitions. The majority of efforts to investigate the characteristics of the QCD plasma are devoted to an ideal, non-dissipative one. To get the results which are highly in accordance with the experiment, it is necessary to bring also in mind the role of... 

In this era, competition in economic fields is undeniable. According to huge amount of foreign trades between countries, economic prosperity of each country causes persuasion of foreign investors to come into that country for investment. Stock Exchanges is one sign of economic prosperity in each country, So prediction of the stock exchanges situation is very important. It is noteworthy that according to the importance of prediction in partial level, the necessity of predicting companies stock price is realized. According to the complicated term in this field, linear methods do not have appropriate efficiency for predicting, so nonlinear methods and especially Artificial Neural Networks are... 

Collision attack is one of the usual attacks in cryptanalysis of hash functions. One method for applying this attack is linear approximation of equivalent compress function. Finding collisions for linearized compress function, having low Hamming weight, with a large probability could provide collisions for the main compress function. For this purpose, the problem of finding collision for used compress function is modeled by that of the linearized one, having low Hamming weight differences with a large probability. The problem of finding collisions with low Hamming weight differences is equivalent to the problem of finding codewords with low Hamming weights in linear binary code. Canteaut and... 

Considering the special importance of network flow problems in human life, as well as the complexity of solving these problems in very large scales, there are numerous methods to solve them and the interior point methods are the most important approaches among them. In a number of methods, a preconditioned conjugate gradient solver has been applied for the solution of the Karush-Kuhn-Tucker (KKT) system, in each interior point iteration; therefore, the selection of an appropriate preconditioner is a special issue. In spite of presenting different preconditioners in recent years, discussion and implementation of a particular class of triangulated graph-based preconditioners is our main... 

The aim of the present research project has been techno-economical analysis of using a CCHP (Combined Cooling Heating and Power) technology at the building of Sharif Energy Research Institute (SERI). The CCHP at SERI is supposed to supply energy required at the building. Useful energy demand at the building include heating in winter, cooling and air conditioning in summer, lighting and power requirement of electric appliance and equipments. Since there are many technologies that could be utilized as CCHP, an optimal model of energy supply system of the building has been developed in order to identify the most appropriate technology. The application of model has enabled techno logical... 

In this thesis, we establish a fixed point result of Krasnoselskii type for the sum A+B, where A and B are continuous maps acting on locally convex spaces. We apply such results to obtain strong solutions for some quasi-linear elliptic equations with lack of compactness. We also provide an application to the existence and regularity theory of solutions to a nonlinear integral equation modeled in a Banach space. Finally, we develop a sequentially weak continuity result for a class of operators acting on vector-valued Lebesgue spaces. Such a result is used together with a geometric condition as the main tool to provide an existence theory for nonlinear integral equations in Lp(E)  

In nanometer technologies, the effect of process variation is observed in Multi-Processor System on Chip (MPSoC) in terms of variation in processors‟ frequency and leakage power. Traditionally, only worst case values of the system parameters were concerned and a worst-case optimization algorithm was employed for an application under design. As previous researches have shown these algorithms are not optimal in terms of parametric yield compared with newly employed statistical optimization algorithms. In this project, we have considered the problem of simultaneously selecting MPSoC architecture (which includes type and number of processors and the communication media) and task and... 

In this thesis we study the structure of locally solvable, solvable, locally nilpotent, and nilpotent maximal subgroups of skew linear groups. In [5] it has been conjectured that if D is a division ring and M a nilpotent maximal subgroup of , then D is commutative. In connection with this conjecture we show that if M a nilpotent maximal subgroup of , then M is an abelian group. Also we show that is a solvable maximal subgroup of real quaternions and so give a counterexample to Conjecture 3 of [5], which states that if D is a division ring and M a solvable maximal subgroup of , then D is commutative. Also we completely determine the structure of division rings with a non-abelian... 

Reduced-order modeling (ROM) is a novel approach in all realms of computational science including reservoir simulation. Among various ROM methods, Trajectory Piecewise Linearization (TPWL) is on its evolution for reservoir applications. Previous investigations reflect promising future for incorporating TPWL into the next generations of enhanced reservoir simulators. In this work, we employ TPWL to investigate the claimed efficiency, robustness and accuracy of this method as a surrogate simulator for a developed reservoir simulator. The self construction of the used simulator gives us the opportunity to explore this method and to examine previous assertions on the subject. The efficiency of... 

The constrained nonlinear systems with large operating regions have attracted great attention due to their correspondence with the most practical systems. There are several tools such as gain scheduling and Nonlinear Model Predictive Control (NMPC) to control them. Gain scheduling, with ability to provide stability guarantees between the estimated stability regions overlapping each other and to cover a large space of the allowable operating range of the system, is an attractive practical approach to control the systems with large operating regions. But this strategy do not account for constraints explicitly by online optimization. On the contrary, NMPC handles constraints on the manipulated... 

In recent decades, widespread application of Linear Complementarity Problems in various branches of science has led to many algorithms which have been proposed to solve these problems in the area of mathematics, economics and computer simulation. Ashtiani used Lemke algorithm for the first time to solve Linear Complementarity Problems in his algorithm for solving Traffic Assignment problem. In this study, Projection Gauss-Seidel algorithm along with two other similar algorithms have been studied for solving Linear Complementarity Problems in Ashtiani Complementarity algorithm and the results are compared with Lemke algorithm. Also an analytical method has been proposed for solving specific... 

Application of the advanced control techniques and information technology in the biomedical engineering have been the focal point of the research communities in biomedical engineering due to the rapid growth of the nonlinear control theories along with the computer hardware. In this work the application of differential geometry and globally linearizing control has been applied to efficiently control the first phase of HIV disease based on the HIV infection model proposed in the literature. All the efforts have been in the way to obtain a suitable scenario of drug administration to suppress and control the infection. In the proposed scenario, drug administration is time dependant and...