Sharif Digital Repository

During the last few years, utilization of distributed generation (DG) in power systems has been widely increased. This trend has magnified studying the effects and impacts of DG on such systems. One of the benefits of DGs in a power system is loss reduction. If determining DG size and place is done properly, the loss of the network can be minimized. Another way of reducing loss in distribution network is by reconfiguring the network. During the reconfiguration, constraints like being radial, avoiding load isolation as well as voltage/current limitations must be taken into consideration. Taking these constraints into account makes reconfiguration an optimization problem. In this project, the... 

Let D be an F-central division algebra of index n. Here, we present a criterion for the triviality of the group G(D) = D∗/NrdD/F (D∗)D′. In fact, we show that G(D) = 1 if and only if F∗2 = F∗2n and SK1(D) = 1 where SK1(D) is the reduced whitehead group of D. Then, we use this criterion to investigate the role of (non-abelian) divisible groups in the structure of division algebras. We prove that if D is not the ordinary quaternion algebra, D is similar to a tensor product of F-central cyclic algebras and D∗ contains a (non-abelian) divisible maximal subgroup, then D = F. In this direction, we observe that if the index of D is a prime, then D is a symbol algebra if and only if D∗ contains a... 

This experimental work is of two parts. First, self-assembled monolayers of cysteamine was formed on the gold electrode surface which leaded to the formation of amine groups on the surface; then amine bond was formed between these amine groups and the carboxylic acid groups of acid treated multi-walled carbon nanotubes (MWCNTs). The modified electrode was used for voltammetric determination of dopamine in the presence of uric acid. In the second part, acid treated MWCNTs were decorated with ruthenium nanoparticles; then the resulting composite was used for surface modification with the exact same procedure as the first part. Ruthenium nanoparticles on the electrode surface were... 

MC Simulation is considered to be one of the most accurate methods for transport of radiation in various media. Computational speed is the limiting factor to apply the MC method in clinical settings. One of the methods to increase the speed in MC simulations is the use of phase space file (PSF). PSF is generated by transporting the particles through the linear accelerator head. The characteristics of these particles crossing a reference plane are stored in the PSF file. The PSF can be used in subsequent simulations as a radiation source. The use of PSF is effective but has a drawback of having latent variance. Latent variance is a problem inherent in using phase space files. Latent variance... 

Blood is one of the most important biological organs. Red blood cell (RBC), as the most abundant cell of blood, plays an important role at life of the living bodies. Unique mechanical properties of RBCs enable them to pass through very narrow vessels. Any abnormality in these mechanical properties will disorder the function of the cell and many diseases affect these properties too. Studying the mechanical properties of RBCs is very importantin that it could result in a disease diagnostic method in a single-cell level. In this thesis we have tried to measure the viscoelastic properties of a single RBC by an optical trap through a passive method. This measurement is made through studying the... 

The base of dielectrophoresis(DEP) technique has been demonstrated through electro-dynamic interactions between an applied non-uniform AC electric field and induced distributed dipoles within a polarized. In particle manipulation and/or separation using the DEP method, knowledge of precise DEP force of a particle is essential in designing a DEP device and improving its separation efficiency and accuracy. In most DEP studies related to particle manipulation and/or separation, however their absolute DEP forces remain unknown[2]. Insufficient information regarding the DEP behavior of particles can result in preventing a strategic maneuver for efficient particle manipulation and/or separation... 

In this study, static recrystallization (Rex) of a low carbon steel after cold rolling has bees simulated under non-isothermal condition by employing cellular automata (CA) method. Symmetric cold rolling and asymmetric cold rolling (ASR) which was arisen by inequality of friction coefficient have been applied as primary cold deformation. Residual stress and strain field after deformation, and temperature rate and distribution of specimens during annealing has been evaluated by employing two different models based on finite element method. Initial microstructure has been developed by haphazardly distribution of grains and topological adjustments were imposed on it. Results of FEM models were... 

Due to the increasing cost of energy, we want in this study to increase energy efficiency and reduce waste of system energy. Oil, gas and petrochemical sector is a widespeard part in Iran, so the study of energy systems in the industry have a paramount importance. The study focused on the Tehran refinery steam and power systems, seeking the most economical system of power and steam for the Tehran refinery. To achieve this goal, with the help of simulation of power and steam system for Tehran refinery with Aspen Utility software, a superstructure obtained. Then, using a sensitivity analysis, we were able to achieve economic arrangment of utility system. In this study by increasing the... 

In this thesis, we want to present methods that are able to solve the assignment tasks problem in a heterogeneous computing system. These methods are two hybrid methods that are constructed by composing Hopefield Neural Networks with Genetic Algorithms and the Simulated Annealing. First, we solve the relaxed problem by applying Genetic Algorithms and the Simulated Annealing and we compare the results of these ways with other traditional methods. Then, we solve the constrained problem with mentioned hybrid methods. The definition of the problem is as following: Consider a distributed computing system which is comprised of set of processors with different speeds but the same structure. We want...