Sharif Digital Repository

Dynamic modeling and process control, especially the equipment of bioreactors and fermenters, have always faced many challenges due to the complexity and high uncertainty of the kinetics of environmental reactions. Among these, semi-continuous fermentation for bioethanol production is one of the important technologies in biochemical industries. The problem of modeling as well as controlling the use of the main discontinuous and semi-continuous methods of ethanol production is the lack of uniform state conditions and the possibility of aerobic and non-aerobic multiplication conditions in two ways. The main goal of this research is to obtain a new method in modeling bioethanol fermentation and... 

In this project dynamic effect of changes in gas turbine load on power plant, reforming and Co2 capture section is investigate. The reason for study of effects change of gas turbine load is that gas turbine determines the performance of the other parts in combined cycle including gas cycle and change of gas turbine load can alter the load and the performance of other parts in the power plant and in other process such as production of synthesis gas and carbon dioxide separation unit. One Autothermal reactor and eight sewgs reactor are utilized to produce gas turbine fuel which is mainly consist of Hydrogen. this part of thesis is to be implemented in the gPROMS from process system enterprise... 

By increasing of population, migration to urban area and industrial development, the concern of environmental pollution becomes more important. Wastewaters are one of the polluting agents which should be collected, treated and reused in a safe and healthy condition. Generally wastewater treatment systems are classified into two major groups, namely aerobic and anaerobic treatment systems.Anaerobic fixed bed reactors are used for decreasing the organic load of wastewater. Enhancement of microbial retention time by attaching the organisms to packings is the most significant advantage of this bioreactor which increases the removal efficiency of organic materials of strength wastewater.In this... 

This work concerns with experimental and modeling investigation of the asphaltene damage removal using ultrasonic wave irradiation. A specific core holder apparatus was designed and utilized for in situ ultrasonic exposure to damaged core plug at different conditions of exposure time, ultrasound power and distances between sound source and plug. Injection of many pore volumes of an asphaltenic crude oil was used for creating asphaltene induced damaged in porous media through permeability measurements. The deposited asphaltene during oil injection as well as asphaltene removal due to ultrasonic exposure was evaluated using IP-143 analysis. The results revealed that ultrasound application... 

Active queue management (AQM) is a key factor in congestion control and should provide appropriate feedback for flow control in traffic sources to overcome the congestion problem. Beside providing congestion control, achieving predictable queuing delay, maximizing link utilization, simplicity and robustness are also the main objectives of an AQM controller. We propose in this thesis an improved queue dynamic model while incorporating the packet drop probability as well. The proposed model is evaluated using ns2 platform. By applying the improved model, a new compensated proportionalintegral- derivative (PID) AQM controller is developed for TCP network. The time-varying nature of the network... 

A coloring of regions is conflict-free if for any covered point in the plane, there exist a region that cover it, with a unique color. In this thesis, we examine the problem of conflict-free coloring of regions in dynamic model, with minimum colors, and with the possibility of recoloring the optimal numbers of colored regions. That means, regions are inserted one by one on the plane, and by inserting any region, inserted regions shall be conflict-free. Dynamic model are divided into three categories: offline model, online with absolute positions model and online with relative positions model. The difference between these three categories is in the information contained in insertion of... 

Vibrations in HAWT reduce their efficiency and increase maintenance costs. In this paper, the blade edgewise vibrations are reduced by using several actuators in different parts of the wind turbine blade and optimization of the number and locations of actuators. The wind turbine blade dynamic behavior is investigated by using dynamic modeling. The actuators are trusses that are located inside each blade and apply control force to different parts of the blade. Active control force is applied to reduce edgewise vibrations. The designed controller is applied and simulated on NREL 5MW wind turbine. By applying the controller, the edgewise vibrations of wind turbine blades are significantly... 

According to high nominal pressure and controllable flow, variable displacement axial piston pumps are used widely in hydraulic industry. However, there still exist many problems and limitations in the areas of design, controllers and performance. To solve the problems without wasting time and money in making prototypes, an accurate dynamic model of the pump is required which predicts pump behavior under various control signals and loads. The lack of simple and practical methods of measuring describing parameters of pump dynamics, makes investigation and verification of such a model very challenging. In this thesis, literature review is presented in a wide range. After investigating of... 

Due to the growing rate of photovoltaic plants in power systems, in the future years this type of plant will have significant contribution in electrical energy generation. For this reason, the impact of photovoltaic plants on various aspects of power system operation should be investigated. In this research dynamic impacts of photovoltaic plants on small signal stability of power systems are analyzed. For this purpose, improved dynamic equivalent models are developed for large-scale photovoltaic plants, based on integration of the plant modules. It is shown that the usual assumption of ideal DC power supply at the input of plant inverter is inappropriate, and that the DC-DC converter and DC... 

In the present thesis, the movement of the clusters of fullerenes and nanocars are separately investigated on graphene surface, using molecular dynamics simulations. Investigating the fullerene clusters with different populations, it is concluded that, as the number of molecules inside the cluster increases, the displacement range of the motion decreases. In fact, some parts of the energy of the fullerene cluster are wasted through the intermolecular interactions, and as a result, the mobility of the cluster diminishes. During the investigation of the three-dimensional structures of fullerene, the wetting property of the clusters is revealed relative to the graphene surface. The decrease of... 

Nowadays, nano-positioners play an important role in advanced technologies, such as atomic force microscopy, genetic manipulation, nano-metrology, nano-fabrication, semi-conductors and etc.In this paper, a dynamical model has been derived for a nano-positioner. This nanopositioner was designed and fabricated in Sharif university of technology. In this paper the mentioned mechanism has been considered as a planar mechanism. First, a finite element model has been developed in Comsol multi-physics software. This model was used as the reference model in the next steps. Afterward, a 10 degrees of freedom model was proposed to estimate the Comsol model. The mass, stiffness, as well as damping... 

The Brushless Doubly Fed Machine (BDFM) has the capability to be employed as a motor in drive applications and as a generator in variable speed wind power applications. The Doubly Fed Induction Generator (DFIG) is currently the main candidate for use in wind power applications while it suffers from the existence of slip-rings and brushes. The BDFM can potentially achieve comparable characteristics to those of DFIG while having brushless operation. This dissertation aims at modeling the BDFM in its steady and dynamic states taking core loss into account. After a short review on structures, advantages and disadvantages of different wind energy conversion systems, the BDFM is introduced as a... 

Fluid flow simulation in heterogeneous, full field porous media, like hydrocarbon reservoirs and underground aquifers usually requires multimillion block models, demanding unpractical computation times. Massive researches have been conducted to upscale these fine grid models to coarse models with manageable block numbers. Many upscaling methods have been proposed. These methods differs regarding their gridding techniques (uniform/ structured or disordered), general applicability (process dependency), maximum coursing level achievable, accuracy of the method and their speed-up factor and extend from simple arithmetic averaging to complicated numerical methods. Applying a very powerful... 

In this project Sharif Gas Turbine laboratory turbojet engine, and the turboshaft engine which is designed based on the turbojet gas generator are statically and dynamically modeled and required functions for turboshaft control are extracted. In static modeling a repetitive process is applied to reach static operation points. Static operation line and static characteristics of turbojet engine are extracted and compared to relevant sources. In dynamic modeling of turbojet engine a lumped volume is allocated to each component of engine and gas dynamic equations are solved in this volume along with individual performance map of engine components to acquire output characteristics in each time... 

This research aims to study the identification of inertia parameters (IPs) of space-robots with the main focus on Active Space-Debris Removal (ASDR) application. In many future space missions, like ASDR, the spacecraft should handle objects (like debris) with unknown IPs. To control and stabilize the spacecraft, it is crucial to identify the dynamic model of the spacecraft in such these missions. On the other hand, uncertainties in the IPs of spacecraft (including space-manipulator) make the identification problem more complex. To overcome the complexities related to mathematical representation of identification equation, a new mathematical tool called Matrix-Set is proposed to develop the... 

In this research, we investigate the role of oil and degree of dependence to it on nexus between financial development and growth volatility. The link between financial development and growthvolatility has been the focus of extensive literature, but no empirical study has been investigated the role of oilin relationship between financial development and growth fluctuations. By using information of 78 developing countries (11 oil exporting and 67 non-oil countries) during 1983-2008, we construct a dynamic model. Difference GMM technique is used to estimate the model. Our findings show that negative impact of financial development on volatility of GDP, Investment and Consumptiongrowth is... 

Gas turbines and centrifugal compressors are the preferred means of compressing the gas in pipeline systems. Both gas turbines and centrifugal compressors exhibit performance characteristics that depend on the operating point imposed on them by the pipeline operation. Simulation of gas turbine-driven centrifugal compressors is necessary for a variety of applications in the general area of pipeline simulation. This research focuses on modeling of twin shaft gas turbine dynamic and steady state performance. For this purpose, it was necessary to evaluate the thermodynamic working process of the gas turbine by using an in-house computer code. At design point, the calculations are solely based on... 

Epilepsy is one of the most common neurological disorders, second only to stroke, with a prevalence of 0.6–0.8% of the world’s population. Epilepsy is not cured, Two-thirds of the patients achieve sufficient seizure control from anticonvulsive medication, and another 8–10% could benefit from respective surgery. For the remaining 25% of patients, no sufficient treatment is currently available. In the recent decent, many studies in this field attempt to predict the onset time of a impending seizure by monitoring the biomedical signals, Electroencephalogram (EEG) Signal processing is one of these biomedical Signals that many In this work, First we talk about the basic concepts of Epilepsy ,... 

CFD models are accurate but time-consuming for simulation and optimization of steam methane reformer and controlling the tube wall temperature, and syngas production rate and unsuitable for online optimization. Empirical data-driven models are less accurate when there are wide variations in operating conditions. The physics-based model presented in this thesis overcomes these limitations. In this model, the furnace side and the process side are divided into zones with uniform temperature and composition, and for each zone, mass, energy and momentum balances are derived. Radiative heat transfer modeling and calculation of exchange areas are accomplished with the zone method. The system of... 

Microrobots are generally suitable for implementation of certain works in miniature dimensions such as micro assembly, microsurgery, adaption with small animals and so on. In this way, there is special position for mobile microrobots capable of moving in the range of more than theirs dimensions. Achivieng to high resolution and high speed locomotion are the challenging issues in the microrobot’s development in which much effort has been done.The goal of this project is dynamic modeling and velocity control of an A-shaped microrobot with with nanometric locomotion. During this project, first the dynamic modeling of microrobot is investigated and simplified based on the previous studies....