Control of a Crystallization Process

, M.Sc. Thesis Sharif University of Technology Ahmadi Orkomi, Ali (Author) ; Shahrokhi, Mohammad (Supervisor)

Abstract

The object of this research is modeling, simulation and control of a crystallization process. Population balance equation (PBE) has been used for modeling of such processes. Most of the existing numerical methods cannot solve the general form of PBE in presence of the breakage and agglomeration terms and some others are not suitable for control objectives, because of their intractable CPU time. In this work a new developed numerical method called conservation element and solution element (CE/SE) has been used for solving general form of multidimensional population balance equations. The accuracy and effectiveness of the scheme is demonstrated through computer simulation. According to the...

Approximate fuzzy feedback linearization of amine gas sweetening plant via genetic algorithm

, Article 19th International Congress of Chemical and Process Engineering, CHISA 2010 and 7th European Congress of Chemical Engineering, ECCE-7, 28 August 2010 through 1 September 2010, Prague ; 2010 Ahmadi Orkomi, A ; Babaei Pourkargar, D ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology

2010

Abstract

A new approach for static state feedback linearization of single input and multi-input systems is put forward. The approach can be applied to wider class of systems than the classical feedback linearization. The main idea is to transform the nonlinear system via a change of coordinates and static state feedback into a linear system with desired dynamics. This circumvents the need to transform the input vector fields into constant vectors in the new coordinates. An amine gas sweetening process has been simulated as a nonlinear system, then the system is linearized using the approximate fuzzy feedback linearization method. The rules of the fuzzy system have been optimized by genetic algorithm...

Simulation and control of multidimensional crystallization Processes

, Article Chemical Engineering Communications ; Vol. 201, Issue. 7 , 2014 , pp. 870-895 ; ISSN: 0098-6445 Orkomi, A. A ; Shahrokhi, M ; Sharif University of Technology

2014

Abstract

In this article, solving the population balance equation (PBE) and controlling the final particle size for crystallization problems have been addressed. For solving the general form of multidimensional PBE, a numerical method called conservation element and solution element (CE/SE) has been used. By applying this method to one- and two-dimensional crystallization problems, it has been shown that this technique can handle all types of source terms in the PBE. Model accuracy has been checked with experimental data reported in the literature and also with the analytical solution of PB-type equations. Control of final particle size was formulated in an optimization framework. To obtain a desired...

Mobile(SMS) Advertising Value Chain, With a Focus on Factors Affecting Subscribers Acceptance of SMS Advertising in Iran

, M.Sc. Thesis Sharif University of Technology Ahmadi, Saeedeh (Author) ; Kermanshah, Ali (Supervisor)

Abstract

Mobile technology has become Ubiquitous and common in all over the world from the first years of 21st century. Mobile has been used as a strong media in marketing and specifically in advertising due to it’s unique features and various functions. Currently (2008) mobile media is not used very aggressively in Iran. Considering the quick expansions of mobile networks in Iran and growth of subscribers, it is anticipated that Mobile will affect many businesses and consumer market very soon in Iran. This study is the first academic research in the country on Mobile advertising via SMS. The purpose of this thesis is to provide the better understanding of the Mobile advertising via SMS in high...

Analysis of Effect of Parametric Oscillation in Phase Noise Degradation in Frequency Multipliers

, Ph.D. Dissertation Sharif University of Technology Ahmadi, Arash (Author) ; Banai, Ali (Supervisor)

Abstract

Variation of the input driving power can cause in some varactor and BJT frequency multipliers parametric instability. If parametric oscillations are present in the circuit, output phase noise of the multiplier degrades remarkably in some specific driving levels. Phase noise of the varactor and BJT multiplier is calculated by the conversion matrix method using generalized nodal analysis. By the conversion method the phase noise degradation can be predicted precisely. In the calculation of phase noise the effect of the noise sources that are modulated by the large signal drive and the conversion of components of the internal noise sources of the device to the output spectrum due to circuit...

Design and Implementation of Novel Devices in Ka Band Using Ridge Gap Waveguide Technology

, Ph.D. Dissertation Sharif University of Technology Ahmadi, Behzad (Author) ; Banai, Ali (Supervisor)

Abstract

Ridge gap waveguide is a new technology with low loss and high power handling capability in millimeter wave(mm-wave) frequencies. In this technology there is no need for electrical connection between the constitutive parts and using dielectric material as a substrate. This thesis focuses on the capabilities of this technology in realization of devices used in communication systems at the mm-wave frequency. Novel devices based on this technology have been designed, fabricated and tested. The main goal of the thesis is realization of the whole RF front end of a communication system in Ka band based on this technology. So at first step, a ridge gap waveguide transmission line is evaluated and a...

Performance Enhancement in Cache Networks

, Ph.D. Dissertation Sharif University of Technology Ahmadi, Mahdieh (Author) ; Movaghar, Ali (Supervisor)

Abstract

Cache networks play a key role in today’s Internet. Inspired by the successful deployment of caching in content delivery networks (CDNs), pervasive caching now is a fundamental concept in storage-assisted future Internet architectures, e.g., information-centric networks (ICN), and 5G. However, despite the clear and increasing economic advantages of caching for the network operators, it does not take place efficiently due to various problems. The emergence of in-network caching has created new challenges for modeling and performance evaluation of networks. In addition, content providers (CPs), who alone have the detailed demand data required for optimal content placement, have no natural...

Design and Implementation of Tunable Microwave Gain Equalizer

, M.Sc. Thesis Sharif University of Technology Ahmadi, Amir Hossein (Author) ; Banai, Ali (Supervisor)

Abstract

Modern broadband microwave and millimeter-wave systems often struggle with excessive pass band ripple and negative gain slopes due to the loss of transmission lines such as coaxial cables, or ripples in the gain characteristic of broadband amplifiers. The common solution for this problem is using a gain equalizer to compensate for the intrinsic pass band variation with some extra loss in the band of interest in return.Designed equalizers often have a constant slope in their bandwidth. However, having ripples in pass band or in other words slope changing in some parts of the band is one of the issues that designers should deal with. In this thesis, after reviewing the previous works on the...

Design and Simulation of ELoran Receiver

, M.Sc. Thesis Sharif University of Technology Abbasi, Fatemeh (Author) ; Fotowat Ahmadi, Ali (Supervisor)

Abstract

In recent years, eLoran system has been introduced as backup to global navigation systems like GPS, because of their vulnerability. eLoran is a low frequency (100 kHz) system. Its long wavelength allows indoor positioning.
Main eLoran advantages rather than Loran-C are: better accuracy (near 10m), using 9th pulse positioning modulation (PPM) as loran data channel (LDC) and all-in-view receivers
In this thesis, eLoran pulses are simulated in GRI. Also, a new analoge-digital circuit for faster pulse detection is developed.
Also, it is proved that an oscillator with same frequency and phase as enterance signal, responses faster than a band pass filter and envelope detector. So, a...

TDC & MMD Design for Bluetooth Low Energy Standard Transmitter

, M.Sc. Thesis Sharif University of Technology Ghadami, Omid (Author) ; Fotowwat Ahmadi, Ali (Supervisor)

Abstract

IoE devices are going to integrate with our environment. It has been predicted that there would be more than 6 connected devices per each person by 2020. Currently what obstruct this technology from continuing its evolusion path, is its dependence on Ultra Low-Power devices, and for this reason there is a huge concenteration on Radio-Frequency standards which can make devices more power efficient. Within these standards, Bluetooth Low Energy (BLE) attracted designers consentration for its similarities with conventional Bluetooth and its dominance in cellphones and other portable devices.In this project, we have attempted to design a trasmitter for BLE standard based on an All Digital Phase...

Development of Fragility Curves of Confined Masonry Buildings

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mohammad Hossein (Author) ; Bakhshi, Ali (Supervisor)

Abstract

Masonry buildings are one of the most vulnerable structures against earthquakes, and therefore their seismic response should be evaluated in order to mitigate casualties in the future. Although there are numerous experimental and analytical studies on these buildings, few have aimed on Confined Masonry (CM) buildings to simulate and predict their seismic performance. To estimate damage, assess vulnerability and choose the best retrofitting method, fragility curves can be utilized as a powerful tool. In this paper, the hysteretic behavior of two typical CM walls with and without opening is calibrated in both In-plane (IP) and Out-of-Plane (OOP) loading directions making use of OPENSEES...

High Efficiency, Low Distortion Boundary Conduction Mode Boost PFCs for Different Power Ranges

, Ph.D. Dissertation Sharif University of Technology Marvi, Mohammad (Author) ; Fotowat-Ahmadi, Ali (Supervisor)

Abstract

In this thesis, new boundary conduction mode boost PFCs are proposed and implemented for different power levels according to the characteristics and requirements of each power level. For medium power applications, we have proposed a new zero voltage switching PFC based on a synchronous boost converter which is controllable with conventional boundary conduction mode PFC control ICs without requiring any additional timing adjustment control circuits other than a special high side driver that consists of only low voltage components. Based on mathematical calculations, we have proposed two sipmle circuit solutions to reduce the high level of line current zero crossing distortion in the proposed...

Numerical Modeling of Deep Geothermal Energy Reservoirs

, M.Sc. Thesis Sharif University of Technology Ahmadi Hosseini, Adel (Author) ; Pak, Ali (Supervisor)

Abstract

Geothermal energy is one of the most important sources of energy that is increasingly becoming more popular all over the world. In this study, the performance of deep geothermal energy as a form of geothermal energy was evaluated using a numerical modeling approach. To do so, first, the thermo-hydraulic behavior of geothermal reservoirs was studied to help achieve the most efficient arrangement for production and injection wells. The results show that to optimize production and injection wells, there are two factors to consider. Firstly, the distance between production and injection wells must be high. Secondly, the production wells must be uniformly distributed throughout the reservoir so...

A Low-power Low-noise Multi-Channel Biopotential Measurement IC with Motion Artifact Suppression Capability

, M.Sc. Thesis Sharif University of Technology Mohammadi, Ehsan (Author) ; Fotowat-Ahmadi, Ali (Supervisor)

Abstract

Long-term Multi-Channel Bio-Signal monitoring in a comfort way is demanding for emerging applications in everyday life. Typically, in multi-channel amplification, one amplifier per channel is employed. However, the bio-signal amplification requires lower bandwidth in comparison with the available speed of CMOS amplifiers. Therefore, it is sensible to develop a practical circuit trading the excess CMOS bandwidth with power consumption. The proposed circuit, which has three inputs, performs amplification through three stages; First, the inputs are applied to a 3 to 1 time-domain multiplexer. Second, a Current Feedback Instrumentation Amplifier (CFIA) is utilized. Finally, the amplified signal...

Finite Element Model Updating Using API User Interface

, M.Sc. Thesis Sharif University of Technology Ahmadi Saniani, Zahra (Author) ; Bakhshi, Ali (Supervisor)

Abstract

Damage in civil infrastructure is an unavoidable phenomenon. Therefore, using structural health monitoring methods is of great importance. In this thesis, the location and severity of damage in a structure are simultaneously determined using the solution of sensitivity equations of the frequency response function and its principal components. The derived sensitivity equations are quasi-linear and do not require higher-order derivatives of the principal components of the frequency response function in their formulation. Using these sensitivity equations, error minimization through the least squares method, and the finite element model updating method along with the API user interface, the...

Reuse of Abandoned Oil Wells Using a Geothermal-Based Hybrid ORC Unit/Thermoelectric Generator: Energy,Exergy, Thermo-economic Analyses and Multi-criteria Optimisation

, M.Sc. Thesis Sharif University of Technology Ali Ahmadi, Mohammad (Author) ; Moosavi, Ali (Supervisor) ; Sadr Hosseini, Hani (Co-Supervisor)

Abstract

In this thesis, three novel geothermal-based ORC systems are proposed to enhance efficiency and to recover the waste heat recovery. The proposed systems are modeled based on basic ORC system (concept 1), ORC system with internal heat exchanger (concept 2), and regenerative ORC system (concept 3). Accordingly, two thermoelectric generators are introduced into the systems to exploit the waste heat of the system. For this purpose, the condenser is replaced by a TEG unit, while the other TEG unit is employed to recover the waste heat of the reinjected geothermal fluid. A comprehensive numerical investigation is conducted to compare the proposed systems from thermodynamic and thermo-economic...

Thermodynamic and transport properties estimation of a complicated mixture of hydrocarbons by fuzzy clustering methods

, Article 19th International Congress of Chemical and Process Engineering, CHISA 2010 and 7th European Congress of Chemical Engineering, ECCE-7, 28 August 2010 through 1 September 2010 ; 2010 Babaei Pourkargar, D ; Ahmadi Orkomi, A ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology

2010

Abstract

Clustering is the term used in several research communities to describe methods for grouping of unlabeled data. The objective in clustering is to divide the data set in such a way that the intra-class similarity is high and inter-class similarity is low. It is very helpful to find a system's states distributions, but when the system's scale is large, e.g., considering a distillation column that has crude oil as its feed, if one of desired is finding concentration of most popular hydrocarbons (ethane, propane, octane, etc.) on each tray, it should be solve species continuity for each component. A mixture of 100 hydrocarbons was classified into 10 clusters by different clustering methods,...

Trade in Intermediate Goods and The Welfare Gain from International Trade

, M.Sc. Thesis Sharif University of Technology Ahmadi Renani, Saber (Author) ; Madanizadeh, Ali (Supervisor)

Abstract

In this thesis, I introduce a general equilibrium model of international trade that takes into account the industry linkages between intermediate goods and consumption goods producers to quantitatively measure the countries’ welfare gains and losses from different trade policies on intermediate and consumption goods. My model extends the inter-industry trade model of Ricardo (1817), intra-industry model of Krugman (1980), and firm heterogeneous model of Melitz (2003). Reduction of tariffs affect welfare of countries through direct effects on income, cost of export, and cost of input bundles of production (labor and intermediate goods), and indirectly through changes in term of trades, and...

Trust-based Probabilistic Key Management in MANETs

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mahdieh (Author) ; Movaghar Rahimabadi, Ali (Supervisor)

Abstract

Self-organized public key management scheme in mobile ad hoc networks (MANETs) is an inevitable solution to achieve different security services. The aim of such schemes is to find an efficient protocol which makes the node able to obtain the authenticated public key of another node. Public key transmission and verification is achieved using certificate chain or message authentication code, thus it needs other nodes cooperation. It is also notable that in heterogeneous MANETs which include malicious nodes, this method suffers from low throughput and spoofing attack. In this thesis, a novel certificateless, on-demand self-organized public key management scheme is proposed which is based on the...

Design and Simulation of a High Speed Li-Fi Receiver

, M.Sc. Thesis Sharif University of Technology Safiallah, Mahyar (Author) ; Fotowat Ahmadi, Ali (Supervisor)

Abstract

LiFi is a bidirectional wireless optical networking technology that uses commercial LEDs for data transmission. In simpler terms, LiFi is considered a light-based WiFi that uses light instead of radio waves to transmit information. Using light to transmit data allows LiFi to deliver a couple of advantages, such as working in areas susceptible to electromagnetic, working across higher bandwidth while offering higher transmission speeds. Finally, the security of this technology is much more than other ways of communication since the light cannot penetrate through walls and doors, so other people who are not in the room could not access data.In this dissertation, a Li-Fi receiver that uses...