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An Uplink Packet Scheduling Algorithm in Fixed PMP WiMAX Networks with TDD Frame Structure
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
Worldwide interoperability for Microwave Access (WiMAX) is one of the most dominant cell-based broadband wireless metropolitan access technologies. Packet scheduling algorithm specifies the packet transmission order. In WiMAX standard, packet scheduling algorithm is not defined and its efficient design is left for developers and researchers. The existing researches in the scope of uplink packet scheduling, which is the most challenging packet scheduling scheme, consider only one cell. However the uplink available resources might not be enough when there are many packets that should be scheduled. To solve this problem, we propose an algorithm that uses the load balancing mechanisms that are...
Controlled Microwave-assisted Synthesis of ZnFe2O4 Nanoparticles and Investigation of their Catalytic Activity in Organic Reactions
, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
ZnFe2O4 nanoparticles have been successfully prepared through a controlled microwave–assisted co-precipitation as well as conventional co-precipitation. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used for the structural, morphological and magnetic investigation of the product. Average particle size was obtained as 12 nm from XRD. Catalytic activity of ZnFe2O4 nanopowder for O-acylation of alcohol and phenol has been investigated. A trace amount of ZnFe2O4 has been effectively used as a nanocatalyst for the acylation of alcohol and phenol in acetic anhydride.
Call Admission Control Schemes in WiMAX Networks
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
The rapid growth of broadband wireless access (BWA) has increased the demand of new application such as VoIP, video conferencing, online gaming each of which has different requirement for quality of service. Due to limited bandwidth provided for these networks, one of the most important issues is how effective we manage bandwidth in order to support requests. The quality of service is an important indicator of the effective management of bandwidth. Using mechanisms of call admission control is a commonly accepted method for balance between quality of service and increase of utilization resource in cellular mobile networks. In fact, ...
Saturation Throughput Analysis of a Cognitive WLAN Overlaid on a Primary Network with Time-Scheduled Users
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor)
Abstract
The activity status of primary users in a cognitive network scenario is a key parameter in saturation throughput of the secondary users. In this respect, usually a simple on-off traffic model with exponentially distributed intervals is exploited. For time-scheduled users in modern common standards like WiMAX or LTE this traffic model is not valid anymore. In this thesis, we focus on the saturation throughput analysis of a cognitive network scenario, comprised of a WLAN overlaid on a network with time-scheduled primary users like WiMAX. In this scenario, the cognitive nodes (CNs) hear downlink map (DL-MAP) and thus, know the frequency and time locations of all allocated slots at each downlink...
Optimization of Maximum Frequency and Power, Extraction of Parameter Data and Final Publication Design of High Power Microwave Pulse Generation Using nonlinear Transmission Line with the Periodic Structure of the Gas Switch
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
High-power (108 – 109 W) RF pulses with a carrier frequency of C band and a duration of several oscillation periods can be produced through direct energy conversion of a travelling high-voltage pulse with the use of nonlinear elements.
Nonlinear transmission lines consist either of lumped nonlinear elements and provide spatial dispersion of excited oscillations or of elements uniformly distributed on a certain line segment. The first type of NLTL’s can be referred to NLTL’s with spatial dispersion. The second type of NLTL’s is ensemble of nonlinear oscillators with a characteristic natural frequency and temporal dispersion. In the first case, the duration of electromagnetic pulses is...
Nonlinear transmission lines consist either of lumped nonlinear elements and provide spatial dispersion of excited oscillations or of elements uniformly distributed on a certain line segment. The first type of NLTL’s can be referred to NLTL’s with spatial dispersion. The second type of NLTL’s is ensemble of nonlinear oscillators with a characteristic natural frequency and temporal dispersion. In the first case, the duration of electromagnetic pulses is...
Primordial Dipole Anisotropy on the Cosmic Microwave Background and Inflation Theory
, M.Sc. Thesis Sharif University of Technology ; Mansouri, Reza (Supervisor) ; Firouzjahi, Hassan (Supervisor)
Abstract
Cosmic Inflation, invented by Alan Guth in 1980’s, solves the shortcomings of the Standard Cosmology such as the flatness, the horizon and the monopoles problems and provides the seeds of large scale structure formation. The quantum fluctuations which are produced during inflationary epoch are redshifted and transferred from Microscopic scales to Macroscopic universe. We can observe this macroscopic fluctuations both on the CMB surface and on large scale structures. Data from WMAP and Planck missions(CMB space Telescopes) suitably confirms the general predictions of single field inflationary scenarios but still people search for finding primordial gravitational waves from the B-Mode signal...
CMB Lensing and Large Scale Structure Bias as a Probe of Beyond and CDM Cosmology
, M.Sc. Thesis Sharif University of Technology ; Baghram, Shant (Supervisor) ; Firouzjahi, Hassan (Supervisor)
Abstract
The standard model of Cosmology known as CDM is established as a cornerstone of modern cosmology. The Cosmic Microwave Background radiation (CMB) and Large Scale Structure (LSS) Observations indicate that almost all observations can be described by a 6-parameter standard model with an initial condition of almost Gaussian, isotropic, scale invariant and adiabatic which can be sourced by inflationary models. Recent observations of Planck collaboration shows almost no deviation from standard picture of single field slow roll inflation. Despite the success of the standard model, the physics of early universe, the nature of dark matter and dark energy is still unknown. The large scale structure...
Assessing Arguments Against Inflation Theory
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
The universe appears to be homogeneous and isotropic as far as we can detect, which is called the Cosmological Principle. Standard big-bang model was successful in describing the universe. For example, it predicts the Hubble’s law of expansion for the universe, existence of the Cosmological background radiation and the correct abundance for the light atomic nuclei. Nevertheless, this model was unable to explain some problems in cosmology, for example horizon problem, smoothness problem and flatness problem. In the early 1980s, Inflation Theory was proposed by Alun Guth and others to resolve these problems in Standard Cosmology; but in two recent decades some contemporary prominent...
Particles in the early Universe: Interface of Cosmology and Particles Massive Neutrinos and Cosmology
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Farzan, Yasaman (Supervisor)
Abstract
Neutrino flavor oscillations are clear evidence of massive neutrinos. It has been for more than a decade that neutrino physics became one of active topics in the field of particle physics and various experiments started studying the flavor oscillation of neutrinos. Unfortunately, experiments studying the flavor oscillations are only sensitive to the mass square difference, and they are incapable of providing more information about the absolute mass scale of neutrinos. Additionally, sterile neutrinos having non-standard interactions are under vast investigations and studies. Determination of neutrino masses and their effective number is among the most challenging problems by which...
Analysis and Design of Substrate Integrated Wavguide Filters Using Contour Integral Method
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
In this thesis a substrate integrated waveguide (SIW) filter is designed and constructed using the contour integral method. A substrate integrated waveguide can overcome the drawbacks of regular waveguides, namely bulkiness, high costs and the difficulty to be integrated with other elements in high frequencies. In planar structures with arbitrary shapes where green’s functions aren’t available, we can use the contour integral method to construct the impedance matrix. Because the SIW structure supports TEn0¬ modes, we can consider SIW as a planar structure and thus use the contour integral method. Regular filter structures are usually analyzed using the FEM method (with HFSS) or the FIT...
Theoretical and Experimental Study to Conversion of AUC to UO2 by Microwave Heating
, Ph.D. Dissertation Sharif University of Technology ; Otukesh, Mohammad (Supervisor) ; Ghannadi Maragheh, Mohammad (Co-Advisor) ; Ghasemi, Mohammad Reza (Co-Advisor)Preparation of Calcium Phosphate Alumina Nano Biocomposites
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Behnam, Ghader (Supervisor)
Abstract
The purpose of this study was aimed to evaluate the effect of Alumina on the sintering, phase development, mechanical properties and biocompatibility of fluoridated hyroxyapatite sintered via conventional furnace and microwave assisted oven. Green compacts having 30wt% Alumina nanoparticles were sintered without pressure at various temperatures (1000-1400°C) for one hour in conventional furnace. Phase composition, thermal behavior and morphological analyses were performed using X-ray diffraction (XRD), simultaneous thermogravimetry and differential thermal analysis (STA), and Scanning Electron Microscopy (SEM), respectively. With the increase in temperature and the Alumina content, severe...
A New Method For Phase Noise Measurement of Microwave Oscillators Using Phase Shifter-Less Frequency Discriminator
, Ph.D. Dissertation Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
In this thesis, a modified method based on frequency discriminator technique is presented for measuring phase noise of microwave oscillators. In the proposed method, the phase shifter is omitted. In contrast, a 90° hybrid with one more channel containing a phase detector, and an LNA is added to the measurement setup. It can be said that an I/Q phase noise detection has been developed. With the proposed method, tuning of the variable phase shifter is not needed anymore. Therefore, the measurement is done automatically and as a result the measurement time is decreased. Beside the wideband property of the new technique, another considerable advantage is that the method is theoretically self...
Sintering Improvement of Nano Hydroxyapatite Bodies by Magnesium Incorporation and Using Microwave Sintering
, M.Sc. Thesis Sharif University of Technology ; Sadrnejhad, Khatiboleslam (Supervisor) ; Behnam Ghader, Ali Asghar (Supervisor)
Abstract
Magnesium is one of most important elements in bio hedroxyapatite. Magnesium effects on all stages of bone growth metabolism. Also increases bone’s osteoblastic and osteoclastic activities. That’s why incorporation of Mg ions into hudroxyapatite structure has become one of interesting fields for bone implants production. In addition Mg can improve sintering and mechanical properties of HAp. Thet’s why in this investigation the effect of incorporated Mg into HAp structure has been studied. Three kinds of powders have been prepared to perform this study. Pure HAp nano powder produced via sol-gel method, Mg contain HAp nano powder produced via sol-gel method and a mixture of nano HAp and nano...
Synthesis of Flavylium Perchlorate Salts via Reaction of Salicylaldehydes and Acetophenones Using Silica Gel.HClO4 Reagent.
,
M.Sc. Thesis
Sharif University of Technology
;
Matloubi Moghaddam, Firouz
(Supervisor)
Abstract
2-flavylium skeletons (2- Phenylbenzopyrylium salts), are often found as the basic structure in anthocyanins; the chromophores in natural pigments which are responsible for intense colors of fruits, leaves and flowers. They are present in plant organs, also to prevent them from environment predation and to protect the plant against ultraviolet irradiation especially in leaves. Aside from their contribution in plant parts, in industry, anthocyanines serve as food colorant, laser dyes and hair growing agents and have considerable biological and pharmaceutical activities like antioxidant, anti cancer, anti inflammatory, anti atherosclerosis, cardio protection and anti aging properties. almost...
An investigation on the Microstructure and Properties of Alumina-Carbon Nanotube (CNT) Nanocomposite Produced by Conventional and Microwave Sintering
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Sadeghian, Zahra (Supervisor) ; Ebadzadeh, Toraj ($item.subfieldsMap.e)
Abstract
Carbon nanotubes were coated with boehmite nanoparticles by sol gel method. According to the TGA analysis, formation of gamma-alumina from boehmite was at 500 . SEM investigation revealed the uniform coverage of gamma-alumina nanoparticles on the surface of CNTs. Composite powders containing 1, 2 and 3vol% of coated CNTs were produced by mixing the coated CNTs with alumina suspension. Phase analysis of composite powder calcined at 500 showed the complete decomposition of boehmite and formation of gamma-alumina. Samples were shaped by cold isostatic pressing at the pressure of 180MPa and sintering was performed using two different methods of conventional and microwave. Existance of the CNTs...
Microwave Inspired Easy-to-Design Nano-Couplers for Hybrid Photonic-Plasmonic Waveguide Structures
, M.Sc. Thesis Sharif University of Technology ; Mehrany, Khashayar (Supervisor)
Abstract
Potential of plasmonic waveguide structures to confine light in sub-wavelength scales attracted many attentions in recent years. Among these structures planar metal-insulator-metal waveguide and plasmonic slot waveguide are more promising. That is because of their easy fabrication process along with their various reported applications. However, there are some obstacles in the path of developing plasmonic integrated circuits, among whichhigh propagation loss can be named as the most important. To solve this issue, photonic waveguides can be used as the lossless interconnections between small footprint plasmonic components on optical chips. Therefore, application of plasmonic slot waveguide...
Photonic Methods for Ultra-broadband RF Arbitrary Waveform Generation
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Mahmood (Supervisor) ; Mehrany, Khashayar (Co-Advisor)
Abstract
This thesis includes five major parts and eight chapters. In the first part, the literature of arbitrary waveform generation is reviewed. The expansion and diversity of telecommunication services like WIMAX , UWB , RoF , satellite telemetry methods and sensor networks require ultra-broadband arbitrary waveform generation methods. The ultra-broadband signals are those signals with normalized bandwidth (%BW is the ratio of signal’s bandwidth to the central frequency) over 15%. The main approach to enjoy the advantages of photonic processing is to modulate microwave signal with the light and then feed it to the optical signal processor. This light processor in case of linearity is called...
Design and Implementation of Tunable Microwave Gain Equalizer
,
M.Sc. Thesis
Sharif University of Technology
;
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, Analysis and Synthesis of Dual-Mode Waveguide Filter in Q Band
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
Today in the most microwave and millimeterwave systems, one or more filters are used due to interference and noise phenomena. Microwave filters are manufactured in different environments such as waveguide, microstrip and SIW. For military and satellite applications that high power handling and low loss are in preference, the only appropriate environment is the waveguide. Other priority which is more important in satellite application is the low weight and small size of the product; Because of that, the idea of dual-mode waveguide filter was proposed in the early 70 decade. These kind of filters are able to produce two poles in one cavity resonator, which can decrease weight and size of the...