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Matrix coherency graph: A tool for improving sparse coding performance
, Article 2015 International Conference on Sampling Theory and Applications, SampTA 2015, 25 May 2015 through 29 May 2015 ; May , 2015 , Pages 168-172 ; 9781467373531 (ISBN) ; Zaeemzadeh, A ; Rahnavard, N ; Khalilsarai, M. B ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Exact recovery of a sparse solution for an underdetermined system of linear equations implies full search among all possible subsets of the dictionary, which is computationally intractable, while ℓ1 minimization will do the job when a Restricted Isometry Property holds for the dictionary. Yet, practical sparse recovery algorithms may fail to recover the vector of coefficients even when the dictionary deviates from the RIP only slightly. To enjoy ℓ1 minimization guarantees in a wider sense, a method based on a combination of full-search and ℓ1 minimization is presented. The idea is based on partitioning the dictionary into atoms which are in some sense...
Improved recovery of analysis sparse vectors in presence of prior information
, Article IEEE Signal Processing Letters ; Volume 26, Issue 2 , 2019 , Pages 222-226 ; 10709908 (ISSN) ; Haddadi, F ; Amini, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this letter, we consider the problem of recovering analysis-sparse signals from under-sampled measurements when some prior information about the support is available. We incorporate such information in the recovery stage by suitably tuning the weights in a weighted ℓ1-analysis optimization problem. Indeed, we try to set the weights such that the method succeeds with minimum number of measurements. For this purpose, we exploit the upper-bound on the statistical dimension of a certain cone to determine the weights. Our numerical simulations confirm that the introduced method with tuned weights outperforms the standard ℓ1-analysis technique. © 1994-2012 IEEE
Generalization of the Online Prediction Problem Based on Expert Advice
, M.Sc. Thesis Sharif University of Technology ; Foroughmand Araabi, Mohammad Hadi (Supervisor) ; Alishahi, Kasra (Co-Supervisor) ; Hosseinzadeh Sereshki, Hamideh (Co-Supervisor)
Abstract
One of the most important problems in online learning is a prediction with expert advice. In each step we make our prediction not only based on previous observation but also use expert information. In this thesis, we study the different well-known algorithms of expert advice and generalize problems when data arrival is in the two-dimensional grid. regret is a well-studied concept to evaluate online learning algorithm. online algorithm when data arrive consecutively in T time step has regret O (√(T)) . regret in two-dimensional grid with T row and P column is O(T√(P)).
2010 MSC: 68Q32 ; 68T05 ; 90C27
2010 MSC: 68Q32 ; 68T05 ; 90C27
On Some Graph Theoretic Properties of Fullerenes
,
M.Sc. Thesis
Sharif University of Technology
;
Akbari, Saeed
(Supervisor)
Abstract
A fullerene graph is a cubic and 3-connected plan graph that has exactly 12 faces of size5 and other faces of size 6, which can be regarded as the molecular graph of fullerene.In the irst part of this thesis we study some important deinitions and theorems whichused in the other parts.A matching of a graph G is a set M of edges of G such that no two edges of M sharean end-vertex; further a matching M of G is perfect if any vertex of G is incident with anedge of M. A matching M of G is maximum if |M| ? |N| for any other matching N in G. Amatching M is maximal if it is not a proper subset of some other matching in G. Obviously,any maximum matching in G is also a maximal matching. An...
Design and Implementation of a Ka-band Power Amplifier in GaAs pHEMT
, M.Sc. Thesis Sharif University of Technology ; Medi, Ali (Supervisor)
Abstract
Power amplifiers are used as the last block of transmitters. This block can be categorized as the one of most important part in communication systems. However, in transmitter systems which require high power to create stable link with the receivers, fabrication process like CMOS are unable to provide such level of power. Thus, designers employ another group of integrated circuits which names MMIC that offers this capability to designers. In this thesis, design procedure of an amplifier in Ka frequency bands is studied. The power amplifier is fabricated in 0.1um GaAs pHEMT.The isolating backvia wall (IBVW) technique hasbeen proposed to improve gain and stability. Some other designtechniques...
Investigation on Insulin Release from Microcapsules Containing Beta Cell
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Vossoughi, Manouchehr (Supervisor)
Abstract
Type 1 diabetes, formerly known as insulin-dependent diabetes, may present at any age, but is the most common type of diabetes affecting children and adolescents. People with type 1 diabetes do not produce enough insulin. This type accounts for 5-10% of all types of diabetes. In this type of diabetes, beta cell destruction occurs in the pancreas. In type 1 diabetes, the pancreas does not secrete any insulin; insulin is a hormone that enables the body to convert glucose in food into energy. If sugar in the blood cannot enter the cells, it accumulates in the arteries and results in high blood sugar. High blood sugar over time can have irreversible effects on various parts of the body. Curcumin...
A Study to Important the Waste Gas and Air Mixing in an Incinerator Using CFD
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Incineration of oil wastes is a very important subject in oil refinery Industries. Such wastes may include toxic ports such as CO or hydrocarbon compounds, in either liquid or gas forms. In this project, we simulate an oil refinery incinerator. The industry has decided to increase the waste capacity to 150% of its design conditions. This causes the appearance of CO and methane at the outlet of incinerator stack. We investigated the incinerator operation and-found that we might solve the pollution problem by re-design of air and waste inlets to the incinerator. In this regard, we first simulated the incinerator in its normal operation to validate our numerical modeling. Next, we assumed...
Jahn-Teller Effect in Diamond Vacancy Under Stress
, M.Sc. Thesis Sharif University of Technology ; Vesaghi, M. A (Supervisor) ; Babamoradi, M (Co-Advisor)
Abstract
Electron states of diamond vacancy under stress were studied theoretically. The generalized Hubbard model is used to calculate the electrons energy levels. The results shows that the degeneracy of some levels (T, with triple space degeneracy) reduced to levels with lower degeneracy (E, with double space degeneracy and A, without degeneracy). Besides this spiting of degeneracy the energy of all states changed and therefore the transition energy between these states changed too. Jahn-Teller effect was observed
Design of Robust Controller for Depth of Anesthesia
, M.Sc. Thesis Sharif University of Technology ; Sadati, Nasser (Supervisor)
Abstract
Automatic control of depth of anesthesia is an important problem in biomedical engineering. The main challenging problem in anesthesia automation is inter-patients differences which is referred to as uncertainty and is crucial in robust controller design. One of the most appropriate tools in designing robust controllers is H_∞ concept. Furthermore, H_2 concept is used to reject the measurement noise which is unavoidable in practical cases. In this project we use mixed H_2/H_∞ concept to design robust controller for depth of anesthesia. Multi-model controller is another approach to design robust controller for depth of anesthesia, which reject measurement noise and also cover the...
Trajectory Optimization of a Dual-arm Cam-lock Robot Considering Redundancy
, M.Sc. Thesis Sharif University of Technology ; Meghdari, A. (Ali) (Supervisor) ; Ghaemi Osgouie, Kambiz (Supervisor)
Abstract
In the present work, trajectory optimization of the Dual-Arm Cam-Lock robot considering kinematic and dynamic redundancy is performed. First, the optimal control problem is solved only considering kinematic redundancy and then is solved considering dynamic redundancy. General form of the dynamic model for the system is developed using Lagrangian relations. Global optimization method is used for redundancy resolution problem. A performance index is defined based on the consumed kinetic energy and is minimized through a desired trajectory using the global optimization method. Formulations of optimal control problem are derived and initial boundary problem is changed to two point boundary value...
Neural Network Control Allocation of Satellites with Redundant CMG
, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
In this study the control allocation with failure tolerance capability in satellite attitude control using Control Moment Gyro (CMG) actuators is investigated. The pyramid configuration is utilized for arrangement of the actuators. Moreover, considering the singularity of the CMGs, controller is designed based on the angular velocity of the gimbals as the controller output, which prevents the singularity of the actuators. The controller is designed based on the optimal control approach and its cost function is the minimum control effort. The response of the system to the optimal controller in two cases of with or without failure of one actuator is investigated and is compared with the...
Simulating Molecular Dynamics of Gold Nanoparticles on the Basis of Clustered and Colloid Models in the Aquatic Environments and Studying the Effect of Dimensions
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In addition to chemical stability and biocompatibility, because of the characteristics of quantum dimensions, gold nanoparticles are used in detecting cancers, imaging and therapeutics .Atomic interactions between gold particles and bioparticles are influenced by the dimensions of gold particles .Therefore, in this project, after introduction of various water models and used potentials for modeling by the method of TIP3P, we studied gold clusters in different dimensions and densities, by using EAM potential in the aquatic environment .Then we can pave the way for studying proteins besides gold nanoparticles, in the future studies. Besides, gold particles were studied as colloid, so as to...
Evaluation of the Surface Activity of Novel Ionic Liquids and Their Application in the Enhanced Oil Recovery Process
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Mokhtarani, Babak (Supervisor) ; Baghban Salehi, Mahsa (Co-Supervisor)
Abstract
The following dissertation discusses Ionic Liquids (ILs) as an alternative to commercial surfactants for use in the Enhanced Oil Recovery process. Ionic Liquids came to researchers’ attention due to their environmental nature and their tolerance for high temperatures and salinity. In this work, firstly, an extensive literature review is carried out, and then, experiments are designed and performed to evaluate ILs’ surface activity and performance in a lab-scale EOR set-up. The Ionic Liquids used in this work consist of three types of methylimidazolium nitrate, [MIM]+[NO3]-, with three different alkyl chain lengths. This combination, and specifically the effect of nitrate anions on EOR and...
Oil Separation from Contaminated Condensates WithFuel in Power Plant by Flotation &Solvent Sublation
,
M.Sc. Thesis
Sharif University of Technology
;
shaygan, Jalaloddin
(Supervisor)
;
Jalali, Morteza
(Supervisor)
Abstract
Some of the thermal power plants use heavy fuel oil as an auxiliary fuel instead of the fuel gas, especially in the cold seasons. In these plants, in order to reduce fuel viscosity, heavy fuel oil is heated in several stages including fuel storage tank, connection lines and oil supply to burner by heat exchange with returned steam from the turbine, which can lead to fuel leakage into the condensates. This contamination is in addition to the contamination that has resulted from leaking seals on steam driven equipments, such as pumps and turbines. Reusing these contaminated condensates as boiler feed water can lead to coking of hydrocarbons and deposition of a hard scale on boiler tube walls....
Designing a Phase Change Main Memory with High Performance and Capacity
, M.Sc. Thesis Sharif University of Technology ; Sarbazi Azad, Hamid (Supervisor)
Abstract
Although phase change memory with multi-bitstorage capability (knownasMLCPCM) of fers a good combination of high bit-density and non-volatility,its perfo rman ceisseverely impacted-by increaseread/write latency. Readlatencyin MLCPCMsincreasesalmostlinearlywithrespecttothenum- berofbitsstoredina-cell.Sincereadaccessesarelatency critical,theycanseverelyimpactsystem performance.This paperalleviatestheproblemofslowreadsinMLCPCMs byexploitingafundamentalproper-tyofMLCPCMdevices: the most-significantbits (MSBs)ofMLCcells canbe readas fas-tasSLCs,whilereadingtheleast-significantbits(LSBs)is slower.WeproposeStripedPCM,SPCM, amemory architec- turethatleveragesthispropertytokeepMLC’sreadlatency...
Estimating the Amount of Evaporation, Salinity, Precipitation and Dissolution of Salt on Lake Urmia
, M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud (Supervisor)
Abstract
Lake Urmia is the largest hypersaline lake in Iran, as well as a significant aquatic habitat. In recent decades, extreme increasing of extent plans and exploitation of water resources in this basin, cause decreasing inflow, water level and creating several environmental and economic issues. In recent decades, the excessive expansion in the development and exploitation of this basin's water resources has resulted in a drop in the flows into the lake, a decline in the lake's water level, and the creation of several environmental and economic issues. In recent years, these stressors have caused the lake's salinity to exceed 400 g/L, and salt deposits have emerged on the lake bottom and...
Credit Rating Agencies during Credit Crunch
, M.Sc. Thesis Sharif University of Technology ; Ebrahimnejad, Ali (Supervisor) ; Hosseinzadeh, Saeed (Supervisor)
Abstract
This study examines the behaviour of credit rating agencies during the credit crunch and compares it with normal economic conditions. The rating agencies claim that when assessing the credibility of firms over time, they can distinguish between short-term and long-term factors of credit shocks. To evaluate this claim, using Moody's rating data and variables that represent the macroeconomic conditions and financial and business risks, we study whether there is a difference in the tendency of rating agencies to downgrade the rating of firms in the periods of the credit crunch. A credit crunch index is used to determine the occurrence of credit cycles, which is obtained from the time series of...
The Analytical Study of the Nonlinear Behavior of Conventional and Retrofitted Khorjini Connections
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
The purpose of this research is to study the behavior of conventional and retrofitted Khorjini connections. Thus the software ABAQUS 6.11 was used to fabricate the FEM models of the connections with experimental prototypes. In analytical studies, 21 specimens with different size of the connection components were analyzed. True stress–strain curves for steel and weld materials were used and damage initiation and revolution were considered in the weld material. Also cracking of the welds were considered by a micromechanical method. Behavioral characteristics of the conventional connections are specified and appropriate relations are suggested, using Stability equations of the connection...
A Mathematical Model to Apportion the Cost of Kidney Purchasing in Domino-paired Donation
, M.Sc. Thesis Sharif University of Technology ; Najafi, Mehdi (Supervisor)
Abstract
The human body normally has two functioning kidneys, while only one of them is sufficient to have a healthy life. However, for those patients having no functioning kidney, transplantation is the most effective treatment. Although deceased donors have been usually used as the main source for kidney donation in many countries, there are several cases focusing on living kidney donation to compensate for the shortage in supply and to reduce the patient waiting time for treatment. Because of this potential, many studies have been conducted to optimize the non-clinical issues of kidney transplant waiting lists. Notwithstanding employing the financial incentives for living kidney donation is...
Design and Construction of a Bent Crystal Spectrometer for Studying Soft X-Rays of Sharif Plasma Focus
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Etaati, Gholam Reza (Supervisor)
Abstract
A soft X-ray spectrometer based on Johann's method and an embedded curved crystal is designed and fabricated for Sharif University of Technology's Plasma Focus (SUT-PF) in this project. Focusing rays with the same wavelength at a point to increase the ray intensity is the reason of choosing the cylindrical curved crystal spectrometer since its performance is inspired to the Bragg's law.The optimal conditions for SUT-PF (pressure and voltage) is adjusted and examined by photodiode detector and the camera pinhole before spectroscopy experiments. The diameter of generated hot spots is measured as 80 microns in the optimal condition.The recorded spectral lines on the radiography film and the...