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A lab-scale set up for thermal radiation experiments with cold junction compensation
, Article Education for Chemical Engineers ; Volume 7, Issue 4 , 2012 , Pages e203-e209 ; 17497728 (ISSN) ; Farhadi, F ; Fallahpour, N ; Sharif University of Technology
2012
Abstract
The concepts of thermal radiation heat transfer are not tangible for many students. Experiments relied on various parameters can clarify the concepts of this mode of heat transfer.A lab-scale set up is described to study the thermal radiation heat transfer experiments. An electrical circuit of the thermopile sensor is designed and manufactured to provide experimental data.The validity of Inverse Square, Stefan-Boltzmann, and Kirchhoff Laws are investigated experimentally in the setup. Results indicate that, it is necessary to consider temperature shifts in the thermopile cold junction which is a potential source of error. Therefore, the output voltage, corresponding to the sensor...
Experimental Studies on Petroleum Hydrocarbons Biodegradation in a Microbial Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid Reza (Supervisor)
Abstract
Environmental issues are more and more considered because of increasing environmental pollution along the industrial growth. In recent years Microbial Fuel Cells (MFCs) have attracted attention of many researchers as a renewable source of clean energy. In this research, wastewaters of purified terephthalic acid (PTA) plant and polyethylene terephthalate (PET) plant were examined in MFC.
Voltage generation in the PTA MFC cycle indicated two steady phases. Produced power was 31.8 mW/m2 (normalized per cathode area) and calculated Coulombic efficiency was 2.05 % for COD removal of 74% during 21 days. Concentration changes of each pollutant indicated that acetic acid (AA) and benzoic acid...
Voltage generation in the PTA MFC cycle indicated two steady phases. Produced power was 31.8 mW/m2 (normalized per cathode area) and calculated Coulombic efficiency was 2.05 % for COD removal of 74% during 21 days. Concentration changes of each pollutant indicated that acetic acid (AA) and benzoic acid...
Investigating the Behaviour of Concrete Deep Beams With Web Openings Using Finite Element Analysis
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Because of absence of adequate studies, design of deep beams with web openings has not yet been covered by most codes of practice. The most studies have been on simply supported deep beams with web openings and have been set up experimentally. There are very few tests of continuous deep beams available in the literature. So it was decided in this thesis the behaviour of concrete continuous deep beams with web openings using finite element software ANSYS to be investigated. Primary purpose of this thesis has been evaluating the use of finite element analysis method for analysis of concrete continuous deep beams with web openings. The next target of this thesis has been assessment of...
Study of the Effects of Rrest Time and Loading Time on Viscoplastic Strain of Asphalt Concrtee
, M.Sc. Thesis Sharif University of Technology ; Tabatabaei, Nader (Supervisor)
Abstract
Asphalt concrete exhibits viscoelastic and viscoplastic behavior which is dependent on rate and temperature. To model this behavior, various mechanical modelshave been presented in which total strain, as the response of the applied stress, is decomposed by various researchers to recoverable and permanent strains.Accumulation and expansion of permanent response result in rutting which is a dominant and prevalent distress in hot mixed asphalt (HMA) in hot climates. The available models are not capable of accurately calculate the viscoplastic strain under cyclic loading.
To close this gap, recovered viscoelastic strain at rest (unloading) period was introduced. This parameter accounted for...
To close this gap, recovered viscoelastic strain at rest (unloading) period was introduced. This parameter accounted for...
Very low rate scalable speech coding through classified embedded matrix quantization
, Article Eurasip Journal on Advances in Signal Processing ; Volume 2010 , April , 2010 ; 16876172 (ISSN) ; Ghaemmaghami, S ; Sharif University of Technology
2010
Abstract
This paper proposes a scalable speech coding scheme using the embedded matrix quantization of the LSFs in the LPC model. For an efficient quantization of the spectral parameters, two types of codebooks of different sizes are designed and used to encode unvoiced and mixed voicing segments separately. The tree-like structured codebooks of our embedded quantizer, constructed through a cell merging process, help to make a fine-grain scalable speech coder. Using an efficient adaptive dual-band approximation of the LPC excitation, where voicing transition frequency is determined based on the concept of instantaneous frequency in the frequency domain, near natural sounding synthesized speech is...
Coupled Flexural-Torsional Vibration Analysis of Micro-Rotors Based on The Non-Classical Theories of Continuum Mechanics
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
Todays, advances in manufacturing technologies have led to design and production of micro-scale elements, including the elements employed in micro-electro-mechanical systems (MEMS). Micro-rotating systems like the micro-turbines are that kind of systems at which the high rotational speeds and the complexity of design and analysis have led to a special attention in modeling and investigating of their dynamic-vibrational behavior. In addition, in small scales, using the non-classical continuum mechanics theories such as the couple stress theory and the strain gradient theory is required to obtain the high precise results. On the other hand, attention to the torsional deformation of rotors...
Scalable speech coding at rates below 900 BPS
, Article 2008 IEEE International Conference on Multimedia and Expo, ICME 2008, Hannover, 23 June 2008 through 26 June 2008 ; 2008 , Pages 85-88 ; 9781424425716 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2008
Abstract
This paper introduces a novel scalable speech coding scheme based on embedded matrix quantization of LSF parameters in an LPC model. In the proposed quantizer, codewords are organized based on a tree structure through a cell-merging process, which leads to a fine-grain scalable coder at rates below 900 bps. Near natural sounding is achieved at very low rates by employing an efficient adaptive dual-band scheme to approximate the LPC excitation signals. Evaluation results, obtained from both overall quality measurement and intelligibility assessment, show that the proposed coder could be a reasonable choice for improving the bottom-line speech quality in low bit rates. © 2008 IEEE
High rate data hiding in speech signal
, Article SIGMAP 2007 - 2nd International Conference on Signal Processing and Multimedia Applications, Barcelona, 28 July 2007 through 31 July 2007 ; 2007 , Pages 287-292 ; 9789898111135 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2007
Abstract
One of the main issues with data hiding algorithms is capacity of data embedding. Most of data hiding methods suffer from low capacity that could make them inappropriate in certain hiding applications. This paper presents a high capacity data hiding method that uses encryption and the multi-band speech synthesis paradigm. In this method, an encrypted covert message is embedded in the unvoiced bands of the speech signal that leads to a high data hiding capacity of tens of kbps in a typical digital voice file transmission scheme. The proposed method yields a new standpoint in design of data hiding systems in the sense of three major, basically conflicting requirements in steganography, i.e....
Effect of radially functionally graded materials on the primary resonances of large amplitude flexural vibration of in-extensional rotating shafts
, Article Engineering Structures ; Volume 226 , 2021 ; 01410296 (ISSN) ; Bagheri, E ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This paper analytically studies the effect of functionally graded materials (FGMs) on the primary resonances of large amplitude flexural vibration of in-extensional rotating shafts with nonlinear curvature as well as nonlinear inertia. The constituent material is assumed to vary along the radial direction according to a power-law gradation. The governing differential equations and the corresponding boundary conditions are derived employing the variational approach. Then, the Galerkin method and the multiple scales perturbation method are utilized to obtain the frequency–response equation. In a numerical case study, the effects of the power-law index on the steady-state responses and locus of...
High rate data hiding in speech using voicing diversity in an adaptive MBE scheme
, Article 2008 IEEE Region 10 Conference, TENCON 2008, Hyderabad, 19 November 2008 through 21 November 2008 ; 2008 ; 1424424089 (ISBN); 9781424424085 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2008
Abstract
This paper addresses a new approach to data hiding that leads to a high data embedding rate of tens of kbps in a typical digital voice file transmission scheme. The purpose of the proposed method is restricted to offline voice transmission that uses stego speech files in wave format. The basic idea of the algorithm is to embed encrypted covert message in the unvoiced bands of spectrum of the cover speech. Inaudibility of the proposed hiding scheme is investigated through both support vector machines (SVM)-based steganalysis and the ITU-T P.862 PESQ standard speech quality assessment. The results assure imperceptibility and transparency of the stego speech
Numerical Modeling of Dynamic Compaction Operation in Sandy Soils Deposits in Order to Provide a Design Approach
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
Dynamic compaction is a widely used soil deep improvement method in dry and/or saturated soils. Despite its vast application, numerical and /or experimental modeling studies of dynamic compaction due to impact are little. In order to clarify the ambiguities in process and to present a comprehensive design approach, numerical modeling of dynamic compaction in dry soils with PISA (A fully coupled dynamic finite element code: Program for Incremental Stress Analysis) has been done. Because the geometry and loading configuration are symmetric around the falling tamper (load centerline), a two-dimensional axisymmetric simulation has been used. Here for sake of simplicity, initial velocity of...
Reliability assessment of distribution system with distributed generation
, Article 2008 IEEE 2nd International Power and Energy Conference, PECon 2008, Johor Baharu, 1 December 2008 through 3 December 2008 ; January , 2008 , Pages 1551-1556 ; 9781424424054 (ISBN) ; Fotuhi Firuzabad, M ; Sharif University of Technology
2008
Abstract
Reliability assessment is of primary importance in designing and planning distribution systems that operate in an economical manner with minimal interruption of customer loads. Distributed generation (DG) is expected to play an increasing role in emerging power systems because they use different type of resources and technologies to serve energy to power systems. DG is expected to improve the system reliability as its backup generation. Since DG units are subject to failures as all other generation units, the random behavior of these units must be taken into account in the analysis. Existence of DG units in a distribution system will effect on restoration time of load points. In this paper,...
Developing a New Framework for Assessing the Impact of Data Uncertainty on Water Quality Index based on Multivariate Analysis
, M.Sc. Thesis Sharif University of Technology ; Sheikholeslami, Razi (Supervisor)
Abstract
Over the past several decades, human activities have resulted in a significant increase in surface and ground water pollution. Human activities have caused significant pollution of surface and groundwater, with pollutants like nitrates, phosphorus, heavy metals, toxins, and chemical fertilizers degrading water quality. In order to control pollution and reduce the concentration of pollutants in water, it is necessary to use appropriate numerical criteria to evaluate and manage the quality of water resources. The water quality index, as a scoring method for investigating the combined effects of independent parameters on overall water quality, is a widely-used metric for measuring the quality...
Application of Data Mining Techniques in Diagnosis & Prediction of Heart Disease
, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
Nowadays, data is the most important asset for health organizations in which the process of collecting, storing and analyzing of data leads to success of health organizations. Many companies have turned to data mining for the beneficial use of these data. The main purpose of data mining is to obtain useful knowledge from existing data. One of the diseases that is very significant for data miners is cardiovascular disease. Cardiovascular disease is the most important cause of death in the world. Therefore, it is necessary to improve the diagnostic and predictive measures of these patients. In this study, a database containing of characteristics of patients with chest pain who referred to...
Torsional vibration induced by gyroscopic effect in the modified couple stress based micro-rotors
, Article European Journal of Mechanics, A/Solids ; Volume 81 , May–June , 2020 ; Asghari, M ; Bagheri, E ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this research, the small-scale effects in the torsional vibration of the micro-rotors with eccentric micro-disks are investigated based on the modified couple stress theory. The torsional deformation of the micro-shaft described by function φ(x,t) is considered to be independent of the flexural deformation described by functions v(x,t) and w(x,t). Using Hamilton's principle, the system of coupled nonlinear governing partial differential equations of motion and the associated boundary conditions are derived. The system of equations includes one corresponding to the torsional deformation and two others corresponding to the flexural deformation. By employing the Galerkin method, the system...
Relaxation of hardening in asphalt concrete under cyclic compression loading
, Article Journal of Materials in Civil Engineering ; Volume 29, Issue 5 , 2017 ; 08991561 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
American Society of Civil Engineers (ASCE)
2017
Abstract
The present experimental study investigated the behavior of hot-mix asphalt (HMA) under repetitive creep and recovery loading. Cylindrical samples of HMA were subjected to trapezoidal and haversine loading followed by unloading. Different amounts of unloading (stress reduction) and relaxation periods (rest periods in complete unloading) were tested. The measured vertical deformation was decomposed into viscoelastic and viscoplastic components. It was observed for cyclic loading that an increase in unloading and/or relaxation period increased the recovery of viscoelastic strain, which in turn increased the accumulated viscoplastic strain in subsequent loading cycles. It appears that...
Application of a mathematical method in calculation of the skin variation during a real field acidizing operation
, Article Chemical Engineering Science ; Volume 192 , 2018 , Pages 829-839 ; 00092509 (ISSN) ; Jamshidi, S ; Jahangiri, H. R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The efficiency of an acidizing operation is usually assessed through ordinary well testing methods. These methods are performed only after the acidizing operation, and it is difficult to monitor and evaluate real-time efficiency of acidizing operation. Understanding the performance of the acidizing during the service, by analysis of the acidizing data is a viable approach to this costly and challenging process. The estimation of the skin changes needs an appropriate mathematical method that can handle the main aspects of an acidizing operation. It is tedious to model a real acidizing operation due to the heterogeneity of the reservoir, an unknown reaction rate of acid in reservoir condition,...
Evaluation of Foundation Flexibility on Seismic Performance of Anchored and Unanchored Aboveground Cylindrical Steel Tanks
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Amin (Supervisor)
Abstract
Liquid storage tanks are important components of lifeline and industrial facilities. Since,many tanks have borne serious damages during past earthquakes, Forcasting seismic behavior of tanks have attracted for numerous researchers who investigated seismic behavior of liquid storage tanks. This Thesis investigates the effects of slab foundation flexibility on seismic behavior of anchored and unanchored aboveground cylindrical steel storage tanks. In this study, finite elements method by ABAQUS software is used for three tanks with height to diameter ratios (H/D) of 0.343 , 0.85, and 1.53. These tanks are excited by seven one-way and three two-way earthquake records which were scaled to Iran...
A consistent incompressible SPH method for internal flows with fixed and moving boundaries
, Article International Journal for Numerical Methods in Fluids ; Volume 81, Issue 10 , 2016 , Pages 589-610 ; 02712091 (ISSN) ; Fatehi, R ; Taghizadeh Manzari, M ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
An improved incompressible smoothed particle hydrodynamics (ISPH) method is presented, which employs first-order consistent discretization schemes both for the first-order and second-order spatial derivatives. A recently introduced wall boundary condition is implemented in the context of ISPH method, which does not rely on using dummy particles and, as a result, can be applied more efficiently and with less computational complexity. To assess the accuracy and computational efficiency of this improved ISPH method, a number of two-dimensional incompressible laminar internal flow benchmark problems are solved and the results are compared with available analytical solutions and numerical data....
Study of Rheology of Suspensions Using SPH Method and Immersed Boundary Method
, M.Sc. Thesis Sharif University of Technology ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
In this thesis, an Incompressible SPH (ISPH) method is used to simulate suspensions. A suspension is assumed to be a mixture of solid particles in a Newtonian fluid. First, renormalization tensors are applied to the discretized equations of SPH method. This leads to a higher accuracy in this method. It should be noted that the projection method is used for ISPH. After that, the Immersed Boundary Method (IBM) is used to model and simulate the presence of solid particles in fluid flow. Some modifications were necessary to use IBM with Lagrangian approach. Then, some benchmark problems are solved to validate the presented method. The main objective of the present thesis is simulation of...