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fundamental-frequency
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Fundamental frequency estimation using modified higher order moments and multiple windows
, Article Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH ; 2011 , Pages 1965-1968 ; 19909772 (ISSN) ; Vaseghi, S ; Milner, B ; Ghorshi, S ; Sharif Univesity of Technology
2011
Abstract
This paper proposes a set of higher-order modified moments for estimation of the fundamental frequency of speech and explores the impact of the speech window length on pitch estimation error. The pitch extraction methods are evaluated in a range of noise types and SNRs. For calculation of errors, pitch reference values are calculated from manually-corrected estimates of the periods obtained from laryngograph signals. The results obtained for the 3 rd and 4 th order modified moment compare well with methods based on correlation and magnitude difference criteria and the YIN method; with improved pitch accuracy and less occurrence of large errors
Phonetic Representation of Intonational Elements in Persian Emotional Speech
, M.Sc. Thesis Sharif University of Technology ; Eslami, Moharram (Supervisor) ; Vazirnezhad, Bahram (Co-Advisor)
Abstract
Theoretically, it has been proved that pitch changes has an specific phonological system in Persian and the main intonational elements (i.e. pitch accent, phrase tone and boundary tones) have a known independent identity and can change independently. These changes give different intonational forms to utterances. In addition, it has been demonstrated that sound pattern of Persian syntax units follow HAP (Head Avoidance Principle) and Always, the farthest argument from the head takes the pitch accent. In the present thesis, phonetic values of intonational elements in 5 emotions of PESD database utterances (i.e. Anger, Disgust, Sadness, Happiness and Fear) are quantified and then, they are...
Phonetics of Persian Intonation
, M.Sc. Thesis Sharif University of Technology ; Eslami, Moharram (Supervisor) ; Sameti, Hossein (Co-Advisor)
Abstract
This study is a research on Persian Intonational System, which was carried out within the Autosegmental-Metrical framework.The intonational elements of Persian are represented by two distinctive levels (High and Low). Persian intonation system enjoys three main elements: pitch accents, Phrase accents and boundary tones. Every intonational element has its own meaning. The data of study is about 200 utterances produced by two Persian native speaker one male and one female. These utterances have been annotated in four levels in PToBI: phoneme level, word level, tone level and break index level. In this study we aimed to formulate the acoustic representation of the intonational elements by three...
Phonetic Representation of Intonation in Persian Vocative Structures
, M.Sc. Thesis Sharif University of Technology ; Eslami, Moharram (Supervisor) ; Bahrani, Mohammad (Co-Advisor)
Abstract
This study investigates the intonational properties of vocative structure in standard Persian in the framework of Auto-segmental-metrical phonology. Pitch accent is one of the elements whithin this framework, that refers to the prominence in the utterance. In Persian all lexical units are stressed in their final syllable and there is a language-specific feature in Persian according to which pitch accents are aligned with lexically stressed syllables. Contrary to the said feature, previous studies claim that in vocative structure, it is the first syllable that is accented, due to the difference existed between intonation pattern of vocative structure compared to its citation form. The data...
Phonetic Representation of Pitch Accent in Persian Words
, M.Sc. Thesis Sharif University of Technology ; Eslami, Moharram (Supervisor) ; Sameti, Hossein (Co-Advisor)
Abstract
The stress positions of the words are determined according to the type of their morphological elements. Persian Words often have a fixed position for stress. However, Persian wordforms show different stress positions, based on their morpheme types or in the other words, their bound-non derivational affixes. Inflectional affixes accept stress, whereas clitics do not. In the present research we studied both types of non derivational affixes considering their phonetic features meaning fundamental frequency and duration. The phonetic representation of the pitch accent as the phonemic- intonational element was given as a result of this study, as well. The differences in the phonetic...
Applications of single-layered graphene sheets as mass sensors and atomistic dust detectors
, Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 11 , 2007 , Pages 99-104 ; 079184305X (ISBN) ; Ahmadian, M. T ; Vafai, A ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2007
Abstract
Molecular structural mechanics is implemented to model vibrational behavior of defect free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nano structures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. Effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. Results of exhibit the principle frequencies are highly sensitive to the added mass in the order of 10-6 fg....
A time modulated array with polarization diversity capability
, Article IEEE Access ; Volume 9 , 2021 , Pages 53735-53744 ; 21693536 (ISSN) ; Fakharzadeh, M ; Akbari, M ; Safavi Naeini, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
The Time Modulated Array (TMA) provides multiple radiation beams at different frequencies, by turning the radiating elements on and off. In this paper, we propose to add polarization diversity to a wireless communication link by leveraging the capabilities of the TMA. The proposed architecture switches between two orthogonal polarizations, instead of turning the antenna off, providing polarization diversity for the receivers. We show that the beams of each polarization at the sidebandsare exactly the same. However, the switching sequence should be optimized for the fundamental frequency to provide the same radiation level at each sideband. Two different switching sequences are proposed,...
Optimization of Porosity Distribution in Functionally Graded Porous Shape Memory Alloy Beams Using Genethic Algorithm
, M.Sc. Thesis Sharif University of Technology ; Arghavani Hadi, Jamal (Supervisor)
Abstract
Shape Memory alloys are a kind of intelligent materials developed in recent years due to their comprehensive use in medical, robotics, and other advanced sciences. Two main characteristics of them are shape memory effect and superelasticity put these materials in the category of advanced materials. Recently, the new branch of them attracted many studies which is the porous shape memory alloys. The importance of this class of material is related to their properties such as bio-compatibility, superelasticity and shape memory effect. Since shape memory alloys are usually expensive, a new field is developed known as functionally graded porosity distribution. This method is performed by...
Nonlinear membrane model for large amplitude vibration of single layer graphene sheets
, Article Nanotechnology ; Volume 22, Issue 30 , June , 2011 ; 09574484 (ISSN) ; Niaki, S. A ; Naghdabadi, R ; Asghari, M ; Sharif University of Technology
2011
Abstract
The nonlinear vibrational properties of single layer graphene sheets (SLGSs) are investigated using a membrane model. The nonlinear equation of motion is considered for the SLGSs by including the effects of stretching due to large amplitudes. The equation of motion is numerically solved utilizing the finite difference method for SLGSs with different initial and boundary conditions, sizes and pretensions. It is concluded that the nonlinear fundamental frequency of SLGSs increases by increasing the pretension and initial velocity. In addition, it is observed that an increase in the pretension weakens the effects of the initial velocity on the fundamental frequency, such that the fundamental...
Size-dependent bistability of an electrostatically actuated arch NEMS based on strain gradient theory?
, Article Journal of Physics D: Applied Physics ; Volume 48, Issue 24 , May , 2015 ; 00223727 (ISSN) ; Pishkenari, H. N ; Yazdi, M. R. H ; Miandoab, E. M ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
This paper deals with the investigation of the size-dependent nature of nonlinear dynamics, in a doubly clamped shallow nano-arch actuated by spatially distributed electrostatic force. We employ strain gradient theory together with the Euler-Bernoulli and shallow arch assumptions in order to derive the nonlinear partial differential equation governing the transverse motion of the arch with mid-plane stretching effects. Using the Galerkin projection method, we derive the lumped single degree of freedom model which is then used for the study of the size effects on the nonlinear snap-through and pull-in instabilities of the arch nano-electro-mechanicalsystem (NEMS). Moreover, using strain...
Free vibration analysis of sandwich conical shells with fractional viscoelastic core
, Article Composite Structures ; Volume 214 , 2019 , Pages 62-72 ; 02638223 (ISSN) ; Shakouri, M ; Haddadpour, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
The vibration characteristics, including fundamental frequencies and loss factors, of a sandwich conical shell with constrained viscoelastic layer is presented. The mechanical properties of viscoelastic core is modeled using Zener fractional order model. The equations of motion are derived employing Donnell representation of classical shell theory and solved using Raighly-Ritz method. The results are compared with other investigations and the effects of geometric parameters including the length to radius, radius to thickness and core to facing thickness on fundamental frequencies and loss factors are studied. © 2019 Elsevier Ltd
Potential application of single-layered graphene sheet as strain sensor
, Article Solid State Communications ; Volume 147, Issue 7-8 , August , 2008 , Pages 336-340 ; 00381098 (ISSN) ; Ahmadian, M. T ; Vafai, A ; Sharif University of Technology
2008
Abstract
Molecular structural mechanics is implemented to investigate the vibrational characteristics of defect-free single-layered graphene sheets (SLGSs), which have potential applications as strain sensors. The effect of strain on the fundamental frequencies of the defect-free zigzag and armchair models with clamped-clamped boundary condition is studied. The atomistic modeling results reveal while sensitivities of the strain sensors are not influenced significantly by chirality, they can be slightly increased by decreasing aspect ratios of the sheets. It is further shown that the SLGSs-based strain sensors are more sensitive to the applied stretch than the SWCNTs versions. © 2008 Elsevier Ltd. All...
Nanoscale vibrational behavior of single-layered graphene sheets
, Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 11 , 2007 , Pages 229-235 ; 079184305X (ISBN) ; Ahmadian, M. T ; Vafai, A ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2007
Abstract
Molecular structural mechanics approach is implemented to investigate vibrational behavior of single-layered graphene sheets. By using the atomistic modeling, mode shapes and natural frequencies are obtained. Vibration analysis is performed under different chirality and boundary conditions. Numerical results from the finite element technique are applied to develop empirical equations via a statistical multiple nonlinear regression model. With the proposed empirical equations, fundamental frequencies of single-layered graphene sheets under considered boundary conditions can be predicted within 3 percent accuracy. Copyright © 2007 by ASME
Time-domain signal analysis using adaptive notch filter
, Article IEEE Transactions on Signal Processing ; Volume 55, Issue 1 , 2007 , Pages 85-93 ; 1053587X (ISSN) ; Karimi Ghartemani, M ; Bakhshai, A ; Sharif University of Technology
2007
Abstract
Noise reduction and signal decomposition are among important and practical issues in time-domain signal analysis. This paper presents an adaptive notch filter (ANF) to achieve both these objectives. For noise reduction purpose, the proposed adaptive filter successfully extracts a single sinusoid of a possibly time-varying nature from a noise-corrupted signal. The paper proceeds with introducing a chain of filters which is capable of estimating the fundamental frequency of a signal composed of harmonically related sinusoids, and of decomposing it into its constituent components. The order of differential equations governing this algorithm is 2n + 1, where n is the number of constituent...
Dynamic control of supported macro/micro-tubes conveying magnetic fluid utilizing intelligibly designed axially functionally graded materials
, Article International Journal of Computer Integrated Manufacturing ; 2021 ; 0951192X (ISSN) ; Mirtalebi, S. H ; Ahmadian, M. T ; Cao, Y ; Suhatril, M ; Assilzadeh, H ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
In this study, dynamic modeling of an elbow axially functionally graded (AFG) macro/micro-tube carrying magnetic flow with different cross-sections is considered. Parametric optimization is performed for vibration suppression of such fluid-interaction systems. Implementing computer simulations, passive vibration control procedures, along with the effect of AFG materials and magnetic properties of the fluid as well as precisely manufactured geometry of the system, is investigated. It is assumed that the material characteristics of the system vary in the longitudinal direction based on exponential and power-law distribution profiles. Influence of the downstream inclination angle and...
A new modeling and control scheme for cascaded split-source converter cells
, Article IEEE Transactions on Industrial Electronics ; 2021 ; 02780046 (ISSN) ; Milimonfared, J ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Cascaded split-source inverter (CSSI) is a new single-stage modular multilevel topology. Each cell of this converter converts DC to AC power in the buck or boost operation mode without any additional power switch. This paper develops a design method based on a detailed model for CSSI. This model shows that energy storage elements experience double-fundamental frequency ripples besides high-frequency ones. It accurately calculates voltage gains and capacitor voltage and inductor current ripples. On the other hand, common carrier-based multilevel modulations have been modified in terms of both reference and carrier signals to control the inverter under symmetric and asymmetric conditions. With...
Nonlinear vibrational analysis of single-layer graphene sheets
, Article Nanotechnology ; Volume 21, Issue 10 , 2010 ; 09574484 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2010
Abstract
Recent experiments have shown the applicability of single-layer graphene sheets (SLGSs) as electromechanical resonators. Existing theoretical models, based on linear continuum or atomistic methods, are limited to the study of linear vibrations of SLGSs. Here we introduce a hybrid atomistic-structural element which is capable of modelling nonlinear behaviour of graphene sheets. This hybrid element is based on an empirical inter-atomic potential function and can model the nonlinear dynamic response of SLGSs. Using this element, nonlinear vibrational analysis of SLGSs is performed. It is shown that the nonlinear vibrational analysis of SLGSs predicts significantly higher fundamental...
Inverse vibration technique for structural health monitoring of offshore jacket platforms
, Article Applied Ocean Research ; Volume 62 , 2017 , Pages 181-198 ; 01411187 (ISSN) ; Lotfi, A ; Dolatshahi, K. M ; Golafshani, A. A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this paper a new approach is introduced for structural health monitoring of offshore jacket platforms. The procedure uses the measured ambient vibration responses and the corresponding readable natural frequencies and mode shapes of the structural system. Since offshore platforms are composed of heavy topsides supported by jacket structures, participation of the first mode is dominant in each direction in the response of the structure under field excitations. Moreover, ambient vibrations such as wave loads and boat impacts only excite the first modes of the structure. Therefore, it is difficult to find higher modes and the pertinent frequencies by use of accelerometers data. The...
Optimal material tailoring of functionally graded porous beams for buckling and free vibration behaviors
, Article Mechanics Research Communications ; Volume 88 , 2018 , Pages 19-24 ; 00936413 (ISSN) ; Arghavani, J ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this paper, assuming porosity varies only along thickness direction, its optimal distributions in functionally graded porous (FGP) beams are tailored. Two multi-objective optimization problems are defined. In the first one, critical buckling load and mass are optimized simultaneously while in the second one, we concentrate on simultaneous optimization of mass and fundamental frequency. Employing Timoshenko beam theory, we present governing equations for a FGP beam. For the solution, we use Ritz method and propose appropriate trial functions according to the boundary conditions (Hinged-Hinged, Clamped-Clamped, Clamped-Hinged and Clamped-Free). Since the porosity distribution along...
Buckling and vibration analysis of FG-CNTRC plate subjected to thermo-mechanical load based on higher order shear deformation theory
, Article Mechanics Based Design of Structures and Machines ; 2020 ; Karbon, M ; Eyvazian, A ; Jung, D. W ; Habibi, M ; Safarpour, M ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
In the present study, based on 12-unknown higher order shear deformation theory (HSDT), buckling and vibration analysis of FG-CNTRC rectangular plate are investigated for various types of temperature distribution and boundary conditions. Implementing Hamilton’s principle, the equations of motion are derived and solved by adopting the Navier solution for the simply supported boundary conditions and DQM method for other boundary conditions. Validation is carried out by comparing the numerical results with those obtained in the open literature. Also, a detailed parametric analysis is carried out to illuminate the influence of different system parameters such as CNT distributions, CNT volume...