Sharif Digital Repository

The human speech signal conveys many levels of information ranging from phonetic content to speaker identity and even emotional status. This thesis deals with the task of open-set speaker identification (SI) from an unconstrained telephone conversation between two speakers. The goal is to find at most two speakers among a known set of target speakers that best match the voice samples of the input speech; the input voice samples are not constrained to the target speaker set. The uni-speaker problem is investigated first. The classic GMM-UBM system for text-independent SI and its adapted form are explored. The use of score-space information is advocated as a complementary source to the... 

In this proposal we pursue structured sparse representations. Recent years have witnessed a tremendous growth in sparse modeling of natural signals. In this model a signal is represented as a linear combination of a few atoms from an often over-complete dictionary. The recent success of compressed sensing is intact due to the property that natural signals often admit sparse representations. Still, sparse representation in its simplest form sometimes fails to capture the intrinsic structure in natural signals. This structure may be embedded in the signal itself or in the relation between different signals of interest. The goal of this research proposal is to exploit the intrinsic structure in... 

Cost-effective and reliable damage detection is critical for utilization of composite materials. This research investigates a wavelet-based approach for SHM and detection of through-thickness crack in different lengths and angles in [0/45/-45/90]s CF/EP composite plate utilizing ANSYS finite element method (FEM) software and digital signal processing technique utilizing MATLAB software. To this end, a dual-PZT actuation scheme is applied, aimed at generating the S0 mode at a square composite plate. This study contributes to the damage detection by developing an improved wavelet-based signal processing technique that enhances the visibility and interpretation of the Lamb wave signals related... 

The current study aimed to investigate the differential effects of multimedia input with no subtitle, subtitle, or caption (L2 subtitle) on vocabulary retention while controlling for the possible effects of students' vocabulary size and language aptitude as covariates. A total of 81 undergraduate university students were assigned to the study from three intact groups at Sharif University of Technology. All of the participants were Persian speakers and were in the age range of 18 and 22 years old; homogeneity of the students regarding their language proficiency was also established. During two different sessions, students' vocabulary size and language aptitude were measured. The groups were... 

In recent years, some listed companies have re-evaluated their assets, an event that has generally received market attention; In fact, the market seems to be reacting very positively to an accounting phenomenon. In this study, we seek to investigate the market reaction to the revaluation of listed companies in Iran. To do this, we first estimate the market reaction to the news of the revaluation of assets. We then examine the possible reasons for the market reaction to the revaluation. Asset revaluation can improve the firm's access to finance by improving some financial ratios; On the other hand, the increase in capital from the revaluation of firms is accompanied by the issuance of bonus... 

Increasing competition in global market and different requirements of customers persuade manufacturers to improve the efficiency of their manufacturing activities. For this end cellular manufacturing systems can be introduced as an innovative and compromising practice for companies. Among the necessary decisions for a successful cellular manufacturing design and implementation, production routing selection (PRS), cell formation (CF), group layout (GL) and group scheduling (GS) are the four most important ones. This research investigates these decisions and proposes a new approach to integrate them. We use important production factors such as production volume, operation sequence, operational... 

Springs parts are widely used in many industries including the automative industries where the disability of the springs can cause damage. Spring forming processes induce residual stresses on the surface of spring. Residual stress is affected by various processes, such as heat treatment or shot peening. When a coiled spring is heat treated, depending on the temperature and time of heat treatment residual stresses are partially relieved, but they generally do not disappear.An important characteristic of spring steel is its resistance against stress relaxation at different temperatures and times. Stress relaxation in valve springs working at high temperatures causes some problems for... 

This thesis aims to develop a numerically efficient nonlinear layer-wise shell element formulation for delamination analysis of laminated composite shell structures. The element, in a mesoscale scheme, is formulated based on a zig-zag theory and features three translational degrees of freedom for each node on the mid-surface of the shell in addition with two rotational degrees of freedom for each layer. In this way, the displacement field is formulated via adapting the Mindlin-Reissner theory in each layer and an ordered second-order algorithm for finite rotations. To verify the proposed formulation, many popular benchmark problems for geometric nonlinear analysis of shell problems are... 

Index funds are one of the most vital financial institutions providing a wide range of values for different investors. Despite the importance of these funds, not only are index funds recently developed, but they also do not replicate their indices effectively. In this paper, we analyze the portfolio performance of the Karafarin Index Fund as an open-end fund for case study in various frameworks. First of all, the asset allocation and security selection attributions are assessed for capturing the capabilities to choose the suitable security at the right time. In addition, this assessment is done for the industry allocation and security selection attribution in the stock portfolio of the... 

The behavior of boundary layer under the effect of the sweep angle is considered. The measurements were performed by a pitot tube rake. Three models with various sweep angels at angles of attack -2, 0 and 2 degree were tested. Both tip and root of all wings were closed by flat plates in order to prevent the flow to roll-up. However the flow field on the wing was still three-dimensional because of the sweep angle. The velocity on the wing has two components; longitudinal and lateral. The cross flow emerges due to the non-equilibrium of pressure and centrifugal forces. The velocity profiles showed that the magnitude of cross flow was stronger near the leading edge of the wing. The cross flow... 

Alumina as an engineering ceramic has special characteristics such as hardness, high abrasive, fatigue and corrosion resistance but suffers from low toughness. One effective method in improving toughness is adding second phases such as tetragonal zirconia and carbon nanotubes.
In this research, alumina- zirconia nanopowders has been prepared by solution combustion method and carbon nanotubes was added to it by two different ways: 1) in situ synthesis of CNTs by CVD 2) dispersion of CNTs by heterocoagulation method. In the case of in situ synthesis of CNTs in AZ matrix, the synthesis temperature and flow ratio of N2/C2H2 gases was investigated and optimum conditions were 800̊C and 300/30,... 

A Flying Electric Generator (FEG) can be a wind turbine which operates at high altitudes, where there is a continuous fast flow of air and converts wind energy to electrical power.The related field is an interdisciplinary area and is mostly related to the Aerospace Engineering and Energy Conversion. We focused on Iran, as one of the few lands in the northern hemisphere that has a high overall amount of high altitude wind energy for at least half of the year over it, according to the information of atlas of airborne wind energy in this work.So to install the FEGs in Iran, we had to find, places with a safe aerial space overhead which grant us reliable spots over country. These places found by...