Sharif Digital Repository

Millions of people are exposed to vehicle noise at their work or residence environment daily and as a result their physical and mental healths get in danger. Subsequently the vehicle noise and vibration become an important factor in vehicle quality. Gearbox is a main element in vehicle powertrain and also an important source of noise and vibration. So inspection of vibration and noise in Gearbox and attempting to reduce it will help to reduce vehicle noise and vibration. This project is based on a deal between sharif university of technology and industry in which the target was to make improvement in every source of noise and vibration in a specific vehicle. The aim of this project is to... 

In the first part of this thesis, the linear and nonlinear governing differential equations of motion of an inclined Euler-Bernoulli beam are used by tacking into account the effect of beam’s mid-plane stretching. Then nonlinear coupled governing partial differential equations of vibrations by including rotation of cross section, longitudinal and transverse displacements in the Timoshenko beam theory on Pasternak foundation under the act of moving concentrated force and as wll as moving mass are drived. To do this the energy method (Hamilton’s principle) based on the large deflection theory in conjuncture with the von-Karman relations is used. These equations are solved by applying... 

Nervous system plays an intricate biological process of man body.Damage of nervous system has serious consequences and is hard to recover, as well as the other parts of the body may not work properly. Many strategies have been used to repair spinal cord injuries in which the main objective is to improve the regeneration of axons and functional recovery. The purpose of this research is introducing neural tissue engineering concepts (e.g. scaffolds, stimulation and etc.) and also design and fabrication suitable for neural tissue engineering. For this purpose the combination of biodegradable polymers (chitosan),conductive polymer (poly-aniline) and carbon nanosheets (graphene) was chosen as the... 

One of usual criterion which detrimines how much two polynomials are close to each other is smallness of the norm of vector that is formed from subtraction of their corresponding coefficients. Using this criterion, in this dissertation we become involved in investigation of two similar problems. First one is determination of the closest non-Hurwitz polynomial to a Hurwitz one. During this activity, the robustness margin of Hurwitz polynomial whose coefficients are subject to uncertainty is determined. The second problem is determination of the closest Hurwitz polynomial to another polynomial which is not Hurwitz. Unlike to the first problem, this problem is extremely hard. The solution of... 

Semi-automated Continuous Speech system deals with collecting corpus speech. It has very different problems in various natural languages because of different types of speech, and collecting speech corpus containing continuous word is very time-and- cost consuming. To overcome this problem, human-based computing techniques are proposed to collect speech corpus. In this thesis, we describe influencing factors in collecting steps of continuous speech and provide a description of human-based techniques to solve problems specially collecting of continuous speech. To collect speech corpus using human-based techniques, a game has been used so that speech corpus of web users are collected during the... 

Simulation optimization has been one of the most important topics in recent years. It is especially useful when the objective function cannot be computed directly or some of the parameters are stochastic. Buffer allocation problem is one of the important problems related to production lines. In this problem the objective is to determine the buffers between workstations so that the throughput is maximized. Non-linear and combinatorial nature of the problem, stochastic factors like machine breakdown or processing times and most importantly lack of a distinct relation for the objective function are the reasons of using simulation ... 

Recent researches show inefficient use of frequency spectrum such that there is shortage of frequency in operation. In order to overcome this problem cognitive radio are introduced that opportunist usage of frequency band is their prominent characteristic. Problems and challenges caused by using these networks are wide and increasing. In this thesis we focus on improving resource management algorithms in cognitive radio. In this study in order to have a dynamic and efficient management in choosing reliable and quality channels, reinforcement learning algorithms are used based upon existing data and experiences. Since this tool has the learning capability and analysis in dynamic situation of... 

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... 

An injector is one of the most important components of the two components chemical propulsion system used in satellite control. The design of an injector is a complicated and time-consuming process and is largely dependent on laboratory data. In this study, the spray characteristics obtained from a small scale swirl injector under different operating conditions have been experimentally measured in a laboratory environment, such as the injector discharge coefficient, spray cone angle, and the distribution of droplets in the field. To calculate the discharge coefficient, the flow rate of the injector has been measured for different operating pressures. The shooting method and image processing... 

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...