Sharif Digital Repository

Tinnitus is understood to be a repeating sound, often in the form of a ringing in one or both ears, in the absence of any external stimulus. There is no definite scientific justification for this condition, but this complication usually occurs due to hearing loss or after aging or acute trauma. A recent community-based epidemiological study found that 17.5% of 60-year-olds and older were suffering from Tinnitus. Despite the significant outbreak and the great impact of this impairment on the quality of life of people with this condition, no definitive treatment has been provided so far. Therefore, further research in this field is of great importance. One of the tools used to carry out these... 

According to clinical surveys, it is estimated that chronic tinnitus is experienced by 10 to 15% of the adult population. Tinnitus is defined as the conscious and involuntary perception of noise or ringing without involvement of either mechanical or external audio source. In recent years, a limited number of studies have investigated the effects of applying transcranial magnetic stimulation (TMS) to ameliorate this condition. TMS is a noninvasive intervention in which magnetic pulses are applied by a coil adjacent to the individual's head. In this study, electroencephalogram (EEG) signals are recorded concurrent and as a follow-up to TMS. This makes it possible to study changes caused by... 

Gravitational lensing affects not only the position and number of images of cosmic objects but also their shapes. In the so-called weak gravitational lensing effects related to shape of the cosmic objects are studied. These require high quality images and wide field of view. Because of technology development and production of multi-chip CCD cameras in recent decades, we are witnessing an increase in the number of projects using weak lensing techniques. Taking instrumental errors into account, the first step in weak lensing studies should be the proper data reduction to produce final images in which instrumental errors are removed and have sufficient precision to be processed. In This thesis... 

The reconstruction conjecture is an open and interesting problem that attracts some reserchers. Although some work toward this problem has been done; but no one have been able to solve it comlpetely. In this thesis, some new theorms are developed which extend the domain of reconstructible graphs. Also, a generalization of graph spectrum -called Alpha Spectrum- is introduced that is very effective in recognization of graphs  

In 1953, Landau expressed the conditions for the existence of tournaments with a prescribed score vector R. Eleven years later, Ryser proposed an algorithm for constructing the tournament matrix with score vector R and showed that any two tournaments with the same score vector can be obtained from one another by a sequence of 3-cycle switches. Last year (2014) Brualdi and Fristcher explained in an article, similar to this process, the existence of, algorithm and switches for loopy tournament and Hankel tournament and similar structure skew-Hankel tournament. This paper is discussed in a chapter of this thesis. In 1991, De Caen found a lower bound for the real rank of a tournament matrix.... 

Partial Differential Equations (PDEs) play a crucial role in modeling various physical, biological, and engineering phenomena. One of the most important and complex of these equations is the Monge-Ampère equation, which appears in various fields including differential geometry and optimization theory. In this thesis, after defining and examining the preliminary properties of the Monge-Ampère measure and defining the Alexandrov weak solution, the existence and uniqueness of this weak solution for the Dirichlet problem are addressed, and finally, the regularity problem is studied  

Nowadays, because of drastically decrease of copper sulfide ore’s grade, and difficulties in leaching of them, new processes of copper production like bioleaching technique become significant. Finding the optimal conditions for bioleaching, require investing a lot of time and cost. Computer simulation is useful in this case. Temperature, affects the kinetics of dissolution reactions, type and growth rate of bacteria, and finally, rate and amount of recovery of valuable copper metal from ores, so determination of temperature within the bioheap is very important. Thermophiles are better than mesophiles in chalcopyrite bioleaching and in the range of 55 to 65 degree centigrade, thermophiles... 

The so-called intersection problem has been considered for many different combinatorial structures, including Latin squares. This intersection problem basically takes a pair of structures, with the same parameters and based on the same underlying set, and determines the possible number of common sub-objects (such as blocks, entries, etc.) which they may have. The intersection problem has also been extended from consideration of pairs of combinatorial structures to sets of three, or even sets of , where may be larger than 3. In this thesis, we study the related problem of determining, for all orders n, the set of integers k for which there exists = 4 Latin squares of order n having... 

In 1989 DiPerna and Lions proved the stability of Boltzmann’s evolution equation using their theory of renormalized solutions. Their result , for the first time, proved the existence of solutions without extra assumptions on the initial condition and on arbitrary time intervals. While the wellknown Grad’s cut-off assumption is present in the original theory, there have been successful generalizations to account for the singular case. Also the renormalization theory has shed light on limiting regimes of the Boltzmann equation. Here we discuss the new techniques that are essential for such generalizations  

This thesis examines the accessibility gap between different modes of transportation in Tehran Province, with a particular focus on public transportation and cycling. The main objective of this research is to calculate and analyze accessibility indicators to various land uses (such as commercial, service, and recreational) around metro stations using two modes of travel: cycling and bus-walking. The study utilizes simulations in Python and geographic libraries to compare these two modes of travel based on four key accessibility indicators: 1) nearest Opportunity, 2) cumulative opportunity, 3) average distance, and 4) gravity-based accessibility to measure the accessibility gap between the... 

In recent years health monitoring and prognostics of complex systems have been considered more than ever.. In the present researh, data - based approach has been selected among various prognostics and health monitoring approaches. One of the most challenging issues in data-based methods is how to map system sensor information to its health status. In this research, different methods of mapping are discussed. The results show that sensor fusion by principal component analysis (PCA) offers acceptable performance. This pattern produces a single-dimensional signal for health monitoring with high reliability.The second challenge is to predict the status and design of the prognostics module. For...