Sharif Digital Repository

An acinus is defined as the complex of airways supplied by one first order respiratory or transitional bronchiole. In this part, the replenishment of oxygen at the alveolar surface occurs by a combination of convective air flow with diffusion of oxygen in the air. So for studying gas exchange in the lung, modeling gas species transport and exchange in an acinus is important. Due to lacking direct measurements of the distribution of oxygen (or carbon dioxide) concentration in the acinus, several mathematical models have been developed and studied by numerical simulations. But in none of them the influence of breathing pattern and the role of blood flow in restricting the gas exchange rate have... 

Increasing in social communication via electronic ways has been made social network analysis of these communications more important each day. One of the most important aspects in social network analysis is community detection in such networks. There are many different ways to extract communities from social graph structure which in some of them the content of communication between actors has been noticed in community extraction algorithm. In this thesis after a short survey over advantages and disadvantages of existing methods for community detection, a new method for extracting communities from social networks has been suggested which in addition to streaming property of data it spot the... 

In line with developments in the technology of integrated circuits, transistors are implemented in silicon. Although the price is reduced; design is more complicated, which causes the efficiency and power consumption to face some difficulties in such design. The reason why modern GDI-based circuit is the focus of attention is that in designing a digital circuit, less power is required while more efficiency is obtained. Lowering the complexity of the logic circuit can bring about reduction of power consumption and propagation delay and decrease the circuit space. GDI-based integrated circuits resemble MOSFET transistors but have fewer transistors and higher performance capability. This study... 

Nowadays environmental issues are of great importance and one of the most paramount issues is the quality of water, because clean water is vital to our existence. Besides different methods for water purification, water quality testing is a useful and needful tool. Traditional methods for determination of water quality parameters are mainly expensive, time consuming and require highly trained staff. In this study, we have described a centrifugal microfluidic platform (Lab- on – a- CD) for simultaneous determination of different physical and chemical parameters including Nitrite, Free Chlorine and pH. All of the processes from sample injection to detection are integrated on this low-cost and... 

Studying the performance of flow meters is of great importance in order to improve their quality. In this study, we are looking for an optimal design for a turbine flow meter in which the measurement accuracy, pressure drop and response speed indices are improved. For this purpose, a turbine flow meter with a diameter of 2 inches has been selected and its performance has been numerically modeled using computational fluid dynamics in a steady and transient state. By modeling the steady state, the measurement accuracy and pressure drop indices are obtained, and by modeling the transient state, the response time of the flow meter is obtained. In order to increase the accuracy of numerical... 

Using cryptographic hardware device is inevitable these days. Hence, the secret information inside these devices should be safe and non-attackable. Simple and differential Power analysis (SPA, DPA), a form of side channel attack, allows attacker to study circuit information leakage by analyzing and monitoring power consumption of a cryptographic hardware device to extract inside information and discovering the secret keys. In this thesis, first, a sample cryptographic hardware device is designed and implemented as an under attack system. Then, another device is designed as an attacker in order to attack the mention sample hardware by analyzing and monitoring its power consumption. A digital... 

Microtubules are hollow cylindrical structures of 25 nanometer diameter inside cell membrane. Microtubule (MT) serves as a cell structure component and vesicular transport inside cell. It has been shown in recent researches that the persistence length in MTs is length dependent and increases about several times of counter length. Also helical structures of MTs have been found recently. In this research using Molecular Dynamic simulation of coarse-grained microtubular structures we compare persistence length of wild and helical microtubular structures. We show that the persistence length in helical structures is independent to the length.
 

Wireless sensor networks have many applications one of which in linear structure is used to control pipeline infrastructure. This thesis focuses on the routing of oil, gas, and water pipelines using wireless sensor networks. There are two algorithms one of which is Jump Always (JA) Algorithm and the other one is Redirect Always (RA) Algorithm. There are designed in Linear Structure of wireless sensor networks that are presented with a hierarchical addressing scheme. A Redirect Jump (RJ) routing protocol is our method that is designed for the hierarchical addressing scheme too. The RJ routing protocol has many benefits compared to the two methods (JA and RA). The RJ algorithm can increase the... 

Phenomena such as collective movements of birds and fish, collective and harmonious activities of ants, termites, bacteria, etc. have inspired engineers to create and develop the idea of swarm robotics. Robotic groups can be used for applications such as searching the environment, patrolling, cooperation in moving heavy objects and so on. One of the issues considered regarding swarm robotics is the formation of geometric shape by the multi robots system. Two main methods are employed for solving the problem of shape formation: the leader-follower method, and the artificial potential functions method.This thesis presents some control algorithms for shape formation in multi-robot systems on... 

One way to increase the efficiency and improve the performance of a gas turbine is to increase the inlet gas temperature. On the other hand, the inlet temperature has an allowable operating range, and increasing it beyond the tolerance of the alloys used in turbine blades causes structural defects and significantly reduces the blade life. Therefore, to increase the blade life, various cooling methods such as internal and layer cooling are used. Considering the blade geometry and cooling paths, accuracy in the manufacturing process is doubly important in the production of these blades. The importance of this issue is that if the cooling channels produced are inconsistent with the design... 

The standard model of Cosmology (SM), based on Einstein’s theory of general relativity (GR), is the best model in describing the cosmic-scale observations. In galactic scales, however, galactic dynamics show a discrepancy between the observed luminous mass and the predicted value from the theory. Two approaches are suggested to eliminate this inconsistency: assuming the existence of dark matter within the context of GR, or modifying the theory of gravity in galactic scales, like MOND or MOG. In this thesis, we study the spherical collapse and the formation of shell galaxies in MOG, in comparison with SM. We introduce the action and the field equations of MOG and the equation of motion of a... 

Medical images contain human body pictures and are widely used for diag-nosis and surgical purposes. Compression is needed for medical images for some applications such as profiling a patient's data or transmission systems. Due to the importance of the information of medical images, lossless or visually lossless compression is preferred. Lossless compression mainly consists of transformation and encoding steps. On the other hand, hardware implementation of lossless compression algorithm accelerates real time tasks such as online diagnosis and telemedicine. Lossless JPEG, JPEG-LS and lossless version of JPEG2000 are few well known methods for lossless compression. In this thesis, we introduce... 

Pitch or fundamental frequency is one of the components of speech production. Pitch detection is the process of determining the period of the vocal cords closure or in other words, the time duration of one glottal closing, opening and returning phase. There are different algorithms for pitch detection purposes, each of which has some advantages and disadvantages. Pitch detection algorithms can be classified into event pitch detection and non-event pitch detection. Dyadic wavelets transform is an example of event pitch detection. Modified higher order moment, which is based on the Autocorrelation function, is non-event pitch detection. Dyadic wavelets transform is a fast and simple pitch... 

Recently, many studies show that Augmented Reality (AR) and Automatic Speech Recognition (ASR) can help people with disabilities. In this thesis we examine the ability of combining AR and ASR technologies to implement a new system for helping deaf people. This system can instantly take a narrator's speech and convert it into a readable text and show it directly on AR display. Also, with this system, people do not need to learn sign-language to communicate with deaf people. To improve the accuracy of the system, we use Audio-Visual Speech Recognition (AVSR) as a backup for the ASR engine in noisy environments. AVSR is one of the advances in ASR technology that combines audio, video and facial... 

Structural Health Monitoring (SHM) means to give a diagnosis of the “state” of the subjects. Small leaks along the entire lengths of oil pipelines are detected and located by monitoring.Nowadays health monitoring of pipeline in water, gas, oil and chemical industry has been the focus of researchers. This is due to the fact that leak accidents may cause great economic problems to human resources as well as extreme environmental pollution. This project focuses on a visual and photographic observation system as leakage detection to monitor long range pipelines. In this system, several cameras with overlapping views are located along the entire lengths of pipelines. We are using digital cameras... 

Digital Signal Processing (DSP) is used in a wide range of applications such as high-definition TV, digital audio, multimedia, digital cameras, radar, sonar detectors, biomedical imaging, global positioning, digital radio, speech recognition and etc. These applications can be implemented by either DSP processors or FPGA technology. Digital Signal Processors are microprocessors specifically designed to handle Digital Signal Processing tasks. These devices have seen a tremendous growth in the last decade, finding use in everything from cellular telephones to advanced scientific instruments. On the other hand, the rise of FPGA in the signal processing realm could be assigned to hardware to... 

In real-time packet-based communication systems one major problem is misrouted or delayed packets which result in degraded perceived voice quality. If some speech packets are not available on time, the packet is known as lost packet. The easiest task of a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system in order to avoid quality reduction due to packet loss a suitable method and/or algorithm is needed to replace the missing segments of speech.There are several methods which have been proposed to reduce the effect of packet loss such as Waveform Substitution, High Order Autoregressive, Linear Prediction (LP),... 

This thesis describes a robust algorithm in speech recognition system based on phoneme recognition. Automatic speech recognition systems (ASR) can be divided into two main types: speaker-dependent continuous speech PC-based systems and speaker-independent continuous-speech server based systems. In speaker- independent systems, there is no need to have knowledge about the speaker(s) before using the system, on the other hand, in speaker dependent systems it is essential to have voice training by the speaker(s) supposed to work with the system. In this thesis, a speaker-independent continuous speech PC-based system has been chosen to work with. Acoustic-phonetic approach has been chosen among... 

Strongly Rayleigh measures are an important class of negatively dependent (repulsive) probability measures. These measures are defined via a geometric condition, called “real stability”, on their generating polynomials, and have interesting probabilistic properties. On one important property of negatively dependent measures is their rigid dependence structure. In other words, the it is impossible for these measures to have strong overall dependencies. In this thesis, we study two manifestations if this phenomenon: (1) paving property and (2) tail triviality. Informally, the paving property states that it is possible to partition the set of the components of every strongly Rayleigh random... 

Reliable communication has become very crucial in the transmission applications. Hence, to design hardware to handle reliability is the most important part of communication. In this work, we propose a new secured ALU (Arithmetic and Logic Unit) against fault attacks that is used in ARM processor which can correct any 5-bit error in any position of 32-bit input registers of ALU. We also designed a BCH (Bose, Chaudhuri, and Hocquenghem) codec (encoder, decoder) using the prototyping FPGA. Further, in this thesis we designed (63, 36) the BCH encoding and decoding system to tolerate the 5-bit faults. The codec system and ALU system are based on using Verilog description language. Since...