Sharif Digital Repository

Our surrounding environment is full of particles with different sizes. These suspended particles enter our body through respiration process, which of course has some negative effects. Therefore, it is very important to comprehend the mechanisms and the effective parameters on these particles motion and their deposition inside the human airway. This work numerically investigates the effects of particles mass and breathing frequency on the deposition of particles in human respiratory system. To this end, a realistic 3-D model of human respiratory system geometry, including nostrils, vestibule, nasal cavity, human sinuses, nasopharynx, oropharynx, larynx, trachea, and main bronchus has been... 

Causation is one of the most old and difficult problems of Metaphysics which is also important in Science and Philosophy of Science. There are three different views in the Ontology of Causation—Eliminativism, Fundamentalism and Reductionism. Also we know that the Ontology of Causation can be equated with the question of the difference between Causal and Non-Causal series of events, such that the answers to this question are correspondent to the mentioned views: 1)Eliminativism: There is not any difference between those two series and the concept of Causation does not have any objective or external being. 2)Primitivism: There is a difference between them but it can not be explained in any... 

In this thesis, an enhanced local mean-field (MF) model that is suitable for simulating the electroencephalogram (EEG) in different depths of anesthesia is presented. The main building elements of the model (e.g. excitatory and inhibitory populations) are taken from two pioneer MF models designed by Steyn-Ross et al and Bojak & Liley, and then a new slow ionic mechanism is included in the main model. Generally, in mean-field models, some sigmoid-shape functions determine firing rates of neural populations according to their mean membrane potentials. In the enhanced model, the sigmoid function corresponding to excitatory population is redefined to be also a function of the slow ionic... 

Electron states of diamond vacancy under stress were studied theoretically. The generalized Hubbard model is used to calculate the electrons energy levels. The results shows that the degeneracy of some levels (T, with triple space degeneracy) reduced to levels with lower degeneracy (E, with double space degeneracy and A, without degeneracy). Besides this spiting of degeneracy the energy of all states changed and therefore the transition energy between these states changed too. Jahn-Teller effect was observed  

The axisymmetric contact problem of a rigid inclusion embedded in the piezoelectric biomaterial frictionless interface subjected to simultaneous far-field compression and electric displacement is addressed. With the aid of a robust technique, the coupled governing integral equations of this mixed boundary-value problem are reduced to decoupled Fredholm integral equations with a constraint equation. A useful limiting case for the contact problem of transversely isotropic bimaterials is addressed. The present solution is analytically in agreement with the existing solution for an isotropic bimaterial. Selected numerical results of interest to engineering applications including the radius of... 

Wireless sensor networks (WSNs) use many tiny sensors to monitor phenomena such as temperature, humidity, brightness and traffic, and then transmit this information to a base station using wireless channels. WSNs find applications in military, ecological, urban and health related areas. Hierarchical wireless sensor networks are kind of sensor networks that use communication entities with different capabilities in terms of energy, processing power, bandwidth, communication range and etc. In this thesis, an introduction to WSNs and their applications, characteristics and designing factors is expressed. It continues on studying the infrastructures and the role of cryptography in enhancing... 

Under Linear Elastic Fracture Mechanics (LEFM) assumptions, the stress at the crack tip is theoretically infinite. Clearly all materials have a finite strength, thus there will always be a plastified zone around the crack tip. If the size of plastic zone is not small compared to the crack size, then linear elastic assumptions are not applicable and a nonlinear model must be used. This damaged zone is referred to as a plastic zone for metals, and a fracture process zone for cementitious materials and ceramics. In this regard a discrete extrinsic cohesive crack model with bilinear traction separation constitutive law, i.e. softening function, is employed and crack propagation is investigated.... 

Most of local thinkers ,who were influenced by Western philosophers of science, and have spoken about religious knowledge, have selected experimental science as standard science and Have tried to find a way trough cultural and other non-scientific channels of science to influence the field of human knowledge by religious teaching's .This expert's are generally opposed to positivist’s models of science, but because of the nature of the Western atmosphere that they breathe, consider the experimental science as the main model of knowledge and the experience as the main method of Acquisition of knowledge. Paya is also one of this thinkers who is influenced by Karl Popper's ideas about the... 

In this thesis, first, random lasing in a three dimensional disordered medium has been simulated using FDTD method and some properties of random lasers which were observed by others in the previous experiments have theoretically been shown. Our simulation results show that when the density of particles increases to an upper limit, the intensity of lasing modes is enhanced. Also, the effects of pumping rate and particle size on the number of lasing modes and their intensity are studied. Lasing threshold of laser modes in different disordered systems is calculated and it is shown that by an appropriate selection of the central frequency of gain line-shape, the output power intensity of random... 

By changing the approaches towards the waste management, it is possible to affect the resource depletion. This research is focused on economic and environmental impacts of waste production and treatment. In this research, the municipal solid waste management system have been evaluated by an integrated approach considering the Life cycle assessment and Emergy assessment methods. The integrated method have been used to evaluate the waste management system more fundamentally and analyze some upstream indicators which are related to natural resource scarcity. At first, some scenarios have been developed based on Life cycle assessment containing possible configurations of technologies. Then, an... 

Depletion of fossil energy reserves and rapid growth of energy demand have been challenging issues in the energy sector. Proper solution of these issues requires development of an integrated and comprehensive approaches. Such conceptual framework could provide an appropriate means for studying energy problems and anlysing the development of efficient technologies which could improve the economic viability and reduce the impact of energy system on the environmental. Therefore, analytical tools need to be developed further and they could be applied for systematic analysis of impact of new energy technologies on the economical efficiency and environmental compatibility of energy... 

Tehran is one of the most polluted megacities in the world, and based on different studies, vehicular sources are responsible for most of the criteria pollutant emissions in this city. The number of vehicles on the streets has been increased drastically leading to growing amount of emission and this trend is continuing. In order to reduce the amount of vehicular emission, it is vital to investigate the factors affecting vehicles emission in this city. This could help to find efficient solutions to improve the situation. Hence, a low-cost methodology to estimate the vehicular emissions is developed. In this... 

In recent years, great attention has been devoted to the design of artificial arms. The most crucial problem in such a design is the trajectory of movement. In this paper, a seven degree of freedom arm is modeled and simulated. Also, the optimization method named “Imperialistic Competitive Algorithm” has been modified and better performance of the new version is presented. Energy optimization is performed based on trajectory of the arm with angular velocity, angular acceleration and joint angles using modified imperialistic competitive algorithm (ICA). Considering ICA as a fast optimization algorithm, it would be reasonable to use this algorithm for robotic purposes for online answering. The... 

Homo-polymer of Polypropylene is a commodity thermoplastic with good physical and mechanical properties along with fair recyclability and cost. However, its application is limited in some cases, especially in automotive industry, due to a lack of toughness. One of the approaches for PP toughening is the copolymerization of PP with some ethylene co-monomers. However, existence of elastomers in this kind of polymers causes a decrease in tensile properties. Besides, glass fibers improve tensile properties of homo-and co-PP and decrease toughness of co-polymers but result in an increase for homo-polymers. A rise in expenditure of energy due to increasing the processing temperature and... 

Nowadays, Machine learning algorithms are used to perform different tasks. Due to the high computational complexity of machine learning methods especially deep learning methods, running these methods efficiently on resource-constrained applications such as the Internet of Things (IoT) is challenging. To address the mentioned limitation, many devices send the raw data to the edge or cloud for classification due to limited computational power. This brings security and privacy issues and increases computational latency and network traffic. Hardware accelerators can be used to overcome this challenge by improving the computational power of the end nodes. Power and energy consumption with... 

Real-time asynchronous data fusion for high-speed phenomena is an important and challenging task in the sensor networks. Examples of data fusion applications in sensor networks are: managing the traffic of maneuvering airplanes and ground vehicles in airside areas of an airport, traffic management in streets and roads, Driver Assistance Systems, guidance of antiaircraft and antimissile missiles. In all the data fusion applications the estimation of the required variables is necessary.
In this research two methods are introduced for real-time asynchronous data fusion, especially for track-to-track fusion of high-speed phenomena in sensor networks. The effectiveness and usability of these... 

Sparse signal representations and its applications has been a hot topic of research in recent years. It has been demonstrated that sparsity prior can be effectively used as a regularization term to solve many of the inverse problems. One of these problems in which sparse representations have been used is image super-resolution (SR). SR is the problem of finding a high resolution (HR) image from one or several low resolution (LR) images. In this dissertation, we have focused on the problem of finding a HR image from only one LR image which is known as example-based SR. There are two kinds of methods for example-based SR: the methods which use neighborhood embedding and the methods which use... 

In this study, Aluminium based nanocomposite with Al3Ti and Al2O3 nanoparticles have been elaborated by mechanical alloying. For this purpose, Al and TiO2 powders have been blended with weight ratios of 10, 20 and 30 percents and were milled using a planetary mill. Morphological variations in different timing periods of mechanical milling process was investigated by Scaning Electron Microscopy (SEM) and The optimal times for alloying were determined for each combination. The pure Aluminium and the powder with 10, 20 and 30%wt reinforcement had coax morphology after respectively for 44, 30, 24 and 14 hours. after studing phase transformations by XRD analysis, the final powders were cold... 

The present paper proposes a micromechanical damage model for two and three dimensional Representative Volume Element (RVE) with randomly distributed cohesive rough slit-like and penny-shaped micro cracks (Barenblatt-Dugdale type). First, the influence of crack roughness on the crack opening under macro hydrostatic stress state is studied and then the energy release contribution to material damage process is estimated. Considering the fractality of the crack trajectories yields to lower values of the volume crack opening. This will result in lower energy release rate in RVE and higher levels of material resistance. Based on the energy release rate of RVE, the effective material properties... 

Many Investigations have been carried out on high work hardening, strengthening and secondary hardening of MP35N superalloy. In this study, behavior of MP35N under uniaxial hot compression at 600 °C with true strain of 0.05, 0.10, 0.16 and 0.22 was investigated. After calculating on stress- true strain curve, work hardening rate versus strain come out. Serrated flow has been seen in all mentioned strains. In TEM investigation on these samples, dislocations array with extended faults and micro twinning have been seen. According to Suzuki mechanism with solute partitioning and diffusion of solute, stacking fault extended. Uninterrupted separations and combinations of partial dislocations lead...