Sharif Digital Repository

This paper develops a novel insight and procedure that includes a variety of algorithms for finding the best solution in a structured multi-agent system with internal communications and a global purpose. In other words, it finds the optimal communication structure among agents and the optimal policy in this structure. First, a unique reinforcement learning algorithm is proposed to find the optimal policy of each agent in a fixed structure with non-linear function approximation like artificial neural networks (ANN) and eligibility traces. Secondly, a mechanism is presented to perform self-organization based on the information of the learned policy. Finally, an algorithm that can discover an... 

This research is trying to investigate the control algorithms of unknown control direction systems. Since Nussbaum function is the most common method which in used for these systems this research focus on this algorithm to overcome control the effect of unknown control direction. This research study the performance of different control algorithms in controlling such systems followed by analysis of two control modes of continuous and discrete using Nussbam Function. Additionally, in continuous mode, the performance of two methods of backstepping and liding mode has been compared on the given system in variety of situation. Results demonstrate that backstepping method shows better performance... 

Adaptive vibration control of a structure under different condition of exciting forces or structural response is the main scope of this research.Using a combination of the pole placement and online Empirical Mode Decomposition (EMD) methods, a new algorithm is proposed for adaptive active control of structural vibration. For this purpose, by structural response which is evaluated from Hilbert-Huang Transform (HHT) and using prior knowledge for corresponding conditions, proper and optimum control forces are applied to structure. Hence, error sources of EMD method in the HHT such as end effects error, mode mixing problem and decomposition resolution are being studied. A modified method based... 

Diesel particulate filters (DPFs) are used in active and passive regeneration exhaust systems in order to reduce the soot emission of diesel engines. Soot regeneration process initiates at a certain minimum temperature. In Compression Ignition (CI) engines, the intake is not throttled usually, and load control is carried out by adjusting the amount of fuel injected into the cylinders. Consequently in low load working condition, as the fuel mass decreases, the air to fuel ratio increases that results in lowered exhaust gas temperature. On the other hand, passive regeneration strategies alone are not enough and it should be backed up by an active regeneration system in order to guarantee... 

In today's world, mobile robots have many applications in defense, transportation and industry. A robot may not be able to handle a mission alone or there may be different roles to perform a mission that a robot alone cannot perform, so the need to work with team robots is felt to the Necessary that by development Robot Technology and Advances in Communication, Microelectronics, Computing Technology, and Multi - Factor Expansion, robotic systems are widely used in theoretical research due to their flexibility, robustness, and scalability. In this research, robots are controlled in a coordinated manner as a team. In this research, algorithms were developed so that in a two and... 

In this project, we have assessed the electrochemical treatment method. In this method, pH decrease of the place where a tumor is located engenders the necrosis of cancer cells and consequently they are destroyed. The process of pH decrease is caused by exerting voltage on electrods that are located near the tumor. The aims of optimizing this methods are to minimize the pH that results in the increase of cancer cell annihilation and to minimize the HClO and Cl2 products which are toxic and chage the healthy tissues to cancer cells. In this project, the model of electrochemical treatment method is explained, and then this model is simulated using the parametes which are provided in the... 

Chemotherapy is a proven and effective systematic approach to treat various types of cancers. Despite its advantages, chemotherapy would kill healthy as well as cancer cells. To overcome this problem, different controlling strategies are implemented. This study aims to provide a medicine drug delivery schedule for chemotherapy (by designing a proper controlling system) based on the verifiable mathematical models. First, the dynamic model is analysed and stability points are reviewed. The selected model has five state variables and two inputs. In this study, the focus is on dynamic model analysis and obtaining an effective and appropriate treatment pattern by designing a proper controller. To... 

In this study, the thermal buckling behavior of thin metal liner reinforced by composite shell in present of the initial imperfection is investigated. For this purpose, the Ryzener – Myndlyn shear-deformation theory & the virtual work method are used to extract equilibrium equations. In this work, the conical shell with c-c, s-s, c-f boundary conditions has been studied. The outer layer of reinforced composite is exposed to constant ambient temperature and iner layer is exposed to heat. Metal liner and reinforced composite shell are merged with together. In other words, the degrees of freedom at each node for both shells are assumed to be equal. Solution method is finite element method using... 

In opportunistic networks, the nodes have ad-hoc communications that are formed directly between them, without any infrastructure, and not by any using any other intermediate node. In case that the destination node is not in the same region as the source during the sending of a message, the source will send the message to one or a few of its neighbors so that they can store and carry out the message to the original destination in cooperation known as Store-Carry-Forward Mechanism. Remarkably, in most cases, the devices involving in this type of network, e.g., smartphones, have limited source of energy or they use a battery, there is a need to minimize the energy consumption in the nodes.... 

One of the methods to enhance the economic performance and safety factor of nuclear power plants is to determine a suitable fuel loading strategy in a reactor core. Different methods have been already elaborated to choose the proper fuel loading pattern. Selection of the best pattern for fuel loading ensures the best use of fissile material and more safety during reactor operation. Perturbation theory method is one the methods which could be used to solve this kind of problems. The effect of non-uniform perturbations on the reactor operation can be evaluated by multigroup calculations and using proper space dependent group constants. In this study, a C# based program is developed to find the... 

The objective of this research is to investigate the use of passive control system to reduce the seismic response of fixed-roof, above-ground, cylindrical steel tanks as well as to decrease the damage caused to these structures in the event of an earthquake. The most crucial step for a safe design in this case is determining the lateral forces due to earthquake with sufficient accuracy; These forces are eventually resisted by the storage tank walls and the supports. Determining analiytical solution to the problem is not possible due to the interaction of the liquid with the structure. Therefore, numerical approach was adopted to determine the response of the tank using ANSYS program. Two... 

The alloy steel plant was exploited in1999; and the maintenance department starts its function and its activities according to the written PM software by Austria’s BOHLER Company. The PM program was written for the entire factory. Having worked with the PM for eight years, now it is possible to evaluate its performance. There are two main problems in the maintenance system; firstly, the existing PM System is incomplete, some important feature of the PM program is incomplete. Secondly there are lacks of a good auditing system to evaluate the PM orders. To evaluate the weakness of the current PM system and to study application of TPM, a section of the factory was... 

Modified Fish-Bone (MFB) Model and Consistent Generic (CG) Model are simplified Multi-Degrees-of-Freedom (MDOF) models, proven to be valuable tools in estimating seismic demands of moment-resisting frames, aimed to reduce the computational costs by decreasing the number of degrees of freedom. The preliminary expansion of these simplified models for steel moment resisting frames (SMRFs) were proposed by considering elastoplastic behavior and is not able to take into account stiffness and strength deteriorations in nonlinear dynamic behavior of structures. However, behavior deterioration affects seismic demands of SMRFs under intense earthquakes. For this reason, the present study is done to... 

The preliminary design of building structures is normally based on the equivalent lateral forces provided in seismic design guidelines. The height-wise distribution of these loads is predominantly based on elastic vibration modes. However, as structures exceed their elastic limits in severe earthquakes, these design load patterns may not necessarily lead to efficient distribution of strength within the structures. To address this issue, several alternative load patterns have been proposed for the seismic design of non-linear structures. However, due to the simplifications involved in the development of these design load patterns, their adequacy needs to be assessed for different structural... 

Developing a simple, cost effective and accurate detection method for L-lysine (Lys), L-leucine (Leu) and glycine (Gly) as the important analytes in clinical diagnostics, biological processes and food industries is of great interest. Therefore, in the first part of this research, cellulose nanofibrils (CNFs) were coated on a quartz crystal microbalance (QCM) surface by spin coating to achieve a QCM biodetector for Gly. Thus, the two-layer CNFs coating was selected as sensing film and was applied for following experiments. In the next step, the coated QCMs were carefully characterized before and after interaction with Gly using water contact angle (WCA), Fourier transform infrared... 

Developing a simple, cost effective and accurate detection method for L-lysine (Lys), L-leucine (Leu) and glycine (Gly) as the important analytes in clinical diagnostics, biological processes and food industries is of great interest. Therefore, in the first part of this research, cellulose nanofibrils (CNFs) were coated on a quartz crystal microbalance (QCM) surface by spin coating to achieve a QCM biodetector for Gly. Thus, the two-layer CNFs coating was selected as sensing film and was applied for following experiments. In the next step, the coated QCMs were carefully characterized before and after interaction with Gly using water contact angle (WCA), Fourier transform infrared... 

Subgraph isomorphism problem is an NP-complete problem, which has diverse applications in different fields such as network problems, image processing, text processing, topography, and bioinformatics. Therefore, many researchers from both theoretical and practical viewpoints have considered it. In this research, we try to offer a proper and efficient method to solve this problem by using constraint programming, which is a powerful and efficient method to model and solve complicated combinatorial optimization problems, and criticality and cruciality concepts from a resource planning scope.
In this regard, first one of the most efficient models among existing constraint programming models... 

This dissertation proposes a probabilistic framework for optimal calibration of design provisions based on the minimization of lifecycle cost (LCC) and its uncertainty. Subsequently, this framework is utilized to determine the optimal robust design base shear coefficient of building structures, and propose a methodology for codifying it while preserving the current structure of the base shear equation. In the first part of the proposed methodology, various structures are designed with different seismic base shears. Then, at each site, their LCC comprising the construction costs and seismic losses is calculated. Various types of seismic loss considered in this study include the direct... 

Dust phenomenon is a combination of tiny particle with urban pollution that it is harmful for respiratory disease. But this phenomenon has been prevalent in our country recently. We utilized NASA satellite pictures to observe dust storms in the present project. We have collected images of possible sources of dust on the days when we are faced with the dust storm phenomenon. Then by processing of NASA satellite pictures (recognition of distribution of optical and particle density in the dust particle arising and comparing results through analysis of these images to estimate the main characteristics of the sampling locations). we have find the desired location for taking samples of soil... 

In the last decade, mechanical metamaterials have attracted more attention due to new design principles that combine the concept of hierarchical architecture with material size effects at the micro or nano scale. This strategy shows extraordinary mechanical performance that we use in unknown parts of the material property space, including strength-to-density ratios, extraordinary flexibility, and the ability to absorb energy with brittle components. The aim of this research was to print metamaterial scaffolds from a combination of biocompatible and bioactive to be used as scaffolds in bone tissue engineering. In addition to the biological properties appropriate to the host tissue, the...