Sharif Digital Repository

Despite advancements in Building Information Modeling (BIM) in the construction industry, issues such as the intangibility of building models and a lack of interaction and opinion-sharing still exist. The integration of Virtual Reality with BIM has rectified these problems. Quantity surveying, material estimation, solving design problems during modeling and preparing a building model containing information are some of the advantages of using BIM in this research. Alongside BIM, VR tools were employed as a mean to increase interaction with the user, boost marketing and pre-sales, create alternative options for building components, and estimate cost and time. Following the development of a... 

Members of Centaurea species are common traditional medicines throughout the world. For this reason medicinal plants are the targets of intense Phytochemical studies. In this research we have investigated Centautea Golestanica which are members of this genus and endemic of Iran. In this research, One Flavonoid, two Sesquiterpenelactones and two triterpenoides were elucidated by advanced spectroscopic techniques such as IR, MS, 1H NMR, 13C NMR and 2D NMR. In continuation of this research, we have reported new and efficient methods for the synthesis of hitherto unknown indole-annulated pentacyclic indolylhydroisoquino lines and naphthooxazocines via tandem dinucleophilic addition of... 

We propose a range-free localization framework in which a network of randomly deployed acoustic sensors can passively use natural acoustic phenomena within its environment to localize itself. We introduce a novel approach for registration of sensors observations which takes advantage of a clustering technique on triplets of associated observations. A Bayesian filtering method is employed to incrementally improve system state estimation as more observations become available. To the best of our knowledge this is the first work done on range-free passive acoustic localization. Furthermore, we have proposed a simple but effective and efficient acoustic detection method which can be used to... 

In this research the effects of cooling slope angle and the temperature of molten steel on globular structure after holding the samples at semisolid state have been investigated. The globular structure of high speed steel in the form of rolled - annealed and as cast condition, has been investigated in the semisolid state. The results showed that the grain sizes of cooling slope samples were lower than the rolled- annealed samples after holding at semisolid temperature. On the other hand, rolled-annealed solid grains had better roundness compared with cooling slope samples. Dissolution of carbides in the austenite phase at grain boundary leads to formation of globular particles in the... 

Nowadays, video search and retrieval is interesting for computer users and it has chief usages for multimedia systems. Video generation rate has increased and Internet as a communication framework is case of its transferring on the world. Because of these, importance of video files is more than past. Searching for finding content will be faster if video files would have indexed with a comprehensive system. The biggest step in this way is power of index generation that would be same or similar to human mind, for improvement of the clustering’s result or classification’s result. For generating suitable indexes, it is necessary to extracting effective features from videos and synthesizing these... 

This research relates to an improved method for making surfactant esters, especially sorbitan monostearate and tristearate. Sorbitan esters of fatty acid, stearate are derived from a reaction between sorbitan and fatty acid. Sorbitan fatty acid ester called sorbitan ester, are surfactants highly safe to use on human body and are widely used as a food additive in the production process as emulsifiers. Sorbitan esters are well known emulsifiers suitable for use in food, pharmaceutical products as well as many other applications. Despite its simple name, sorbitan ester is complex mixture of molecules. One such technique involves direct esterification of sorbitol or an intramolecular condensate... 

This thesis describes different neural networks models and an approximation based neural network controller for autonomous underwater vehicles (AUVs). The online multilayer perceptron neural networks (OMLPNN) have been designed to perform modeling of AUVs of which the dynamics are highly nonlinear and time varying. The online recurrent multilayer perceptron neural networks (ORMLPNN) have been additionally designed to generate a memory to pervious states and increase the performance of the modeling. The designed OMLPNN and ORMLPNN with the use of backpropagation learning algorithm have advantages and robustness to model the highly nonlinear functions. The proposed neural networks architecture... 

The Machinable Austempered Ductile Iron (MADI), a new group of Austempered Ductile Iron (ADI), has been developed to remove the problems (hardness and cost) of ADI cast iron. MADI is a special kind of ductile iron which has proper machinabilty properties. This kind of ductile iron can be produced using a specific chemical composition and defined heat treatment process. By providing these conditions, the hardness of the cast iron will be in the range of as-cast cast iron. On the other hand, because of the especial production process, the cost of the final shape casting will be lower than ADI cast iron. In the present work, firstly the effect of heat treatment parameters, including the time... 

When the reservoir energy is too low for the well to flow, or the production rate desired is greater than the reservoir energy can deliver, it becomes necessary to put the well on some form of artificial lift to provide the energy to bring the fluid to the surface. Continuous flow gas lift is one of the most common artificial lift methods widely used in the oil industry. In continuous gas lift, gas at high-pressure is injected in a suitable depth into the tubing, to gasify the oil column, and thus facilitate the production. Every well has an optimal gas lift operating point at which it will produce the most fluid. Ideally, if there is no restriction in the total amount of gas available,... 

The use of distributed generation (DG) units provides several advantages for the utility distribution grid. Mostly power electronics converter is used as an interface to connect a DG unit to a utility grid. A DG unit normally operates in a grid-connected mode. In this mode, the host grid dominantly dictates the voltage amplitude and frequency of the local load at the point of common coupling (PCC) and the DG unit controls its real/reactive power components. Separation of the DG unit and its dedicated load from the host grid is called islanding. Subsequent to the formation of an island, due to the lack of control over the voltage magnitude and frequency, the islanded DG system becomes... 

Atom transfer radical polymerization (ATRP) is a convenient approach to synthesis of polymer with narrow molecular weight distribution. ATRP of acrylamide (AAm) is taken into consideration because of the intrinsic properties of acrylamide such as water solubility and biocompatibility. As reported in many recent works, polymerization of acrylamide by this method didn’t provide monomodal molecular weight distributions. In best condition with strong ligands such as Me4Cyclam, polymerization was carried out in a short time with high yield but polymerization was not highly controlled. It was shown that polymerization of acrylamide under typical ATRP condition displayed a much lower ATRP... 

Liquid storage tanks are important components of lifeline and industrial facilities. Since,many tanks have borne serious damages during past earthquakes, Forcasting seismic behavior of tanks have attracted for numerous researchers who investigated seismic behavior of liquid storage tanks. This Thesis investigates the effects of slab foundation flexibility on seismic behavior of anchored and unanchored aboveground cylindrical steel storage tanks. In this study, finite elements method by ABAQUS software is used for three tanks with height to diameter ratios (H/D) of 0.343 , 0.85, and 1.53. These tanks are excited by seven one-way and three two-way earthquake records which were scaled to Iran... 

Peppermint oil is one of the most often used food ingredients and it is volatile. Many common procedures such as microencapsulation have been used for protecting volatile food ingredients. For this research, L-menthol was chosen as the core material to be encapsulated. L-menthol is responsible for the minty flavor and cooling sensation of food and pharmaceutical products. The encapsulation of L-menthol was prepared by complex coacervation, using gum Arabic and gelatin as wall material and tannic acid as cross-linking agent. The effect of various processing parameters, including wall material, core material, tannic acid and tween¬80 concentrations, on particle size and efficiency was... 

Determining the optimized number and best locations for new wells is a challenging problem due to the nonlinearly correlation and uncertainty associated with engineering, geological and economical variables affecting reservoir performance. The proposed location and configuration for new producers and injectors is usually nontrivial because of the complexity of the fluid flow in highly heterogeneous reservoirs. It depends on reservoir and fluid properties, well and surface equipment specifications and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the numerical simulator as the evaluation function is the most common... 

Nowadays, most of businesses are becoming computer-based. This trend causes the organizations to become more vulnerable to internal and external threats. Internal threats are done through insiders. Insiders unlike outsiders have capabilities which aid them to easily carry out their illicit activities. Unfortunately, most of research in computer security has focused on the outsider threats, whereas the most damaging is the result of insiders’ illicit activities.This dissertation addresses three primary necessities of the research in the area of insider threat: a consistent definition of insider threat, a classification of types of insider threats, and a classification of vulnerabilities which... 

In this thesis, following a short introduction to investment problem, this problem is investigated with both probabilistic and universal approach. Using the concept of the set of reference algorithms, we present a mathematical definition for universality. We then give examples of universal algorithms for investment and prove their universality. These algorithms are:
Universal Portfolios without Side Information, Universal Portfolios with Side Information, Universal Portfolios with Semi-Constant Rebalanced Portfolio, Universal Portfolios with Switching.
We then present a new algorithm called “Universal Portfolio with Multiple Side Information Sources”. This algorithm is applied in... 

Integrity of closed-loop systems with integral action control is characterized by using a series of successively more difficult to obtain conditions: Integral Stabilizable (IS), Integral Controllable (IC), Integral Controllable with Integrity (ICI), and Decentralized Integral Controllability (DIC). The IS condition requires that for a Linear Time-Invariant (LTI) finitedimensional (FD) plant, G(s), one finds a stabilizing decentralized controller with integral action. For G(s) to be IC, in addition to being IS, one should be able to reduce the gain of
all control loops by the same factor from a finite value to (but not including) zero without introducing instabilities. ICI requires that... 

Dams are huge structures in which safety is a very important issue because a failure will result in loss of lives and finance. Several approximate equations for the approximate analysis of arch dams already exist. These equations are usually obtained by considering the behavior of the dam as a shell. Approximate methods are much faster in comparison to the exact methods and give young design engineers who do not have the experience of designing inside view of displacements, stresses and strains. The aim of this project is to compare the results of approximate analysis of arch dams with the results of finite element models and clarify the points of dams in which approximate analysis methods... 

In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO.... 

Intraction in multi input multi output (MIMO) system makes control of these systems difficult.There are two ways to control such systems; Centralized and Decentralized control. One way in which a centralized controller is designed is using a precompensator. With application of the pre-compensator, the MIMO sytem is decoupled into several SISO systems and one can control these seperatly. Almost all previews methods for the design of pre-compensator assume that the model of the plant containsno uncertainties.In this thesis a new method is proposed which takes into account model uncertaintes in the design of the pre-compensator.The form of the uncertainties considred an interval-parametric