Sharif Digital Repository

Regarding the increasing application of fast boats in the world, studying the motions and dynamic performances of these boats is consequently effective and vital.Vast activities take place in all over the world yearly. General performances hull tests occur in marine laboratories such as Wave maker and carriage. Model hull test is one of effective branches of the naval architecture engineering. This method is also based on dimensional analysis. In this thesis,after understanding the waves and the methodology, a computer program was developed to predict motions of a high speed craft in regular and irregular waves (Heave and Pitch). Slamming is one of the most important parameters on a high... 

In this thesis we ascribe a one graph to groups and investigate the relations between groups structure and graph. Let G be a group. The prime index graph of G, denoted by π(G), is the graph whose vertex set is the set of all subgroups of G and two distinct comparable vertices H and K are adjacent if and only if the index of H in K or the index of K in H is prime.Also, The intersection graph of G denoted by Γ(G), is the graph whose vertex set is the set of all non-trivial proper subgroups of G and two distinct vertices H and K are adjacent if and only if H ⋂ K≠ {e}, where e denoted the identity element of G. We denote the complement of Γ(G) by Λ(G). In this thesis we consider the following... 

We extend the work of Chari et al. (2007) to Iran’s economy institutions and introduce two additional wedges—the trade wedge and the oil wedge. The measured trade wedge value is regressed on nominal exchange rate, and thus we decompose the measured trade wedge into two components. One component represents the effect of nominal exchange rate on trade barriers and the other is representative of the effect of international sanctions in trade barriers. Then we evaluate the contribution of these two components of the trade wedge to the macroeconomic fluctuations in Iran from 2012 to 2014. Our results suggest that the trade wedge is crucial to account for the behavior of imported intermediate... 

In recent years, planing boats have been used in more exposed areas, for instance as patrol boats, pilot boats, coast guard and small naval vessels. When such a small vessel operating in a rough-water environment, frequently experiences violent motions and vertical acceleration. Even on calm water, porpoising may occur and may be severe as the speed is increased. Operation of the crew, equipments and overall operability of the vessel always suffer from mentioned motions. In the present study, the impact of fixed and controlled interceptors on a planing crafts hydrodynamic and seakeeping quality is investigated through application of an experimental and theoretical methods. Two scaled-down... 

Rehabilitation of disabled people faced some fundamental changes during past two decades. In the past, the main goal was to reduce the negative effects of disability but now various approaches are used to restore limb movement. As these people own weak muscles due to their lack of physical training, they need Intensive physiotherapy exercises to retrieve their body strength. As a consequence, rehabilitation centers are more willing to employ new ways. These new ways exert less physical pressure on physiotherapists. It helps them to be immuned from diseases like Arthritis or back injuries that is common in such servises. So the movement assisting devices can be of a great help for both... 

Nowadays, one of the most major problems in drilling industry is Lost Circulation in different formations. Lost Circulation increases non-productive time, expenditures and environmental damages. Lost Circulation can happen in natural or induced fractures, cavernous formations and high permeable rocks and it can be subcategorized in seepage, medium, severe or complete type based on the severity of the problem. For addressing this issue, different methods are suggested. One of the most considered of these methods is using Lost Circulation Materials (LCM). In this thesis, it was tried to manage the situation with Designing and engineering of lost circulation materials for different lost... 

Water saturation is a critical parameter in hydrocarbon reservoir studies, directly impacting the assessment of recoverable volumes and production planning. Accurate calculation of this parameter in carbonate reservoirs is particularly important, as precision in its determination can lead to optimal decision-making in exploration and production. Traditional methods such as Archie and Indonesia equations, despite their widespread use, may yield inaccurate results due to their dependence on empirical coefficients and limitations in specific field conditions. In this study, we employed artificial intelligence models, including Random Forest and Symbolic Regression, to develop more accurate... 

The level of current and voltage harmonics in power networks has been increased due to the widespread use of power electronic equipment. This increase may, in turn, result in damage to power system equipment in addition to extra power losses in the network. In order to assess the level of harmonics, it is required to monitor power networks using power quality analyzers. However, due to the high costs, only limited number of measurements can be used in practice. The task of harmonic state estimation is to identify the location and magnitude of harmonic sources and to estimate the harmonic voltage and current by partial measurements. Due to the high price of measurement instruments and... 

This study presents an efficient decision making model for tourism services managers. Decisions of bundle pricing and ordering for a perishable multi-product jointly are considered in a multiple period horizon to maximize the expected profit of the firms. The retailer uses bundling strategy for products pricing to give customers discount when buying a bundle of products. The discretionary sales is incorporated which authorizes managers to save inventory for satisfying future demand even if some present demand is lost.
For solving the problem in deterministic case, we apply modified-genetic algorithm and in stochastic case, sequential quadratic programming (SQP), stochastic simulation and... 

The microstructures of stainless steels consist of an austenitic matrix with almost continuous network of primery carbides.This class of steel had replaced the traditional super alloys with a reduction in costs and has similar properties under conditions of creep, which is one of the principal degradation mechanisms leading to failure in service at elevated temperaturs , therefore, their mechanical properties such as tensile strength and creep resistance are particularly important in hot deformation. Recently the effects of temperature and aging time on static strain aging in worked stainless steel have been investigated. In this study the deformation behavior of HP-series austenitic... 

Titania is semiconductor material and have many applications including photocatalysis, photochromic, air and water purification, sensors, and solar cell. In electrophoretic deposition, charged particles dispersed in a stable suspension move towards an oppositely charged electrode, and form dense layer of deposit on it. In this investigation electrophoretic deposition of titania nano-particles in suspensions prepared by different solvents (methanol, ethanol and butanol) with and without dispersant (triethanolamine and polyethylenimine), was studied. Well stabilized suspensions, prepared for electrophoretic deposition. The effects of solvent type, additive concentration, mechanism of particles... 

In this M.S. dissertation numerical study of slinger fuel distributer has been studied. This type of atomizer has been used in mini turbojets like Teledyne CAE.
The main purpose of this work was obtaining spray structure of slinger atomizers. This goal was achieved by implementing a UDF code in FLUENT® software to model the primary atomization that include variation of fluid from exit of slinger disk bores till formation of primary droplet. In FLUENT® the DPM method and its ability to utilizing Lagrangian approaches have been used. The result of this model is validated by the data from experimental test that can be found in Articles. This is the first time that spray structure of slinger... 

The process of injecting acid or acidizing, is one of the most common ways to stimulate oil and gas wells. The purpose of this process is to increase the productivity of the well by increasing the permeability of the reservoir rock around the well. This is especially important in carbonate reservoirs due to damage to the formation and low intrinsic permeability in some places. In order to minimize the effects of structural damage, conventional wormhole channels are created to pass through the injured area. One of the important factors in acid validation is achieving optimal injection rate, which means obtaining the highest permeability with the lowest amount of injected acid.Numerous... 

Electric vehicles (EVs) will be used rampantly in future transportation system. Although the uncontrolled charging of these EVs will be threatening for the stability and sustainability of the grid, a well-suited energy trading policy may provide a number of beneficial services to the grid as well as preserving the sustainability of the system along with heightening the performance of operation. In this paper, by taking advantage of block rate tariff, a wholesale pricing policy is introduced. A multi-objective approach is utilized to address the cost reduction and load levelling services, concurrently, in order to guarantee the profits of the both the grid and EVs. Due to the high... 

Periodic mesoporous organosilicas (PMOs) are a new class of porous materials with high surface area, ordered structures, and uniform pore sizes. There is a high structural diversity in these materials due to the possibility of choosing different building blocks, functionalization and chemical modification of organic groups. Considering the stated advantages, the synthesis and application of different classes of adsorbents based on periodic mesopore organosilica compounds are the main goals of this thesis. In this regard, in the first research, an attempt was made to use organosilica precursors based on the tyrosine amino acid in the preparation of PMO and then its adsorption capacity towards... 

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... 

Nowadays, cancer, which has been mentioned as the disease of the century, is the second leading cause of death throughout the world, and its incidence is constantly increasing. Isolation of circulating tumor cells is one of the most critical steps in diagnosing and controlling cancer progression. Due to the rarity of cancer cells compared to other cells in the blood sample, the isolation process requires optimal and high-precision devices. With the advent of inertial microfluidics, the ability to control the particles movement, the processing of blood samples as quickly and accurately as possible, and the viability of cells with a high percentage, introduced microfluidic systems as a... 

Dams are one of the vital infrastructures of the country and their correct use can have a significant impact on reducing costs and increasing their productivity. Due to the fact that dams are mainly large structures with a large number of components and with many complications of operation and maintenance, their operation and maintenance require spending a lot of money. On the other hand, the depth and volume of water behind the dams and the entanglement of the connection between the dams and the surrounding environment make the operation and maintenance of dams face many risks. The use of new technologies that can reduce the costs and risks of operating and maintaining dams can greatly help...