Sharif Digital Repository

Our problem is to evaluation state and form of a tracer passing through the vessel. Using this method, we can identify the effect of during used in some defected parts of body. This evaluation leads to in solving a Laplace equation with mixed boundary condition. Separating that problem, we reach to a collection of algebraic and linear equations. Solving this system, we approximate coefficients of the solution with a series the existence and uniqueness of and analytic solution has been proved using the Eigen functions finally, using numerical algorithms, we have interpreted the analytical solutions.
 

This thesis is based on articles [18,15]. Zhao [18] has studied a free boundary problem modeling the growth of tumors with drug application. In this model live cells are two kindes: proliferative cells and quiescent cells. This model consists of two nonlinear second-order parabolic equations describing the diffusion of nutrient and drug concentration, and three nonlinear first-order hyperbolic equations describing the evolution of proliferative cells, quiescent cells and dead cells. He has proved that this free boundary problem has a unique global solution. Tao and Chen [15] have studied another free boundary problem modelling the growth of an avascular tumour with drug application. The... 

Selective withdrawal from water and settlement reservoirs and tanks is necessary for water and environmental systems. Perforated pipes can be used for selective withdrawal within the length of these reservoirs. In this method, the lateral inflow through perforations leads to the outlet of the pipe that is placed in a depth of fluid. In relation to the hydraulics of perforated pipes, most studies are about drainage pipes and perforated pipes that are used as wellbores in horizontal wells, but application of these pipes have not been investigated in submerged situations. Capacity estimation of perforated pipes based on inside diameter of the pipe, material of the pipe, perforations of the... 

Nowadays, as a result of rapid changes of market, it is necessary to reduce the period between design and manufacturing of a new product. Among them, process planning is one of the most difficult elements of production chain and also, there are a few numbers of experts in this field. In addition, this process is time-consuming and costly. So, it is important for companies to reduce the period of new product’s presentation by reduction of process planning duration. On the other hand, it is proved that the lowest level of integration in CIM systems is in CAPP section. Integration provides sharing data in the system, so the other parts of production systems can exchange product information and... 

In this paper, the Hopfield neural network models have investigated. Also the similar model with time -varying delays and constant coefficients has considered and with establishing some criterions, existence solution and it's exponential stability of the solution is investigated. Moreover, some special conditions for exponential stability by impulses and exponential stability by periodic impulses are obtained  

One of the miscellaneous units that are frequently used in water and wastewater systems is flush tank. Flush tank increases the self cleaning velocity in the conduit, and helps to clear the conduits from deposits and contaminations. While these units have been used for many years, there is not enough information about the hydraulic performance of these units in respect to the discharge, distance from the tank and the pipe hydraulics. In this paper the experimental results from observed hydrographs at different distances from the flush tank in a pipe has been presented. The variables include; volume of releasing water (or inlet hydrograph), upstream head, pipe diameter (3 and 4 cm), pipe... 

Air entering in to the water supply systems and occurrence of two-phase flow makes several problems in design and operation of these systems by damaging the structures and making indefinite and complicated conditions. Existence of some singularities like contractions in pipelines makes the conditions more indefinite. So an experimental study is performed in order to investigate the two-phase flow hydraulic properties in a rectangular channel in presence of an area contraction. The contraction ratio is σ=0.44, whereby the test section is included two different rectangular channels from 60 × 100 mm to 40 × 67 mm. Four series of experiments are performed using four types of transitions with... 

In this thesis we investigating two models of cancer invasion .First, a general mathematical model of cancer invasion is presented. In this model there are three factors: tumor cell, extracellular matrix and enzyme. The model consists of a parabolic partial differential equation (PDE) describing the evolution of tumor cell density , an ordinary differential equation modeling of extracellular matrix and a parabolic PDE governing the evolution of the matrix degrading enzyme concentration. This model is investigated in two special versions for existence and uniqueness of global solutions. In the first model we neglect the remodeling term, this model is named the chemotaxis-haptotaxis model.... 

In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,... 

In this thesis, we consider the motion of a stretched string coupled with a rigid body at one end and we study the existence of periodic solution when a periodic force acts on the body. In this hybrid system, there is a weak dissipation that characterizes. The main difficulty of the study is related to the weak dissipation which does not ensure a uniform decay rate of the energy. In this thesis, firstly, under the condition of 0 1 0 , we prove there exists a periodic solution. Then, we change the conditions on , Indeed, we restrict ourselves to solve the problem. In this case, under the condition of 0 2 0 , we show there is a periodic solution for rational periods. In the last part, by... 

Nowdays, many of communication systems working together. The fist part of each communication system is related to separating a desired part of system input signal. This is called channelisation. Channelization is a process where single, few, or all channels from a certain frequency band are separated for further processing. The separation of single channel is usually done by down-conversion followed by filtering and optional sample-rate conversion. A straightforward implementation for multi channel sepration, which is also the traditional implementation of wideband channelizer, is to simply use a single-channel channelizer for each channel. A few applications require that an input signal be... 

ISO 10303 Standard also known as STEP, is an standard in the domain of mechanical manufacturing that describes data relating to drawings, design, machining, process planning, engineering and other aspects of product which all together can describe the entire life cycle of products. However, as this standard is newly born and developing these data models are expensive and time consuming, so far, no data model for description of cutting tools is developed. In this project we study the STEP parts and protocols to understand how data is stored. We study EXPRESS Modeling language, the language developed as part of the STEP standard which is the official language of data modeling in STEP. And use... 

In this thesis, three mathematical models are considered for the viral dynamics of HIV-1. The first model is an HIV infection model with saturation infection and intracellular delay, which forms a three-dimensional differential equations system, the second model includes an eclipse stage of infected cells, The viral dynamics of this model is described by four nonlinear ordinary differential equations, and finally, we study a delayed six-dimensional HIV model with CTL immune response, in fact, the main issue is the analysis of the second model (model including an eclipse stage for the infected cells).In this thesis is obtained sufficient conditions for persistence or eradication of the... 

Nowadays, because of high volume and growth of data in industrial organizations and productive factories, registration and storing of data have forgotten manual and tradition styles for which using automation and mechanized machinery and systems has been a necessary task. In order to reach to this revolution, need to some tools, facilities and methods which can fulfill this requirement is felt strongly. Therefore, high volume of data is considered as an advantage because based on precise analysis it is possible to make logical management decisions with less risk. During last years, statistical and numerical methods and simulation were used to discover knowledge and information when one of... 

Decision making is one of the most critical issues in engineering field. The Axiomatic Design is recently known as one of the most robust tools for decision making task. Axiomatic design is a engineering theory that provides a systematic framework for decision making using two axioms. These two axioms called Independence and Information axioms are both used to do the task.In this thesis, the information axiom is used to select the best machine (operation) for manufacturing cylindrical parts. To do that, three criteria including surface roughness, dimensional accuracy and cost have been chosen.Finally a comparison to the result of this methodology and the result of Analytical Hierarchy... 

We Consider the Chemotaxi Systems in a smooth bounded domain as follow:{ █(ut = Δu-χ∇.(u∇v)+ f (u) x ϵ Ω ,t>0 @ @τ vt =Δv-v+u x ϵ Ω ,t>0)┤ Where χ∈ and f(u) =Au - Buα generalizes the logistic function with A≥0, B>0 and α>1. First for τ=0, global existence of such solutions for any nonnegative initial data is proved under the assumption that . Moreover, boundedness properties of the constructed solutions are studied. Next we assume that 2=α, τ>0 and we consider nonnegative solutions of the Neumann
Boundary value problem for the chemotaxis system above in a smooth bounded convex domain . We will see that if B is sufficiently large then for all sufficiently smooth initial data the... 

In this study, the effect of submerged vanes on the bed scouring and deposition pattern at a 90̊ open-channel junction was investigated. First, the bed formation without submerged vanes were studied under the effect of hydraulic variables like the discharge ratio of tributary to main channel and the ratio of mean approach velocity to the threshold velocity. The results show that scour holes enlarge with time while they move towards the downstream and the outer wall in the main channel. Also, by increasing the ratio of mean approach velocity to the threshold velocity about 0.5, the maximum scour depth occurred at the downstream junction corner with time. In the second stage, the proper vane... 

In this thesis, a complete analysis of a general within-host models of malaria is done. This model generalizes the models in epidemiological literature. In this study, we propose another equation for immune effectors reaction. In this thesis, we find out that the global stability of disease free equilibrium is obtained when the reproduction number R0 < 1. When R0 ≥ 1, at least one endemic equilibrium exists. The local and global asymptotic stability is investigated. Finally, numerical simulations are done to illustrate the influence of immune effectors reaction  

Today’s businesses strategies are changing from traditional point of view to globalization and distributed enterprise. Companies have to consider flexibility in term of quantity and variety. They have to manage and organize the product development chain where low cost resources are available. Therefore, enterprises and companies should facilitate the flow of information and increase the interoperability between distributed agents. The main information flow occurs in CAD/CAM/CNC chain. Information flow at the end of the chain has always been the main obstacle to enable interoperability. Old Standards for programming CNC machine tools are the main problem to exchange data and facilitate...