Sharif Digital Repository

Dengue is one of the most important infectious diseases in the world. This disease is a viral infection that is transmitted to humans through the bite of a mosquito called Aedes aegypti. For this reason, geographical regions infected with this type of mosquito are at risk of Dengue outbreak. In this thesis, we first present a mathematical model describing the geographical spread of Dengue disease, which includes the movement of both the human population and the winged mosquito population. This model is derived from a mixed system of partial and ordinary differential equations. Our proposed model has the ability to consider the possibility of asymptomatic infection, so that the presence of... 

This research discusses the issue of exploitation of cloud computing in facilitating the responsibilities of a project manager in construction project management. The need for reliable and affordable technologies is ever more important in today's business world due to the amount of economic contraction and losses that take place every day; cloud computing fills this gap. For this purpose, we are presenting a cloud-based Project Management Software named Field wire that is specially designed to manage construction projects in the cloud computing environment. The various procedures of a project, due to their complex nature, are largely made up of tasks which cannot be carried out by one... 

Assurance about projects and industrial plans success always had been one of the most important concerns of investors. Car manufacturing industry is not excluded. In this project the painting line in zagrosskhodro company using electro deposition method is reviewed , analyzed, and investment feasibility study of such method is investigated . All aspect of investment including financial and economic aspect is reviewed by UNIDO methodology.
The outcome is described here briefly.
1- Production volume in this plan in complete capacity is equal to 40000 bodies in a year.
2- The primary fixed investment capital is 132,187,912,140 Rls.
3- Sum of fixed expenses of production is ... 

Multimedia retrieval systems are gradually playing a critical role in our everyday life to facilitate interacting with massive amount of personal or professional images, music and video archives. So far, many systems have been proposed among them relevance feedback based content based multimedia (especially image) retrievals has been proved to be more effective. However there is still a problem called semantic gap, in finding proper mapping between low-level features used by CBIR systems and user’s high-level concepts. On the other hand graph cuts have been a great powerful tool for solving many computer vision problems. They benefit from robust optimization algorithm called maximum flow/... 

Slug Flow is one of the most important schemes of two-phase air/water flow, which is quite complex and quite different to a single-phase flow. Also one of the common water conveyance systems is a rectangular tunnel which may have adverse slope at some parts of the tunnel. In this study the hydraulic of slug flow in rectangular tunnels with variable slope from horizontal to adverse have been considered using experimental setup. About 150 tests were carried out for different air/water discharge ratios and adverse slopes, and dynamic pressure fluctuations together with the slug period were measured. It was observed that the pressure fluctuations increase as the air to water ratio increases and... 

In this thesis, a new non-linear control synthsis technique (θ - D) approximation) is discussed. This approach achieves suboptimal solutions to a class of non-linear optimal control problems characterized by a quadratic cost function and a plant model that is a_ne in control. An approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation is sought by adding perturbations to the cost function. By manipulating the perturbation terms both asymptotic stability and suboptimality properties are obtained. The new technique overcomes the large-control-for-large-initial-states problem that occurs in some other Taylor series expansion based methods. Also this method does not require excessive... 

We consider the following viscous Hamilton-Jacobi Equations for :

The aim of this paper is to investigate relations between:
(i) The existence of global solutions,
(ii) The existence of stationary solutions (with gradient possibly singular on the boundary), and we obtain precise description of these relations. Namely, (i) imply that (ii), and this case all global solutions converge uniformly to unique stationary solutions. In the redial case, we prove converse of this result. Moreover, for certain smooth function we obtain the existence of global classical solutions with gradient blow-up in infinite time. For or for Cauchy problem, we establish similar relations. Our... 

Wireless communication networks such as cell phones are rapidly expanding and every day they attract more users. Information flow in these networks is basically through free space. Thus, theses networks are inherently subjected to eavesdropping. Cryptography based on the secure key is the well known traditional way of protecting information security in wireless networks. However, these cryptosystems are just computationally secure and have their vulnerabilities. Information theoretic security is a relatively new method which doesn’t rely on any preshared key or key infrastructure and uses inherent characteristics of the communication channel to provide robust and provable security.In this... 

In this study, the effect of submerged vanes on the flow pattern and dimensions of separation zone at a 90˚ open-channel Junction were investigated. The experiments were conducted in three stages. First, for validity of data with the results of webber et al, using ADV, velocities was teken without submerged vanes.in the second stage, experiments with dye injection was performed at confluence for several initial arrangement of vanes. From 54 different arrangements, two arrangements were selected. In three stage, three dimensional velocities was teken in two arrangement selected. Due to the significant reduction the size of separation zone in one of these arrangements, with moving this... 

Considering the significant role of process plans in computer-aided manufacturing, a lot of researches have been conducted to fulfill the gap between the different aspects of process planning systems. However, there is still a wide gap for process planning systems to completely fulfill the requirements. In this research an expert system for turning operation is proposed. The system is capable of suggesting appropriate machining parameters with the aid of an inference engine. The proposed system has an integrated data structure based on ISO 10303 (STEP) standard for both geometric design data and machining parameters. In this system, geometric design data is stored in a database with a data... 

In this thesis we study the problem of existence and multiplicity of positive periodic solution to the scalar ODE , , where is a positive function on , super linear at zero and sub linear at infinity, and is a -periodic and sign indefinite weight with negative mean value. We first show the nonexistence of solution for some classes of nonlinearities when is small. Then, using critical point theory, we prove the existence of at least two positive -periodic solutions for large. Then, we prove the existence of a pair of positive -periodic solutions as well as the existence of positive sub harmonic solutions of any order for the scalar second order ODE where is same as above,... 

A voting protocol was introduced by Popveniuc in 2006; it is receipt freeness, so appeared to be resistant against the bribed voter. In 2009 Clark using the bribed contract, and attacked to the voting protocol, in the elections by two candidates. He showed that this protocol is not resistant to the bribed voter. In this thesis, we use game theory and graph to extend the bribed contract for n candidates. Thus with the help of a graph, we show that this protocol with any number of candidates, is not resistant to the bribed voter, and we show that by increasing the number of candidates, the resistance of the protocol would be high and if the number of candidates is n, the success rate of this... 

The brushless DC Limited-Angle Torque Motor (LATM) has been widely used in area of aerospace equipment, robot drives, optical scanning systems and any drive systems that require limited motion, ranging from the simple ON-OFF servo valves to the accurate tracking of a reference signal. This paper presents the optimum design procedures of a brushless direct current limited-angle torque motor. According to a request from industry, a two-pole torque motor with a toroidal armature winding was designed based on analysis of magnetic equivalent circuit of motor structure, and using selected ferromagnetic material and rare-earth permanent magnets (PM). To select the best design solution and optimize... 

In this thesis , we consider the generalized lienard system (dx/dt=1/(a(x)) [h(y)-F(x)])¦(dy/dt=-a(x)g(x) )and under suitable assumptions on a , F , g , h we obtain sufficient and necessary conditions for the intersection of all orbits with the vertical isocline y=F(x) . using these conditions we give some sufficient condition for the oscillation of solutions . then existence and uniqueness of periodic solutions for a kind of lienard equation with a deviating argument are studied . finally we study existence and uniqueness of limit cycles for the generalized lienard system(x ̇=ϕ(y)-F(x))¦(y ̇=-g(x))
 

Electronic voting is one of the applications of electronic systems, in which collection and tallying the votes are performed electronically. In electronic voting systems, cryptography is used to provide security requirements but defects of the cryptography have made the electronic voting protocol designers to use strong assumptions which are impractical or hard to implement.In this research, some of the strong assumptions in electronic voting protocols are studied and the soloution of solving them is given. First, the assumption of trusting to the tally authority in electronic voting protocols which are based on deniable authentications is considered and a new internet voting protocol based... 

In order to protect the proxy signers’ privacy, many anonymous proxy signature schemes have been proposed. As far as we know, there is no provable secure anonymous proxy signature scheme without random oracles. Because the provable security in the random oracle model has received a lot of criticism, in this thesis, the aim is proposing the first provable secure anonymous proxy signature in the standard model based on existing standard assumptions.It is shown in the standard model that, the proposal is anonymous against full key exposure and existential unforgeable with the computational Diffie Hellman (CDH) and Subgroup Hiding (SGH) assumptions in bilinear groups.To provide anonymity for proxy... 

Increasing use of World Wide Web and users tend to accompany in the electronic transaction has caused a fair exchange becomes very important and pervasive electronic transaction. These transactions have a lot of usage and benefits. In this study, the optimistic fair exchange has been studied. It is a special case of the fair exchange while having more advantages than the fair exchange. A situation considered that a signer could not sign a message by himself so he delegates his right in signing to a person as a proxy signer. In this study, a protocol of optimistic fair exchange for proxy signature is presented. So, the proxy signer can accompany in the optimistic fair exchange instead of the... 

CIM includes major components with different performances, although in last decades any researchers starting a way to high level of integration in these functions. Process planning and scheduling are two tasks of manufacturing that searches have not paid attention to them. In the other word there is a good environment for integration studies but researchers didn’t find best approach for integrating these two tasks.The proposed approach can quickly integrate these two functions and be implemented in a company without working process planning and scheduling departments separately. This methodology consists of four main modules that introduced in detail in this study. They are Integrated... 

A flexible manufacturing system (FMS) is a manufacturing system in which there is the capability of handling the variations in product's features which is the result of ever-changing customer demands. The flexibility attributes to utilize the resources in a more effective manner. On the other hand, the control of such systems would become more complicated. FMS needs CNC machines and robots and other resources for establishing the flexibility and enhancing the efficiency of the whole system. Also it needs to integrate the resources to reach flexibility. In order to reach this goal, an integrator framework is proposed in which the machining data of CNC machine is received through a STEP-NC... 

Lean management is an approach to running an organization that supports the concept of continuous improvement, a long-term approach to work that systematically seeks to achieve small, incremental changes in processes in order to improve efficiency and quality. In this research, design and implementation of Lean Management concept in a production company was addressed. The method for implementing lean management is based on Jackson & Jones Method in implementing a lean management system. This method starts with the business renewal process. The output of this process is company’s vision and a development plan. After that, the first strategic improvement cycle starts for a period. There are...