Sharif Digital Repository

Time based competition is considered as an importance strategy in the contemporary manufacturing systems. Reconfigurable Manufacturing System (RMS) is a new paradigm that not only produces the products with high productivity but also allows for rapid response to market changes. Despite the large impact on company performance, the importance of due date setting and order planning processes and related decisions is underexposed in the literature of RMS. The most important contribution of this thesis is orders planning under setting due date in make-to-order RMS environment. This thesis seeks to determine the best selection of several orders, their sequencing and corresponding configurations... 

Considering the competitive environment of businesses, organizations are forced to focus on reduction of product life cycle. Product development processes are usually start with the idea “customer’s needs” and its evaluation, and then implementation testing, marketing and etc. To maintain competiveness the process of product development should be considered continuously. Since the life cycle of products are reducing by introduction of new technologies, one may select the strategy of product development by changing the functions of the current product. Annual exhibitions that are involved in innovations, where technology-driven organizations participates to introduce their new products... 

In today’s industrial world production is considered as a competitive weapon. This has caused many companies active in this field to move towards creating competitive advantage to reduce costs of design, construction and increase production. In particular molding as one of the main industries is among the most economical technological resources of each country. About 50 to 70 percent of the price of a production operation is spent of the strip of sheet by pressing; thus the proper design of a strip of sheet has a great impact on the mold design. Today, in most sectors of the industry there is a need for cutting and packaging of products and form molding and glass cutting to fitting the... 

Supply chain as one of the most important and critical parts of the production process; could have significant effect on efficiency and productivity of the firms.Integration of supply chain (components from upstream to downstream of production system) has been recently noticed and considered remarkably since it could have a considerable impact on functional variables in supply chain systems such as: cost reduction, responsiveness, service level and decision making process. On the one hand, in the last decade, new trends in global economics and the ongoing pattern in multinationals to outsource their manufacturing process have made the integration process challenging and difficult. On the... 

The tourism industry, as the world's largest industry, plays a significant role in the economic status of developing and developed countries, and has been among the fastest growing sectors in other industries in recent decades.The important role of the tourism industry in economic development has begun since the 19th century, but it has quickly traveled its course as a global industrial one.This rapid growth will enable us to exploit the potential of this industry with the growth of technology and knowledge.Designing a platform with the ability to link up the supply and demand among existing individuals as potential sources of resources to reduce the cost and facilitate tourism with a cheap... 

Today, in order to keep up the competition in the market, companies need to use the latest technologies, methods, processes, applications, etc. to find the best services and products. For this, companies and organizations need more dynamism to make the best decisions that can accelerate business process changes. Cloud computing, which is one of the newest and most important business models, can contribute to their success by sharing information and production resources between organizations, as well as helping them compete globally with each other's capabilities. In this research, a multi-objective model is proposed to optimize customer decision-making in using cloud computing and the... 

this work devoted to the optimal control problem for an ecosystem composed of one predator and two competing preys, and our goal is to maximize the total density of the three populations. we first investigate the existence and uniqueness of the positive strong solution for the controlled system, and find an optimal solution under given initial conditions. then we establish the first order necessary optimality condition, and point out that the optimal control has a bang-bang form. moreover, the second order necessary and sufficient optimality conditions are established  

Today, due to the development of information technology and fierce competition among manufacturers, the need to reduce the production costs and increase the variety are strongly felt. Each process in the cloud manufacturing is first considered as a service product development, and then, specializing each of these services, provides us a lower cost, along with a higher accuracy, and quality.The modern world is the world full of uncertainty. The uncertainty, which causes the manufacturers to develop products that consume a large quantity of, fixed costs. That is why utilizing such a perspective can reduce investment risk in a new product development. Combining the production services by... 

Kanban is a tool developed by Toyota Motors Corporation to increase productivity and eliminate waste from their large-scale manufacturing processes. Recently, the system has been used as a tool of choice in Lean software development. Kanban system is the inventory stock control system that triggers the signal for production of product based on actual customer requirement.The present thesis is researching the advantages and disadvantages that Kanban system implementation might cause to the material management processes of a manufacturing facility as well as the theoretical and/or practical reasons behind these results. On an empirical level, the research question is analyzed by participating... 

globalization has let suppliers to geographically distribute across the globe, and for accomplishing the final product resources need to be gathered. So, Cloud manufacturing is a new paradigm which provides ubiquitous, convenient, on-demand network access to a shared pool of configurable manufacturing resources distributed across the globe. On the other hand, in recent years the product delivery system has faced a significant amount of changes with reducing cost and waiting time of last-mile delivery. Unmanned aerial vehicles, or drones, have the potential to deal with these issues effectively. This research developed a mathematical formulation to investigate the optimum routing and... 

In this study, we will examine persistence of various kinds of seasonally forced epidemiological models and seasonally varying predator-prey models. The results of our study regarding persistence of the models will be shown via basic reproduction number. We will show that, in the framework of our study and under some conditions, persistence is obtained as long as the basic reproduction number is bigger than one. We will also prove that, in the framework of our study and under sufficient conditions, if the basic reproduction number is smaller than one, the species under discussion won’t survive in the predator-prey models, and the disease(s) would go extinct in the epidemiological... 

Technological progress, complexity in costumers’ needs and distributed resources make extreme competition in business environment. It produces some novel concepts. In this research, we concentrate on cloud manufacturing which was generated by using cloud computing concepts and focuses on resources sharing between various manufacturers. One of key problems in this field is service composition. In this work, I have proposed a mathematical model with binary variables for service composition problem in multi-cloud manufacturing environment. In this model, I’ve considered for qualities of services (cost, time, energy, reliability) as objective functions. Cost and time functions include the cost... 

One of the most important issues in the cloud computing space is the problem of combining services in which after receiving customer demand. Cloud Composition in Cloud manufacturing is explained to meet customer demands. Each of them is done by one (or several) manufacturing plants. This is important for improving cloud manufacturing.The main purpose of service composition is allocation of activities to vendors. Purposes such as minimizing cost and time and constraints such as confirmation minimum reliability and accessibility for vendors are considered. Providing a segmented production system as a service is another way to reduce costs and speed up response and the agility of the system has... 

this thesis , we examine several types of neural networks , including the Hopfield and Cohen- Gro ssberg neural networks , which have discrete time delays in neuronal states and discrete time delays in the time derivative of neuronal states . The study of these Stabilities is mainly done by constructing Lyapunov function and by using it , the global asymptotic stability is studied . A comparison between these Stabilities will also be made and examples for the application of the results will be provided  

In season 1, we introduce a mathematical model of the in vivo progression of Alzheimer’s disease with focus on the role of prions in memory impairment. Our model consists of differential equations that describe the dynamic formation of Aβ -amyloid plaques based on the concentrations of Aβ oligomers, PrPC proteins, and the Aβ-×-PrPC complex, which are hypothesized to be responsible for synaptic tox- icity. We prove the well posedness of the model and provided stability results for its unique equilibrium, when the polymerization rate of β-amyloid is constant and also when it is described by a power law. In seson 2, We consider the existence and uniqueness of solutions of an initial-boundary... 

The subject of health and particularly medicine, has always been very important. The volume of medicine's demands is excessive, and medicine is considered as one of the sensitive and vital goods, so the accuracy in using the medicine and the timeliness of its use and access are among the strict requirements in the field of pharmaceutical flow. As we know, with the purpose of achieving the best healing effect and cure the disease, several drugs for a specific disease are usually used simultaneously. Therefore, an order containing different types of drugs must be delivered on time, together, and simultaneously. By focusing on the supply chain, companies are experiencing significant reductions... 

This thesis studies a haptotaxis system proposed as a model for oncolytic virotherapy , accounting for interaction between uninfected cancer cells , infected cancer cells , extracellular matrix (ECM) and oncolytic virus . In addition to random movement , both uninfected and infected tumor cells migrate haptotactically toward higher ECM densities; moreover , besides degrading the non-diffusible ECM upon contact the two cancer cell populations are subject to an infection-induced transition mechanism driven by virus particles which are released by infected cancer cells ,and which assault the uninfected part of the tumor .The main results assert global classical solvability in an associated... 

This research investigates the role and effects of knowledge management processes in reducing both cost and waste at the Dorsa Leather Goods Company. This methodology is based on both qualitative and quantitative research methods. The qualitative stage consists of analysis of past research and interviews with all levels of management. This stage leads to identifying knowledge management factors, effective in reducing cost and waste. Subsequently, we identified five main aspects encompassing all the effective aforementioned factors. These aspects are strategic, organizational structure, human resource, organizational culture, and technological infrastructure.The quantitative stage is... 

We study the Navier-Stokes equations with an extra Eddy viscosity term in the whole space . We introduce a suitable regularized system for which we prove the existence of a regular solution defined for all time. We prove that when the regularizing parameter goes to zero, the solution of the regularized system converges to a turbulent solution of the initial system. In the first chapter, we have dedicated the necessary preliminaries and then in the second chapter, we have introduced the types of solutions. The third chapter introduces the necessary tools and their properties, with the help of which in the next chapter we have been able to make estimates and obtain their extensions to prove... 

This dissertation is devoted to the mathematical theory of two-dimensional injection of incompressible, irrota-tional, and inviscid fluids issuing from two infinitely long nozzles into a free stream.. In general, there is a free interface with constant jump of the Bernoulli constant on it, which is different and more difficult than the previous related works. Physically, it is called the collision fluid. The main result in this paper is that for given two co-axis symmetric infinitely long nozzles, imposing the incoming mass fluxes in the two nozzles, there is a unique piecewise smooth fluid collision function such that its free interface arises from the collision of fluids. It is a...