Sharif Digital Repository

With the growth of spreading information across social networks, users face with many options. More specifically, try to find out information is so troublesome in this context.In response to this problem, recommender systems aim at providing suggestions of interest for end-users. Also, we see many social networks in real-life which have the potential to be used in a variety of recommender systems. In the bipartite networks of users and items weighted edges is formed between each user and each item in the training set. On the other hand, developing a recommender system that takes into account the social network of the user improves the accuracy of traditional recommender systems.The purpose... 

Photochromism is defined as a reversible transformation of a chemical species between two forms having different absorption spectra induced in one or both directions by photoirradiation. Among various organic photochromic compounds, including spiropyrans, azobenzenes, spirooxazines, dyarylethenes and fulgides, spiropyranes have been attracted more attention due to their more sensitivity towards photo, pH, heat, pressure and solvent polarity. UV irradiation of spiropyrans, breaks the C-O bond of pyran ring and makes cis-trans isomers. Therefore, closed structure of the molecule, named as spiro (SP), is converting into the flattered and conjugated merocyanine (MC). Mc is photochromism, polar... 

Cracks or construction joints in an overlayed pavement can propagate into the overlay over time due to various factors, the most important of which are traffic and temperature loading, and cause premature failure of pavement. This propagated cracks are called reflective cracks and the phenomenon of crack propagation into the overlay is called reflective cracking. Use of stress-absorbing membrane interlayers (SAMI) is one of the ways can reduce the occurrence of reflective cracking and/or delay it. One of the most common SAMIs is an asphalt mixture consists of bitumen and aggregate layed down between the old and the veneer layers. The function of the SAMI depends on several factors such as... 

Back then and still now natural calamities have been a serious threat for energy systems. On that front, this thesis constitutes a three-stage mixed integer linear programming (MILP) model to enhance the resilience of power distribution systems to deal with disas-trous events. The proposed model involves in pre-, mid-, and post-event stages. In this con-text, to increase the preparedness of the power distribution system, system operator recon-figures the system by taking benefit of remote-control switches (RCSs), manual switches (MSs), and distributed generations (DGs) before the natural calamity hits. The proposed model contemplates the traveling time of crew teams to the MS sites in order... 

Using flapping motions, birds produce aerodynamic forces required to fly. Flapping wing aerodynamics is one of the most complicated problems in unsteady aerodynamic field. Experimental study on the structure, the way of production and growth and the feasibility of controlling the leading edge vortex are the main goals of this research in order to improve the aerodynamic performance of flapping wings. Since leading edge vortex structure appears in both upstroke and downstroke of a complete storke in flapping motion, controlling the structure in one of the half-storkes can provide the possibility of having a better aerodynamic performance. In this research, the wing is designed and... 

Collaboration of different agencies working together in a geographical location to reduce waste and optimize the sharing of resources such as energy, raw materials, water, technology, information, etc., made Eco Industrial Parks (EIPs) as a significant step toward sustainability. EIPs has been the focus of increased attention in recent years. Much of the research on industrial parks is related to water and energy network design. This project seeks to identify suitable water network designs for eco industrial parks by identifying the challenges associated with industrial parks. Then, by presenting nonlinear mathematical model and related optimization solution, the superiority of the proposed... 

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... 

It is undeniable that there is a great disagreement in the every field of religion. Reductionists argue that awareness of disagreements reduces the justification and rationality of beliefs, including religious beliefs. In contrast, non-reductionists believe that while reductionism may be true in other domains, it is not necessarily true in religion, because religious beliefs have characteristics that can deny a reductionist argument. They are in the realm of religion. In this thesis, I will discuss issues related to those characteristics that can deny reductionist argument in the realm of religion. In this thesis, I try to show that the arguments and responses presented in defense of the... 

In this project, a fault-tolerant attitude control system is developed for thruster-driven satellites. The proposed method has the advantage over current state-of-the-art approaches in that it does not require a fault detection and isolation system. Generalized moments are generated by a robust controller that is designed using mixed sensitivity H_∞ and μ-synthesis by DK-iteration. Moreover, a pulse-width modulation technique with quadratic programming optimization is tuned to map the controller outputs to thruster on-off commands as efficiently as possible. The controller is designed to tolerate up to ±30% perturbations in inertia properties and thrust degradations up to 90% of the nominal... 

Use of renewable energy has already increased significantly. One of the renewable and suitable sources for replacement with fossil fuels is wind energy, especially wind turbines. But the design, construction, installation maintenance and operation of wind turbines are relatively expensive. One of the most expensive parts of a wind turbine is its gearbox. Wind turbines gearbox due to fluctuating loads unexpected is likely to suffer a premature fatigue. The purpose of this project is to calculate some of the oscillating loads applied to the gearbox and then to investigate the effect of these loads on the service life of the gearbox components. Tower shadow effect and wind shear effect are the... 

In recent years, and with the development of information technology in various aspects of life, the growth of energy consumption in this sector has accelerated. With the advent of cloud computing and the development of its users, data centers have become one of the largest consumers of energy in the world. Adverse effects of fossil fuel consumption on the one hand and the global energy crisis as a limiting factor for development, on the other hand, have doubled the importance of managing the issue and reducing energy consumption in this sector. The two main energy-related concerns in data center construction are clean energy and energy management. The use of new energy and natural facilities... 

The complexity of today's world has led us to the point where we will have problems in the intellectual and practical fields without relying on the testimony of experts. Maybe if we could measure the validity of the information by our own knowledge, we would definitely choose this option. But social life has made us rely on others to get the beliefs we need. We consider most of the beliefs we acquire in school, universities, in science books, news, debates and television documentaries to be examples of knowledge. We also claim to know a set of beliefs presented to us by experts. We consider experts as reliable people and we rely on them. In the meantime, we know that we have no other reason...