Sharif Digital Repository

Considering continuous growth of communication infrastructure and devices and the number of service and manufacturing firms, competition in the market is becoming tougher and more complicated as time goes by. In this situation firms need to be adapted to the varying needs of the market and keep the quality of their products high and their prices stable to exist and grow. Accordingly, one of the consequences of current competitive market is the continuous decrease in firms' products and services life cycles. Following this situation, firms and researchers have employed different tools to approach this goal which is shortening products and services life cycles. One of the most efficient tools... 

The purpose of this thesis is to improve the protocols for recording and transmitting medical data in terms of security and performance using blockchain technology. The approach we take in this Thesis differs in three respects from most articles written in this field. The first is that unlike those who look at the blockchain as a black box and take advantage of only its positive features, we consider the details and challenges it creates for us and solve them in order to use it. The second important point is to justify the use of blockchain in this design. It can be seen in many designs that the use of this technology is useless according to their model and goals. Finally, one of the most... 

Occurrence of scouring around the seabed pipelines can lead to pipe failure and pose a serious threat to the marine environment, economic losses and waste of oil and gas. Therefore, to prevent the occurrence of scouring, by simulating this phenomenon and identifying the parameters affecting it, we can help to design a more efficient placement of pipes in the seabed. Various methods such as potential flow theory and turbulent single-phase and two-phase models have been proposed to simulate this phenomenon. The purpose of this article is to simulate and investigate the effective parameters of this phenomenon by combining computational fluid dynamics and separate elements. The innovation of... 

Creating any project requires investment, time, and resources. Many construction projects have failed despite considerable money invested in them. A common cause of this failure is improper planning. One of the most important parts of project planning is the feasibility study which is missing in many projects in Iran. However, the fundamental reasons that prevent construction project managers and owners from efficiently performing feasibility studies in their projects have not been investigated in the country yet. In this study, we aim to evaluate this aspect of the construction projects in the country by investigating the structure of feasibility studies in the building construction... 

The first step in improving traffic safety and reducing damage to road users is to evaluate traffic safety and identify black spots, which is possible in statistics-based methods using traffic accident data from previous years. One of the disadvantages of statistical methods is the existence of a series of limitations in collecting accident data and spending a lot of time and money. The purpose of this research is to provide a technique to evaluate traffic safety and estimate the number of accidents using the traffic conflict technique and extreme value theory modeling. The method of conducting this research is based on image processing, recording, and analysis of the conflict index of two... 

WO3 is known as a photocatalyst in the visible light region, but with lower efficiency compared to more interesting semiconductor photocatalysts such as TiO2 and ZnO. Many attempts have been done to increase the efficiency of this photocatalyst by incorporating metal and metal oxide nanoparticles or recently carbon nanotubes.On the other hand, application of graphene, as an unrolled carbon nanotube, for increasing the photocatalytic activity of TiO2 and ZnO has shown positive results. Furthermore, it was reported that such semiconductor photocatalysts (and very recently WO3) can photocatalytically reduce the chemically exfoliated graphene oxide sheets under UV-vis irradiation.
In this... 

Graphene is a one layer atom thickness and zero energy gap so for using it in nano electronic and transistors baised on graphene it's energy gap should be opened.one of the methods for opening graphene band gap is creating nano scale boundaries or synthesize graphene nanoribbons. One of the new methods for graphene nanoribbon synthesize is longitudinal opening of carbon nanotube. In this thesis graphene nanoribbons synthesize with this method and analyze with AFM and Raman spectroscopy. Carbon nanotubes also have energy gap and IR absorption recently they used for living cell destruction. In this thesis we synthesize graphene nanoribbons and analyzing their optical absorption and use it for... 

TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy... 

Graphene nanogrids fabricated by graphene nanoribbons obtained through oxidative unzipping of multi-walled carbon nanotubes, used as two-dimensional selective templates for accelerated differentiation of human mesenchymal stem cells (hMSCs), isolated from umbilical cord blood, into osteogenic lineage. The biocompatible and hydrophilic graphene nanogrids showed high actin cytoskeleton proliferations that coinciding with patterns of the nanogrids. The amounts of proliferations found are slightly better than proliferation on hydrophilic graphene oxide (GO) sheets, and significantly higher than non-uniform proliferations on hydrophobic reduced graphene oxide (rGO) sheets and polydimethylsiloxane... 

One atom thick layer of pure carbon in bonded and hexagonal lattice is named graphene. graphene has unique mechanical, optical, thermal and electrical properties and because of these properties has grabbed attention. graphene has been made from high pure graphite by different methods such as CVD(chemical vapor deposition) , chemical exfoliation , micromechanical cleavage and colloidal suspension. through these methods, green methods for synthesis of graphene, using eco-friendly reductants during synthesis of graphene instead of hydrazine and recently using waste(not graphite) are attractive for synthesis of graphene. Following this idea , a group has produced graphene from wastes such as... 

Graphene oxide is a single sheet of Carbon atoms which has been arranged on a two-dimensional honeycomb lattice. Functional groups such as epoxy, carboxyl and carbonyl are located on basal plane and at the edges of graphene oxide and they localize electrons on the surface of graphene oxide and open band gap in its band structure. Pure graphene has zero band gap, so existence of fluorescence properties is unlikely; but graphene oxide has fluorescence properties due to band gap in its band structure. Fluorescence properties of graphene have been used in live cell imaging and drug delivery, so study and increasing of fluorescence properties is significantly important. The purpose of this... 

Graphene is a two dimensional lattice which is created from carbon atoms. Having special feature, it has such various medical usage, for example in diagnosing and treating cancer. Adding a particular factor to graphene could improve their efficiency. In comparis on with graphene itself, graphene oxide and reduced graphene oxide are much more successful in diagnosing and treating than others because of their higher hygroscopic. Recent studies state that hydrogenized combinations including hydrogenized graphene show desired results. Due to its higher hygroscopic and the possibility of adherence to the cells, hydrogenized graphene could be very effective in diagnosing and treating the sarcomas.... 

This study discusses about mass customization and optimization of supply network in which both goal considering to set the flow of raw material and final product to satisfy the customer demand. The mass customization is more important concept in this study, so that this goal is placed to the first objective. In this research, the model which contained both goal is presented. The model focus on mass customization and try to satisfy various products demand, which constitute 3 kind of speed demands. Each product can satisfy in 3 way: fast, normal, slow.In the first model the new approach present in which the speed affects all of supplying, manufacturing and distributing system. The system try... 

Knowledge Based Firms are considered to be important for the economic development of a country in regards to both employment growth and innovative activity. The latter is believed to contribute significantly to the increase in productivity and therefore the competitiveness of Iran’s economy. This study contributes to the above literature by investigating the factors that are believed to treat the growth of such firms in Iran. The purpose of this study is to identify functional risks of vital signs monitors via Fault Tree Analysis (FTA) method to use as a guide for manufacturers to identify and control hazards. Therefore, 30 knowledge based firms were selected as sample. Then, based on a... 

The Internet is often used for communication-based applications such as online banking, stock trading, and shopping where service interruption is unacceptable. Thus, analysis of the impact of the failures of hardware, software, and related services’ performance quality of the service provided to users is of importance to designers and managers in these functions. In this study, we developed a strategy to the design of a dynamic combination of file servers with the aim of providing reliability and SLA. At first, we examine the reasons for the violation of service level in file host services and datacenters, and then we introduce the criteria to measure the violation of service level on the...