Sharif Digital Repository

In order to respond to the concerns of safety and productivity of construction operations, in this research, the model based on discrete event simulation has been proposed. In this model, with simulation of different scenarios of construction operation in planning and designing phases, before starting construction operation, the level of safety and productivity of each scenario evaluates concurrently. The Scenario that best meets the safety and productivity concerns concurrently has been selected for operation. In order to evaluate the feasibility of the model in construction operation, the model has been implemented in a fabrical example. The operation of installing tiles on the sloping... 

In this study, the micro and nano particles of substituted strontium hexaferrites with nominal composition of SrFe12-xTix/2Znx/2O19 (x=0, 0.5, 1, 1.5, 2 and 2.5) were prepared by a co-precipitaion method. Ferrite-PVA composites (70:30) with thickness of 1.8mm were prepared at 220°C and 50Mpa. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were employed for characterization of synthesized powders and composites. XRD and FTIR results showed that single phase hexaferrite were obtained for almost all of the... 

Nowadays, video search and retrieval is interesting for computer users and it has chief usages for multimedia systems. Video generation rate has increased and Internet as a communication framework is case of its transferring on the world. Because of these, importance of video files is more than past. Searching for finding content will be faster if video files would have indexed with a comprehensive system. The biggest step in this way is power of index generation that would be same or similar to human mind, for improvement of the clustering’s result or classification’s result. For generating suitable indexes, it is necessary to extracting effective features from videos and synthesizing these... 

In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO.... 

Determining the optimized number and best locations for new wells is a challenging problem due to the nonlinearly correlation and uncertainty associated with engineering, geological and economical variables affecting reservoir performance. The proposed location and configuration for new producers and injectors is usually nontrivial because of the complexity of the fluid flow in highly heterogeneous reservoirs. It depends on reservoir and fluid properties, well and surface equipment specifications and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the numerical simulator as the evaluation function is the most common... 

Recently, low temperature carburizing of stainless steels, especially austenitic stainless steels, have been considered by so many researchers. The improvement of tribological properties of which is so impressive so much so that such properties like hardness and wear resistance increase to manifold. In this research, low temperature carburizing was done on two kinds of precipitation hardenable stainless steels 17-4 and 13-8 Mo. After that, microstructural investigations were done on the carburized surfaces and in 5, 10, 20, 80, and 150 micrometer depths. Moreover, in each depth, in order to phase structure and tribological properties investigation, XRD and microhardness tests were done,... 

Since investing in the stock market is always known as one of the ways to increase capital, many researches have been done in the field of portfolio selection in order to provide methods to earn more profit and control investment risk. One of the influential factors in increasing the profit from the portfolio is the proper prediction of future of shares. Therefore, in many research, various methods and tools have been used to predict the future of shares more accurately. One of these tools is forecasting the market regime. In this research, harmonic patterns have been used to predict the market regime. Also, based on the harmonic patterns, the scope of entry into the transaction, the... 

In this thesis, following a short introduction to investment problem, this problem is investigated with both probabilistic and universal approach. Using the concept of the set of reference algorithms, we present a mathematical definition for universality. We then give examples of universal algorithms for investment and prove their universality. These algorithms are:
Universal Portfolios without Side Information, Universal Portfolios with Side Information, Universal Portfolios with Semi-Constant Rebalanced Portfolio, Universal Portfolios with Switching.
We then present a new algorithm called “Universal Portfolio with Multiple Side Information Sources”. This algorithm is applied in... 

In this thesis, we propose a new method for deriving the achievability results in quantum information theoretic problems. The calssical quan- tum decoupling lemma is an essential component in our method. Assume that each classical source is randomly binned at a finite rate. We find sufficient conditions on these rates such that the bin indices are nearly mutually independent of each other and of a quantum source Qn. Us- ing this theorem in conjunction with the calssical quantum Slepian Wolf (CQSW) result, this method suggest a new comprehensive framework for the achievability of network quantum information theoretic prob- lems. We’ve used the new method to redrive the Holevo bound, private... 

In modern cryptography the main goal in symmetric cryptography algorithms is that the security of the protocol should be only dependent on the secrecy of key. Further, secret key agreement has a major role in perfect security. However, it is impossible to share a secrete key only by the use of a public channel and there must be another shared source. This source can be for instance random variables with some joint distribution (as in source model classical key distillation problem) or it can be some entangled quantum systems (as in quantum key distillation problem). The question here is that with the optimum efficiency, what is the maximum number of key bits that can be distilled from one... 

Security in operational cryptography systems is expressed as computational, in the sense that breaking these systems is not possible in polynomial time. Nowadays, advances in computing power of processors and the development of quantum computers, has incresed concerns about the security of cryptographic systems. This is the cause of proposing the information theoretic secrecy in recent decades. In information theoretic secrecy topics, recovering data at target receiver side with zero error should be acomplished along side with defining security criterias. Information leakage is one of the most common security measures. there are another security measures such as rate-distortion, maximal... 

Today, social networks have provided an environment for disseminating all kinds of information and news among the people. One of the challenges of ex-panding social networks is reading and trusting fake news propagating against accurate information. Fake news is false information that the author intention-ally produces and publishes. Due to the destructive effects of spreading fake news, determining the trustworthiness of news is one of the critical issues in the so-cial, political, and economic fields. In this research, we worked on detecting fake news on social media using multimodal data. To solve the problem of fake news detection, we used the text and images of the information. Transfer... 

Elements of a theory of cooperation and coordination in networks will be developed. Rather than considering a communication network as a means of distributing information, or of reconstructing random processes at remote nodes, we ask what dependence can be established among the nodes given the communication constraints. Specifically, in a network with communication rates {R(i,j)} between the nodes, we ask what the set of all is achievable joint distributions p(x1,…,xm) of actions at the nodes of the network. After describing the concepts of empirical coordination for some special networks, we will consider secrecy concepts in coordination. Then we will discuss the concepts of strong... 

The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and... 

Reducing interconnection costs on chip and power consumption are important issues in designing processors. In a processor, a significant amount of total chip power is consumed in the interconnection. The goal of this research is to find a way to reduce power consumption in the interconnection. In this project we propose a new data sending method in which an LZW-like compression algorithm is exploited to compress data before sending it over the interconnection. Then, the codes of the compressed data are sent through the interconnection in order to reduce the number of dynamic cycles. The simulation results show that using this method can reduce 52% of dynamic power consumption  

In the current study, design, fabrication, and characterization of a novel conductive nanocomposite scaffold for nerve tissue engineering applications is reported. For this purpose, the highly conductive polyaniline/graphene nanocomposite (PAG) was synthesized via emulsion polymerization, used for fabrication of conductive chitosan/gelatin/PAG scaffolds, and the effect of PAG amount on the various properties of scaffolds were investigated. The synthesized graphene, polyaniline, and PAG were characterized and the obtained results revealed that partially exfoliated graphene nanosheets and highly conductive PAG with a conductivity of about 12 S.cm-1 and 7 S.cm-1, respectively were obtained. The...