Sharif Digital Repository

In this essay we study the concepts of nuclearity in C-algebras, and amenability in Banach algebras. A proof on the "every amenable C-algebra is nuclear" is studied. A Banach algebra A is called amenable if every continous derivation D : A ! E , is inner i.e. there exists anif in this denition E is a dual Banach A-module and norm continuity replace by w-continuity then we have Connes-amenability; Connes-amenability was rst considered for von Neumann algebras in [J-K-R] (and thus should perhaps be called Johnson-Kadison-Ringrose amenability). The reason why this notion of amenability is usually associated with A. Connes are his papers [Conn 1] and [Conn 2] The name "Connes-amenability" seems... 

We propose a model for friction between two rough surfaces based on extreme value statistics (EVS). Different models for single-asperity contact, including adhesive and elasto-plastic contacts, were combined with EVS. The Hertzian model for contacts and Gumbel distribution for summit heights show the closest conformity with Amonton’s law. The range over which Gumbel distribution mimics Amonton’s law is wider than that of the Greenwood–Williamson (GW) model. In comparison with other EVS distribution, Gumbel distribution seems the proper choice for summit‘ s height. Interestingly, here again, elasto-plastic contact and Gumbel distribution for summits achieve the best conformity with Amontons... 

This thesis is going to investigate the ontological foundation of Science and Tool. To this aim, it refers to Heidegger’s works especially the Being and time. Heidegger gets involve in analyzing Science in the Being and Time. He emphasizes on importance of establishment of a fundamental knowledge which should ontologically recognize basic concepts and methods of Sciences, to cause a real progress in sciences. Heidegger also asserts that the Mathematical interpretation of the world is not a fundamental, and it must be replaced with phenomenological interpretation, which clarifies the ontological foundation of the theoretical view, and regards to all aspects of world’s existence. In this... 

In this treatise, it will be shown that the subject of faith is the subject who loves God and in showing her love to God, she sacrifices her dearest things in the world. By doing that, she would free herself from everything that mind herself. She doesn’t do this action to be given a better reward by God. Her motivation for performing this action is nothing but love. Meanwhile, the subject of faith hopes God to respond to her love and engage in an I-Thou relationship with her. Now, her hope would be justified when God plays an active role in the world and admires her action, i.e., when eros can be attributed to God  

Dispersed phase holdup has been measured in a 75 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phases flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis holdup in transition and emulsion regions. Empirical correlations are derived for prediction of... 

Uranium separation from other metals in ore and nuclear waste is one of the most important stagesin nuclear fuel cycling. Solvent extraction is the common method for uranium extraction that reagent plays important rule in this technique. In this investigation, uranium solvent extraction is carried out by Cyanex 301 as reagent from nitric acid. At beginning, equilibrium batch extraction was carried and the effect of parameters such as pH, reagent concentration, temperature, shaking time of two phases, volumetric ratio of two phases, diluent and nitric acid concentration on extraction was investigated and optimum value of parameters was calculated. Uranium concentration effect was also... 

In this thesis, we evaluate the maximum stable throughput of a cognitive multi-hop IEEE 802.11-based WLAN overlaid on a cellular network. In the considered scenario, the secondary users operate in the downlink or uplink frequency band of primary network and transmit their data in free primary channels using OFDM technique. The activity of primary nodes is modeled independently by ON-OFF alternating states. To model the scenario, each secondary user is modeled with an open queueing network. The queueing network can model the transmission of data as well as the effect of primary users. By writing the traffic equations of the queueing network and applying the stability conditions, we are able... 

In this thesis the effect of frame aggregation mechanism in maximizing throughput in Wireless Local Area Networks (WLANs) have been investigated. Frame aggregation has become a part of the IEEE 802.11 standard as the amendment IEEE 802.11n. First, we have a quick review on access control layer in IEEE 802.11 standard then illustrate the necessity of frame aggregation. Afterwards, we propose an analytical model for the analysis of an IEEE 802.11n network comprised of an Access Point (AP) and several conventional nodes, all in the coverage area of each other. This analytical model focuses on downlink throughput; therefore only AP uses frame aggregation and the other nodes use basic IEEE 802.11... 

Collaborative fltering (CF) is one of the best and widely employed approaches in Recommender systems (RS). This approach tries to fnd some latent features for users and items so it would predict user rates with these features. Early CF methods used matrix factorization to learn users and items latent features. But these methods face cold start as well as sparsity problem. Recent years methods employ side information along with rating matrix to learn users and items latent features. On the other hand, deep learning models show great potential for learning effective representations especially when auxiliary information is sparse. Due to this feature of deep learning, we use deep learning to... 

The transportation is one of the important components in the economies of different countries. In the maritime transportation network, the demand is usually not balanced in different routes, and this imbalance results to accumulation of containers in a node. In order to sustain the problem, firms have to reposition empty equipment from a surplus location to a shortage location, which causes the problem of “Empty Repositioning Problem”. In this study, pricing strategies in one transportation market with two locations are considered; while there is ERP problem in issue. The problem is solved by Bertrand game method. The research is divided into two parts of the monopoly network and the duopoly... 

Navigation is the science of determining the velocity and attitude of a moving object in every given moment. There have been many methods for navigation. Nowadays with the advancement of technology, advanced navigation systems have been developed. Although each of these navigation systems have their pros and cons, in order to improve the overall performance of the system and to solve their problems, these systems are integrated.The goal of this project is to present an integrated cascade method to decrease error and also decrease dependence on GPS. In this project, INS, DVL & GPS are integrated with the cascade method.To achieve this, INS-GPS and INS-DVL integration are first performed. The... 

In this research, a nanocomposite blend of polyamide 6/polystyrene containing polyaniline-coated carbon nanotubes was fabricated via melt blending method, aiming to achieve electrical conductivity in the range of static dissipation. The effect of weight percentage of nanofillers and surface modification of carbon nanotubes with polyaniline on the electrical properties and microstructure of the nanocomposite was investigated. To promote compatibility between the immiscible polyamide 6 and polystyrene polymers, PS-g-MA compatibilizer was utilized, and its effect on the morphology of the nanocomposite blend was examined. Additionally, the influence of weight percentage of nanofillers and the... 

In recent decades, especially with the increase of greenhouse gases and global warming, land degradation has become one of the important global environmental issues. Land degradation has significant impacts on soil performance, vegetation cover, crops, and even the dispersion of dust particles. Land degradation is a complex phenomenon that is affected by multiple factors. Thus, it is necessary to identify these factors and then assess the degree of vulnerability and resilience to it globally. Proper indicators can clarify the integration and effective linkage between related parameters. This study aims to develop a Land Degradation Vulnerability Index (LDVI) using parameters such as...