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A composite-metric based path selection technique for the Tor anonymity network
, Article Journal of Systems and Software ; Volume 103 , 2015 , Pages 53-61 ; 01641212 (ISSN) ; Kharrazi, M ; Sharif University of Technology
Abstract
The Tor anonymous network has become quite popular with regular users on the Internet. In the Tor network, an anonymous path is created by selecting three relays through which the connection is redirected. Nevertheless, as the number of Tor users has increased substantially in recent years, the algorithm with which the relays are selected affects the performance provided by the Tor network. More importantly as the performance suffers, users will leave the network, resulting in a lower anonymity set and in turn lower security provided by Tor network. In this paper, we proposed an algorithm for improving performance and security of the Tor network, by employing a combination of different...
Toward an intelligent approach for determination of saturation pressure of crude oil
, Article Fuel Processing Technology ; Volume 115 , 2013 , Pages 201-214 ; 03783820 (ISSN) ; Shokrollahi, A ; Arabloo, M ; Gharagheizi, F ; Mohammadi, A. H ; Sharif University of Technology
2013
Abstract
Bubble point pressure is a crucial PVT parameter of reservoir fluids, which has a significant effect on oil field development strategies, reservoir evaluation and production calculations. This communication presents a new mathematical model to calculate the saturation pressures of crude oils as a function of temperature, hydrocarbon and non-hydrocarbon reservoir fluid compositions, and characteristics of the heptane-plus fraction. The model was developed and tested using a total set of 130 experimentally measured compositions and saturation pressures of crude oil samples from different geographical locations covering wide ranges of crude oil properties and reservoir temperatures. In-depth...
A vagueness-based obfuscation technique for protecting location privacy
, Article Proceedings - SocialCom 2010: 2nd IEEE International Conference on Social Computing, PASSAT 2010: 2nd IEEE International Conference on Privacy, Security, Risk and Trust, 20 August 2010 through 22 August 2010 ; August , 2010 , Pages 865-872 ; 9780769542119 (ISBN) ; Sharif University of Technology
2010
Abstract
Technical evolution of location technologies has augmented the development and growth of location-based services. With widespread adoption of these services, threats to location privacy are increasing, entailing more robust and sophisticated solutions. This paper proposes an intuitive obfuscation-based scheme, which uses vagueness in human perception of nearness to provide a flexible and robust location privacy scheme. Key to this work is the concept of vagueness degree, which aims to enhance its robustness against privacy attacks. Furthermore, our scheme is totally in line with human perception of privacy and provides a solution, which mostly suits proximity-based services, social...
Dynamic simulation of natural gas transmission pipeline systems through autoregressive neural networks
, Article Industrial and Engineering Chemistry Research ; Volume 60, Issue 27 , 2021 , Pages 9851-9859 ; 08885885 (ISSN) ; Bozorgmehry Boozarjomehry, R ; Sahlodin, A. M ; Sin, G ; Mansouri, S. S ; Sharif University of Technology
American Chemical Society
2021
Abstract
Transmission of natural gas from its sources to end users in various geographical locations is carried out mostly by natural gas transmission pipeline networks (NGTNs). Effective design and operation of NGTNs requires insights into their steady-state and, particularly, dynamic behavior. This, in turn, calls for efficient computer-aided approaches furnished with accurate mathematical models. The conventional mathematical methods for the dynamic simulation of NGTNs are computationally intensive. In this paper, the use of autoregressive neural networks for cost-effective dynamic simulation of NGTNs is proposed. Considering the length, diameter, roughness, and elevation as the main...
Application of constrained multi-variable search methods for prediction of PVT properties of crude oil systems
, Article Fluid Phase Equilibria ; Vol. 363 , 15 February , 2014 , pp. 121-130 ; ISSN: 03783812 ; Amooie, M. A ; Hemmati-Sarapardeh, A ; Ghazanfari, M. H ; Mohammadi, A. H ; Sharif University of Technology
Abstract
Accurate prediction of the PVT properties of reservoir oil is of primary importance for improved oilfield development strategies. Experimental determination of these properties is expensive and time-consuming. Therefore, new empirical models for universal reservoir oils have been developed as a function of commonly available field data. In this communication, more than 750 experimental data series were gathered from different geographical locations worldwide. Successive linear programming and generalized reduced gradient algorithm as two constrained multivariable search methods were incorporated for modeling and expediting the process of achieving a good feasible solution. Moreover,...
Fuzzy system design for automatic irrigation of agricultural fields
, Article Expert Systems with Applications ; Volume 210 , 2022 ; 09574174 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
One of the main challenges in arid and semi-arid regions is the lack of water for various purposes such as industrial and agricultural applications. The problem is even more significant in traditional agriculture. The geographical location, climatic conditions, average annual rainfall, vegetation, air pollution and turbidity, and canopy of plants are important and lead to different water consumption in plants. Therefore, proper water consumption in agriculture in most countries leads to food security and a better supply of crops. In this research, we propose a fuzzy system that has eight inputs and seven outputs. Inputs include soil moisture, relative humidity, air temperature, wind speed,...
Application of a maintenance management model for iranian railways based on the markov chain and probabilistic dynamic programming
, Article Scientia Iranica ; Volume 16, Issue 1 A , 2009 , Pages 87-97 ; 10263098 (ISSN) ; Hakhamaneshi, R ; Sharif University of Technology
2009
Abstract
Railway managers have a strong economic incentive to minimize track maintenance costs, while maintaining safety standards and providing adequate service levels to train operators. The objective of this study is to apply a procedure for making optimal maintenance decisions in Iranian Railways. This study consists of two parts. First, a cumulative damage model, based on a Markov process, is applied to model the deterioration of the track. For this reason, tracks are categorized into six classes, so that those tracks with similar traffic loads and geographical location are collected into one class. The track survey data from 215 blocks (4,228 km) of the ten divisions of the Iranian Railway...