An inspection game to provide incentive for cooperation with corrupted inspectors

, Article Proceedings of the 2012 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining, ASONAM 2012 ; 2012 , Pages 730-732 ; 9780769547992 (ISBN) Kolahdooz, Y ; Safari, M. A ; Sharif University of Technology

2012

Abstract

Open and autonomous environments, such as peer to peer networks or many social networks, are efficient only if cooperation among nodes is ensured. In order to ensure cooperative behavior, we have added a new node type to the system, called inspector and used game theoretical tools to analyze the system. Inspectors punish both misbehaving nodes as well as nodes who provide dishonest ratings about other peers. Analyzing the proposed inspection game ensures that corruption of inspectors and misbehavior of nodes is bounded. The game enables the system designer to set the amount of corruption that is allowed according to the budget

Incentive Compatible Trust Management Mechanism in Distributed Systems

, M.Sc. Thesis Sharif University of Technology Kolahdooz, Yalda (Author) ; Safari, Mohammad Ali (Supervisor)

Abstract

Traditional security approaches prevented participants of an environment from malicious behavior by closely monitoring every transaction of the network. Such approaches are very costly in modern autonomous systems, besides, they are also impossible to apply in many cases. Trust management mechanisms are developed in order to ensure safe interactions with unknown parties in such open environments. Most trust management mechanisms rely on testimonies of interaction participants as the source of information to estimate a peer’s reputation. The first challenge that arises here is the lack of incentives for providing such information. Even if interaction parties are encouraged to report the...

Study of Stability of Unsaturated Railway Embankment Founded on Saline and Desalinated Loess

, M.Sc. Thesis Sharif University of Technology Kolahdooz, Ali (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)

Abstract

Loess with a dispersion potential is one of the problematic soils of Iran. This study aims to investigate the impact of dispersion potential on the water flow in a three-phase medium and determine the effect of salinity on the stability of an unsaturated railway embankment by employing the soil-water retention curves of the materials. To satisfy this objective, the natural dispersive loess of the Chabahar region is desalinated in this study and the hydraulic properties of both saline and desalinated soils are comprehensively investigated. First, the soil-water retention curves of the materials are measured through the filter paper test method. Afterward, the saturated hydraulic conductivity...

Apatite Digestion and Two-step Leaching in Concentrate Sulfuric Acid for Recovery of REEs’ Cerium, Lanthanum, Neodymium and Yttrium

, M.Sc. Thesis Sharif University of Technology Kolahdooz, Mohammad Reza (Author) ; Yoozbashizadeh, Hossein (Supervisor)

Abstract

Nowadays, apatite mineral is one of the most sought for the recovery of rare earth elements. This mineral is also the main source of phosphoric acid production. To achieve this end, apatite has to react with sulfuric acid to give phosphoric acid. This process is called the wet process. During the wet process, more rare elements enter the remaining solids called phosphogypsum (PG). For the dissolution of rare elements, PG, which is the same as chalk, can be leach with an acidic solution. In this project, the phosphate concentrate from Chadormalu iron ore waste after characteristics diagnosis is digested in concentrated sulfuric acid at temperatures below 100 ° C, and then hydration is...

A numerical study on the effect of salinity on stability of an unsaturated railway embankment under rainfall

, Article 4th European Conference on Unsaturated Soils, E-UNSAT 2020, 19 October 2020 through 21 October 2020 ; Volume 195 , 2020 Kolahdooz, A ; Sadeghi, H ; Ahmadi, M. M ; GDS; VJ Tech ; Sharif University of Technology

EDP Sciences 2020

Abstract

Dispersive soils, as one of the main categories of problematic soils, can be found in some parts of the earth, such as the eastern-south of Iran, nearby the Gulf of Oman. One of the most important factors enhancing the dispersive potential is the existence of dissolved salts in the soil water. The main objective of this study is to explore the influence of water salinity on the instability of a railway embankment due to rainfall infiltration. In order to achieve this goal, the embankment resting on a dispersive stratum is numerically modeled and subjected to transient infiltration flow. The effect of dispersion is simplified through variations in the soil-water retention curve with salinity....

Stability analysis of a railway embankment on a collapsible-dispersive stratum under transient flow

, Article 16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019, 14 October 2019 through 18 October 2019 ; 2020 Ahmadi, M. M ; Sadeghi, H ; Kolahdooz, A ; AECOM; CECI Engineering Consultants, Inc.; CECI Nova Technology Co. Ltd.; et al.; Hwang Chang General Contractor Co., Ltd; SINOTECH Engineering Consultants, Ltd ; Sharif University of Technology

Asian Regional Conference on Soil Mechanics and Geotechnical Engineering 2020

Abstract

Collapsible-dispersive soil is one of the most challenging types of problematic soils having the adverse effects of both collapsible and dispersive soils for construction. A natural occurrence of this type of soil was recently encountered along some part of the Chabahar-Zahedan railway line in Southeast of Iran. Indeed, the construction phase was stopped after facing several geotechnical problems along the railway embankment partly constructed such as local and general subsidence, non-uniform settlements of structural elements, etc. Relatively high natural porosity as well as pore water salinity were found responsible for those problems. Therefore, this study aims to conduct a three-phase...