Sharif Digital Repository

Semantic classification of words based on unsupervised learning methods is a challenging issue in computational lexical semantics. The goal of this field of study is to recognize the words that are in the same semantic classes; i.e., can have the same set of arguments. Among all word categories, verb is known as one the most important and is assumed as the central part of the sentence in certain linguistic theories such as case grammar and dependency grammar. Based on Levin’s idea, diathesis alternations and the similarity between these alternations are the clues for the semantic classification of verbs. This idea is verified in languages such as English and German with promising results.... 

The subject of project scheduling is one of classic subjects in project management, and It contains the wide range of optimization problems. Using making changes in variables and constraints , it is possible to create new problems which seem better in the real world. Project tasks need resources for implementation. In some cases, it is considered that any time there are enough resources. In some other cases, it assumes, resources are limited, and resource optimum purchasing is the purpose, which this kind of issues is named resources investment problems (RIP). In this research it assumes, project necessary resources, are rented and renting costs depends on the time of owning. In standard... 

Network coding as an efficient approach for performance improvement of communication networks has been introduced by Ahlswede et al. Despite simple forwarding schemes, in network coding scenarios, intermediate nodes forward the encoded version of their received packets. In wireless Networks, resource allocation includes routing, network coding, flow control, scheduling and power control.In this dissertation a joint scheduling, routing, flow control and Inter-session NC formulation based on a convex optimization problem is studied. Our formulation integrates the optimal scheduling, flow control and Inter-session network coding with a modified version of minimum delay routing. We propose a way... 

Supported Ionic Liquid Membranes (SILMs) are fabricated by saturating the pores of a porous support with ionic liquids. To assess the performance of SILMS, it is necessary to obtain data about the properties of ionic liquids such as diffusivity, solubility, and etc. To accomplish this task, in this project the permeability and diffusivity of CO2 and CH4 through three immidazolium-based ionic liquids: [bmim][PF6], [hmim][Tf2N], and "1-methyl-3-(3- tri methoxi silil propyl) imidazolium bis (tri fluoro methyl solphonyl)" , in the temperature range between 27-45 ℃ and pressures within 10-50 kPa, are measured. It is shown in data validation section that the results of this study are in good... 

Reduction in the oil reserves level and the increasing of fossil fuel prices and GHG has led to growing value of attention to biodiesel. Reserves of fossil fuels are running out and should have proper alternative for them. Environmental benign and renewable properties of biodiesel make it consider suitable candidate to replace fossil fuels.
In this study, continuous production of biodiesel and optimization of important and influential parameters have been investigated. The method is concluded of trans esterification of soya oil with methanol as feed in presence of homogeneous catalyst of NaOH. The reactor was simple with high efficiency and low operational and investment cost. The... 

Nowadays, by distributed software development growth based on pull-requests, it is possible to review code changes before integrating into the master program by a third-party, informally and tool-based which is called Modern Code Review (MCR). Effectively performing MCR can facilitate the software evolution phase through reducing post-release defects. In MCR, after sending the pull request, the developer invites appropriate reviewers to inspect his code. Due to the high volume of requests and potential reviewers in many projects, selecting the appropriate reviewer is difficult and time consuming. Previously, a variety of recommender systems have been proposed that use methods based on... 

Concerns have increased about global warming caused by CO2 emissions in the atmosphere. At the moment, carbon capture and storage is the best available solution. Among the current technologies for CCS, amine-based chemical absorption appears to be the most common method. Amines show several inherent drawbacks such as high vapor pressure, high energy consumption in regeneration, corrosivity and degradability. So, researchers have developed new solvents with the foresight of being superior to amines. Ionic liquids (ILs) are among the most suitable alternatives. The most prominent feature of ILs is their tunable thermophysical properties. In this work, physical absorption by ILs is chosen as... 

Antioxidants are compounds with anti-cancer, anti-bacterial, anti-viral, anti-aging and anti-allergic properties. In the present study, a quantum mechanical approach has been used to shed light on the presence effect of glycoside group on the antioxidant ability of chrysin as one of the most important consumable flavonoids and two glycoside derivatives, chrysin-6-C-fucopyranoside and chrysin-3-malonyl-6-C-fucopyranoside which has electron-withdrawing group (EWG) in its C3 of glycoside group. Density functional theory (DFT) using B3LYP and UB3LYP functional and split-valance 6-311++G ** basis set were used to optimize chrysin, its different derivatives, and their radicals. Analysis of...