Sharif Digital Repository

As fossil fuels are still the world's most important source of energy, as well as the maturity of most of the world's oil reservoirs, there is a need for enhanced oil recovery methods to meet the world's increasing oil demands. MEOR methods are new and promising methods that are still in the research and development stage. One of the MEOR methods is the use of biosurfactants, which increase the oil recovery by two mechanisms: 1) reducing the interfacial tension between water and oil and 2) changing the wettability of the rock. In this study, the performance of two glycolipid biosurfactants, rhamnolipid and sophorolipid, in increasing oil recovery has been investigated. Initially, surface... 

The methods of Enhanced Oil Recovery (EOR) from reservoirs have been taken into consideration recently due to the decline in oil reserves and the rise in energy demand. Studies and investigations indicate the tremendous potential of chemical approaches based on injecting ionic liquids into the porous media with the goal of improving oil recovery. Additionally, hydrogels and polymers, which are two of the process' primary materials, are thought to be good alternatives. In the current study, a hydrogel based on carboxymethyl cellulose was first created and synthesized. Ionic liquids based on imidazolium and triflate anion were then added, and their effectiveness in enhancing the properties... 

The following dissertation discusses Ionic Liquids (ILs) as an alternative to commercial surfactants for use in the Enhanced Oil Recovery process. Ionic Liquids came to researchers’ attention due to their environmental nature and their tolerance for high temperatures and salinity. In this work, firstly, an extensive literature review is carried out, and then, experiments are designed and performed to evaluate ILs’ surface activity and performance in a lab-scale EOR set-up. The Ionic Liquids used in this work consist of three types of methylimidazolium nitrate, [MIM]+[NO3]-, with three different alkyl chain lengths. This combination, and specifically the effect of nitrate anions on EOR and... 

Diversity of new traffic patterns, due to new applications such as cloud computing, online gaming, Internet of Things (IoT), and Video on Demand (VoD), have pushed more dynamic behavior and faster reconfiguration to traditional networks. Elastic Optical Network (EON) is a new concept to response these requirements. Spectrum efficiency will be increased by exploiting OFDM-based elastic optical network. As a result, increasing fiber nonlinear effects would be a consequence of compression of spectrum. Optical Amplifier is used in optical networks to compensate fiber loss along the optical path. Amplifiers placement, in most of papers, is considered fixed at the end of each invariant span. This... 

The measure of success in a company is determined by a high performing workforce that demonstrates the competencies necessary to drive the business success, while meeting the organization's strategic goals. This is where competency-based human resource management becomes important. The main factor contributing to the above noted area is the identification of core competencies. There has been a lot of research in this area during the past few years. Each research demonstrates an approach for the development of critical human resource competency models in an organization. In order to determine the foregoing competency model, the early studies in this area have been focused on the distinction... 

Voluntary turnover has direct and indirect expenses for organizations and for this purpose; it has one of the richest literatures in academic works. Due to the especial role of knowledge workers in organizations, these expenses in knowledge-based organizations are more important and more costly than that of other organizations. One of the latest theories in the field of voluntarily turnover was introduced by Lee and Mitchell (1994) that was named “Unfolding Model of Turnover” to describe the process of decision of voluntary turnover. This theory is distinguished from its similar theories from two main aspects: First, they introduced new elements like shock. Second, they introduced... 

Career Orientations or career choices, can be affected by internal and external factors. External factors are the environmental conditions that the reward and the attractiveness of selecting a career choice are dependent to them. Internal factors include the needs of oneself from his/her job, his/her beliefs and his/her skills and competencies about the job. In this research the internal antecedents of managerial and technical orientations between programmers have been identified. On the other hand the perception of people about the compensation system as an external factor which can affect the mentioned relationships, have been analyzed. It seems that this is the first research which career... 

Women are going to play more important roles in the economy of most countries including Iran. Hence, since the number of entrepreneurs among women is increasing, identifying characteristics and other factors that cause these group to be successful, is a critical issue. Studies show that entrepreneurs, especially women entrepreneurs, face numerous problems in their career. These problems are especially more demanding in societies with unique cultural attributes. Therefore, applying personal and managerial solutions in order to overcome these problems are necessary. On the other hand, researchers believe that one of the most effective and beneficial concepts helping entrepreneurs in their... 

The main purpose of this study is to evaluate the linkage between two constructs about teamwork activities. One of them is "self-leadership in teamwork", the extent to which a person could control and manage his thoughts and activities in teamwork. The other is "shared leadership orientation", which is about orientation of people to contribute in leadership processes. This linkage evaluated with consideration of "self-efficacy in shared leadership" as a moderator.
Questionnaires of self-leadership in teamwork and self-efficacy in shared leadership elicited from literature with a little change and shared leadership questionnaire developed in another study by the author.Questionnaires... 

The present study was performed aiming to identify the ethical dilemmas human resource managers confront with in Iranian project-based organizations as well as to trace out the underlying causes. “Ethical dilemma” refers to a decision making situation in which ethical considerations render all the alternatives inapt, thence making the decision making process ethically complex. First of all, a theoretical framework was developed based on the preceding research; then, the study was further conducted utilizing a qualitative research method with an exploratory approach. The data were collected using in-depth interviews and analysed using the theme analysis method. The corresponding interviewees... 

Using Distributed leadership framework while studying the leadership phenomena in teams, especially in educational environment, has received more attention by scholars in these years. Although the results of these researches indicated positive consequences mostly, the need for exploratory studies to identify situational and contextual factors in distributed leadership effectiveness has been mentioned. In other words, it has been suggested that the effectiveness of distributed leadership in teams may be affected by situational and contextual factors. In the current multiple case study, after the initial study of leadership and its functions in some schools of Sharif University of Technology,... 

The influence mechanisms of executive/non-executive board compostion on board’s attribution style have been explored. In two case studies, I have examined boards’ causal interpretation about a critical incident which had a significant impact on firm performance. A qualitative research approach has been taken in the case studies. Data was gathered through semi-structured interviews with all board members and was analyzied with the theme analysis method. According to the results, board of directors’ collective attribution formation process can be devided into three stages of members’ expression of information and facts at board meetings, forming the individual judgements of members and at... 

Emergency Department (ED) overcrowding is one the most problems and challenges that every Emergency Department all over the world is facing with. This problem leads to some problems like prolonged waiting times and Length of Stay in Emergency Department. “Boarding time” is one of the most important ones, which is the time a patient spend for being transferred from Emergency Department to one of the Hospital Inpatient Wards. One important solution to this problem is “overflowing”, and it means allocating patients to an alternative ward rather than their primary ward. In practice, the overflowing process usually controlled in a myopic manner. Limited number of researches that focus in this... 

Due to the vast application of networks in the modeling of problems, the analysis of networks has been gaining a noticeable importance in recent researches. There are some cases in which we are looking for nodes that are highly connected to other nodes. However, the detailed information of the network structure is not always available; or because of complexity, it is not possible to investigate whole network and pick high-degree nodes; or investigating the network completely is too time-consuming. In such cases, algorithms which do not need the whole network information play a significant role. Friendship paradox as a topological feature of graphs can be helpful in designing such algorithms.... 

It has been reported that in some organizations despite delegation according to its concept, some of the organization members don’t have an internal motivation to use the autonomy that has been delegated to them. This problem might have different aspects. From the self-determination theory perspective, this might be because of unsatisfied basic needs of the person. For example, if all options the person has, are desirable or all of the options are undesirable and the person can’t choose between them. This might result in unsatisfied basic needs of the person. Due to these conditions, there is a probability that she won’t have an internal motivation to use autonomy. In some researches, it has... 

In this research study, the reciprocal relationship between Emergent States and Team Processes has been analyzed in boards of directors, by using case study method with semi-structured interview as the method of data collection and thematic analysis as the method of data analysis. This research was conducted on the companies which are active in Information Technology industries, their size is in the range of SMEs, and have passed the early startup stage and an external investor has joined the board. After thematic analysis, narrating each case’s story, and theoretical analysis on each case, the obtained results are demonstrated with discussion on both cases, introducing a theoretical model,... 

The present study aimed to investigate the application of self-leadership strategy by participants in a training course of employment interview through the role playing method to face the relevant challenges. Solving or regulation of the challenges in a training course can result in participants’ learning improvement. This course was taken place as a part of the Human Resource Management Course in 2017 in the graduate school of management and economics at Sharif University of Technology. Initially, background and models were reviewed, and then the research theoretical framework was developed accordingly. In addition, since the subject was rather new, a qualitative research method by... 

The purpose of the present study is to facilitate the implementation of "organizational complex change" that is important in today's organizational competitive environment. To this end, and to increase employees' commitment to change, the study utilized the role of "authentic leadership" and "self-determination theory." In this study, using data from 269 employees involved in an organizational complex change, relationships between variables were tested to finally see how authentic leadership for change can enhance employees' "affective commitment" to change. For this purpose, exploratory factor analysis and multiple regression were conducted on the data and 3 out of 5 hypotheses were... 

Computer video games have had a huge growth in recent years, and Dota 2 is one of the most popular video games and e-sports right now. In this research, Dota 2 drafting phase is studied by using stochastic processes and probabilistic models. This phase is modeled as a POMDP (Partially Observable Markov Decision Process) for the first time. Afterwards, the model is solved using data mining methods and machine learning algorithms. A large database of the game's match data is created, and six different machine learning algorithms are used to predict the match outcome based on the drafting stage. The prediction accuracy and power of these algorithms is compared, and finally, a program is...