Sharif Digital Repository

Three-phase inverters as a UPS are very common in industry and non-linear loads such as rectifiers are growing in industry. Three phase inverter with non-linear load can lead to highly distorted output voltage which can make problem for sensitive loads such as servers etc. Parallel configuration of three-phase inverters, also have the same problem with non-linear loads. Droop control and Master/slave control methods are two major methods which investigated in this thesis. This paper proposes a method for reducing voltage THD in three phase inverters with non-linear load. The proposed method considers the load current as a disturbance and provide a control strategy to reject it using the... 

Effect of utilizing Central Beam Column (CBC) structure on shallow, large span underground spaces excavation is studied. The CBC method focuses on increasing the overall rigidity of tunnel supporting system prior to full face excavation, in which central drift excavation is limited to the dimensions of the central beam and column to reduce disturbances. Constructing the central beam and column structure, the excavation is completed with NATM excavation method in a symmetric manner about centerline. In CBC method on each side of the centerline there is an arch structure composed of the initial lining resting on roof beam on top and bottom beam at the invert. The roof and bottom beams take the... 

In this research, we studied the effect of compatibilizer and short glass fiber on microstructure and mechanical properties of PBT/PC blends. Fisrt, Antioxidants and sodium pyrophosphate dibasic were used to suppress transesterification in PBT/PC Blend. The results showed that best composition occur when both of them are used. In the next step, we used 3%wt MBS (methyl methacrylate-butadiene-styrene) and saw that this weight percent of this compatibilizer doesn’t useful. Moreover addition of short glass fiber to PBT/PC was examined and the results showed that mechanical properties of composite are extensively increased. Also in this step, we proved this idea that we can replace some of PBT... 

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... 

The quality is the last word of customer satisfaction concept. The structure and the main goal of many of large and small companies have been formed with systems aggregate related to process and product quality. Whereas quality is not achieved only under the protection of inspecting and controlling, then the quality management standards have been designed and produced to control all the activities and organization effective processes. Quality management standards in auto industries have been developed with increasing of customer desire and their severity simultaneously. Which the set of some standards such as ISO 9000, QS 9000, VDA, … and the most ISO TS 16949 requirements have been used.... 

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... 

A hierarchical production system in make-to-order environment is presented in this thesis. This production system is consisted of three different decision making levels. Maximum acceptance for production within customer specified time interval was done in the first stage, which is called order arriving stage, based on different client criteria, type of demanded product, and production system constraints. A new hierarchical decision making structure for accepting or rejecting arriving orders is proposed in this level. The output of this acceptance level is orders having maximum production system defined criteria, and minimum production cost along with order delivery time with minimum delay is... 

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... 

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...