Sharif Digital Repository

Multi-participant virtual environments are network applications that simulate the experience of real-time interaction among multiple usersdistributed all over the internet In order to share the common sense of time and place, multiple entities interacting in the shared virtual environment should become aware of the modification to the shared environment, or the result of on the other objects interactions shortly after such events occur. This is achieved through the distribution of update messages. As the number of users and entities increases, there is a considerable increase in the amount of update messages exchanged among the users and entities. This is considered as one of the most... 

With the expansion and increasing complexity of network infrastructures, anomaly detection in network time series has become a key challenge in the fields of system security and reliability. However, existing research in this area faces fundamental issues such as bad-labeled datasets, inappropriate evaluation metrics, and overly complex deep learning methods. Additionally, the lack of sufficient attention to specific scenarios, such as identifying issues related to servers, clusters, and network nodes, raises questions about the effectiveness of current solutions. This study aims to provide a comprehensive approach for anomaly detection in net-work time series, with a special focus on... 

In the Ion Implanter system a controled current through a tungesten filament, supplies the heat which causes the thermoionic emmition to ionize the gas molecules. Then the negativly charged electrones that are boiled off the filament, and also the ones that are removed from the outer ring of the gas molecules during the ionization process, are attracted by an adjustable voltage source. In this thesis, two resonant converter topologies are proposed to designe and to implement the adjustable current and voltage sources for ion implantation system. Unlike the PWM converters soft switching techniques, used auxiliary circuits to reduce the switching losses and EMI noises, in the proposed resonant... 

In this thesis, the relationships between various leadership styles and organizational citizenship behaviors (OCBs) were examined. For this, with a qualitative perspective and using the Grounded Method as the research methodology, dominant OCBs, effective leadership styles, the relationships between leadership behaviors and OCBs, and other influencing parameters were identified. In this regard, with a preliminary feasibility study, the possibility of implementing this research was verified and then, by using twelve in-depth interviews, required information was gathered. Main categories were recognized by coding the data and analyzing the relationship between the coded information. The... 

Several studies in the field of performance management have paid attention to the effect of systemic and instrumental factors on the effectiveness of performance management system. However, the impact of communication and relational factors has received less attention. Furthermore, it seems that similar approach has been used in organizations for considering systemic factors in designing performance management systems rather than human factors. The goal of this research was to study the relationship between employees' trust in their manager as an relational variable with the effectiveness of performance management system and to compare this relationship with the relationship between the... 

Nowadays in high-tech industries there is a serious demand for using advanced materials. Functionally graded materials (FGMs) are in the last generations of these group of materials. FGMs have shown good behavior in special conditions. According to sensitive applications of FGMs , there is a large amount of effort to understand it’s behavior in the presence of crack. Finite element method and other numerical methods, in recent years are widely used in modeling fracture problems.Remeshing requirements and mesh sensitivity are among the disadvantages of analyzing crack growth using the conventional FEM. Recent finite element methods such as extended finite element method, are proposed to model... 

According to sensitive applications of polymers and polymeric materials, there is a large amount of efforts to understand its behavior in the presence of crack. In this thesis, the influence of nonlinear behavior of the polymers is investigated on the behavior of theory fracture process zone. First, a nonlinear rate-dependent cohesive rule based on a novel incorporation by Schapery nonlinear coefficients is suggested to model crack growth in the case of polyethylene which is well-defined through the Schapery nonlinear constitutive equation. As the matter between the crack faces in a polymeric medium like polyethylene may tolerate large strain ranges during crazing and before complete... 

Mass transfer of a drop moving in a bulk fluid is an interesting subject which has attracted a lot of attention. Understanding effective parameters in this process would be helpful in order to increase the efficiency of the industrial processes related to mass transfer. In this research, the deformation and mas transfer of a moving drop was studied numerically. Navier-Stokes equations and concentration equation were solved separately with a VOF method in an axisymmetric domain using Fluent software. Comparision between numerical results and former experimental results proves the accuracy of the modelling in both fields of deformation and mass transfer. Moreover, effects of the physical... 

In today’s competitive world, productivity is one of the main components that guarantee the success and profitability of an industry or a project. This research has studied productivity of dam construction projects in Iran that are usually classified as mega projects. First, the major factors influencing productivity of dam construction projects in Iran were identified and evaluated. Three main sources of information namely; literature review, records and lesson learned from previous projects and experts’ opinions were used to identify these factors. Then, 41 main factors influencing productivity were selected and the effect of each factor was measured based on the results obtained from... 

This thesis presents the seismic performance evaluation of steel MRFs with nonlinear replaceable links. Although existing MRFs can provide life safety during a design level earthquake, they are expected to sustain significant damage at the locations of flexural yielding fuses in the beams .These drawbacks can be mitigated by introducing replaceable links at the locations of expected inelastic action. Codes require that the span-to-depth ratio of the beams in moment resisting frames (MRF) should be limited to guarantee the development of plastic hinges with a sufficient length at beam ends. To overcome the abovementioned limits, in this paper a new replaceable shear structural fuse is... 

The primary purpose of the present research is development and implementation of advanced state estimation and control techniques for space rendezvous and docking. To achieve this aim, the present study has first investigated the use of graph neural networks (GNNs) to filter out the noise of the sensor data in the state estimation process. The measurement package is consisted of a gyroscope, star trackers, and a GPS sensor providing inputs to the GNNs. The obtained results showed that the use of GNNs significantly improves the accuracy of the state estimation compared to traditional methods. In addition, the study has focused on developing advanced control techniques for spacecraft position... 

Software defect prediction is a significant and growing field in software development that focuses on identifying software modules prone to defects before the testing phase. The challenge of lacking historical data has shifted software defect prediction towards a cross-project approach. In this method, identifying defective software modules in a project (target project) is done using historical data collected from other projects (source project). The difference in data distribution between source and target projects is a major challenge in cross-project defect prediction. One way to overcome this challenge is the appropriate selection of the source project, which most existing studies... 

The purpose of this study was to identify the dimensions of readiness for change in senior managers in the academic environment. In the literature, the emotional component of readiness for change requires more empirical research. The main question of this research is to identify cognitive and affective dimensions of readiness for change. This research has an exploratory approach, and a qualitative research method has been used to reach the research goals. In order to answer the questions of this research, a case study of Strategic Budgeting Implementation Plan at Sharif University of Technology has been studied. Interviews were conducted with the heads of the depatments of Sharif University... 

This thesis seeks to identify the critical barriers to strategy implementation in an Iranian firm, and also concentrates on the readiness for strategy implementation phase. Previous studies show that many of strategic plans fail in implementation phase. Therefore, implementation and readiness for implementation phases are both important phases. The very few studies in this topic in Iranian industrial context illustrate the same issue in local context; however, these barriers may vary from one context to another. Different approaches and frameworks in the literature have been reviewed in order to build a theoretical frame work to seek the barriers to implementing a strategic plan in an... 

Despite the profound impact of formal strategic planning on the performance of companies, there have been a few researches on the factors that influence the starting phase of strategic planning process. This research tries to identify these factors and clarify the decision process of conducting strategic planning. In other words, the main purpose of this study is to identify the rationales of companies for initiation of strategic planning. Regarding limited previous studies on this topic, especially about the decision process about conducting strategic planning in Iranian companies, the case study methodology is used. The study is conducted in two phases. In the first phase, five companies... 

Understanding the behavioral processes of boards has been a new line of inquiry in the board literature. This study has focused on the leadership roles of heads of boards of subsidiary companies in a corporation. This subject is widely practical in most industries but rarely explored. An embedded multiple case study design was used to compare the leadership roles of heads of boards of two groups of boards with high and low effectiveness in a corporation assessed by a multi-source appraisal method. Based on several interviews with different stakeholders of the corporation within subsidiary boards of these two groups and the staff managers of the parent company, we compared the mechanisms that... 

The present study investigates the relationships between feedback-seeking dimensions (frequency, method, timing, and content) and two types of individual performance (goal achievement and behavior-related performance). In addition, the relationships between feedback-seeking motives and feedback-seeking dimensions are examined. The purpose is to identify new explanations for the inconclusive results of the direct relationship between feedback-seeking and performance in the literature. Moreover, this study investigates work motivations based on self-determination theory as the antecedents of feedback-seeking motives. This study contains one qualitative phase and two quantitative ones.... 

This study investigated the relationships between team identification and attendance intention in Iranian football matches, specifically examining the impact of constraints on this relationship. The research focused on Esteghlal Football Club, one of Iran's most popular teams, which faces a paradox of having a large fan base (35-40 million supporters) but relatively low stadium attendance rates (below 50% capacity). The study employed a mixed online sampling method (convenience and snowball) with 182 Esteghlal fans who had attended at least one stadium match. Data was collected using three validated questionnaires: team identification (18 items, 6 dimensions), attendance intention (4 items,...