Sharif Digital Repository

Crumb rubber, produced from shredding of scrap or refused tires, is one of the most commonly used modifiers of asphalt. Asphalt rubber, in addition to mitigating some of the environmental problems of disposing scrap tire, improves the flexural strength of pavement, extends the life of pavement and reduces the maintenance costs. The properties of asphalt rubber are highly dependent on the type and composition of base asphalt, type and amount of crumb rubber, and the production method.The goal of this research is to investigate the performance properties of asphalt rubbers produced from Iranian asphalt and crumb rubber, using an industrially feasible method. The Superpave testing procedure was... 

Pulsating heat pipes have been more studied in recent two decades as effective tools in dissipating waste heat from electronic components. Due to oscillating fluid flow model, these tubes have the potential of converting waste energy to power. This research presents a system that makes this potential to act. In this system, the oscillating slug-plug fluid flow pattern in an open-looped pulsating heat pipe makes a permanent magnet which is levitated in Ferrofluid to vibrate in an electromagnetic vibration-based generator in order to induce electro motive force. The fluid flow regime in pulsating heat pipe has been simulated numerically with finite element scheme. The model results for fluid... 

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... 

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... 

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 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... 

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... 

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.... 

Mutually coupled oscillator arrays may be used for power combining at the millimeter-wave region. In addition, these arrays have the capability of beam steering without the use of any phase shifter. Using the strong coupling method is inevitable to obtain synchronization between all elements in the large arrays. One of the challenges in strongly coupled oscillators is the multi-moding problem or oscillation at undesired frequencies. In this thesis, we obtain mode distributions in a one-dimensional and a two-dimensional array with rectangular boundary, using a method based on circuit equations in the frequency domain. Then, we compared the results with the previous works and also verified... 

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... 

Transport phenomena i.e. momentum, heat and mass transfer are occurring inside the eye constantly. Any disturbance in each of these could lead to diseases or ocular problems. Konwledge of transport phenomena can help surgeons and specialists to identify problems more easily and cure the problems effectively. Further more, these phenomena have a great impact on drug delivery inside the eye. Therefore deep understanding of them makes investigation of different therapies easy and convenient. Consequently this understanding could lead to choose the best method and route of administration available. A precise model which is in consistence with the real human eye has been developed and the ocular... 

Willingness to communicate (WTC) has recently received great attention in the area of second language learning. Thus, the concept of willingness to communicate and what would influence the students' willingness to communicate gain importance. The current study employed a hybrid design to probe Iranian students' willingness to communicate. First, self-report questionnaires were administered to 431 language learners to collect quantitative data. Then, interviews were conducted with 41 randomly selected learners who had already completed the questionnaires. Pearson correlation coefficient, one-way ANOVA, independent t-test through SPSS .16 and the Structural Equation Model (SEM) analyses...