Sharif Digital Repository

Residential location choice is one of the most important decisions that households should make. This decision has many effects on household's travel patterns and urban built environment. Considering predetermined residential locations is one of the weaknesses of these models. Joint modelling of residential and work location choices is a solution to this problem. So far, multinomial logit, nested logit and mixed logit are the structures that have been used for this joint modeling. Independence from irrevelant alternatives, forcing sequential structure and complicated calculations in large dimension problems are respectively weaknesses of mentioned structures. In this researsh a copula based... 

This research studies multi-objective master production schedule (MPS) and advanced order commitment (AOC) in two-stage supply chains. Simulation-based experimental analysis evaluates the impact of environmental and MPS design factors on schedule cost and instability. The results provide insight into multi-objective MPS design considerations through rolling schedule policies. The study reveals that the manufacturer's production smoothness utility coefficient and its interaction with other experimental factors considerably impact the system's performance. In addition, it introduces a simulation framework with embedded mixed integer programming models that could be used as a framework for... 

A lot of researchers have suggested that ostracism as a disruptive behavior, has been widespread among organizations and a lot of researches has been studied its consequences in recent years.This research studies ostracism’s consequences and proposes a theoretical model of organizational ostracism with affective commitment, intention to turnover and organizational dependability as one of affective commitment’s antecedents. This study has been done on 231 employees of three medium knowledge-based organizations to identify the effects of ostracism on employee’s turnover behavior. Results show that ostracism, due to its impact on the affective commitment of ostracized peoples, reduces this type... 

Purpose: The purpose of this thesis was to identify active followership behaviors of followers in interaction with autocratic leaders. An active follower thinks critically and takes initiatives.
Design: Given that Followership literature is still in its infancy, the research questions needed a qualitative approach, in this case grounded theory. In total, 19 top- & middle-level managers were interviewed as leaders and followers, accordingly, using semi-structured interviews.
Findings: 4 categories of active followership were found, each having 3-4 specific behaviors. These categories are: precautionary behaviors, facilitating behaviors, modificating behaviors, and consolidating... 

There is no consensus definition of cynicism in literature. In this research different definitions of cynicism have been investigated and two concept of organizational cynicism and trait cynicism have been taken into consideration. Organizational cynicism is a negative attitude that is prevalent in employees. In literature some antecedents and consequences of organizational cynicism have been suggested. It seems organizational cynicism can be investigated in a more complex relations. The focus of this research is on the mediating role of organizational cynicism on the likely relations between politics perception and organizational commitment. That is to say organizational cynicism can... 

Feedback-seeking behavior is the effort of employees to get feedback from the environment and around people about their performance. One of the research questions in this field is about the factors that increase this behavior in the staff. Transformational leadership as a leadership style, stimulates, and motivates followers to achieving desirable operational results. In addition, an important consequence of this style could be increasing the followers' capabilities. Transformational leaders are trying to empower their followers to build and empower them, which can provide a strong incentive for employees to move and grow, which may encourage them to have a better performance. One of... 

Although existing literature on organizational culture and its change process contains meaningful and rich theories but our studies show that there is no perfect and detailed framework on linking organizational culture change and corporate entrepreneurship culture. In addition to that, Gamification –defined as taking the game design elements into non-game contexts– is a fruitful and academically rich research area. Fortunately an idea proposed recently to explain a method for enhancements in organizational culture in general, and in corporate entrepreneurship culture in particularby Yavari and Jafarian based on using game mechanisms. In their paper "A Gamification-Based Method for Corporate... 

Considering the importance of biocompatibility of implantable prothesis’, metallic alloys have weaker corrosion resistance than ceramics. In order to extend usage of nanomaterials to improve the bio-properties of materials, Nano-structured ceramic coatings are being suggested to improve corrosion resistance and biocompatibility of prosthesis. Meanwhile, very good properties of TiN, such as corrosion resistance and mechanical properties as a thin film coating are undeniable. In this study, TiN and Ti2N thin film were deposited on Ti-based substrate, using PVD and Magnetron sputtering at different argon to nitrogen ratio. The crystal structure of the films was examined using Grazing XRD... 

Modeling and performance evaluation of the real time distributed systems is a significant problem. Stochastic activity network is one of the high level models used for this purpose. This network is an extension of generalized stochastic Petri net which is more powerful and flexible than other Petri net extensions. Checking the satisfiability of properties such as performance, dependability and user's expected properties is considerable in these models. Thus, using the approaches and generating modeling and model checking tools with the mentioned purpose is attractive. A model checker automatically checks the correctness of the system behaviors as properties against the model by getting the... 

Processalgebras,acompositionalmethodofmodelingsystemsandtheirbehavioural features, have been a key instrument in the verification of systems and have strived to completely span a whole spectrum of verification solutions for diverse areas of applications. In this sense, modeling and analysis of the performance metrics in a Mobile Ad hoc Network (MANET) in contrast to other systems, face different challenges which demand different strategies. Hence, our goal here is to model and analyze the qualitative and quantitative aspects of MANETs within one especially designed compositional framework. To achieve this framework, we will first have a look at the different methods which aim to model MANETs... 

In recent years, we have seen the proliferation of real-time and time-dependent systems. They have increased both in number and in complexity. Due to their increasing complexity, we need to model them and become assured of their correctness. Several formalisms have been devised for time-dependent systems. They include timed automaton and timed extensions of Petri nets. Our focus is on timed extension of activity networks and its model checking. Activity networksare powerful formalisms which allow designers to model the system in a natural, small and conceivable manner. This way, timed extension of activity networks can greatly help modelers. In this thesis, we propose a method to specify the... 

Blackhole and grayhole attacks have been become two of the major security concerns in mobile ad hoc networks (MANET). To achieve security in MANETs, a lot of mechanisms had been proposed by now. Using intrusion detection systems(IDSs) is one of the important mechanism to reach this goal. Thus, a well-known IDS was chosen and analyzed in this thesis. Furthermore, a collaborative bayesian filter approach for this intrusion detection system was proposed to enhance its performance. Then the performance of this approach was considered. This intrusion detection system was analyzed using stochastic modeling like continuous time markov chain(CTMC), stochastic reward net(SRN) and stochastic... 

For increasing safety of driving, intelligent vehicles in vehicular ad hoc networks (VANETs) communicate with each other by sending announcements. The existence of a system that guarantees the trustworthiness of these announcements seems necessary. The proposed system generating announcements should be preserved from internal and external attackers that attempt to send fake messages. In this thesis, we use a group-based endorsement mechanism based on threshold signatures against internal attackers. We choose NTRUSign as a public key cryptosystem for implementing the Public Key Infrastructure (PKI) for decreasing signature generation and verification times. This approach optimizes the network... 

The daily growth of cloud computing usage for data based applications and Internet services has caused many challenges in the sense of storage cost, data access performance, QoS provision such as availability, scalability, pay-as-you-go model conformation and etc. Data replication is one of the most important mechanisms for data management in distributed systems. It creates some replicas of data and distributes them to the network. The number of replicas, the time for creating a new replica, the way of their distribution among the nodes and replica replacement strategy in the case of storage unavailability are some important challenges in data replication context. Replication is extensively... 

With the growth of spreading information across social networks, users face with many options. More specifically, try to find out information is so troublesome in this context.In response to this problem, recommender systems aim at providing suggestions of interest for end-users. Also, we see many social networks in real-life which have the potential to be used in a variety of recommender systems. In the bipartite networks of users and items weighted edges is formed between each user and each item in the training set. On the other hand, developing a recommender system that takes into account the social network of the user improves the accuracy of traditional recommender systems.The purpose...