Sharif Digital Repository

Drought is one of the most serious hazards that has more effect on human societies than the others. Scentific researches have important roles in drought planning and management of water resources, especially in time of crisis and predicted big event by the event that the crisis management turnover. The main objective of this research is to develop an approach to analyze the spatial patterns of meteorological droughts based on annual precipitation data in Iran. By using a nonparametric spatial analysis neural network algorithm, the normalized and standardized precipitation data are classified into certain degrees of drought severity (extreme drought, severe drought, mild drought, and... 

The role of context for better decision-making has been a topic of significant research effort over the years. Context-aware systems are able to adapt their operations to the current context without explicit user intervention and thus aim at increasing usability and effectiveness by taking environmental context into account. These systems exploit information about the context of use, such as the location, tasks and preferences of the user, in order to adapt their behavior in response to change operating environments and user requirements. Pervasive computing sketches a pleasant vision for future computing environments that computing power is present anywhere anytime. Utilizing context,... 

Aromatic aldehydes and ketones are readily acetalized or ketalized under microwave irradiation in the presence of water as a solvent  

A four-step synthetic strategy was applied to achieve novel methacrylic monomers. 5-Norbornene-2,2-dimethanol was prepared from a Diels–Alder reaction of cyclopentadiene and acrolein, followed by the treatment of the adduct with an HCHO/KOH/MeOH solution. The resulting 1,3-diol (1) was then acetalized with different aromatic aldehydes having OH groups on the ring to produce four spiroacetal derivatives. The reaction of methacryloyl chloride with the phenolic derivatives led to four new methacrylic monomers that were identified spectrochemically (mass, FTIR, 1H-NMR, and 13C-NMR spectroscopy). Free radical solution polymerization was used to prepare novel spiroacetal–norbornene containing... 

Several methodologies with their own characteristics have been proposed in the area of agent-oriented software engineering. Consequently, deciding which methodology to select in a specific case is an important issue and it can lead to decrease software development cost and effort. Thus, importance of evaluation of methodologies will be highlighted in choosing the appropriate methodology in the development process of an application. It can also help in developing new methodologies and improving existing ones. In this paper, we are going to provide an evaluation framework of agent oriented methodologies. To demonstrate the usage of the suggested framework, it is applied to evaluate two... 

Mobile Ad hoc Networks (MANETs) are based on the assumption of that all participants in the network cooperate and forward packets towards the destinations. However, due to the limited nature of the nodes' resources, a node may decide not to cooperate to save its resources while still using the network. Such behavior of some nodes may degrade the whole network performance. To cope with such a situation, we propose a Stable path, Low overhead, Truthful, and Cost efficient (SLTC) routing protocol which stimulates nodes to cooperate. SLTC utilizes the game theoretic notion of mechanism design. To the best of our knowledge, SLTC is the first protocol attaining the message complexity of O(nd),... 

In New applications of Mobile Ad hoc Networks (MANETs), nodes may decide not to cooperate in routing protocols in order to save their limited resources while still using the network to relay their own traffic. Exhibiting such a selfish behavior by even a few nodes may degrade network performance and other cooperating nodes may find themselves unfairly loaded. To cope with such a situation, we propose a Stable path, Low overhead, Truthful, and Cost efficient (SLTC) routing protocol which stimulates nodes to cooperate and act truthfully by utilizing the game theoretic notion of mechanism design. To the best of our knowledge, SLTC is the first protocol attaining the message complexity of O(nd),... 

A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition  

Prevention of unauthorized access to services in mobile ad hoc networks is a more sophisticated problem than access control in other networks, due to interconnection facilities and lack of any fixed network infrastructure in such networks. Therefore regarding the nature of these networks, controlling access to services should be in a decentralized manner providing good performance and preserving network security. In this paper, we propose a decentralized Cooperation Enforcement Based Access Control (CEBAC) framework for mobile ad hoc networks. CEBAC comprises several groups of Service Authorizers, each issuing Credentials for access to a specific kind of services. The User Authorization for... 

Applications in pervasive computing environment exploit information about the context of use, such as the location, tasks and preferences of the user, in order to adapt their behavior in response to changing operating environments and user requirements. Utilizing context with aid of ontology in data and model, decision support systems can provide better and more desirable support to their users. The effects and advantages of exploiting ontology in user modeling and DSS is discussed. We propose a framework of a Ontology-based Decision Support System (O2DSS), including ontology in model base, database and their advantages. © 2008 IEEE  

Due to the shortcomings of the traditional construction project management system, there is a feeling among those involved in this industry that new tools and approaches should be used to facilitate simple and complex operations. On the contrary, there is no integrated database for all construction sectors, and of course the relationship between these sectors is a major problem for any construction project. The technology and tool that overcomes many of these shortcomings is BIM technology. This paper seeks to identify all the challenges that hinder the successful implementation of BIM and determine important challenges based on Z-DEMATEL-ISM Hybrid approaches. The DEMATEL method is used to...