Sharif Digital Repository

Structural and system reliability of a typical jet vane (JV) thrust vector control (TVC) subsystem subjected to stochastic loadings is investigated. Jet vane TVC (JVTVC) is used in many aerospace liquid and solid propulsion systems. For the purpose of this work, JVTVC structural reliability of a solid rocket propulsion system is computed using an explicit closed-form limit state function. The JV structure is influenced by the internal ballistic loads emanating out of the solid rocket propulsion internal ballistic, whose performance is modeled via a one-dimensional uniform flow assumption at the engine steady operating condition. Subsequently, JV structural reliability is predicted using the... 

In order to improve the communications inside and outside the enterprise, efficient utilization of enterprise capitals and make improvements in the services and products of enterprise, many enterprises have turned to use enterprise resource planning (ERP) systems. On the other hand, the more the role of knowledge assets in enterprises grows, the higher the position of knowledge management (KM) in the enterprises becomes and it gradually becomes fundamental to success. The role of knowledge management in today’s knowledge-based world has attracted considerable attention to this topic in industry and academia. The use of ERP and knowledge management in enterprises for the continuation of... 

As the role of IT becomes more eminent, IT management frameworks become more demanding. Although each of the IT management frameworks focuses on a particular part of this wide scope, implementing frameworks individually, wastes budget and time and results in incompatible or redundant artefacts. The question we want to answer in this research is if a comprehensive IT management methodology could be implemented to provide all the effective results of different IT management frameworks, yet to avoid redundancies and costs of implementing each framework separately. In this study, the integration of the ITIL framework as the most well-known IT service management framework, the COBIT framework as... 

Information technology (IT) is a vital part of every organization today. Not only the products and services are based on IT, but also IT is necessary for supporting the organization's processes. As the role of IT becomes more eminent, IT management frameworks become more demanding. IT management guarantees the optimal utilization of IT resources within an organization. Although each of the IT management frameworks focuses on a particular part of this wide scope, implementing frameworks individually, wastes budget, and time results in incompatible or redundant artifacts. The question we want to answer in this research is if a comprehensive IT management methodology could be implemented to... 

In this work, the effect of the accumulative roll bonding (ARB) process on the microstructure, mechanical properties, and corrosion characteristics of AZ31 Mg alloy was investigated. First, the ARB process up to 3 cycles at 350 °C was applied to annealed AZ31 Mg alloy sheets. Then, all samples were characterized via microstructure observations, mechanical investigations, and also, electrochemical analyses, and immersion tests in simulated body fluid (SBF) solution. In addition, the L929 cell line was used to evaluate the cytotoxicity of the samples. The obtained results showed that after the third ARB cycle, the average grain size in the annealed sample decreased from ~ 14 to ~ 3 µm. Some... 

A new algorithm named random particle optimization algorithm (RPOA) for local path planning problem of mobile robots in dynamic and unknown environments is proposed. The new algorithm inspired from bacterial foraging technique is based on particles which are randomly distributed around a robot. These particles search the optimal path toward the target position while avoiding the moving obstacles by getting help from the robot's sensors. The criterion of optimal path selection relies on the particles distance to target and Gaussian cost function assign to detected obstacles. Then, a high level decision making strategy will decide to select best mobile robot path among the proceeded particles,... 

Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's... 

Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images... 

In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p