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data-models
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Evaluation of Data Models for the Purpose of Storage and Retrieval of Data and Knowledge Contained in Social Networks
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
Online Social Networks have become indispensable platforms to model social interactions and for the retrieval of knowledge based on economical, political, social and ... criteria. The importance of social networks for such uses stems from the vast amount of social data that it gathers for use by researchers. Aside from it’s impact on the field of social network analysis, the ever-growing use of social media by users has added even more importance to social network data as it contains a history of the users virtual life. Unfortunately research on proposals to support the management of this vast amount of data, whether for the conceptual modeling of social data or to provide a uniform modeling...
Improvement of Software Quality Attributes based on the Properties of Relational and Non-relational data Models
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
With the growing use of computer systems, especially in form of web applications, software development and customer requirements has become more complex. Modern computer systems are supposed to achieve non-functional requirements in addition to functional requirements. Non-functional requirements are also called software quality attributes. One of the most important quality attributes for today's software systems is performance. Today’s softwares due to the growing number of their users, need more efficiency than ever to properly meet the performance request.Storage components and databases are the most important factors in causing performance bottlenecks in web applications. Most of...
Long Term Effective Factors on House Price of Metropolises of Iran
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
The notable share of housing sector in GDP (approximately five percent) shows this sector’s relation with macroeconomic activities. On the other hand, House as an asset leads housing sector to be affected by monetary and fiscal variables. A dynamic panel data was used in this study to evaluate the relations between housing sector and some macroeconomic variables in metropolises of Iran. As results show, in long term growth of liquidity, GDP per capita and sharp ratio have positive effects, and land per capita has negative effect on housing price in metropolises of Iran. Price increases have not been equal in different cities. Inequality of land price between metropolises and between...
Structural Model of Real Exchange Rate with Emphasis on the Terms of Trade Effect
, M.Sc. Thesis Sharif University of Technology ; Abedini, Javad (Supervisor)
Abstract
Despite the relative weakness of exchange rate structural models in determination short term fluctuations, observations show that real exchange rate respond to some fundamental economic variables. Due to the growing foreign sector of national economies, recent studies pay special attention to the impact of terms of trade on currency exchange rate. In this study, a structural model of the real exchange rate between the 70 currencies and during the period 1980-2010 has been developed in the context of panel data. Empirical micro-founded model are based on theoretical general equilibrium. Important features of such study are stationary of variables and causality test. Determination the effect...
A Z approach to formalization and validation of ORM models
, Article Communications in Computer and Information Science, 20 July 2011 through 22 July 2011 ; Volume 194 CCIS , July , 2011 , Pages 513-526 ; 18650929 (ISSN) ; 9783642226021 (ISBN) ; Mirian Hosseinabadi, S. H ; Springer ; Sharif University of Technology
2011
Abstract
In this paper we present a formal definition of the basic concepts and notations of Object Role Modeling (ORM) using the Z formal specification language. Most of ORM concepts such as object and relationship types, value types, objectification, reference schemes, sub-types, roles and constraints such as uniqueness, mandatory, cardinality, subset, equality, exclusive and ring constraints are specified formally. Population is specified as objects, relationships and roles instances. These are specified using Z axioms and diagram instances are specified using Z schemas. This would enable validation and reasoning on the formal properties of ORM diagrams such as detecting constraint contradictions...
On optimal online algorithms for energy harvesting systems with continuous energy and data arrivals
, Article IEEE Wireless Communications Letters ; Volume 6, Issue 3 , 2017 , Pages 286-289 ; 21622337 (ISSN) ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Energy harvesting (EH) has been developed to extend the lifetimes of energy-limited communication systems. In this letter, we consider a single-user EH communication system, in which both of the arrival data and the harvested energy curves are modeled as general functions. Unlike most of the works in the field, we investigate the online algorithms which only acquire the causal information of the arrival data and the harvested energy processes. We study how well the optimal online algorithm works compared with the optimal offline algorithm, and thus our goal is to find the lower and upper bounds for the ratio of the completion time in the optimal online algorithm to the optimal offline...
Introducing a roadmap to implement the universal manufacturing platform using axiomatic design theory
, Article International Journal of Manufacturing Research ; Volume 5, Issue 2 , 2010 , Pages 252-269 ; 17500591 (ISSN) ; Houshmand, M ; Sharif University of Technology
2010
Abstract
In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. To realise interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i utilising interfaces ii utilising neutral formats. Standard for the Exchange of Product data (STEP) plays a significant role as a neutral data model to integrate design, manufacturing and other activities in product life cycle. To implement a Universal Manufacturing Platform (UMP), a systematic roadmap is required. The current paper proposes such a roadmap using the methodology of Axiomatic Design (AD)
Reliability analysis of rotating cracked blade using modal data
, Article 2017 International Conference on Mechanical, System and Control Engineering, ICMSC 2017, 19 May 2017 through 21 May 2017 ; 2017 , Pages 78-84 ; 9781509065295 (ISBN) ; Zabihollah, A ; Behzad, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
This paper deals with vibrational behaviors of blades with cracks which are key components in rotating machines. However, since modelling and analysis of real blade is a complex problem, a simplified cantilever beam with both chordwise (in X-Y plane) and flapwise (in X-Z plane) motion are modeled instead. Finite Element Method (FEM) is used to model beam and to investigate its natural frequencies with a crack. Finally a limit function using modal data is developed and reliability analysis of beam model is performed. © 2017 IEEE
Model-data interaction in groundwater studies: Review of methods, applications and future directions
, Article Journal of Hydrology ; Volume 567 , 2018 , Pages 457-477 ; 00221694 (ISSN) ; Ataie Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
Elsevier B.V
2018
Abstract
We define model-data interaction (MDI) as a two way process between models and data, in which on one hand data can serve the modeling purpose by supporting model discrimination, parameter refinement, uncertainty analysis, etc., and on the other hand models provide a tool for data fusion, interpretation, interpolation, etc. MDI has many applications in the realm of groundwater and has been the topic of extensive research in the groundwater community for the past several decades. This has led to the development of a multitude of increasingly sophisticated methods. The progress of data acquisition technologies and the evolution of models are continuously changing the landscape of groundwater...
An Object-Oriented Framework for Integration of Robot and CNC Machines in Flexible Manufacturing Systems
, M.Sc. Thesis Sharif University of Technology ; Hooshmand, Mahmoud (Supervisor)
Abstract
A flexible manufacturing system (FMS) is a manufacturing system in which there is the capability of handling the variations in product's features which is the result of ever-changing customer demands. The flexibility attributes to utilize the resources in a more effective manner. On the other hand, the control of such systems would become more complicated. FMS needs CNC machines and robots and other resources for establishing the flexibility and enhancing the efficiency of the whole system. Also it needs to integrate the resources to reach flexibility. In order to reach this goal, an integrator framework is proposed in which the machining data of CNC machine is received through a STEP-NC...
Using diagenetic processes in facies modeling of a carbonate reservoir
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 35, Issue 6 , Jan , 2013 , Pages 516-528 ; 15567036 (ISSN) ; Dehghan, A. A ; Lakzaie, A ; Sharif University of Technology
2013
Abstract
The construction of a facies model could be employed as a conditional data for any property simulation that results in a more reliable reservoir characterization in further steps. In this study, an Iranian gas reservoir with six wells was studied to determine the 3D reservoir facies model. Fifteen reservoir facies were first detected along one of the wells with detailed core and thin section descriptions. Due to the significant difference between the core and log data resolution, facies were clustered into four major groups regarding the digenetic processes and petrophysical lithofacies properties (permeability and porosity). The lithofacies specification effect on petrophysical properties...
LAYMOD: A layered and modular platform for CAx product data integration based on the modular architecture of the standard for exchange of product data
, Article International Journal of Computer Integrated Manufacturing ; Volume 25, Issue 6 , 2012 , Pages 473-487 ; 0951192X (ISSN) ; Valilai, O. F ; Sharif University of Technology
2012
Abstract
Nowadays, companies strive to survive in a competitive global environment. Reduction of product development cycle plays a major role in market penetration and cost reduction. To speed up product development/modifications, it is suggested to adopt a collaborative product development approach. Collaborative design and manufacture requires an integrated platform to support related CAx product data models. To integrate CAx product data, a number of solutions are proposed. The most successful solution is adopting the STandard for Exchange of Product Data (STEP). In the course of the STEP standard structure and procedure development, two approaches can be recognised: classical and modular. The...
Optimization assisted asphaltene deposition modeling in porous media during a natural depletion scheme
, Article Petroleum Science and Technology ; Volume 30, Issue 9 , Mar , 2012 , Pages 958-965 ; 10916466 (ISSN) ; Bagheri, M ; Kharrat, R ; Ghazanfari, M ; Ghotbi, C ; Sharif University of Technology
2012
Abstract
Changes in thermodynamic properties such as pressure, temperature, and composition may result in asphaltene precipitation and deposition in porous media. In addition, asphaltene deposition can cause wettability alteration, permeability reduction, and ultimately a decrease in the productivity of a reservoir. Natural depletion is one of the most common processes of asphaltene deposition in which pressure changes destabilize the dissolved asphaltene in the oil and settle them onto the rock surface. In this work, natural depletion experiments in consolidated core samples were performed under simulated reservoir conditions to obtain reliable data and analyze the asphaltene deposition mechanisms....
LAYMOD; a layered and modular platform for CAx collaboration management and supporting product data integration based on STEP standard
, Article World Academy of Science, Engineering and Technology ; Volume 78 , 2011 , Pages 625-633 ; 2010376X (ISSN) ; Houshmand, M ; Sharif University of Technology
2011
Abstract
Nowadays companies strive to survive in a competitive global environment. To speed up product development/modifications, it is suggested to adopt a collaborative product development approach. However, despite the advantages of new IT improvements still many CAx systems work separately and locally. Collaborative design and manufacture requires a product information model that supports related CAx product data models. To solve this problem many solutions are proposed, which the most successful one is adopting the STEP standard as a product data model to develop a collaborative CAx platform. However, the improvement of the STEP's Application Protocols (APs) over the time, huge number of STEP...
Viral cascade probability estimation and maximization in diffusion networks
, Article IEEE Transactions on Knowledge and Data Engineering ; 28 May , 2018 ; 10414347 (ISSN) ; Beigy, H ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
People use social networks to share millions of stories every day, but these stories rarely become viral. Can we estimate the probability that a story becomes a viral cascade If so, can we find a set of users that are more likely to trigger viral cascades These estimation and maximization problems are very challenging since both rare-event nature of viral cascades and efficiency requirement should be considered. Unfortunately, this problem still remains largely unexplored to date. In this paper, given temporal dynamics of a network, we first develop an efficient viral cascade probability estimation method, VICE, that leverages an special importance sampling approximation to achieve high...
In-flight estimation of time-varying aircraft center of gravity position based on kinematics approach
, Article Journal of Aircraft ; Volume 55, Issue 5 , 2018 , Pages 2037-2049 ; 00218669 (ISSN) ; Saghafi, F ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2018
Abstract
In-flight aircraft center of gravity (COG) position estimation is investigated in this study based on the kinematics approach. The Quad-M basics of system identification requirements are carefully investigated for time-invariant and time-varying COG estimation during airdrop maneuver as a case study that contains both conditions. Modeling and simulation of airdrop maneuver are employed to prepare the required maneuver and measurement data for this investigation. The relative-acceleration equation, as a model structure, and parameter modeling of time-varying COG location and acceleration are introduced into the system identification and parameter estimation framework. The Kalman filter method...
Deep private-feature extraction
, Article IEEE Transactions on Knowledge and Data Engineering ; 2018 ; 10414347 (ISSN) ; Taheri, A ; Shamsabadi, A. S ; Katevas, M ; Haddadi, H ; Rabiee, H. R. R ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
We present and evaluate Deep Private-Feature Extractor (DPFE), a deep model which is trained and evaluated based on information theoretic constraints. Using the selective exchange of information between a user's device and a service provider, DPFE enables the user to prevent certain sensitive information from being shared with a service provider, while allowing them to extract approved information using their model. We introduce and utilize the log-rank privacy, a novel measure to assess the effectiveness of DPFE in removing sensitive information and compare different models based on their accuracy-privacy trade-off. We then implement and evaluate the performance of DPFE on smartphones to...
Direction-of-arrival estimation for temporally correlated narrowband signals
, Article IEEE Transactions on Signal Processing ; Volume 57, Issue 2 , 2009 , Pages 600-609 ; 1053587X (ISSN) ; Nayebi, M. M ; Aref, M. R ; Sharif University of Technology
2009
Abstract
Signal direction-of-arrival (DOA) estimation using an array of sensors has been the subject of intensive research and development during the last two decades. Efforts have been directed to both, better solutions for the general data model and to develop more realistic models. So far, many authors have assumed the data to be independent and identically distributed (i.i.d.) samples of a multivariate statistical model. Although this assumption reduces the complexity of the model, it may not be true in certain situations where signals show temporal correlation. Some results are available on the temporally correlated signal model in the literature. The temporally correlated stochastic Cramér-Rao...
Dealing with feature interactions for prismatic parts in STEP-NC
, Article Journal of Intelligent Manufacturing ; Volume 20, Issue 4 , 2009 , Pages 431-445 ; 09565515 (ISSN) ; Xu, X ; Lazcanotegui, I ; Sharif University of Technology
2009
Abstract
Determining the precedence of machining features is a critical issue in feature-based process planning. It becomes more complex when geometric interaction occurs between machining features. STEP-NC, the extension of STEP (ISO 10303) standard developed for CNC controllers, is a feature-based data model. It represents all the geometric and topological product data minus feature interactions. In this paper, machining precedence of interactive and non-interactive STEP-NC features is discussed. Local and global precedence of machining features are defined on the basis of geometric constraints, such as geometric interaction of features and feature approach face and technological constraint such as...
A time warping speech recognition system based on particle swarm optimization
, Article 2nd Asia International Conference on Modelling and Simulation, AMS 2008, Kuala Lumpur, 13 May 2008 through 15 May 2008 ; 2008 , Pages 585-590 ; 9780769531366 (ISBN) ; Razzazi, F ; Rahmani, A. M ; Gharan, S. O ; Sharif University of Technology
2008
Abstract
In this paper, dynamic programming alignment is replaced by a particle swarm optimization (PSO) procedure in time warping problem. The basic PSO is a very slow process to be applied to speech recognition application. In order to achieve a higher performance, by inspiring of PSO optimization methodology, we introduced a PSO Inspired Time warping Algorithm (PTW) that significantly increase the computational performance of time warping in alignments of long length massive data sets. As a main enhancement, a pruning strategy with an add-in controlling threshold is defined in PTW that causes a considerable reduction in recognition time, while maintaining the system accuracy comparing to DTW. ©...