Search for: model-complexity
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    Modeling topological characteristics of BitTorrent-like peer-to-peer networks

    , Article IEEE Communications Letters ; Volume 15, Issue 8 , August , 2011 , Pages 896-898 ; 10897798 (ISSN) Farzad, A ; Rabiee, H. R ; Sharif University of Technology
    This letter presents a complex network model for the BitTorrent; the most popular peer-to-peer network. Three important topological characteristics; (i) degree distribution, (ii) clustering coefficient and (iii) average path length of this network are analytically modeled. The analytical computations are confirmed by simulations. Moreover, the accuracy of the proposed model was confirmed by exploiting a BitTorrent simulator  

    Circuit model for mode extraction in lossy/lossless photonic crystal waveguides

    , Article Journal of the Optical Society of America B: Optical Physics ; Volume 29, Issue 1 , 2012 , Pages 170-177 ; 07403224 (ISSN) Habibi, N ; Khavasi, A ; Miri, M ; Mehrany, K ; Sharif University of Technology
    An approximate circuit model is proposed for mode extraction in two-dimensional photonic crystal waveguides. The dispersion equation governing the complex propagation constant of the photonic crystal waveguide is then related to the resonance condition in the proposed circuit model. In this fashion, a scalar complex transcendental equation is given for mode extraction. To avoid searching for the complex roots of the derived scalar dispersion equation, however, the real and imaginary parts of the sought-after propagation constant are extracted by using the physical resonance condition and its corresponding quality factor in the here-proposed circuit model, respectively. All the necessary... 

    Application of FEM simulation of chip formation to stability analysis in orthogonal cutting process

    , Article Journal of Manufacturing Processes ; Volume 14, Issue 3 , 2012 , Pages 188-194 ; 15266125 (ISSN) Mahnama, M ; Movahhedy, M. R ; Sharif University of Technology
    Elsevier  2012
    Models for chatter prediction in machining often use a mechanistic force model that calculate the force as the product of a material dependent cutting constant and chip area. However, in reality, the forces are the result of complex interaction between the tool and the chip, and are affected by many factors. The effects of these complex, and often nonlinear, factors on the machining dynamics may only be included in chatter prediction if the chip formation process is simulated concurrently with simulation of the machining dynamics. In this paper, finite element simulation of the chip formation process is combined with simulation of chatter dynamics and the inter-relationship between the chip... 

    Persian language understanding using a two-step extended hidden vector state parser

    , Article IEEE International Workshop on Machine Learning for Signal Processing, 18 September 2011 through 21 September 2011 ; September , 2011 , Page(s): 1 - 6 ; 9781457716232 (ISBN) Jabbari, F ; Sameti, H ; Hadi Bokaei, M ; Sharif University of Technology
    The key element of a spoken dialogue system is a spoken language understanding (SLU) unit. Hidden Vector State (HVS) is one of the most popular statistical approaches employed to implement the SLU unit. This paper presents a two-step approach for Persian language understanding. First, a goal detector is used to identify the main goal of the input utterance. Second, after restricting the search space for semantic tagging, an extended hidden vector state (EHVS) parser is used to extract the remaining semantics in each subspace. This will mainly improve the performance of semantic tagger, while reducing the model complexity and training time. Moreover, the need for large amount of data will be... 

    Implementation of phase change thermodynamic probability for unsteady simulation of cavitating flows

    , Article International Journal for Numerical Methods in Fluids ; Volume 66, Issue 12 , 2011 , Pages 1555-1571 ; 02712091 (ISSN) Asnaghi, A ; Jahanbakhsh, E ; Seif, M. S ; Sharif University of Technology
    The aim of this work is to investigate the non-equilibrium effects of phase change in cavitating flows. For this purpose, the concept of phase change thermodynamic probability is used along with homogeneous model to simulate two-phase cavitating flows. For simulation of unsteady behaviors of cavitation, which have practical applications, unsteady PISO algorithm based on the non-conservative approach is utilized. For multi-phase simulation, single-fluid Navier-Stokes equations, along with the volume fraction transport equation, are employed. In this paper, phase change thermodynamics probabilities and cavitation model is briefly summarized. Thus, derivation of the cavitation model, starting... 

    Mechanical behavior of electrical hollow composite post insulators: Experimental and analytical study

    , Article Engineering Structures ; 2015 , Pages 129-141 ; 01410296 (ISSN) Epackachi, S ; Dolatshahi, K. M ; Oliveto, N. D ; Reinhorn, A. M ; Sharif University of Technology
    Elsevier Ltd  2015
    Electrical post insulators are important components of electrical substations since any type of failure in such insulators leads to the breakdown of the local network. Although the electrical substations are often in service condition, any horizontal excitation due to the earthquake, or any extreme event, may cause lateral deformation and damage to the post insulators. Hollow composite post insulators, a new and evolving technology, have a very complex mechanical behavior due to their materials and connections. To date, the design of such post insulators has been based on the limited test results available in the literature. Most of experiments have been conducted on small-scale specimens... 

    Statistical error analysis for dimensional control in automotive body assembly process

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 3 , 2010 , Pages 329-334 ; 9780791849170 (ISBN) Khodaygan, S ; Movahhedy, M. R ; Mirabolghasemi, A ; Zendehbad, M ; Moradi, H ; Sharif University of Technology
    In mechanical assemblies, the performance, quality, cost and assemblability of the product are significantly affected by the geometric errors of the parts. This paper develops the statistical error analysis approach for dimensional control in automotive body multi-station assembly process. In this method, the homogeneous transformation matrices are used to describe the location and orientation of part and assembly features and the small homogeneous transformation matrices are used to model the errors. In this approach, the effective errors in automotive body assembly process are classified in three categories: manufacturing errors (dimensional and geometric tolerances), locating errors... 

    Modeling performance of hadoop applications: A journey from queueing networks to stochastic well formed nets

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 14 December 2016 through 16 December 2016 ; Volume 10048 LNCS , 2016 , Pages 599-613 ; 03029743 (ISSN) ; 9783319495828 (ISBN) Ardagna, D ; Bernardi, S ; Gianniti, E ; Karimian Aliabadi, S ; Perez Palacin, D ; Requeno, J. I ; Carretero, J ; Nakano, K ; Ko, R ; Mueller, P ; Garcia Blas, J ; Sharif University of Technology
    Springer Verlag  2016
    Nowadays, many enterprises commit to the extraction of actionable knowledge from huge datasets as part of their core business activities. Applications belong to very different domains such as fraud detection or one-to-one marketing, and encompass business analytics and support to decision making in both private and public sectors. In these scenarios, a central place is held by the MapReduce framework and in particular its open source implementation, Apache Hadoop. In such environments, new challenges arise in the area of jobs performance prediction, with the needs to provide Service Level Agreement guarantees to the enduser and to avoid waste of computational resources. In this paper we... 

    A novel model for complex permittivity of glass for propagation modeling in millimeter-wave band

    , Article Mediterrannean Microwave Symposium, MMS 2009 ; 2009 ; 9781424446643 (ISBN) Arvani, F ; Shishegar, A. A ; Sharif University of Technology
    In radio channels modelings, the phases and amplitudes of the rays undergo some modifications when they are reflected from or transmitted through a particular material. These reflection and transmission coefficients make use of the electrical properties of the materials, thus, it is essential to know the values of the relative dielectric constant and of the conductivity or the loss tangent of the materials that appear in the propagation environments. In this paper, a theoretical model based on the inter-molecule interactions, has been developed and used to estimate the dielectric parameters of glass. ©2009 IEEE  

    An enhanced neural network model for predictive control of granule quality characteristics

    , Article Scientia Iranica ; Volume 18, Issue 3 E , 2011 , Pages 722-730 ; 10263098 (ISSN) Neshat, N ; Mahloojifl, H ; Kazemi, A ; Sharif University of Technology
    An integrated approach is presented for predicting granule particle size using Partial Correlation (PC) analysis and Artificial Neural Networks (ANNs). In this approach, the proposed model is an abstract form from the ANN model, which intends to reduce model complexity via reducing the dimension of the input set and consequently improving the generalization capability of the model. This study involves comparing the capability of the proposed model in predicting granule particle size with those obtained from ANN and Multi Linear Regression models, with respect to some indicators. The numerical results confirm the superiority of the proposed model over the others in the prediction of granule...