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    A new MCMC sampling based segment model for radar target recognition

    , Article Radioengineering ; Volume 24, Issue 1 , 2015 , Pages 280-287 ; 12102512 (ISSN) Hadavi, M ; Radmard, M ; Nayebi, M ; Sharif University of Technology
    Czech Technical University  2015
    Abstract
    One of the main tools in radar target recognition is high resolution range profile (HRRP). However, it is very sensitive to the aspect angle. One solution to this problem is to assume the consecutive samples of HRRP identically independently distributed (IID) in small frames of aspect angles, an assumption which is not true in reality. However, based on this assumption, some models have been developed to characterize the sequential information contained in the multi-aspect radar echoes. Therefore, they only consider the short dependency between consecutive samples. Here, we propose an alternative model, the segment model, to address the shortcomings of these assumptions. In addition, using a... 

    On Mixing Time for Some Markov Chain Monte Carlo

    , M.Sc. Thesis Sharif University of Technology Mohammad Taheri, Sara (Author) ; Alishahi, Kasra (Supervisor)
    Abstract
    Markov chains are memoryless stochastic processes that undergoes transitions from one state to another state on a state space having the property that, given the present,the future is conditionally independent of the past. Under general conditions, the markov chain has a stationary distribution and the probability distribution of the markov chain, independent of the staring state, converges to it’s stationary distribution.
    We use this fact to construct markov chain monte carlo, which are a class of algorithms for sampling from probability distributions based on constructing a markov chain that has the desired distribution as its stationary distribution. The state of a chain after a large... 

    Geometrical Structure of Neuron Morphology

    , Ph.D. Dissertation Sharif University of Technology Farhoodi, Roozbeh (Author) ; Fotouhi, Morteza (Supervisor)
    Abstract
    The tree structure of neuron morphologies has excited neuroscientists since their discovery in the 19-th century. Many theories assign computational meaning to morphologies, but it is still hard to generate realistic looking morphologies. There are a few growth models for generating neuron morphologies that correctly reproduce some features (e.g. branching angles) of morphologies, but they tend to fall short on other features. Here we present an approach that builds a generative model by extracting a set of human-chosen features from a database of neurons by using the naïve Bayes approach. Then by starting from a neuron with a soma we use statistical sampling techniques to generate... 

    Efficient fuzzy Bayesian inference algorithms for incorporating expert knowledge in parameter estimation

    , Article Journal of Hydrology ; Volume 536 , 2016 , Pages 255-272 ; 00221694 (ISSN) Rajabi, M. M ; Ataie Ashtiani, B ; Sharif University of Technology
    Elsevier 
    Abstract
    Bayesian inference has traditionally been conceived as the proper framework for the formal incorporation of expert knowledge in parameter estimation of groundwater models. However, conventional Bayesian inference is incapable of taking into account the imprecision essentially embedded in expert provided information. In order to solve this problem, a number of extensions to conventional Bayesian inference have been introduced in recent years. One of these extensions is 'fuzzy Bayesian inference' which is the result of integrating fuzzy techniques into Bayesian statistics. Fuzzy Bayesian inference has a number of desirable features which makes it an attractive approach for incorporating expert... 

    Polynomial segment model for radar target recognition using Gibbs sampling approach

    , Article IET Signal Processing ; Volume 11, Issue 3 , 2017 , Pages 285-294 ; 17519675 (ISSN) Hadavi, M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    Institution of Engineering and Technology  2017
    Abstract
    High resolution range profile (HRRP) is a widely noted tool in radar target recognition. However, its high sensitivity to the target's aspect angle makes it necessary to seek solutions for this problem. One alternative is to assume consecutive samples of HRRP identically and independently distributed in small frames of aspect angles, an assumption which is not true in reality. Based on this simplifying assumption, some models, such as the hidden Markov model, have been developed to characterise the sequential information contained in multi-aspect radar echoes. As a result, these models consider only the short dependency between consecutive samples. Considering such issues, in this study, the... 

    Use of Data Assimilation Methods for Multiphase Flow in Porous Media

    , M.Sc. Thesis Sharif University of Technology Najafi, Hossein (Author) ; Rajabi Ghahnavieh, Abbas (Supervisor) ; Bazargan, Hamid (Co-Supervisor)
    Abstract
    The importance of optimizing the extraction process of available resources increases each day due to the increasing energy consumption and the lack of energy resources. Oil and gas are one of the most important sources of energy. Although existing oil and gas resources are thought to be sufficient to meet the growing energy demand for the next few decades, given the non-renewable nature of these resources and the growing demand for oil and gas, it will become much harder to meet the future energy demand. Many existing oil fields are now in the process of maturing, and the discovery of large new oil fields is rare. As a result, new technologies must be used in the future to meet this demand,... 

    A brown dwarf orbiting an M-dwarf: MOA 2009-BLG-411L

    , Article Astronomy and Astrophysics ; Volume 547 , 2012 ; 00046361 (ISSN) Bachelet, E ; Fouqué, P ; Han, C ; Gould, A ; Albrow, M. D ; Beaulieu, J. P ; Bertin, E ; Bond, I. A ; Christie, G. W ; Heyrovský, D ; Horne, K ; Jørgensen, U. G ; Maoz, D ; Mathiasen, M ; Matsunaga, N ; McCormick, J ; Menzies, J ; Nataf, D ; Natusch, T ; Oi, N ; Renon, N ; Tsapras, Y ; Udalski, A ; Yee, J. C ; Batista, V ; Bennett, D. P ; Brillant, S ; Caldwell, J. A. R ; Cassan, A ; Cole, A ; Cook, K. H ; Coutures, C ; Dieters, S ; Dominik, M ; Dominis Prester, D ; Donatowicz, J ; Greenhill, J ; Kains, N ; Kane, S. R ; Marquette, J. B ; Martin, R ; Pollard, K. R ; Sahu, K. C ; Street, R. A ; Wambsganss, J ; Williams, A ; Zub, M ; Bos, M ; Dong, S ; Drummond, J ; Gaudi, B. S ; Graff, D ; Janczak, J ; Kaspi, S ; Kozłowski, S ; Lee, C. U ; Monard, L. A. G ; Muñoz, J. A ; Park, B. G ; Pogge, R. W ; Polishook, D ; Shporer, A ; Abe, F ; Botzler, C. S ; Fukui, A ; Furusawa, K ; Hearnshaw, J. B ; Itow, Y ; Korpela, A. V ; Ling, C.H ; Masuda, K ; Matsubara, Y ; Miyake, N ; Muraki, Y ; Ohnishi, K ; Rattenbury, N. J ; Saito, T ; Sullivan, D ; Sumi, T ; Suzuki, D ; Sweatman, W. L ; Tristram, P. J ; Wada, K ; Allan, A ; Bode, M. F ; Bramich, D. M ; Clay, N ; Fraser, S. N ; Hawkins, E ; Kerins, E ; Lister, T. A ; Mottram, C. J ; Saunders, E. S ; Snodgrass, C ; Steele, I. A ; Wheatley, P. J ; Bozza, V ; Browne, P ; Burgdorf, M. J ; Calchi Novati, S ; Dreizler, S ; Finet, F ; Glitrup, M ; Grundahl, F ; Harpsøe, K ; Hessman, F. V ; Hinse, T. C ; Hundertmark, M ; Liebig, C ; Maier, G ; Mancini, L ; Rahvar, S ; Ricci, D ; Scarpetta, G ; Skottfelt, J ; Southworth, J ; Surdej, J ; Zimmer, F ; Sharif University ot Technology
    2012
    Abstract
    Context. Caustic crossing is the clearest signature of binary lenses in microlensing. In the present context, this signature is diluted by the large source star but a detailed analysis has allowed the companion signal to be extracted. Aims. MOA 2009-BLG-411 was detected on August 5, 2009 by the MOA-Collaboration. Alerted as a high-magnification event, it was sensitive to planets. Suspected anomalies in the light curve were not confirmed by a real-time model, but further analysis revealed small deviations from a single lens extended source fit. Methods. Thanks to observations by all the collaborations, this event was well monitored. We first decided to characterize the source star properties... 

    The use of Bayesian nonlinear regression techniques for the modelling of the retention behaviour of volatile components of Artemisia species

    , Article SAR and QSAR in Environmental Research ; Volume 23, Issue 5-6 , 2012 , Pages 461-483 ; 1062936X (ISSN) Jalali Heravi, M ; Mani-Varnosfaderani, A ; Taherinia, D ; Mahmoodi, M. M ; Sharif University of Technology
    2012
    Abstract
    The main aim of this work was to assess the ability of Bayesian multivariate adaptive regression splines (BMARS) and Bayesian radial basis function (BRBF) techniques for modelling the gas chromatographic retention indices of volatile components of Artemisia species. A diverse set of molecular descriptors was calculated and used as descriptor pool for modelling the retention indices. The ability of BMARS and BRBF techniques was explored for the selection of the most relevant descriptors and proper basis functions for modelling. The results revealed that BRBF technique is more reproducible than BMARS for modelling the retention indices and can be used as a method for variable selection and...