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    Coding advantage decomposition inequality for the space-frequency block codes

    , Article IET Communications ; Vol. 8, Issue. 4 , 2014 , Pages 500-507 ; ISSN: 17518628 Morsali, A ; Tofigh, S ; Mohammadian, Z ; Talebi, S ; Sharif University of Technology
    Abstract
    In this study, the authors present a new criterion which can be used to decompose the coding advantage (CA) of space-frequency block codes (SFBCs). The proposed decomposition separates the CA into two parts, called precoder-CA and channel-CA. The precoder-CA represents the effects of the precoder and the signal constellation, and can be used in the design of the precoder of SFBCs. The channel-CA, on the other hand, gives an indication of the effects of the channel characteristics, and can be utilised for optimising the permutation parameter. The authors have shown that the proposed decomposition method leads to a lower computational complexity for the optimisation procedure compared with the... 

    Performance analysis of asynchronous optical code division multiple access with spectral-amplitudecoding

    , Article IET Communications ; Vol. 8, Issue. 6 , April , 2014 , pp. 956-963 ; ISSN: 17518628 Sedaghat, M. A ; Muller, R. R ; Marvasti, F ; Sharif University of Technology
    Abstract
    In this study, the performance of a spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system in the asynchronous regime is evaluated using a Gaussian approximation of the decision variable for codes with fixed cross-correlation used in SAC-OCDMA systems. The authors consider the effect of phase-induced intensity noise (PIIN), thermal noise and shot noise. Moreover, the validity of the Gaussian approximation is confirmed by a Kolmogorov-Smirnov fitness test. For sake of comparison, the bit error rate (BER) of the asynchronous SAC-OCDMA system is also plotted numerically in comparison with the BER of the synchronous SAC-OCDMA. They show that a SAC-OCDMA system without... 

    Mono-modal image registration via correntropy measure

    , Article Iranian Conference on Machine Vision and Image Processing, MVIP ; Sept , 2013 , Pages 223-226 ; 21666776 (ISSN) ; 9781467361842 (ISBN) Ghaffari, A ; Fatemizadeh, E ; Sharif University of Technology
    IEEE Computer Society  2013
    Abstract
    The registration of images is a fundamental task in numerous applications in medical image processing. Similarity measure is an important key in intensity based image registration. Here, we propose correntropy measure as similarity measure in mono modal setting. Correntropy is a important measure between two random variables based on information theoretic learning and kernel methods. This measure is useful in non-Gaussian signal processing. In this paper, this measure is used in image registration. Here, we analytically illustrate that this measure is robust in presence of spiky noise (impulsive noise). The experimental results show that the proposed similarity has better performance than... 

    Visual tracking using sparse representation

    , Article 2012 IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2012, 12 December 2012 through 15 December 2012, Ho Chi Minh City ; 2012 , Pages 304-309 ; 9781467356060 (ISBN) Feghahati, A. H ; Jourabloo, A ; Jamzad, M ; Manzuri Shalmani, M. T ; Sharif University of Technology
    2012
    Abstract
    In this work we present a sparse dictionary learning method, specifically tuned to solve the tracking problem. Recently, sparse representation has drawn much attention because of its genuineness and strong mathematical background. In this paper we present an online method for dictionary learning which is desirable for problems such as tracking. Online learning methods are preferable because the whole data are not available at the current time. The presented method tries to use the advantages of the generative and discriminative models to achieve better performance. The experimental results show our method can overcome many tracking challenges  

    A grouped batch means approach to monitor autocorrelated processes

    , Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 1 , 2007 , Pages 580-588 ; 9781627486811 (ISBN) Morovatdar, R ; Akhavan Niaki, S. T ; Sharif University of Technology
    2007
    Abstract
    In order to monitor auto-correlated processes, many kinds of model-free control charts have been recently proposed based on the methods used in simulation output analysis. However, these control charts always have a restricting assumption that a large volume of observations is available while defects within them are scarce (zero-defect or high-quality processes). In this paper, we develop a new type of model-free unweighted batch means control charts, called grouped batch means (GBM) to monitor autocorrelated processes. In addition to its better performance in some cases, the GBM control chart can be applied not only to high-quality processes but also to all kinds of auto-correlated... 

    Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes

    , Article Journal of Industrial and Engineering Chemistry ; 2015 ; ISSN: 1226086X Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Abstract
    Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.% of palladium on activated carbon)... 

    Two layers beamforming robust against direction-of-arrival mismatch

    , Article IET Signal Processing ; Volume 8, Issue 1 , 2014 , Pages 49-58 ; ISSN: 17519675 Rahmani, M ; Bastani, M. H ; Shahraini, S ; Sharif University of Technology
    Abstract
    The presence of the desired signal (DS) in the training snapshots makes the adaptive beamformer sensitive to any steering vector mismatch and dramatically reduces the convergence rate. The objective of the present study is to propose a new adaptive beamformer which is robust against direction-of-arrival (DOA) mismatch and its convergence rate is not sensitive to the presence of the DS. This method is applicable to the arrays with specific structure such as the linear array. Our approach is based on the DS elimination from the training snapshots and the sub-array beamforming technique. To accomplish this goal, a blocking matrix which converts the primary data to the DS-free data is... 

    Belief propagation-based multiuser receivers in optical code-division multiple access systems

    , Article IET Communications ; Volume 7, Issue 18 , 2013 , Pages 2102-2112 ; ISSN: 17518628 Sedaghat, M. A ; Nezamalhosseini, A ; Saeedi, H ; Marvasti, F ; Sharif University of Technology
    2013
    Abstract
    In this study, the authors investigate the performance of optical code-division multiple access (OCDMA) systems with belief propagation (BP)-based receivers. They propose three receivers for the optical fibre channel that provide a trade-off between detecting complexity and system performance. The first proposed receiver achieves a performance very close to the so-called known interference lower bound. The second receiver exhibits a considerably less complexity at the expense of a slight degradation in performance. They show that the third BP-based receiver, which is a simplified version of the second receiver, is surprisingly the same as the so-called multistage detector in OCDMA systems.... 

    Experimental analysis of a Ranque-Hilsch vortex tube for optimizing nozzle numbers and diameter

    , Article Applied Thermal Engineering ; Volume 61, Issue 2 , 2013 , Pages 500-506 ; 13594311 (ISSN) Mohammadi, S ; Farhadi, F ; Sharif University of Technology
    2013
    Abstract
    A brass vortex tube with changeable parts is used to obtain the optimum nozzle intake numbers and diameter. The effects of inlet pressure and CF (cold fraction) are also investigated. Results illustrate that increasing the number of nozzles causes a temperature drop and the optimum nozzle diameter corresponds to quarter of vortex tube diameter. The distance between cold end orifice and nozzle intakes is investigated in this work and it is found that for a better performance, this distance should be decreased. A series of experiments conducted to investigate the CF effect on VT performance and an optimum amount for this parameter is found. A two-dimensional computational fluid dynamics... 

    Laminar falling film flow of aqueous Li Br solution on a horizontal elliptical tube

    , Article International Journal of Fluid Mechanics Research ; Volume 40, Issue 4 , 2013 , Pages 324-343 ; 10642277 (ISSN) Abyaneh, M. H. J ; Saidi, M. H ; Sharif University of Technology
    2013
    Abstract
    Flow hydrodynamics of laminar falling film of aqueous Li Br solution (Li Br - H2O) on a horizontal elliptical tube has been investigated in this research. The film velocity distribution and film thickness, namely, the flow characteristics are determined by solving analytically simultaneous simplified Navier - Stokes equations and continuity equation in polar and Cartesian coordinates. The analysis is based on steady state laminar flow of falling liquid film of Li Br - H2O on a horizontal elliptical tube in polar model and Cartesian model (CM), for cases in which traction on the film surface is considered negligible. Models are compared with each other in three cases of aspect ratios (Ar),... 

    The use of ANN to predict the hot deformation behavior of AA7075 at low strain rates

    , Article Journal of Materials Engineering and Performance ; Volume 22, Issue 3 , 2013 , Pages 903-910 ; 10599495 (ISSN) Jenab, A ; Karimi Taheri, A ; Jenab, K ; Sharif University of Technology
    2013
    Abstract
    In this study, artificial neural network (ANN) was used to model the hot deformation behavior of 7075 aluminum alloy during compression test, in the strain rate range of 0.0003-1 s-1 and temperature range of 200-450 C. The inputs of the model were temperature, strain rate, and strain, while the output of the model was the flow stress. The feed-forward back-propagation network with two hidden layers was built and successfully trained at different deformation domains by Levenberg-Marquardt training algorithm. Comparative analysis of the results obtained from the hyperbolic sine, the power law constitutive equations, and the ANN shows that the newly developed ANN model has a better performance... 

    Integrating constrained random waves in endurance time analysis of offshore structures subjected to sea waves

    , Article Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, 1 July 2012 through 6 July 2012 ; Volume 2 , July , 2012 , Pages 677-684 ; 9780791844892 (ISBN) Matin Nikoo, H ; Estekanchi, H ; Zeinoddini, M ; Golestani, M ; Sharif University of Technology
    2012
    Abstract
    This paper introduces a novel methodology for design and assessment of offshore structures exposed to irregular sea waves. For this, Constrained NewWave (CNW) is integrated with the Endurance Time Analysis (ETA) methodology, which is basically developed for the performance based analysis of onshore structures to earthquake loads. In this approach, the offshore structure is simulated in time-domain under a set of calibrated intensifying wave functions. They are devised to represent a gradually increasing roughness of the sea state by time. A performance index such as base shear, drift or stress in a critical structural members are monitored until they reach to a predefined maximum value. A... 

    Novel coarse timing synchronization methods in OFDM systems using fourth-order statistics

    , Article IEEE Transactions on Vehicular Technology ; Volume 64, Issue 5 , 2015 , Pages 1904-1917 ; 00189545 (ISSN) Mohebbi, A ; Abdzadeh Ziabari, H ; Shayesteh, M. G ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    In this paper, the problem of coarse timing synchronization in orthogonal frequency-division multiplexing (OFDM) systems is investigated, and two new timing metrics with better performance are presented. The new metrics take advantage of two novel differential normalization functions that are based on the fourth-order statistics and are designed depending on the value of carrier frequency offset (CFO). The proposed timing metrics are theoretically evaluated using two different class separability criteria. It is shown that the new schemes considerably increase the difference between the correct and wrong timing points in comparison with previous methods. The computational complexity of the... 

    Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes

    , Article Journal of Industrial and Engineering Chemistry ; Volume 28 , August , 2015 , Pages 202-210 ; 1226086X (ISSN) Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2015
    Abstract
    Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.%... 

    Dynamic simulation of the biped normal and amputee human gait

    , Article Mobile Robotics: Solutions and Challenges - Proceedings of the 12th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2009, 9 September 2009 through 11 September 2009, Istanbul ; 2010 , Pages 1113-1120 ; 9814291269 (ISBN) ; 9789814291262 (ISBN) Shandiz, M. A ; Farahmand, F ; Zohour, H ; Sharif University of Technology
    2010
    Abstract
    A two-dimensional seven link biped dynamic model was developed to investigate the mechanical characteristics of the normal and amputee locomotion during the complete gait cycle. The foot-ground contact was simulated using a five-point penetration contact model. The equations of motion were derived using Lagrange method. Optimization of the normal human walking model provided constant coefficients for the driving torque equations that could reasonably reproduce the normal kinematical pattern. The resulting torques were then applied to the intact joints of the amputee model with a prosthetic leg equipped with a kinematical driver controller for the ankle and either a hydraulic, elastic or... 

    Receivers' placement of a MIMO radar in the presence of mountains

    , Article 2014 International Radar Conference, Radar 2014 ; 2014 ; ISBN: 9781479941957 Radmard, M ; Nazari Majd, M ; Bahrololoom, E ; Chitgarha, M. M ; Nayebi, M. M ; Sharif University of Technology
    Abstract
    This paper studies the placement of antennas in presence of mountains for widely separated multiple-input multiple-output (MIMO) radar. One of the challenges in this configuration is proper placement of the receive antennas in order to achieve good performance. We derived Neyman-Pearson decision rule for target detection. Via several scenarios we show that proper placement of receivers can provide better performance  

    Prediction of CO2 loading capacity of chemical absorbents using a multi-layer perceptron neural network

    , Article Fluid Phase Equilibria ; Volume 354 , September , 2013 , Pages 6-11 ; 03783812 (ISSN) Bastani, D ; Hamzehie, M. E ; Davardoost, F ; Mazinani, S ; Poorbashiri, A ; Sharif University of Technology
    2013
    Abstract
    A feed forward multi-layer perceptron neural network was developed to predict carbon dioxide loading capacity of chemical absorbents over wide ranges of temperature, pressure, and concentration based on the molecular weight of solution. To verify the suggested artificial neural network (ANN), regression analysis was conducted on the estimated and experimental values of CO2 solubility in various aqueous solutions. Furthermore, a comparison was performed between results of the proposed neural network and experimental data that were not previously used for network training, as well as a set of data for binary solutions. Comparison between the proposed multi-layer perceptron (MLP) network and... 

    Greenhouse gas emission measurement and economic analysis of Iran natural gas fired power plants

    , Article Energy Policy ; Volume 60 , 2013 , Pages 200-207 ; 03014215 (ISSN) Shahsavari Alavijeh, H ; Kiyoumarsioskouei, A ; Asheri, M. H ; Naemi, S ; Shahsavari Alavije, H ; Basirat Tabrizi, H ; Sharif University of Technology
    2013
    Abstract
    This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are... 

    An improved real-coded bayesian optimization algorithm for continuous global optimization

    , Article International Journal of Innovative Computing, Information and Control ; Volume 9, Issue 6 , 2013 , Pages 2505-2519 ; 13494198 (ISSN) Moradabadi, B ; Beigy, H ; Ahn, C. W ; Sharif University of Technology
    2013
    Abstract
    Bayesian optimization algorithm (BOA) utilizes a Bayesian network to estimate the probability distribution of candidate solutions and creates the next generation by sampling the constructed Bayesian network. This paper proposes an improved real-coded BOA (IrBOA) for continuous global optimization. In order to create a set of Bayesian networks, the candidate solutions are partitioned by an adaptive clustering method. Each Bayesian network has its own structure and parameters, and the next generation is produced from this set of networks. The adaptive clustering method automatically determines the correct number of clusters so that the probabilistic building-block crossover (PBBC) is... 

    Visible light-induced photocatalytic reduction of graphene oxide by tungsten oxide thin films

    , Article Applied Surface Science ; Volume 276 , 2013 , Pages 628-634 ; 01694332 (ISSN) Choobtashani, M ; Akhavan, O ; Sharif University of Technology
    2013
    Abstract
    Tungsten oxide thin films (deposited by thermal evaporation or sol gel method) were used for photocatalytic reduction of graphene oxide (GO) platelets (synthesized through a chemical exfoliation method) on surface of the films under UV or visible light of the environment, in the absence of any aqueous ambient at room temperature. Atomic force microscopy (AFM) technique was employed to characterize surface morphology of the GO sheets and the tungsten oxide films. Moreover, using X-ray photoelectron spectroscopy (XPS), chemical state of the tungsten oxide films and the photocatalytic reduction of the GO platelets were quantitatively investigated. The better performance of the sol-gel tungsten...