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Sudoku rectangle completion (Extended Abstract)
, Article Electronic Notes in Discrete Mathematics ; Volume 49 , November , 2015 , Pages 747-755 ; 15710653 (ISSN) ; Mahmoodian, E. S ; Sharif University of Technology
Elsevier
2015
Abstract
Over the last decade, Sudoku, a combinatorial number-placement puzzle, has become a favorite pastimes of many all around the world. In this puzzle, the task is to complete a partially filled 9 × 9 square with numbers 1 through 9, subject to the constraint that each number must appear once in each row, each column, and each of the nine 3 × 3 blocks. Sudoku squares can be considered a subclass of the well-studied class of Latin squares. In this paper, we study natural extensions of a classical result on Latin square completion to Sudoku squares. Furthermore, we use the procedure developed in the proof to obtain asymptotic bounds on the number of Sudoku squares of order n
Transversals and multicolored matchings
, Article Journal of Combinatorial Designs ; Volume 12, Issue 5 , 2004 , Pages 325-332 ; 10638539 (ISSN) ; Alipour, A ; Sharif University of Technology
2004
Abstract
Ryser conjectured that the number of transversals of a latin square of order n is congruent to n modulo 2. Balasubramanian has shown that the number of transversals of a latin square of even order is even. A 1-factor of a latin square of order n is a set of n cells no two from the same row or the same column. We prove that for any latin square of order n, the number of 1-factors with exactly n - 1 distinct symbols is even. Also we prove that if the complete graph K2n, n ≥ 8, is edge colored such that each color appears on at most n-2 2e edges, then there exists a multicolored perfect matching. © 2004 Wiley Periodicals, Inc
An algebraic gain estimation method to improve the performance of HMM-based speech enhancement systems
, Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 336-339 ; 9781424467600 (ISBN) ; Sameti, H ; Veisi, H ; Sharif University of Technology
Abstract
An extension to conventional Hidden Markov Model (HMM)-based speech enhancement method is developed. An algebraic method is proposed to estimate gain of speech and noise in order to improve the quality of the estimated speech. Different pronunciations and intonations may affect speech gain. Besides, gain of noise may vary remarkably from one environment to the other one. This may lead in a mismatch between energy contour of trained models and energy contour of noisy speech signal. In this work, speech gain and noise gain are estimated based on an algebraic method simultaneously in order to match gain of noisy speech and noisy model. To carry out this procedure an extension of least square...
A lower bound for the length of a partial transversal in a Latin square
, Article Journal of Combinatorial Theory. Series A ; Volume 115, Issue 7 , 2008 , Pages 1103-1113 ; 00973165 (ISSN) ; Shor, P. W ; Sharif University of Technology
2008
Abstract
It is proved that every n × n Latin square has a partial transversal of length at least n - O (log2 n). The previous papers proving these results (including one by the second author) not only contained an error, but were sloppily written and quite difficult to understand. We have corrected the error and improved the clarity. © 2008
Field-induced quantum phase transition in the anisotropic kondo necklace model
, Article Physical Review B - Condensed Matter and Materials Physics ; Volume 75, Issue 17 , 2007 ; 10980121 (ISSN) ; Langari, A ; Sharif University of Technology
2007
Abstract
The anisotropic Kondo necklace model in two and three dimensions is treated as a genuine model for magnetic to Kondo singlet quantum phase transitions in the heavy fermion compounds. The variation of the quantum critical point with anisotropy parameters has been investigated previously in the zero-field case. Here, we extend the treatment to finite fields using a generalized bond operator representation including all triplet states. The variation of critical tc with magnetic field and the associated phase diagram is derived. The influence of anisotropies and the different g factors for localized and itinerant spins on the field dependence of tc is also investigated. It is found that three...
A new bound on the size of the largest critical set in a Latin square
, Article Discrete Mathematics ; Volume 267, Issue 1-3 SPEC , 2003 , Pages 13-21 ; 0012365X (ISSN) ; Mahmoodian, E. S ; Sharif University of Technology
2003
Abstract
A critical set in an n×n array is a set C of given entries, such that there exists a unique extension of C to an n×n Latin square and no proper subset of C has this property. The cardinality of the largest critical set in any Latin square of order n is denoted by lcs(n). In 1978, Curran and van Rees proved that lcs(n)n 2-n. Here, we show that lcs(n)n 2-3n+3. © 2002 Elsevier Science B.V
N-way partial least squares with variable importance in projection combined to GC × GC-TOFMS as a reliable tool for toxicity identification of fresh and weathered crude oils
, Article Analytical and Bioanalytical Chemistry ; Volume 407, Issue 1 , 2014 , pp 285-295 ; ISSN: 16182650 ; Parastar, H ; Sharif University of Technology
Abstract
In this study, N-way partial least squares (NPLS) is proposed to correlate comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC × GC-TOFMS) data of different aromatic oil fractions (fresh and weathered) to their toxicity values. Before NPLS modeling, since drift and wander of baseline interfere with information of sought analytes in GC × GC-TOFMS data, a novel method called two-dimensional asymmetric least squares is thus developed for comprehensive correction of the baseline contributions in both chromatographic dimensions. The algorithm is termed comprehensive because it functions to correct the entire chromatogram in both dimensions and it preserves the...
On the Latin Square of Groups and their Coloring
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor)
Abstract
A Latin square of order n, is an n n array filled with n different symbols, each occurring exactly once in each row and exactly once in each column.Two cells of a Latin square are independent when they are not in the same row, or in the same column and they are not the same symbol. If they are not independent, they are called dependent. A k-coloring of a Latin square is assigning k colors to its cells where no two dependent cells have the same color. The smallest k for which we have a k-coloring for a Latin square L with k colors is called chromatic number of L and we denote it by L). If we consider the Cayley table of an arbitrary finite group of order n, then we have a Latin square of...
A simple method for pulse repetition interval estimation and tracking radar pulse trains with complex pulse repetition interval modulations
, Article Advanced Science Letters ; Volume 19, Issue 8 , 2013 , Pages 2262-2265 ; 19366612 (ISSN) ; Keshavarzi, M ; Amiri, K ; Sharif University of Technology
2013
Abstract
In an electronic warfare environment, an electronic support system receives signals emitted by different radars. One of the key tasks in an electronic support system is PRI estimation tracking Pulse Trains using Pulse Repetition Interval (PRI) of these signals. In this paper we present a simple method for PRI estimation and tracking radar pulse trains with complex PRI Modulations. This method uses nonlinear least square, Pisarenko and innovative methods for PRI estimation and tracking pulse train. Simulation results show high robustness of the proposed method against noise (spurious and missing pulses)
Passive position finding of stationary targets: Based on circulation and the least square concept
, Article ISPACS 2012 - IEEE International Symposium on Intelligent Signal Processing and Communications Systems ; 2012 , Pages 390-394 ; 9781467350815 (ISBN) ; Mahdavi, A ; Jamshidi, Z ; Sharif University of Technology
2012
Abstract
A method for two dimensional position finding of stationary targets whose bearing measurements suffers from indeterminable bias and random noise has been proposed. The algorithm uses convex optimization to minimize an error function which has been calculated based on circular as well as linear loci of error. Taking into account a number of observations, certain modifications have been applied to the initial crude method so as to arrive at a faster, more accurate method. Simulation results of the method illustrate up to 30% increase in accuracy compared with the well-known least square filter
A linear algebraic approach to orthogonal arrays and Latin squares
, Article Ars Combinatoria ; Volume 105 , 2012 , Pages 3-13 ; 03817032 (ISSN) ; Mahdian, M ; Mahmoodian, E. S ; Sharif University of Technology
2012
Abstract
To study orthogonal arrays and signed orthogonal arrays, Ray-Chaudhuri and Singhi (1988 and 1994) considered some module spaces. Here, using a linear algebraic approach we define an inclusion matrix and find its rank. In the special case of Latin squares we show that there is a straightforward algorithm for generating a basis for this matrix using the so-called intercalates. We also extend this last idea. Copyright
Multiple-chi-square tests and their application on distinguishing attacks
, Article 2011 8th International ISC Conference on Information Security and Cryptology, ISCISC 2011, 14 September 2011 through 15 September 2011, Mashhad ; 2011 , Pages 55-60 ; 9781467300773 (ISBN) ; Salmasizadeh, M ; Mohajeri, J ; Sharif University of Technology
2011
Abstract
Chi-square tests are vastly used for distinguishing random distributions, but extra care must be taken when using them on several independent variables. We noticed, the chisquare statistics, in some previous works, was computed half of its real value. Thus, to avoid possible future confusions, we formulize multiple-chi-square tests. To show the application of multiple-chi-square tests, we introduce two new tests and apply them to Trivium as a special case. These tests are modifications of ANF monomial test and, when applied to Trivium with the same number of rounds, the data complexity of them is roughly 24 times smaller than that of previous ANF monomial test
Comparative study of partial least squares and multivariate curve resolution for simultaneous spectrophotometric determination of pharmaceuticals in environmental samples
, Article RSC Advances ; Volume 5, Issue 86 , Aug , 2015 , Pages 70017-70024 ; 20462069 (ISSN) ; Shaye, H ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
The potentials of partial least squares regression (PLSR) and multivariate curve resolution alternating least squares (MCR-ALS) are evaluated for the simultaneous determination of diclofenac (DCF), naproxen (NAP), mefenamic acid (MEF) and carbamazepine (CBZ) as target analytes and gemfibrozil (GEM) as an interference in synthetic and real environmental samples. The analysis of first-order UV-Vis spectra is performed using PLSR with different variable selection methods, which include variable importance in projection (VIP), recursive weighted partial least squares (rPLS), regression coefficient (RV) and uninformative variable elimination (UVE), and using MCR-ALS with correlation constraint...
A MAP-Based order estimation procedure for Sparse channel estimation
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 25 2015 through 28 August 2015 ; Volume 9237 , August , 2015 , Pages 344-351 ; 03029743 (ISSN) ; 9783319224817 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
Springer Verlag
2015
Abstract
Recently, there has been a growing interest in estimation of sparse channels as they are observed in underwater acoustic and ultrawideband channels. In this paper we present a new Bayesian sparse channel estimation (SCE) algorithm that, unlike traditional SCE methods, exploits noise statistical information to improve the estimates. The proposed method uses approximate maximum a posteriori probability (MAP) to detect the non-zero channel tap locations while least square estimation is used to determine the values of the channel taps. Computer simulations shows that the proposed algorithm outperforms the existing algorithms in terms of normalized mean squared error (NMSE) and approaches...
Parameter identification of a parametrically excited rate micro-gyroscope using recursive least squares method
, Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1889-1900 ; 10263098 (ISSN) ; Salarieh, H ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
Estimation of physical parameters of a parametrically excited gyroscope is studied in this paper. This estimation is possible by reading the input and output data of the gyroscope. Because of different faults in the manufacturing process and tolerances, physical parameters of a gyroscope are not exactly same as the expected values of the manufacturer. Moreover, changing of temperature, humidity, external acceleration, etc. can change the physical parameters of the gyro. Thus, the physical parameters of gyroscope are not fixed values and may deviate from the desired designed values. The physical parameters of gyroscope determine the optimal region for working of gyroscope. Thus, if the...
Fabrication, characterization, and error mitigation of non-flat sun sensor
, Article Sensors and Actuators, A: Physical ; Volume 261 , 2017 , Pages 243-251 ; 09244247 (ISSN) ; Durali, M ; Rashidian, B ; Jalali, M. A ; Sharif University of Technology
Abstract
We report the design, fabrication and error analysis of a sun sensor array composed of six photodiodes. The sensor estimates the direction of the sun using a linear least squares method. The performance of the sensor is deteriorated by three major sources: fabrication errors, scattered environmental light, and inexact modeling of photodiodes. Using a calibration procedure and modeling the uniform component of the environmental light, we mitigate the first two errors and significantly reduce root mean squared error from 2.63° to 0.83°. For a Field of View (FOV) of 110°, the maximum estimation error also drops from 3.8° to 1.6°. Through exact mathematical modeling of photodiodes, we...
Adaptive input-output linearization control of pH processes
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 3 , 2008 , Pages 25-35 ; 10219986 (ISSN) ; Shahrokhi, M ; Mehrabani, A ; Sharif University of Technology
2008
Abstract
pH control is a challenging problem due to its highly nonlinear nature. In this paper the performances of two different adaptive global linearizing controllers (GLC) are compared. Least squares technique has been used for identifying the titration curve. The first controller is a standard GLC based on material balances of each species. For implementation of this controller a nonlinear state estimator is used. Some modifications are proposed to avoid the singularity of the observer gain. The second controller is designed based on the reduced state equation. Through computer simulations, it has been shown that the performances of the second GLC is superior and it is more robust to process...
An accurate FIR approximation of ideal fractional delay in hilbert space
, Article Fourth IEEE International Symposium on Signal processing and Information Technology, ISSPIT 2004, Rome, 18 December 2004 through 21 December 2004 ; 2004 , Pages 507-512 ; 0780386892 (ISBN) ; Nabavi Lishi, A ; Hessabi, Sh ; Kamyabpour, N ; Sharif University of Technology
2004
Abstract
This paper presents an improved low order technique for the design of FIR fractional delay (FD) filters. This method is based on a new use of the least square method in Hilbert space to approximate the ideal FD transfer function with a FIR filter. The main advantages of the resulting filter are: very good response at all frequencies and a good method to create very small delay. Design examples are demonstrated to illustrate the effectiveness of this new design approach. © 2004 IEEE
On the possible volumes of μ-way latin trades
, Article Aequationes Mathematicae ; Volume 63, Issue 3 , 2002 , Pages 303-320 ; 00019054 (ISSN) ; Billington, E. J ; Bryant, D. E ; Mahmoodian, E. S ; Sharif University of Technology
Birkhauser Verlag Basel
2002
Abstract
A μ-way latin trade of volume s is a set of μ partial latin rectangles (of inconsequential size) containing exactly the same s filled cells, such that if cell (i, j) is filled, it contains a different entry in each of the μ partial latin rectangles, and such that row i in each of the μ partial latin rectangles contains, set-wise, the same symbols and column j, likewise. In this paper we show that all μ-way latin trades with sufficiently large volumes exist, and state some theorems on the non-existence of μ-way latin trades of certain volumes. We also find the set of possible volumes (that is, the volume spectrum) of μ-way latin trades for μ = 4 and 5. (The case μ = 2 was dealt with by Fu,...
Hybrid active noise control of a one-dimensional acoustic duct
, Article Journal of Vibration and Acoustics, Transactions of the ASME ; Volume 124, Issue 1 , 2002 , Pages 10-18 ; 10489002 (ISSN) ; Alasty, A ; Ohadi, A. R ; Sharif University of Technology
2002
Abstract
Based on the closed-form solution of a one-dimensional wave equation, the primary, secondary and acoustic feedback paths for the active control of sound in an acoustic duct have been investigated. Accurate models for the condenser microphone and loudspeaker, which include both the electro-mechanical and mechano-acoustical couplings as well as acoustical damping, have been considered. A generalized form of the filtered-x least mean square (FXLMS) algorithm that uses a more general recursive adaptive weight update equation to improve the performance of the FXLMS algorithm has been developed. Computer simulations were carried out to investigate the performance of acoustical feedback and...