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dolatabadi--shayesteh
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TCAS Logic Improvement for Airliners Formation Flights
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
This study explores the trajectory optimization of two aircrafts’ formation flight seeking minimization of fuel consumption and flight duration while considering activation of the Traffic Collision Avoidance System (TCAS) during the flights. In order to model the effects of this system, a set of codes has been developed in the Matlab software environment, which utilizes an estimation model of induced drag for each aircraft by their relative positions. Also, position rotation is allowed, and the number and location of rotations are controllable by the user. The TCAS determines the allowable distances between aircrafts during flights based on relative velocities and relative heading angles....
A sampling theorem for convex shapes with algebraic boundaries
, Article 2017 12th International Conference on Sampling Theory and Applications, SampTA 2017, 3 July 2017 through 7 July 2017 ; 2017 , Pages 499-503 ; 9781538615652 (ISBN) ; Amini, A ; Sharif University of Technology
2017
Abstract
In this paper we present a sampling result about continuous-domain black and white images that form a convex shape. In particular, we will study shapes whose boundaries belong to the zero-level sets (roots) of bivariate polynomials. In [1] it was shown that generalized 2D moments of the image can lead to annihilation equations for the coefficients of the bivariate polynomial that determine the boundary of the shape. More precisely, when the bivariate polynomial is of degree n (which has n(n+3)/2 non-trivial coefficients), the results in [1] indicate that for invertibility of the linear annihilation equations, 2D moments of up to degree 3n-1 (overall equation moments) are required. In this...
Design of an Adaptive Controller for Uncertain Fractional-order Systems Subject to Actuator Failure
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
The objective of this research is to design an adaptive controller for a class of fractional-order nonlinear systems in the strict-feedback form with unmodeled dynamics. Actuator saturation and actuator fault are also considered. All of the system states are assumed to be measurable, and all the sensors can be faulty. Fractional-order systems are chosen because, in the modeling of physical systems, the fractional-order calculus is often preferable to the classical integer-order calculus. The controller is designed by using the backstepping design technique. The fuzzy logic systems are used to eliminate the problem of "explosion of complexity" in the conventional backstepping method and also...
Modeling jumps in organization of petroleum exporting countries basket price using generalized autoregressive heteroscedasticity and conditional jump
, Article Investment Management and Financial Innovations ; Volume 13, Issue 4 , 2016 , Pages 196-202 ; 18104967 (ISSN) ; Gharaati, S ; Dolatabadi, I ; Sharif University of Technology
LLC CPC Business Perspectives
2016
Abstract
This paper uses autoregressive jump intensity (ARJI) model to show that the oil price has both GARCH and conditional jump component. In fact, the distribution of oil prices is not normal, and oil price returns have conditional heteroskedasticity. Here the authors compare constant jump intensity with the dynamic jump intensity and evidences demonstrate that oil price returns have dynamic jump intensity. Therefore, there is strong evidence of time varying jump intensity Generalized Autoregressive Heteroscedasticity (GARCH) behavior in the oil price returns. The findings have several implications: first, it shows that oil price is highly sensitive to news, and it does settle around a trend in...
Design of Toeplitz Measurement Matrices with Applications to Sparse Channel Estimation in Single-Carrier Communication
, M.Sc. Thesis Sharif University of Technology ; Amini, Arash (Supervisor)
Abstract
Channel estimation is one of the fundamental challenges in every communication system and different algorithms have been proposed to deal with it. Obviously, type of a communication channel is an important factor in choosing the appropriate method for channel estimation. Sparse channels are one kind of them that occur in many real-world applications such as wireless communication systems. In addition, emergence of a new means in signal processing to deal with sparse signals, known as Compressed Sensing(CS), paved the way for their extensive usage in many applications including sparse channel estimation.On the other hand, one of the most fundamental problems in sparse signal recovery using CS...
Exact symbol and bit error probabilities of linearly modulated signals with maximum ratio combining diversity in frequency non-selective Rician and Rayleigh fading channels
, Article IET Communications ; Volume 5, Issue 1 , January , 2011 , Pages 12-26 ; 17518628 (ISSN) ; Sharif University of Technology
2011
Abstract
The exact symbol and bit error probabilities of linearly modulated signals in frequency non-selective Rician fading channels with Lth diversity branches are derived, where coherent detection with maximum ratio combining (MRC) is used at the receiver. For performance evaluation, the multiplicative distortion is combined with the additive Gaussian noise and form an additive noise is formed. This method allows computing the exact symbol and bit error probabilities of M-ary phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM), M-ary amplitude modulation (M-AM) and M-ary amplitude modulation phase modulation (M-AMPM) for any arbitrary bit mappings. The results contain several...
An Investigation on Mechanical Behavior of Polypropylene/Polyethylene Blend - Calcium Carbonate Nano Composite
,
M.Sc. Thesis
Sharif University of Technology
;
Bagheri, Reza
(Supervisor)
Abstract
Polymer blending has an important role in preparation of materials with suitable properties without synthesizing new polymers. One of these blends is polypropylene (PP)/ polyethylene (PE). PE is added for improving the impact strength and toughness of PP. For improvementof the properties, a compatibilizer is used due to incompatibility of the PP/PE blend. Improving the impact properties is usually related to the reduction in stiffness. Considering the importance of stiffness in many industrial applications, mineral fillers are employed for increasing the stiffness. In this research, the goal has been to manufacture polypropylene-based ternary composite(Polypropylene/ Polyethylene/Nanometric...
Multiple-access performance analysis of combined time-hopping and spread-time CDMA system in the presence of narrowband interference
, Article IEEE Transactions on Vehicular Technology ; Volume 58, Issue 3 , 2009 , Pages 1315-1328 ; 00189545 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2009
Abstract
We consider a combined time-hopping (TH) and spread-time (ST) multiple-access technique that uses an internal code. In this method, the duration of each bit is divided into Ns frames. The outputs of the encoder and a pseudorandom (PN) sequence specify the number of the frame in which the data bit is transmitted in ST code-division multiple-access (ST-CDMA) form using the second PN sequence. We consider the correlator receiver, followed by the channel decoder. We obtain the performance of the combined method in additive white Gaussian noise (AWGN) and fading channels in the presence of multiple-access interference (MAI) and narrowband interference (NBI). We also consider the conventional...
Methylene blue removal using modified celery (Apium graveolens) as a low-cost biosorbent in batch mode: Kinetic, equilibrium, and thermodynamic studies
, Article Journal of Molecular Structure ; Volume 1173 , 2018 , Pages 541-551 ; 00222860 (ISSN) ; Bastani, D ; Shayesteh, H ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Celery residue modified with H2SO4 was utilized as a low-cost adsorbent for elimination of methylene blue cationic dye from aqueous solution in batch adsorption process. The adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). The efficacy of dye removal of the modified celery residue (MCR) was verifying by changing adsorbent dose, contact time, pH, initial dye concentration, and temperature. The isotherm models analysis shows that the experimental data can be better demonstrated by Freundlich isotherm model. In order to evaluate the best fit isotherm, three error analysis methods (χ2, ARE and MPSD) as well as correlation...
Equilibrium, kinetic and thermodynamic studies of a low-cost biosorbent for the removal of Congo red dye: Acid and CTAB-acid modified celery (Apium graveolens)
, Article Journal of Molecular Structure ; Volume 1176 , 2019 , Pages 181-193 ; 00222860 (ISSN) ; Bastani, D ; Shayesteh, H ; Sharif University of Technology
Elsevier B.V
2019
Abstract
This study introduces a new and bio-friendly adsorbent based on natural and cetyltrimethylammonium bromide (CTAB) modified adsorbent, celery (Apium graveolens) residue for removal of organic pollutants. The adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and pHpzc techniques. Removal applicability and efficiency of this biosorbent were studied using Congo red (CR) as a sample organic pollutant. To reach the best results, main parameters such as pH, adsorbent mass, contact time, initial dye concentration and temperature were optimized through the adsorption experiments in a batch system. The kinetic and isotherm of CR removal...
An internally coded time-hopping spread-time CDMA scheme for UWB systems and its performance analysis
, Article 2007 IEEE Radio and Wireless Symposium, RWS, Long Beach, CA, 9 January 2007 through 11 January 2007 ; 2007 , Pages 511-514 ; 9781424404452(ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2007
Abstract
We consider an internally coded multiple access technique for Ultra Wide-Band systems which combines time-hopping (TH) and spread-time (ST) techniques using a super-orthogonal encoder. In this method, the duration of each bit is divided into Ns frames. The outputs of a superorthogonal encoder and a PN sequence specify the frame number, in which the data is transmitted in spread-time CDMA form using the second PN sequence. We consider soft decision before Viterbi decoding at the receiver. We obtain the performance of the proposed method. We also consider the uncoded ST-CDMA system and compare its performance with our method. The results indicate that our method has much more better...
Internally coded multicarrier frequency-hopping CDMA communication system and its performance analysis
, Article IET Communications ; Volume 2, Issue 2 , 2008 , Pages 255-265 ; 17518628 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2008
Abstract
A new internally coded scheme that combines frequency hopping (FH) and multicarrier (MC) code division multiple access (CDMA) techniques using a super-orthogonal encoder is proposed. In this method, the total bandwidth is partitioned into Ns1 disjoint bands and each band is also segmented into Ns2 subbands. On the basis of a super-orthogonal encoder output and a pseudorandom sequence, one of the Ns1 bands is selected. The data bit is then transmitted in the band in the form of the multicarrier FH (MC-FH) CDMA scheme, that is, Ns2 carriers are transmitted in the Ns2 subbands of the selected band. At the receiver, both hard and soft detectors are used. The performance of the proposed method in...
Performance analysis of an internally coded MC-FH-CDMA system
, Article 2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, ICT-MICC 2007, Penang, 14 May 2007 through 17 May 2007 ; February , 2007 , Pages 23-28 ; 1424410940 (ISBN); 9781424410941 (ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2007
Abstract
We consider an internally coded scheme for multicarrier frequency-hopping CDMA (MC-FH-CDMA) communication systems. In this method, the total bandwidth is partitioned into Ns1 disjoint bands and each band is also segmented into Ns2 subbands. Based on the super-orthogonal encoder output and a pseudorandom (PN) sequence, one of the Ns1 bands is selected. Then, the data is transmitted in that band in the form of multicarrier frequency-hopping technique using BPSK modulation. At the receiver front end, we use soft detector, then we apply Viterbi decoding algorithm. We evaluate the performance of the proposed method. The results indicate that our method outperforms the previously presented uncoded...
Performance analysis of an internally coded time-hopping spread-time CDMA system in the presence of interference
, Article 2008 5th IEEE Consumer Communications and Networking Conference, CCNC 2008, Las Vegas, NV, 10 January 2008 through 12 January 2008 ; 2008 , Pages 430-434 ; 9781424414574 (ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2008
Abstract
In this paper, we consider the internally coded time-hopping spread-time multiple access scheme introduced in [1]. We evaluate the performance of the correlator receiver followed by the Viterbi algorithm in fading channel. We analyze the effect of multiple access interference (MAI) and narrowband interference (NBI). We also provide simulation results and further evaluate the performance of the system for the ultra wide band (UWB) application with the UWB channel model specified by the IEEE 802.15.4a group. For comparison, we consider the conventional ST-CDMA system. The results indicate that our method has much better performance while it has the same bandwidth and spectral efficiency as the...
A new TH/DS-CDMA scheme for UWB communication systems and its performance analysis
, Article 2006 IEEE Radio and Wireless Symposium, San Diego, CA, 17 January 2006 through 19 January 2006 ; Volume 2006 , 2006 , Pages 147-150 ; 0780394127 (ISBN); 9780780394124 (ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2006
Abstract
We propose a new multiple access technique for Ultra Wide-Band (UWB) systems based on time-hopping (TH) and direct sequence (DS) spread spectrum techniques. In this method, the duration of each bit is divided into N s frames each one consisting of Nh chips. The outputs of a super-orthogonal encoder and a PN sequence specify the frame number, in which the data is transmitted in DS spread-spectrum form using the second PN sequence. We consider hard decision with threshold and soft decision before Viterbi decoding at the receiver. We evaluate the performance of the proposed method and compare it with the conventional DS-CDMA system. The results show that the proposed method has the best...
Various multirate time-hopping UWB systems and performance evaluation
, Article 2004 IEEE International Symposium on Spread Spectrum Techniques and Applications, ISSSTA 2004, Sydney, 30 August 2004 through 2 September 2004 ; 2004 , Pages 120-124 ; Nasiri Kenari, M ; Sharif University of Technology
2004
Abstract
We consider multirate time-hopping ultra-wideband (TH-UWB) communication systems where each user can have several multirate services. We investigate both constant spreading factor scheme, which uses multicode, and variable spreading factor scheme, which uses constant chip time and variable frame number. For multicode structure, we consider two methods. In the first, one kind of signature (PN) code is used to distinguish users and their diverse services alike. Whereas in the second one different users and different services of the same user are distinguished through two kinds of signature codes, namely PN code and Walsh code, respectively. For variable spreading factor scheme, one signature...
Measuring Concentration of Heavy Metals in Waste Water Using Biosensor
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Kalantarian, Asadollah (Supervisor)
Abstract
Wastewater, especially with heavy metal contamination, is a global environmental concern. Numerous techniques have been tested for online controlling and monitoring the concentration of heavy metal ions; yet, there are many challenges in performing these techniques. Biosensor is cheap, easily available, simple, fast, selective, sensitive, and repeatable so it is an excellent alternative for the detection and quantification of hazardous particles in the wastewater. In this study, a Nano biosensor with high detection of copper ions has been fabricated. PEDOT:PSS as a highly conductive polymer is coupled with gold nanoparticles to modify the surface of graphite electrode and results in higher...
Adaptive handover algorithm in heterogeneous femtocellular networks based on received signal strength and signal-to-interference-plus-noise ratio prediction
, Article IET Communications ; Volume 8, Issue 17 , 27 November , 2014 , Pages 3061-3071 ; ISSN: 17518628 ; Yousefi, S ; Shayesteh, M. G ; Sharif University of Technology
2014
Abstract
In this study, an efficient handover algorithm based on the received signal strength (RSS) prediction is presented for two-tier macro-femtocell networks in which, because of the fading effects of channel and short coverage range of femtocells, ping-pong handovers may take place. In the proposed approach, first each mobile station (MS) uses the recursive least square algorithm for predicting the RSS from the candidate base stations (BSs) including both femtocell and macrocell BSs. Then, according to the predicted RSS values, several future values of signal-to-interference plus noise ratio (SINR) are calculated. Afterwards, the candidate list of BSs is pruned according to the estimated future...
Resource allocation in integrated femto-macrocell networks based on location awareness
, Article IET Communications ; Volume 9, Issue 7 , 2015 , Pages 917-932 ; 17518628 (ISSN) ; Solouk, V ; Shayesteh, M. G ; Sharif University of Technology
2015
Abstract
This study presents an efficient fractional frequency reuse scheme for macrocell network which uses six directional antennas to cover the outer region and analyses the performance. Cross-tier interference between macrocell and femtocell networks leading to throughput and outage probability degradation is a major issue in two-tier networks when femtocells are deployed in co-channel with macrocells. In this study, the received interference from the macrocell network to femtocell network is analysed. Then, based on the degree of received interference, an algorithm for orthogonal resource allocation to femtocells with low cross-tier interference is presented. According to the introduced scheme,...
Higher order statistics for modulation and STBC recognition in MIMO systems
, Article IET Communications ; Volume 13, Issue 16 , 2019 , Pages 2436-2446 ; 17518628 (ISSN) ; Kalbkhani, H ; Shayesteh, M. G ; Sharif University of Technology
Institution of Engineering and Technology
2019
Abstract
Identification of modulation and space-time block code (STBC) is an important task of receivers in applications such as military, civilian, and commercial communications. Here, we consider multiple-input multiple-output (MIMO) systems. We propose two methods for STBC identification when the modulation is known. We also introduce a method for joint identification of code and modulation. Additionally, we present an enhanced zero-forcing (ZF) equaliser to improve the separation between the features of different classes. Higher order cumulants are used as the statistical features. In the first method of STBC identification, after the proposed equalisation, received data samples are segmented,...