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Comprehensive reactive receiver modeling for diffusive molecular communication systems: reversible binding, molecule degradation, and finite number of receptors
, Article IEEE Transactions on Nanobioscience ; Volume PP, Issue 99 , 2016 ; 15361241 (ISSN) ; Arjmandi, H ; Burkovski, A ; Schober, R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper studies the problem of receiver modeling in molecular communication systems. We consider the diffusive molecular communication channel between a transmitter nanomachine and a receiver nano-machine in a fluid environment. The information molecules released by the transmitter nano-machine into the environment can degrade in the channel via a first-order degradation reaction and those that reach the receiver nanomachine can participate in a reversible bimolecular reaction with receiver receptor proteins. Thereby, we distinguish between two scenarios. In the first scenario, we assume that the entire surface of the receiver is covered by receptor molecules. We derive a closed-form...
Over-and under-convergent step responses in fractional-order transfer functions
, Article Transactions of the Institute of Measurement and Control ; Volume 32, Issue 4 , June , 2010 , Pages 376-394 ; 01423312 (ISSN) ; Haeri, M ; Tavazoei, Mohammad Saleh ; Sharif University of Technology
2010
Abstract
In this paper we highlight a remarkable difference between the step responses of a classical second-order transfer function and its fractional-order counterpart. It can be easily shown that the step response of a stable classical second-order transfer function crosses its final value infinitely over time. In contrast, it is illustrated here that the step responses of a fractional-order counterpart of the classical second-order model possess only a finite number of such crossovers. In other words, for such a system one can find a specific time instant after which the step response is over or under-convergent to its final value. This property interprets some phenomena observed in the...
Higher-order four-wave mixing modeling in DWDM networks
, Article Physica Scripta, Belgrade ; Volume T157 , 15 November , 2013 ; 02811847 (ISSN) ; Noshad, M ; Sharif University of Technology
2013
Abstract
In this paper, we derive a theoretical model for the higher-order four-wave mixing (FWM) power in wavelength division multiplexing networks with non-zero dispersion shifted fibers for the first time. We have investigated the higher-order FWM power theoretically and by numerical simulations. Dividing the fiber into a finite number of elements and applying the boundary conditions allow us to derive an expression for the second-order power penalty. At the end of each element, we derive the first-order FWM power for all wavelengths and use these values to calculate the second-order FWM power in the next element. Consequently, for each channel we can compute the total second-order FWM power...
Theoretical modeling and simulation of higher order FWM crosstalks in multichannel WDM optical communication systems
, Article Advanced Materials Research, Xiamen ; Volume 660 , 2013 , Pages 130-134 ; 10226680 (ISSN) ; 9783037856413 (ISBN) ; Noshad, M ; Farrokhi, A ; Sharif University of Technology
2013
Abstract
In this paper, we derive a theoretical model for the higher order FWM power in WDM networks with NZDSF fibers for the first time. We have investigated the higher order FWM power theoretically and by numerical simulations. Dividing the fiber into finite number of elements and applying the boundary conditions, allow us derive an expression for second order power penalty. At the end of each element we derive the first order FWM power for all wavelengths and use these values to calculate the second order FWM power in the next element. Consequently, for each channel we can compute the total second order FWM power penalty at the end of the fiber
Achievable rates with quantised channel state information in a multiple-access channel with one cognitive transmitter
, Article IET Communications ; Volume 4, Issue 11 , 2010 , Pages 1373-1380 ; 17518628 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2010
Abstract
The authors investigate the achievable rates of a multiple-access channel with one cognitive transmitter in a fading channel. The cognitive transmitter uses dirty-paper coding to mitigate the known interference. They assume partial transmit channel state information which is obtained through a quantised limited feedback. In this model, the receiver sends as feedback only a finite number of bits describing the fading coefficients. Numerical results show that different quantisation schemes must be used for different transmitters (cognitive and non-cognitive) in order to maximise their rates. Also, the number of quantisation bits allocated to each channel coefficient (i.e. the channels from the...
Local excitation of a perfectly conducting slab with finite or infinite number of slits and the role of proper complex waves
, Article IEEE Transactions on Antennas and Propagation ; Volume 68, Issue 8 , 2020 , Pages 6154-6161 ; Rejaei, B ; Memarian, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
The physics and modes of radiation in structures exhibiting extraordinary transmission (ET) can be best studied using Green's function formalism. In this article, we find the electromagnetic response to local excitation of a canonical structure exhibiting ET, and investigate the role of complex waves. The structure is a perfectly conducting slab having a finite or infinite number of through-slits. The solution breaks up the field into even and odd modes, and solves for the fields of the structure with a finite number of slits, by setting up an integral equation. The solution is then extended to find Greens' function of the infinitely periodic structure. The dispersion relations of the...
Solution of population balance equations in emulsion polymerization using method of moments
, Article Chemical Engineering Communications ; Volume 200, Issue 1 , 2013 , Pages 20-49 ; 00986445 (ISSN) ; Shahrokhi, M ; Abedini, H ; Sharif University of Technology
2013
Abstract
In this work, the method of moments is used for solution of population balance equations appearing in modeling of emulsion polymerization (EP). The zero-one model without coagulation effect and the pseudo-bulk model including coagulation effect are investigated as two common approaches for modeling EP processes. The fixed quadrature method is used to close the set of moment equations, and the maximum entropy approach is applied to reconstruct the particle size distribution from a finite number of its moments. Comparing the results with those obtained by the high-precision finite volume technique indicates that, despite the low computational load of the moment method, it has an acceptable...
Polarization maintaining optical fiber multi-intruder sensor
, Article Optics and Laser Technology ; Volume 44, Issue 7 , October , 2012 , Pages 2026-2031 ; 00303992 (ISSN) ; Bathaee, M ; Tofighi, S ; Bahrampour, A ; Farman, F ; Vali, M ; Sharif University of Technology
Elsevier
2012
Abstract
In this paper, an optical fiber multi-intruder sensor based on polarization maintaining optical fiber (PMF), without any interferometric fiber loop, is introduced. To map the local coordinates of intruders on the beating spectrum of the output modes, radiation from a ramp frequency modulated laser is injected at the input of PMF optical fiber sensor. It is shown that the local coordinates and some characteristics of intruders can be obtained by the measurement of the frequencies and amplitudes of the output mode beating spectrum. Generally the number of beating frequencies is more than the number of intruders. Among the beating frequencies, a group with maximum signal to noise ratio is...
Structural reliability of offshore platforms considering fatigue damage and different failure scenarios
, Article Ocean Engineering ; Volume 46 , June , 2012 , Pages 1-8 ; 00298018 (ISSN) ; Golafshani, A. A ; Akrami, V ; Sharif University of Technology
2012
Abstract
Structural systems will normally fail as a consequence of a chain of different components failure es. In this paper, fatigue reliability of fixed offshore platforms is investigated by analyzing different failure scenarios. In order to evaluate the occurrence probability of a special scenario, it is divided into a finite number of sub-scenarios. All combinations of time sequences are generated for a given sequence of failures, using a specially developed program. In order to calculate the occurrence probability of each scenario, a massive reliability analysis should be done for each of corresponding sub-scenarios. A large number of sub-scenarios should be analyzed, therefore implementing time...
Corrected formulation for estimation of ripple in large aspect ratio tokamaks
, Article Journal of Fusion Energy ; Volume 31, Issue 2 , 2012 , Pages 195-197 ; 01640313 (ISSN) ; Khorasani, S ; Sharif University of Technology
Abstract
The finite number of toroidal field coils of a tokamak destroys the perfect axisymmetry of the device. The coils produce a short wavelength ripple in the toroidal magnetic field strength as a field line follows round the torus, which becomes important in transport and confinement properties of plasma. Hence, a quick and accurate estimation of ripple becomes important. We have noticed that a previously reported analytical formulation by Princeton Plasma Physics Laboratory team is not applicable to our large aspect ratio tokamak, and have devised a slightly modified form which has greatly improved the accuracy of the analytical fit
Stabilization of fractional order systems using a finite number of state feedback laws
, Article Nonlinear Dynamics ; Volume 66, Issue 1-2 , 2011 , Pages 141-152 ; 0924090X (ISSN) ; Sedigh, A. K ; Haeri, M ; Sharif University of Technology
Abstract
In this paper, the stabilization of linear time-invariant systems with fractional derivatives using a limited number of available state feedback gains, none of which is individually capable of system stabilization, is studied. In order to solve this problem in fractional order systems, the linear matrix inequality (LMI) approach has been used for fractional order systems. A shadow integer order system for each fractional order system is defined, which has a behavior similar to the fractional order system only from the stabilization point of view. This facilitates the use of Lyapunov function and convex analysis in systems with fractional order 1
Evaluating the effect of using different sets of enrichment for FAs on fuel management optimization using CA
, Article Annals of Nuclear Energy ; Volume 38, Issue 4 , 2011 , Pages 835-845 ; 03064549 (ISSN) ; Fadaei, A. H ; Zahedi, E ; Sharif University of Technology
Abstract
In nuclear reactor core design, achieving the optimized arrangement of fuel assemblies (FAs) is the most important step towards satisfying safety and economic requirements. In most studies, nuclear fuel optimizations have been performed by using a finite number of different types of FAs. However the effect of FA numbers with different enrichments and the difference between their maximum and minimum enrichment values can be important and should be evaluated in the optimization process. This research is aimed at evaluating the effect of using different enrichment values for FAs. This issue has been investigated by focusing on two parameters, namely, the initially selected enrichment and the...
A moment method analysis of the gain spectrum in bi-directionally pumped Raman amplifiers through continuous-spectrum radiation
, Article Optics and Laser Technology ; Volume 42, Issue 2 , 2010 , Pages 332-335 ; 00303992 (ISSN) ; Pourmoghadas, A ; Sharif University of Technology
2010
Abstract
A semi-analytical method is proposed to solve the equations governing a bi-directionally pumped Raman amplifier through continuous-spectrum radiation. The governing equations are systems of uncountable Nonlinear Ordinary Differential Equation (NODE). By applying the moment method, the uncountable system of NODE is reduced to a system of finite number of NODEs. This system of equations is solved numerically and the results are compared with that of the full numerical method. It was shown that the moment method is a powerful and efficient technique for the analysis of a bi-directionally pumped Raman amplifier through continuous-spectrum radiation
An efficient numerical algorithm for stability testing of fractional-delay systems
, Article ISA Transactions ; Volume 48, Issue 1 , 2009 , Pages 32-37 ; 00190578 (ISSN) ; Karimi Ghartemani, M ; Sharif University of Technology
2009
Abstract
This paper presents a numerical algorithm for BIBO stability testing of a certain class of the so-called fractional-delay systems. The characteristic function of the systems under consideration is a multi-valued function of the Laplace variable s which is defined on a Riemann surface with finite number of Riemann sheets where the origin is a branch point. The stability analysis of such systems is not straightforward because there is no universally applicable analytical method to find the roots of the characteristic equation on the right half-plane of the first Riemann sheet. The proposed method is based on the Rouche's theorem which provides the number of the zeros of a given function in a...
State waypoint approach to continuous-time nonlinear optimal control problems
, Article Asian Journal of Control ; Volume 11, Issue 6 , 2009 , Pages 669-676 ; 15618625 (ISSN) ; Tazaki, Y ; Imura, J. I ; Sharif University of Technology
2009
Abstract
In this paper, we propose an optimal control technique for a class of continuous-time nonlinear systems. The key idea of the proposed approach is to parametrize continuous stale trajectories by sequences of a finite number of intermediate target states; namely, waypoint sequences. It is shown that the optimal control problem for transferring the state from one waypoint to the next is given an explicit-form suboptimal solution, by means of linear approximation. Thus the original continuous-time nonlinear control problem reduces to a finite-dimensional optimization problem of waypoint sequences. Any efficient numerical optimization method, such as the interior-reflection Newton method, can be...
Apnea bradycardia detection based on new coupled hidden semi Markov model
, Article Medical and Biological Engineering and Computing ; 12 November , 2020 ; Shamsollahi, M. B ; Ge, D ; Beuchee, A ; Hernandez, A. I ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2020
Abstract
In this paper, a method for apnea bradycardia detection in preterm infants is presented based on coupled hidden semi Markov model (CHSMM). CHSMM is a generalization of hidden Markov models (HMM) used for modeling mutual interactions among different observations of a stochastic process through using finite number of hidden states with corresponding resting time. We introduce a new set of equations for CHSMM to be integrated in a detection algorithm. The detection algorithm was evaluated on a simulated data to detect a specific dynamic and on a clinical dataset of electrocardiogram signals collected from preterm infants for early detection of apnea bradycardia episodes. For simulated data, the...
Health monitoring of structures using few frequency response measurements
, Article Scientia Iranica ; Volume 17, Issue 6 A , NOVEMBER-DECEMBER , 2010 , Pages 493-500 ; 10263098 (ISSN) ; Kianian, M ; Ghodrati, E ; Sharif University of Technology
2010
Abstract
The development of damage detection techniques for offshore jacket structures is vital for preventing catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitoring. In this approach, the concept of a minimum rank perturbation theory is used. The feasibility of using a finite number of sensors and its effect on damage detection capabilities is investigated. In addition, the performance of the proposed method is evaluated in the case of multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform
Revised guided mode expansion on dispersive photonic media
, Article Photonic and Phononic Crystal Materials and Devices IX, San Jose, CA, 27 January 2009 through 29 January 2009 ; Volume 7223 , 2009 ; 0277786X (ISSN) ; Sodagar, M ; Khoshnegar, M ; Khorasani, S ; Chamanzar, M. R ; Adibi, A ; Sharif University of Technology
2009
Abstract
A novel plane-wave-based approach for analytical treatment of dispersive relation is developed and applied to analyze the behavior of electromagnetic waves in plasmonic-photonic-crystal slabs. Here Drude model is used for describing frequency dependent permittivity of plasma rods in host dielectric medium. In the present work, dispersion relation below and above the light line is calculated approximately by means of Maxwell-Garnett effective medium and Revised Plane Wave Method (RPWM). The eigen-functions are then used in Revised Guided Mode Expansion (RGME) as the set of orthonormal bases. Following this procedure, the accurate band structure is obtained. In these kind of methods there are...