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Neural networks in identification of helicopters using passive sensors
, Article 2006 IEEE International Conference on Systems, Man and Cybernetics, Taipei, 8 October 2006 through 11 October 2006 ; Volume 1 , 2006 , Pages 7-10 ; 1062922X (ISSN); 1424401003 (ISBN); 9781424401000 (ISBN) ; Faghihi, A. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2006
Abstract
An Artificial Neural Network (ANN) based helicopter identification system is proposed. All helicopters emit certain characteristic acoustic signatures, which are specific to them. This is due to some differences in their structures and design. These differences in acoustic signatures can be used with neural networks for detection and classification of different types of helicopters. The conventional system uses the ratio of the main-rotor blade passage frequency (bpf) to the tail-rotor bpf. The ANN is trained to use similar main/tail-rotor information, in addition to the parametric spectral representation technique (Reflection Coefficients). It is also shown that the classifier performance...
Limiting Geodesics for First-Passage Ppercolation on Subsets of Z^2
, M.Sc. Thesis Sharif University of Technology ; Haji Mirsadeghi, Mir Omid (Supervisor)
Abstract
In this dissertation, we investigate the problem of the existence of finite geodetic sequences from point to point (0, n). This has not been proven in the general case. In this dissertation, we present an article that illustrates this question in a particular case of z ^ 2 subspaces whose self and complement are infinite and connected (e.g., slit planes, half-planes, and sectors). Writing x_n for the sequence of boundary vertices, we show that the sequence of geodesics from any point to x_n has an almost sure limit assuming only existence of finite geodesics. For all passage-time configurations, we show existence of a limiting Busemann function. Specializing to the case of the half-plane, we...
First-passage-time processes and subordinated Schramm-Loewner evolution
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 84, Issue 1 , July , 2011 ; 15393755 (ISSN) ; Rajabpour, M. A ; Rouhani, S ; Sharif University of Technology
2011
Abstract
We study the first-passage-time processes of the anomalous diffusion on the self-similar curves in two dimensions. The scaling properties of the mean-square displacement and mean first passage time of the fractional Brownian motion and subordinated walk on the different fractal curves (loop-erased random walk, harmonic explorer, and percolation front) are derived. We also define natural parametrized subordinated Schramm-Loewner evolution (NS-SLE) as a mathematical tool that can model diffusion on fractal curves. The scaling properties of the mean-square displacement and mean first passage time for NS-SLE are obtained by numerical means
Optimal paths on the space-time SINR random graph
, Article Advances in Applied Probability ; Volume 43, Issue 1 , 2011 , Pages 131-150 ; 00018678 (ISSN) ; Blaszczyszyn, B ; Haji Mirsadeghi, M. O ; Sharif University of Technology
Abstract
We analyze a class of signal-to-interference-and-noise-ratio (SINR) random graphs. These random graphs arise in the modeling packet transmissions in wireless networks. Tn contrast to previous studies on STNR graphs, we consider both a space and a time dimension. The spatial aspect originates from the random locations of the network nodes in the Euclidean plane. The time aspect stems from the random transmission policy followed by each network node and from the time variations of the wireless channel characteristics. The combination of these random space and time aspects leads to fluctuations of the SINR experienced by the wireless channels, which in turn determine the progression of packets...
Considering wave passage effects in blind identification of long-span bridges
, Article Conference Proceedings of the Society for Experimental Mechanics Series ; Volume 5 , 2013 , Pages 53-66 ; 21915644 (ISSN); 9781461465638 (ISBN) ; Ghannad, M. A ; Norman, J ; Crewe, A ; Abazarsa, F ; Taciroglu, E ; Sharif University of Technology
2013
Abstract
Long-span bridges usually experience different input excitations at their ground supports that emanate from differences in wave arrival times, and soil conditions, as well as loss of coherency in arriving waves. These spatial variations can drastically influence the dynamic response; hence, this phenomenon must be considered in any vibration-based identification method. There are numerous Multi-Input Multi-Output (MIMO) identification techniques that may be applied to data recorded at long-span bridges that experience spatial variations in their input motions. However, inertial soil-structure interaction effects severely reduce the accuracy of these techniques because the actual Foundation...
Analytical and numerical studies of sequence dependence of passage times for translocation of heterobiopolymers through nanopores
, Article Journal of Chemical Physics ; Volume 129, Issue 23 , 2008 ; 00219606 (ISSN) ; Roshani, F ; Nourmohammad, A ; Sahimi, M ; Rahimi Tabar, M. R ; Sharif University of Technology
2008
Abstract
We consider chaperone-assisted translocation of biopolymers with two distinct monomers or bases A and B, with the size of the chaperones being λα, where α is a monomer's size. The probability that A and B are neighbors in the biopolymer is PAB. A master equation is used, together with the detailed-balanced condition, in order to derive analytical results for the statistics of the first-passage times of the biopolymer as a function of PAB, λ, and the biopolymer's configuration. Monte Carlo simulations have also been carried out in order to compute the same quantities for biopolymers with 100-900 monomers and several λ. The results indicate nontrivial dependence of the variance of the...
Macroscopic Superposition in Quantum Systems
, Ph.D. Dissertation Sharif University of Technology ; Karimipour, Vahid (Supervisor)
Abstract
Quantum mechanics provides a deep understanding of atoms and their interaction with light. As long as we consider only microscopic systems on the scale of an atomic radius, objections to quantum properties such as quantum superposition are nevertheless rare, mainly because of the overwhelming experimental evidence. When it comes to macroscopic systems, many things are not clear anymore. For example,everyday objects of macroscopic size do not exist in superposition of their different states. The reason is that a quantum system interacts with its environment locally,which destroys non-local quantum correlation within the system, larger objects interact with the environment more intensively and...
Flow and heat transfer analysis of turbine blade cooling passages using network method
, Article ASME 2012 Gas Turbine India Conference, GTINDIA 2012 ; 2012 , Pages 523-531 ; 9780791845165 (ISBN) ; Izadi, A ; Fathi, A ; Khaledi, H ; Sharif University of Technology
2012
Abstract
Modern turbine blades are cooled by air flowing through internal cooling passages. Three-Dimensional numerical simulation of these blade cooling passages is too time-consuming because of their complex geometries. These geometrical complexities exist as a result of using various kinds of cooling technologies such as rib turbulators (inline, staggered, or inclined ribs), pin fin, 90 and 180 degree turns (both sharp and gradual turns, with and without turbulators), finned passage, by-pass flow and tip cap impingement. One possible solution to simulate such sophisticated passages is to use the one-dimensional network method, which is presented in the current work. Turbine blade cooling channels...
Sequence dependence of the binding energy in chaperone-driven polymer translocation through a nanopore
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 1 , January , 2011 ; 15393755 (ISSN) ; Ejtehadi, M. R ; Metzler, R ; Sharif University of Technology
2011
Abstract
We study the translocation of stiff polymers through a nanopore, driven by the chemical-potential gradient exerted by binding proteins (chaperones) on the trans side of the pore. Bound chaperones prevent backsliding through the pore and, therefore, partially rectify the polymer passage. We show that the sequence of chain monomers with different binding affinity for the chaperones significantly affects the translocation dynamics. In particular, we investigate the effect of the nearest-neighbor adjacency probability of the two monomer types. Depending on the magnitude of the involved binding energies, the translocation speed may either increase or decrease with the adjacency probability. We...
Hierarchal assessment of noise pollution in urban areas - A case study
, Article Transportation Research Part D: Transport and Environment ; Volume 34 , January , 2015 , Pages 95-103 ; 13619209 (ISSN) ; Karimi, E ; Nassiri, P ; Monazzam, M. R ; Taghavi, L ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Noise pollution in urban areas has many harmful effects on the citizens. There are varieties of noise generation sources of which the traffic noise could be a major source. The point which is perhaps less noticed is that sound level is not the only parameter to indicate the extent and intensity of noise pollution. Situation of urban land uses, distribution of population centers and types of passages can deeply affect the concern on this environmental issue but not with a similar ratio. This article presents an overlaying technique to define noise prone areas using all different factors involved. A case study was carried out in the District 14 of Tehran Metropolitan City where there are busy...
Experimental and numerical investigation on the effect of blade number on vibrations of industrial fans
, Article COMADEM 2010 - Advances in Maintenance and Condition Diagnosis Technologies Towards Sustainable Society, Proc. 23rd Int. Congr. Condition Monitoring and Diagnostic Engineering Management, 28 June 2010 through 2 July 2010 ; February , 2010 , Pages 473-480 ; 9784883254194 (ISBN) ; Ebrahimi, A ; Oskouie, S. N ; Massoumi, H ; Sharif University of Technology
Abstract
In this paper, the effect of blade number on the vibration behavior of industrial fans has been studied experimentally and numerically. Two similar industrial fans with similar specifications and only different blade numbers were chosen in a plant. The vibration levels were measured on these fans and the results revealed that the blade passage phenomenon is the main cause of vibrations on both fans. Both fans and their structures were modeled numerically and the performance characteristics, vibratory forces and vibration response of structure were calculated. The results showed that the number of blade has small effect on vibratory forces compared to the performance characteristics. The...
Efficiency of long-range navigation on Treelike fractals
, Article Chaos, Solitons and Fractals ; Volume 122 , 2019 , Pages 102-110 ; 09600779 (ISSN) ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
To get a deep understanding of a diffusion process and realizing the most efficient methods for investigating a real network, has always been of great interest and utility to us. In this work, we aim to study and compare our mobility in a network using a normal random walk and a long-range navigation strategy such as Lévy Walk. We study the Global Mean First Traverse Distance (GMFTD) and the entropy rate for this long-range navigation process and later, compare with a normal walk strategy. For this study, GMFTD is utilized instead of Global Mean First Passage Time (GMFPT). The reason for such a choice is the fact that for more accurate and precise results, we need to also take into account...
Fast multiqubit gates by adiabatic evolution in interacting excited-state manifolds of rydberg atoms and superconducting circuits
, Article Physical Review X ; Volume 10, Issue 2 , June , 2020 ; Mølmer, K ; Sharif University of Technology
American Physical Society
2020
Abstract
Quantum computing and quantum simulation can be implemented by concatenation of one- and two-qubit gates and interactions. For most physical implementations, however, it may be advantageous to explore state components and interactions that depart from this universal paradigm and offer faster or more robust access to more advanced operations on the system. In this article, we show that adiabatic passage along the dark eigenstate of excitation exchange interactions can be used to implement fast multiqubit Toffoli (Ck-NOT) and fan-out (C-NOTk) gates. This mechanism can be realized by simultaneous excitation of atoms to Rydberg levels, featuring resonant exchange interaction. Our theoretical...
Introducing shell formation and a thermodynamics-inspired concept for swarm robotic systems
, Article Robotics and Autonomous Systems ; Volume 148 , 2022 ; 09218890 (ISSN) ; Alasty, A ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this article, a new formation for swarm robotic systems is introduced. This formation, which is made up of a portion of swarm members and encircles the whole swarm, is called the shell formation. In this regard, an effective algorithm for developing the shell formation in swarm robotic systems is established. The interaction mechanism among swarm agents is based on the method of artificial potential fields and the local rule of the nearest neighbor. Subsequently, inspired by the thermodynamic science and based on the introduced shell formation, the thermodynamic concept of pressure is generalized to swarm robotic systems. Finally, the efficacy of the introduced shell formation in solving...
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
, Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on...
Heat transfer intensification of turbulent forced convection by inserting discontinuous twisted tapes in a wavy tube; hydrothermal and thermodynamics analysis
, Article Chemical Engineering and Processing - Process Intensification ; Volume 181 , 2022 ; 02552701 (ISSN) ; Sadrhosseini, H ; Kazemzadeh Hannani, S ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The current study presents a numerical investigation on turbulent hydrothermal characteristics in a wavy passage equipped with discontinuous twisted tapes. The working fluid is water and passage walls are kept under constant wall temperature. The effect of Reynolds number (Re = 2500, 4500, 6500, 8500 and 10500), twist angle (TA = 90∘ and 180∘) and inclination angle (IA = 15∘ and 30∘) on velocity fields and streamlines, temperature contours, Nusselt number, friction factor, turbulent kinetic energy (TKE), thermal performance factor (TPF), energy efficiency factor (EEF) and entropy generation rate are evaluated. More uniform temperature and velocity fields can be found as both wavy passage and...