Loading...
Search for:
interferometry
0.006 seconds
Total 35 records
Transport of small polar molecules across nonporous polymeric membranes: I. Experimental procedures and data analysis
, Article Journal of Membrane Science ; Volume 211, Issue 2 , 2003 , Pages 193-214 ; 03767388 (ISSN) ; Farhadpour, F. A ; Soltanieh, M ; Bansal, A ; Sharif University of Technology
2003
Abstract
The transient measurement of concentration profile within the liquid boundary layer close to the membrane interface and the flux of permeating species across the membrane coupled with transient model of membrane allows a more critical evaluation of membrane transport performance. The experimental procedure for transient measurement of pervaporation fluxes and data obtained for the {ethanol-water}/silicone rubber system and experimental set up for transient dialysis measurement by interferometry technique for the same system was described. A detailed analysis of optical effect accounting for the light deflection in a medium of varying refractive index profile was presented. A numerical...
Study of thermal behavior of α-PbO2, using TG and DSC
, Article Journal of Thermal Analysis and Calorimetry ; Volume 92, Issue 3 , 2008 , Pages 917-920 ; 13886150 (ISSN) ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
2008
Abstract
Using two techniques of thermogravimetry and differential scanning calorimetry under O2 gas atmosphere from 25 to 600°C, the thermal behavior of laboratory-produced compound lead(IV) oxide α-PbO2 was investigated. The identity of products at different stages were confirmed by XRD technique. Both techniques produced similar results supporting the same decomposition stages for the compound. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported. © 2008 Springer Science+Business Media, LLC
Ramsey interferometry with a two-level generalized Tonks-Girardeau gas
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 76, Issue 3 , 2007 ; 10502947 (ISSN) ; Del Campo, A ; Lizuain, I ; Muga, J. G ; Sharif University of Technology
2007
Abstract
We propose a solvable generalization of the Tonks-Girardeau model that describes a coherent one-dimensional (1D) gas of cold two-level bosons which interact with two external fields in a Ramsey interferometer. They also interact among themselves by idealized, infinitely strong contact potentials, with interchange of momentum and internal state. We study the corresponding Ramsey fringes and the quantum projection noise which, essentially unaffected by the interactions, remains that for ideal bosons. The dual system of this gas, an ideal gas of two-level fermions coupled by the interaction with the separated fields, produces the same fringes and noise fluctuations. The cases of time-separated...
Macroscopic superpositions via nested interferometry: Finite temperature and decoherence considerations
, Article New Journal of Physics ; Volume 14 , November , 2012 ; 13672630 (ISSN) ; Jeffrey, E ; Ghobadi, R ; Simon, C ; Bouwmeester, D ; Sharif University of Technology
2012
Abstract
Recently, there has been much interest in optomechanical devices for the production of macroscopic quantum states. Here we focus on a proposed scheme for achieving macroscopic superpositions via nested interferometry. We consider the effects of finite temperature on the superposition produced. We also investigate in detail the scheme's feasibility for probing various novel decoherence mechanisms
Positioning of geostationary satellite by radio interferometry
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 55, Issue 2 , 2019 , Pages 903-917 ; 00189251 (ISSN) ; Behnia, F ; Haghshenas, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
There are several perturbations that force the satellite orbit to deviate from the elliptical form. To cope with these perturbations, station keeping is applied. For accurate station keeping, determination of the true satellite orbit is necessary. Radio interferometry is one of the techniques used for determining azimuth and elevation look angles of a satellite. In this paper, we introduce three structures based on interferometry for determining the view angles of satellites. The estimated angles are combined with range measurement for orbital positioning of geostationary (GEO) satellites. In the proposed interferometry structures, to acquire the required angular accuracy, the distance...
Incoherent holographic optical phase conjugation for imaging through a scattering medium
, Article IEEE Transactions on Instrumentation and Measurement ; Volume 70 , 2021 ; 00189456 (ISSN) ; Kavehvash, Z ; Fathi, H ; Aghaeizadeh Ghezelghaya, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this article, we present a novel framework based on incoherent holography (IH) and optical phase conjugation (OPC) principle for imaging through scattering media. While many different methods have recently addressed the issue of focusing light inside scattering media or through-scatterer imaging, the majority of them suffer from severe drawbacks, such as demanding for a high-intensity and narrow-bandwidth laser illumination and an extremely stable optical setup in digital holography as the normal disadvantages of interferometry. On the contrary, our proposed framework relaxes the need for interferometry by getting advantage of its IH-based structure. Our newly presented approach for...
Vibrational Analysis of the Middle Ear Ossicular Chain by Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Hoviat Talab, Maryam (Supervisor)
Abstract
The work reported in this dissertation is the result of a joint venture of biomedical scientists and engineers for understanding human middle ear mechanics through finite element modeling and analysis. The main objective of the research is to explore the middle ear dynamics by using an accurate finite element model of the human middle ear. The research started with developing a systematic and accurate geometric modeling method that can be employed to reconstruct the middle ear from the histological sections of a human temporal bone. Using the method, a solid model of human middle ear was constructed which reveals excellent accuracy in geometry. Then a finite element model of the human middle...
Uncontrolled disorder effects in fabricating photonic quantum simulators on a kagome geometry: A projected-entangled-pair-state versus exact- diagonalization analysis
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Vol. 89, Issue. 6 , 2014 ; ISSN: 10502947 ; Dezfouli, B. G ; Ghasemipour, F ; Rezakhani, A. T ; Saberi, H ; Sharif University of Technology
Abstract
We propose a flexible numerical framework for extracting the energy spectra and photon transfer dynamics of a unit kagome cell with disordered cavity-cavity couplings under realistic experimental conditions. A projected-entangled pair state (PEPS) Ansatz to the many-photon wave function allows us to gain a detailed understanding of the effects of undesirable disorder in fabricating well-controlled and scalable photonic quantum simulators. The correlation functions associated with the propagation of two-photon excitations reveal intriguing interference patterns peculiar to the kagome geometry and promise at the same time a highly tunable quantum interferometry device with a signature for the...
Multiuser orthogonal signal division multiplexing for doubly-selective fading channel in autonomous vehicular communications
, Article 1st International Conference for Students on Applied Engineering, ICSAE 2016, 20 October 2016 through 21 October 2016 ; 2017 , Pages 323-327 ; 9781467390538 (ISBN) ; Dehghani Soltani, M ; Azami, H ; Mashhadi, S ; Al-Shibaany Z. Y. A ; Hameed A. F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Communication networks with highly mobile users are emerging rapidly. Autonomous vehicular communication is an interesting example of such systems. High mobility speed causes drastic change in channel states, and consequently a doubly selective fading scenario is a proper model for such channels. In this paper, by considering this proper model, we introduce a multiuser system based on orthogonal signal division multiplexing in a cognitive radio scenario. Carrier interferometry codes are also utilized in this system. By designing the transmitter and receiver, the performance of such system is investigated. We show that this system works properly when users are moving rapidly, and moreover the...
A novel model for three-dimensional imaging using interferometric ISAR in any curved target flight path
, Article IEEE Transactions on Geoscience and Remote Sensing ; Vol. 52, issue. 6 , 2014 , pp. 3236-3245 ; ISSN: 01962892 ; Bastani, M. H ; Sharif University of Technology
Abstract
Using a second receiver antenna close to the main transceiver antenna of inverse synthetic aperture radar (ISAR), it is possible to find 3-D positions of target scattering points. Such system is called bistatic, monopulse, or interferometric ISAR (InISAR). In the conventional model of ISAR, the unknown flying object should have a linear trajectory, and only small deviations from this trajectory can be compensated. Target motions which are highly nonlinear or curvy cannot be used in the conventional model. In this paper, we propose a new model for InISAR to process all collected data from the target, regardless of the form of the flight path. More accuracy is achieved for 3-D positioning of...
Propagation of light in Schwarzschild geometry
, Article Proceedings of SPIE - The International Society for Optical Engineering, 25 January 2010 through 28 January 2010 ; Volume 7597 , 2010 ; 0277786X (ISSN) ; 9780819479938 (ISBN) ; Sharif University of Technology
2010
Abstract
In this paper, the equivalent medium of Schwarzschild metric is discussed. The corresponding ray-tracing equations are integrated for the equivalent medium of the Schwarzschild geometry, which describes the curved space around a spherically symmetric, irrotational, and uncharged blackhole. We make comparison to the well-known expression by Einstein. While Einstein's estimate is reasonably good for large closest distances of approach to the star, it disregards the optical anisotropy of space. Instead, Virbhadra's estimate which takes the effects of anisotropy of Schwarzschild metric is shown to be more consistent with numerical simulations. Hence, a true physical anisotropy in the velocity of...
Positioning of geostationary satellite by Radio Interferometry
, Article IEEE Transactions on Aerospace and Electronic Systems ; 2018 ; 00189251 (ISSN) ; Behnia, F ; Haghshenas, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
There are several perturbations that force the satellite orbit to deviate from the elliptical form. To cope with these perturbations, station keeping is applied. For accurate station keeping, determination of the true satellite orbit is necessary. Radio interferometry is one of the techniques used for determining azimuth and elevation look angles of a satellite. In this paper we introduce three structures based on interferometry for determining the view angles of satellites .The estimated angles are combined with range measurement for orbital positioning of geostationary (GEO) satellites. In the proposed interferometry structures, to acquire the required angular accuracy, the distance...
The effect of direct and cross-rolling on mechanical properties and microstructure of severely deformed aluminum
, Article Journal of Materials Engineering and Performance ; Vol. 23, Issue 1 , 2014 , pp. 115-124 ; ISSN: 10599495 ; Kazeminezhad, M ; Sharif University of Technology
Abstract
Severely deformed commercial pure aluminum sheets by constrained groove pressing are direct and crossrolled. The grain size evolution and dislocation density during rolling are studied using Williamson-Hall analysis on x-ray diffraction patterns of the deformed samples. These results and optical microscopy observations show that subsequent direct or cross-rolling of constrained groove pressed aluminum can produce elongated fine grains. The minimum crystallite size is achieved after cross-rolling of constrained groove pressed samples. By direct-rolling or cross-rolling of annealed sheet, the maximum intensity in x-ray diffraction patterns remains on (200) like annealed aluminum but...
Prediction of the effect of heat generation in ballscrew on the accuracy of CNC milling machine
, Article Proceedings - 2012 14th International Conference on Modelling and Simulation, UKSim 2012, 28 March 2012 through 30 March 2012 ; March , 2012 , Pages 278-282 ; 9780769546827 (ISBN) ; Movahhedy, M. R ; Naebi, A ; Pasban, S ; Sharif University of Technology
2012
Abstract
In high speed machining, friction between the moving parts, generates heat. One of the major causes of thermal errors in linear axes is the heat generated in ball screw during operation at high speed. Thermal errors affect the accuracy of the linear axes and can cause a deviation from the nominal machining circular motion. The subject of this paper is to study the effects of feed velocity and ball screw Preload on the accuracy of circular motion. The temperature rise in the ball screw is measured by a laser thermometer. The errors in the linear and circular motions are measured by laser interferometer and ball bar. Training a neural network by the test results, thermal errors in all parts of...
Optimum quantum state of light for gravitational-wave interferometry
, Article Optics Communications ; Volume 283, Issue 6 , 2010 , Pages 1012-1016 ; 00304018 (ISSN) ; Bahrampour, A. R ; Shojai, F ; Sharif University of Technology
Abstract
The laser interferometric gravitational-wave detectors are sensitive to the quantum state of light employed in the dark port of interferometric system. In this paper a general quantum state for the dark input port is assumed. The quantum state of light is expanded versus the Fock states. The quantum noise of interferometric system is computed as a function of the quantum state of light. The variational method and the genetic algorithm are employed to determine the coefficients of the dark input port and the laser input power for the minimization of the quantum noise. Calculation shows that the optimum quantum state for the dark input port is very close to the vacuum squeezed state. For this...
Enhanced resolution fiber optic strain sensor based on Mach-Zehnder interferometer and displacement sensing principles
, Article ELECO 2009 - 6th International Conference on Electrical and Electronics Engineering, 5 November 2009 through 8 November 2009 ; 2009 , Pages II302-II306 ; 9789944898188 (ISBN) ; Nurmohammadi, T ; Ounie, S ; Sadighi Bonabi, R ; Sharif University of Technology
Abstract
In this study, a novel scheme for fiber optic strain sensor has been introduced. This scheme is indeed a Mach-Zehnder interferometer followed by a displacement sensor. The strain is applied to an optical fiber which is the main branch of the Mach-Zehnder interferometer and causes an alteration in the interferometer's output intensity. The output beam is then spread on a mirror located in front of the fiber head. The head of the fiber and the mirror form a displacement sensor configuration. The portion of the reflected beam, gathered by the fiber, is a function of the distance between the fiber head and the mirror. So, applying strain causes a new change in the gathered intensity due to the...
Compact cross form antenna arrays intended for wideband two dimensional interferometric direction finding including the channel phase tracking error
, Article AEU - International Journal of Electronics and Communications ; Volume 83 , 2018 , Pages 558-565 ; 14348411 (ISSN) ; Farzaneh, F ; Sharif University of Technology
Elsevier GmbH
2018
Abstract
The interferometer method as one of the most accurate schemes for wideband direction finding (DF) is used. The interferometer method has various algorithms which can be implemented depending on the required specifications. The advantages and disadvantages of these algorithms have been evaluated and the appropriate algorithm for a general practical case in view of the ambiguity resolution is proposed. The receivers’ channel phase tracking error is of significant concern in practice in interferometric DF systems. The induced error due to channels phase tracking error is estimated. Furthermore the use of physically realizable antennas, achievement of high accuracy, minimum number of antennas...
Wideband two dimensional interferometric direction finding algorithm using base-triangles and a proposed minimum planar array
, Article AEU - International Journal of Electronics and Communications ; Volume 105 , 2019 , Pages 163-170 ; 14348411 (ISSN) ; Farzaneh, F ; Sharif University of Technology
Elsevier GmbH
2019
Abstract
In wideband interferometric direction finding ambiguity is inevitable due to practical antenna array dimensions. A new algorithm for wideband interferometer direction finding is developed to resolve the ambiguity problem with minimum number of antennas. The method is based on direction finding by three antennas arranged at the three vertices of a triangle named the base-triangle. A two dimensional matrix of ambiguous angles is generated. The ambiguity problem is resolved by an auxiliary base-triangle formed by a fourth antenna in the arrangement. The common angle between the two ambiguous directions derived from the two base-triangles, is the desired angle. As such a four antenna array is...
Bringing Schrödinger's cat to life with non-equilibrium respiration
, Article Journal of Optics (United Kingdom) ; Volume 22, Issue 5 , 2020 ; Naeij, H. R ; Shafiee, A ; Sharif University of Technology
IOP Publishing Ltd
2020
Abstract
In this study, we have proposed a method based on non-equilibrium effects to generate the superposition of macroscopically distinguishable quantum states, known as Schrödinger cat states, by using a Mach-Zehnder interferometry type experiment. The interaction of the input number state with a Kerr medium in the presence of a couple of heat baths in different temperatures in the interaction picture and without imposing a Markov assumption is considered. We have shown that the study of dynamics of the cat states under non-equilibrium condition opens up a way for the robustness of quantum features against the destructive role of the environment, even at high temperature limits. It is verified...
Quantum motion effects in an ultracold-atom mach-zehnder interferometer
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 78, Issue 1 , 2008 ; 10502947 (ISSN) ; Mousavi, V ; Seidel, D ; Muga, J. G ; Sharif University of Technology
2008
Abstract
We study the effect of quantum motion in a Mach-Zehnder interferometer where ultracold, two-level atoms cross a π2-π-π2 configuration of separated, laser illuminated regions. Explicit and exact expressions are obtained for transmission amplitudes of monochromatic, incident atomic waves using recurrence relations which take into account all possible paths: the direct ones usually considered in the simple semiclassical treatment, but including quantum motion corrections, and the paths in which the atoms are repeatedly reflected at the fields. © 2008 The American Physical Society