The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Pengyu Guan - One of the best experts on this subject based on the ideXlab platform.

  • Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM
    2020
    Co-Authors: Edson P. Da Silva, Robert Borkowski, Fabian Schwartau, Simone Gaiarin, Miguel I. Olmedo, Armand Vedadi, Molly Piels, Michael Galili, Pengyu Guan, Sergei Popov
    Abstract:

    Abstract: We discuss the benefits and limitations of optical time-division multiplexing(OTDM) techniques based on the optical generation of a Periodic Train of sinc pulses forwavelength-division multiplexing (WDM) transmission at high baud rates. It is shownhow the modulated OTDM spectrum bandwidth is related to the optical comb parametersand the pulse shaping of the modulating waveforms in the electrical domain. Such de-pendence may result in broadening of the modulated spectra, which can degrade theperformance of Nyquist-WDM systems due to interchannel crosstalk penalties. However,it is shown and experimentally demonstrated that the same technique of optical pulseTrain generation can be allied with digital pulse shaping to improve the confinement ofthe modulated spectrum toward the Nyquist limit independently of the number of OTDMtributaries used. To investigate the benefits of the proposed approach, we demonstratethe first WDM Nyquist-OTDM signal generation based on the Periodic Train of sinc pulsesand electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demon-strated over a dispersion uncompensated link up to 640 km, with full-field coherentdetection at the receiver. It is shown that such a design strategy effectively improves thespectral confinement of the modulated OTDM signal, providing a minimum intercarriercrosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.Index Terms: Coherent communications, Nyquist-OTDM.

  • Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM Transceivers
    IEEE Photonics Journal, 2016
    Co-Authors: Edson P. Da Silva, Robert Borkowski, Stefan Preußler, Fabian Schwartau, Simone Gaiarin, Miguel I. Olmedo, Armand Vedadi, Molly Piels, Michael Galili, Pengyu Guan
    Abstract:

    We discuss the benefits and limitations of optical time-division multiplexing (OTDM) techniques based on the optical generation of a Periodic Train of sinc pulses for wavelength-division multiplexing (WDM) transmission at high baud rates. It is shown how the modulated OTDM spectrum bandwidth is related to the optical comb parameters and the pulse shaping of the modulating waveforms in the electrical domain. Such dependence may result in broadening of the modulated spectra, which can degrade the performance of Nyquist-WDM systems due to interchannel crosstalk penalties. However, it is shown and experimentally demonstrated that the same technique of optical pulse Train generation can be allied with digital pulse shaping to improve the confinement of the modulated spectrum toward the Nyquist limit independently of the number of OTDM tributaries used. To investigate the benefits of the proposed approach, we demonstrate the first WDM Nyquist-OTDM signal generation based on the Periodic Train of sinc pulses and electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demonstrated over a dispersion uncompensated link up to 640 km, with full-field coherent detection at the receiver. It is shown that such a design strategy effectively improves the spectral confinement of the modulated OTDM signal, providing a minimum intercarrier crosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.

Lianbo Deng - One of the best experts on this subject based on the ideXlab platform.

  • multi Periodic Train timetabling using a period type based lagrangian relaxation decomposition
    Transportation Research Part B-methodological, 2017
    Co-Authors: Wenliang Zhou, Junli Tian, Min Jiang, Lianbo Deng
    Abstract:

    To provide passengers with strict regularity of Train operation, this research is devoted to modeling and solving the multi-Periodic Train timetabling problem to simultaneously optimize operation periods, arrival times, and departure times of all period types of Trains on a double-track rail network. Based on the construction of a weighted directed graph, a multi-path searching model, namely, a 0-1 linear programming model, is built to minimize the total travel time of all period-types of Trains subject to many operational consTraints, including station parking capacity and Train minimum load factors. After decomposing this model by introducing some Lagrangian multipliers to relax its complicated consTraints, a solution algorithm, including a multi-path simultaneous searching sub-algorithm for each period-type of Train, is designed to optimize both the feasible and dual solutions, which correspond to the upper and lower bounds, respectively. Finally, the performance, convergence, sensitivity, and practicability of our method are analyzed using many instances on both a small rail network and the high-speed railway between Beijing and Shanghai in China.

Wenliang Zhou - One of the best experts on this subject based on the ideXlab platform.

  • a mixed integer linear programming method for simultaneous multi Periodic Train timetabling and routing on a high speed rail network
    Sustainability, 2020
    Co-Authors: Wenliang Zhou
    Abstract:

    To avoid conflicts among Trains at stations and provide passengers with a Periodic Train timetable to improve service level, this paper mainly focuses on the problem of multi-Periodic Train timetabling and routing by optimizing the routes of Trains at stations and their entering time and leaving time on each chosen arrival–departure track at each visited station. Based on the constructed directed graph, including unidirectional and bidirectional tracks at stations and in sections, a mixed integer linear programming model with the goal of minimizing the total travel time of Trains is formulated. Then, a strategy is introduced to reduce the number of consTraints for improving the solved efficiency of the model. Finally, the performance, stability and practicability of the proposed method, as well as the impact of some main factors on the model are analyzed by numerous instances on both a constructed railway network and Guang-Zhu inter-city railway; they are solved using the commercial solver WebSphere ILOG CPLEX (International Business Machines Corporation, New York, NY, USA). Experimental results show that integrating multi-Periodic Train timetabling and routing can be conducive to improving the quality of a Train timetable. Hence, good economic and social benefits for high-speed rail can be achieved, thus, further contributing to the sustained development of both high-speed railway systems and society.

  • multi Periodic Train timetabling using a period type based lagrangian relaxation decomposition
    Transportation Research Part B-methodological, 2017
    Co-Authors: Wenliang Zhou, Junli Tian, Min Jiang, Lianbo Deng
    Abstract:

    To provide passengers with strict regularity of Train operation, this research is devoted to modeling and solving the multi-Periodic Train timetabling problem to simultaneously optimize operation periods, arrival times, and departure times of all period types of Trains on a double-track rail network. Based on the construction of a weighted directed graph, a multi-path searching model, namely, a 0-1 linear programming model, is built to minimize the total travel time of all period-types of Trains subject to many operational consTraints, including station parking capacity and Train minimum load factors. After decomposing this model by introducing some Lagrangian multipliers to relax its complicated consTraints, a solution algorithm, including a multi-path simultaneous searching sub-algorithm for each period-type of Train, is designed to optimize both the feasible and dual solutions, which correspond to the upper and lower bounds, respectively. Finally, the performance, convergence, sensitivity, and practicability of our method are analyzed using many instances on both a small rail network and the high-speed railway between Beijing and Shanghai in China.

I V Zotova - One of the best experts on this subject based on the ideXlab platform.

  • Generation of Train of Ultrashort Ka-band Pulses by Helical Gyro-TWTs with Nonlinear Cyclotron Resonance Absorber in the Feedback Loop
    2018 43rd International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2018
    Co-Authors: N S Ginzburg, A S Sergeev, Mikhail N. Vilkov, G.g. Denisov, S.v. Samsonov, I V Zotova
    Abstract:

    Based on a time-domain model we demonstrate that a Periodic Train of powerful ultrashort microwave pulses can be generated in an electron oscillator consisting of helically corrugated gyrotron travelling wave tube (gyro-Twt)and saturable absorber based on cyclotron resonance interaction of radiation with initially rectilinear electron beam. The gyro-TWT operates at the second cyclotron harmonic while in the absorber interaction at the fundamental harmonic should be realized. According to simulations with the parameters of an experimentally realized Ka-band gyro-TWT, the peak power of generated pulses with duration of 200 ps is about 400 kW.

  • Mode-locked electron oscillator based on two coupled helical gyro-TWTs
    2017 Eighteenth International Vacuum Electronics Conference (IVEC), 2017
    Co-Authors: I V Zotova, N S Ginzburg, A S Sergeev, Mikhail N. Vilkov, G.g. Denisov, S.v. Samsonov, S. V. Mishakin
    Abstract:

    Based on a time-domain model we demonstrate that a Periodic Train of powerful ultrashort microwave pulses can be generated in an electron oscillator consisting of two coupled helically corrugated gyrotron travelling wave tubes (gyro-TWTs) operating in regimes of amplification and saturable absorption, respectively. Mechanism of pulse formation in such an oscillator is based on the effect of passive mode-locking widely used in laser physics. Saturable absorption can be implemented in a gyro-TWT in the Kompfner dip regime by a proper matching of the guiding magnetic field. According to simulations with the parameters of an experimentally realized Ka-band gyro-TWT, the peak power of generated pulses with duration of 200 ps can achieve 400 kW.

  • conversion of an electromagnetic wave into a Periodic Train of solitons under cyclotron resonance interaction with a backward beam of unexcited electron oscillators
    Physical Review Letters, 2014
    Co-Authors: I V Zotova, N S Ginzburg, A S Sergeev, E R Kocharovskaya, Yu V Zaslavsky
    Abstract:

    The possibility of the conversion of intense continuous microwave radiation into a Periodic Train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a Train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons.

Edson P. Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM
    2020
    Co-Authors: Edson P. Da Silva, Robert Borkowski, Fabian Schwartau, Simone Gaiarin, Miguel I. Olmedo, Armand Vedadi, Molly Piels, Michael Galili, Pengyu Guan, Sergei Popov
    Abstract:

    Abstract: We discuss the benefits and limitations of optical time-division multiplexing(OTDM) techniques based on the optical generation of a Periodic Train of sinc pulses forwavelength-division multiplexing (WDM) transmission at high baud rates. It is shownhow the modulated OTDM spectrum bandwidth is related to the optical comb parametersand the pulse shaping of the modulating waveforms in the electrical domain. Such de-pendence may result in broadening of the modulated spectra, which can degrade theperformance of Nyquist-WDM systems due to interchannel crosstalk penalties. However,it is shown and experimentally demonstrated that the same technique of optical pulseTrain generation can be allied with digital pulse shaping to improve the confinement ofthe modulated spectrum toward the Nyquist limit independently of the number of OTDMtributaries used. To investigate the benefits of the proposed approach, we demonstratethe first WDM Nyquist-OTDM signal generation based on the Periodic Train of sinc pulsesand electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demon-strated over a dispersion uncompensated link up to 640 km, with full-field coherentdetection at the receiver. It is shown that such a design strategy effectively improves thespectral confinement of the modulated OTDM signal, providing a minimum intercarriercrosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.Index Terms: Coherent communications, Nyquist-OTDM.

  • Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM Transceivers
    IEEE Photonics Journal, 2016
    Co-Authors: Edson P. Da Silva, Robert Borkowski, Stefan Preußler, Fabian Schwartau, Simone Gaiarin, Miguel I. Olmedo, Armand Vedadi, Molly Piels, Michael Galili, Pengyu Guan
    Abstract:

    We discuss the benefits and limitations of optical time-division multiplexing (OTDM) techniques based on the optical generation of a Periodic Train of sinc pulses for wavelength-division multiplexing (WDM) transmission at high baud rates. It is shown how the modulated OTDM spectrum bandwidth is related to the optical comb parameters and the pulse shaping of the modulating waveforms in the electrical domain. Such dependence may result in broadening of the modulated spectra, which can degrade the performance of Nyquist-WDM systems due to interchannel crosstalk penalties. However, it is shown and experimentally demonstrated that the same technique of optical pulse Train generation can be allied with digital pulse shaping to improve the confinement of the modulated spectrum toward the Nyquist limit independently of the number of OTDM tributaries used. To investigate the benefits of the proposed approach, we demonstrate the first WDM Nyquist-OTDM signal generation based on the Periodic Train of sinc pulses and electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demonstrated over a dispersion uncompensated link up to 640 km, with full-field coherent detection at the receiver. It is shown that such a design strategy effectively improves the spectral confinement of the modulated OTDM signal, providing a minimum intercarrier crosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.