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Plain and oscillatory solitons of the cubic complex Ginzburg-Landau equation with nonlinear gradient terms
Get PDFIn this work, we present parameter regions for the existence of stable plain solitons of the cubic complex Ginzburg-Landau equation (CGLE) with higher-order terms associated with a fourth-order expansion. Using a perturbation approach around the nonlinear Schrdinger equation soliton and a full numerical analysis that solves an ordinary differential equation for the soliton profiles and using the Evans method in the search for unstable eigenvalues, we have found that the minimum equation allowing these stable solitons is the cubic CGLE plus a term known in optics as Raman-delayed response, which is responsible for the redshift of the spectrum. The other favorable term for the occurrence of stable solitons is a term that represents the increase of nonlinear gain with higher frequencies. At the stability boundary, a bifurcation occurs giving rise to stable oscillatory solitons for higher values of the nonlinear gain. These oscillations can have very high amplitudes, with the pulse energy changing more than two orders of magnitude in a period, and they can even exhibit more complex dynamics such as period-doubling
Nonlinear Compensation Assessment in Few-Mode Fibers via Phase-Conjugated Twin Waves
Get PDFIn this paper, we further explore the concept of phase-conjugated twin waves (PCTW) for nonlinear cancellation in space-division multiplexed (SDM) systems. Previously, we demonstrated that the PCTW technique can successfully provide nonlinear cancellation in SDM systems. In this paper, we investigate the cases where two and four spatial modes are copropagating in a multimode fiber, considering three link lengths (1000, 3200, and 8000 km). Weak-and strong-coupling regimes are also evaluated. Our numerical simulation results show an average performance improvement > 10 dB after a 1000 km transmission link
Future liquefied natural gas business structure: a review and comparison of oil and liquefied natural gas sectors
No full textThe liquefied natural gas (LNG) trade provides the means of trading gas globally and represents about 10% of the gas trade. The forecasts show the LNG business will grow, over the next 20 years, at about twice the rate of the whole gas trade. Although the current state of LNG trade is well studied, the literature on the future business structure of it is limited and conflictual. This work considers the future LNG business structure by comparing the development trajectories of the oil and LNG sectors. In addition, it assesses the conclusions drawn by researchers against this background and the current pattern of change in the industry. The comparison involves three stages: (1) trade flows-oil and LNG trade flows are very similar, mainly due to the common distribution of the oil and gas reserves. (2) Supply chain configuration-the international trade for both fuels is tanker based thus allowing for a similar market responsive trade policy, i.e., real-time destination selection (spot sale) at a global scale. (3) Institutional developments-the current transparent and competitive global oil trade, with prices dominated by physical and paper markets, was driven previously by long-term contracts, in the same manner as the current LNG business. This analysis, together with transaction cost economics, supports the argument that, in future, LNG spot trade will increase and give rise to a competitive and globally unified LNG market. Further-more, LNG pricing will become transparent and would be dominated by physical and paper markets benchmark prices. (C) 2016 John Wiley & Sons, Ltd
New framework for optimal scheduling of combined heat and power with electric and thermal storage systems considering industrial customers inter-zonal power exchanges
No full textIntroducing Combined Heat and Power (CHP) units into Active Distribution Network (ADN) can significantly affect the problem of optimal generation scheduling. A new method for solving the problem of Optimal Scheduling of Combined Heat and Power (OSCHP) units of an ADN with Electric Storage Systems (ESSs) and Thermal Storage Systems (TSSs) considering Industrial Customers (ICs) Inter-Zonal Power Exchanges (IZPEs) is presented. The ADN operator may use CHP units to supply its ICs and based on smart grid conceptual model, it can transact electricity with upstream network. However, the electricity transactions between the ADN and its ICs in normal and contingency scenarios may highly complicate this problem. In this paper, linearization techniques are adopted to linearize equations and a two-stage stochastic mixed integer linear programming (SMILP) model is utilized to solve the problem to determine the optimal generation scheduling units. The first stage models the behaviour of operation parameters, minimizes the operation costs, and checks the feasibility of the ICs' requested firm and non firm IZPEs, while the second stage considers system's stochastic contingency scenarios. The competitiveness of ADN in the deregulated market can be improved by adjusting the proposed decision variables in the two-stage optimization procedure. The proposed method is applied to 18- and 123-bus IEEE test systems to thoroughly demonstrate the benefits of implementing inter-zonal power exchanges
Fabry-Perot cavity based on polymer FBG as refractive index sensor
Get PDFThe use of a polymer fiber as a refractive index sensor is proposed. A fiber Bragg grating is inscribed near the fiber tip and the fiber is cut shorter thus creating a Fabry-Perot cavity. The reflections between the fiber Bragg grating and the fiber end-face create a Fabry-Perot interferometer. The sensor was characterized to refractive index changes at constant temperature and to temperature at constant refractive index using a fast Fourier transform analysis of the interference signal. The sensor revealed a sensitivity of-1. 94 RIU-1 with a resolution of lx10(-3)RITJ and low sensitivity to temperature, with a cross sensitivity to temperature of 3. 6x10(-4)RIU/degrees C
