Non-Linear Employment Effects of Tax Policy

We study the non-linear propagation mechanism of tax policy in a heterogeneous agent equilibrium business cycle model with search frictions in the labor market and an extensive margin of employment adjustment. The model exhibits endogenous job destruction and endogenous hiring standards in the form of occasionally-binding zero-surplus constraints. After parameterizing the model using U.S. data, we find that the dynamic response of employment to a temporary change in the labor income tax is highly non-linear, displaying sizable asymmetries and state-dependence. Notably, the response to a tax rate cut is at least twice as large in a recession as in an expansion.

Comparison of Two Versions of the MNLS With the Full Water Wave Equations

Versions of the non-linear Schrödinger equation are frequently used for modelling the non-linear propagation of water waves. In this paper, we compare two models against the results of fully non-linear numerical simulations. We consider uni-directional versions of the non-linear Schrödinger equation of Dysthe et al. with the hybrid model of Trulsen et al. The model of Trulsen et al. is shown to have clear advantages in all situations considered including modelling wave crest statistics for highly non-linear cases. However, for very broad bandwidths this model does start to break down, presumably due to the inherent limitation of the envelope representation of water waves. This in turn leads to a small, non-physical, leakage of energy in nonlinear simulations, although, this leakage is much smaller than for the version with 5th order linear dispersion relationship.

Performance of optical amplifiers with regard to the power penalties of a DWDM XGS-PON

Introduction:This article is the product of the research “Simulation level performance analysis of optical amplifiers for a DWDM XGS-PON network environment”, supported by the Research Group in New Technologies in Telecommunications (GNTT) of the University of Cauca during 2019. Problem:For the implementation of XGS-PON optical network architectures, amplification processes are required. These generate power penalties that lead to the presence of non-linear phenomena, significantly degrading network performance. Objective:To analyze the performance of a DWDM / XGS-PON network architecture, respecting the power penalties generated by implementing different types of optical amplifiers in different amplification modes. Methodology:Compilation of relevant bibliography on long-range network architectures with symmetric speeds of 10 Gbps. Results:Not working in the ideal region of amplification affects the performance of a DWDM XGS-PON network, generating a migration of a linear to non-linear propagation regime, due to the presence of power penalties such as FWM. Conclusion:With this investigation it is possible to determine which amplifier should be used according to the needs of the optical network, evaluating the different alternatives available in the market, depending on the cost, configuration and performance of the system. Originality:A new research is carried out for the performance of DWDM XGS-PON state-of-the-art network architectures, regarding the incidence of non-linear propagation phenomena. Restrictions:In some cases, the simulation tool requires a high consumption of machine resources and processing time.

Underwater Acoustic Communication for The Marine Environment’s Monitoring

Within the possibilities of non-linear acoustics, the parametric effect offers a range of acoustic applications that are currently being exploited in different areas. In underwater acoustics, environmental monitoring and security are one of the applications that can benefit from these technologies, allowing the transmission of information in a directivity controlled and efficient manner. An essential aspect for the optimal functioning of these technologies is the choice of the modulation that best suits the needs of communication. In the present work, different modulation techniques are explained, through their non-linear propagation, that allows generating the signals to be propagated. Among the modulations presented in this work, we have Amplitude Modulation (AM), Continuous Phase Frequency Shift Keying (CPFSK), and Linear Frequency Modulation (LFM) modulations normally used in communications. These modulations are performed with a modulating signal (sine and sine-sweeps type) whose non-linear demodulation determines the shape of the 1 and 0 bits, through the transmission of a bit string. With all this, comparisons are made between each technique, to obtain a more precise detection and discrimination of the bits.

“Three Sisters” Measured As a Triple Rogue Wave Group

On November 30, 2018, our attention was caught when analyzing wave profile time series measured by a platform mounted wave sensor (a SAAB REX radar) at Ekofisk, central North Sea. The 20-minute time series had not only one, but three consecutive waves with individual heights that all were more than twice the significant wave height, the two last of them being almost equally high with a factor 2.35 to the significant wave height of 4m (from 4σ(η), over 20 minutes). Counting three rogue waves in one sequence seems to be very rare. In this study we analyze how the shape is evolving in space and time using linear and non-linear propagation methods developed by Mark Donelan [1,2] and Karsten Trulsen [3,4]. Weather conditions and characteristics of the sea state with the ‘Three Sisters’ (named the “Justine Three Sisters”) are presented. It is found that the Three Sisters occurred in a crossing sea condition, with wind sea and swell coming from directions 60 degrees apart, with about same frequency, but very different energy.

Face-to-Face Collisions of Bright and Dark Ion Acoustic Solitons in Superthermal Electrons for Different Geometrical Configurations

The face-to-face collision of ion acoustic solitons (IASs) in superthermal plasmas composed of positive and negative ion fluids and superthermal electrons is investigated for different geometrical configurations. For the generic case, the extended Poincaré-Lighthill-Kuo (EPLK) analysis is employed to obtain the extended Korteweg-de Vries (EKdV) equations and phase shift equations. The non-linear propagation and the face-to-face collision of bright and dark IASs are studied. In addition, when the concentration of ion reaches the critical value, the EPLK method is applied to obtain the modified Korteweg-de Vries (mKdV) equations and the phase shift relations, which govern the excitation and the face-to-face collision of bright and dark IASs. Appropriately, the effects of several parameters such as the electron concentration, the superthermality of electrons and the diversity in the system’s geometry under consideration on the trajectories of IASs after the collision are discussed. Numerical calculations lead to some highlights on the properties of bright and dark IASs (e.g. in laboratory plasmas such as laser–matter/plasma interaction experiments and in astrophysical environments such as lower part of magnetosphere).