Discrete Schemes for a Class of Semilinear Hyperbolic Eqution

This paper focuses on the numerical algorithm of a class of semilinear hyperbolic equation. The dissipation term and external force source term existing in the equation enhance the nonlinearity of the model and make the nonlinear effect complicated. However, this nonlinear effect has a great influence on the discrete scheme, which cannot be neglected. Discretizing the nonlinear terms to ensure the validity of the scheme is the core issue in this paper. An effective scheme based on linearization techniques and iteration theory is proposed. It is based on the finite difference method. The efficiency of the proposed schemes was verified via some numerical examples showing that they compare well with existing methods.

The effect of prey refuge on the dynamics of three species food web system

In this paper, a mathematical model is proposed to study the effect of prey refuge on the dynamics of three species food web system. The food web comprises of a single prey and two competing predators. The two predators predate their prey following Holling type II functional response. In this work we discussed boundedness of the system, existence condition of the equilibrium points and the Jacobean matrix is obtained by linearization techniques. The local stability of the equilibrium points was discussed by using Routh-Hurwitz criteria and the global stability of the equilibrium points by constructing suitable Lyapunov function. Numerical simulation is conducted to support the analytical result. Finally, the effect of prey refuge on the dynamics of one prey two predator was discussed based on the analytical and numerical simulation results. From the numerical simulations, it is found that the dynamical system is persistent for a small value of the refuge constant. However, an increase in the refuge constant leads to the extinction of one of the predator species.

Digital predistortion of radio over fiber (RoF) link using hybrid Memetic algorithm

Despite their many advantages over other communication links, radio over fiber (RoF) links also suffer from nonlinearity. This limits the dynamic range performance of the RoF link. Linearization techniques like digital predistortion can be explored for mitigating this nonlinearity. A hybrid optimization algorithm called hybrid Memetic algorithm, which uses the benefits of both Tabu search algorithm and Memetic algorithm, is used for parameter estimation of the digital predistorter. Simulation results demonstrate that the hybrid Memetic algorithm offers very promising outcomes.

Linearization as a Solution for Power Amplifier Imperfections: A Review of Methods

Development of 5G networks requires a substantial increase to both spectral and power efficiency of transmitters. It is known that these two parameters are subjected to a mutual trade-off. To increase the linearity without losing power efficiency, linearization techniques are applied to power amplifiers. This paper aims to compare most popular linearization techniques to date and evaluate their applicability to upcoming 5G networks. The history of each respective linearization technique is followed by the main principle of operation, revealing advantages and disadvantages supported by concluding the latest research results. Three main groups of linearization methods currently known are feedforward, feedback, and predistortion, each with its own tradeoffs. Although digital predistortion seems to be the go-to method currently, other techniques with less research attention are still non-obsolete. А generalized discussion and a direct comparison of techniques analyzed are presented at the end of this paper. The article offers a systematic view on PA linearization problems which should be useful to researchers of this field. It is concluded that there are still a lot of problems that need to be addressed in every linearization technique in order to achieve 5G specifications.

Algebraic Collision Attacks on Keccak

In this paper, we analyze the collision resistance of the two smallest versions of Keccak which have a width of 200 and 400 bits respectively. We show that algebraic and linearization techniques can serve collision cryptanalysis by using some interesting properties of the linear part of the round function of Keccak. We present an attack on the Keccak versions that could be used in lightweight cryptography reduced to two rounds. For Keccak[40, 160] (resp. Keccak[72, 128] and Keccak[144, 256]) our attack has a computational complexity of 273 (resp. 252.5 and 2101.5) Keccak calls.

A multivariate spectral quasi-linearization method for the solution of (2+1) dimensional Burgers’ equations

In this paper, we introduce the multi-variate spectral quasi-linearization method which is an extension of the previously reported bivariate spectral quasi-linearization method. The method is a combination of quasi-linearization techniques and the spectral collocation method to solve three-dimensional partial differential equations. We test its applicability on the (2 + 1) dimensional Burgers’ equations. We apply the spectral collocation method to discretize both space variables as well as the time variable. This results in high accuracy in both space and time. Numerical results are compared with known exact solutions as well as results from other papers to confirm the accuracy and efficiency of the method. The results show that the method produces highly accurate solutions and is very efficient for (2 + 1) dimensional PDEs. The efficiency is due to the fact that only few grid points are required to archive high accuracy. The results are portrayed in tables and graphs.

Linearity Improvement of Bulk Driven Floating Gate OTA Using Cross-Bulk and Quasi-Bulk Techniques

In this paper, two highly linear OTAs are presented using a combination of three linearization techniques: floating gate, bulk driven, and source degeneration. In the first OTA, bulk driven floating gate MOSFETs are used as input transistors. The input signal given at the bulk terminals of these input transistors are in the opposite phase of the input signal provided to one of the gates of the respective floating gate MOSFET. This cross-coupling method resulted in a highly linear voltage-to-current conversion at the cost of reduced transconductance. In the second proposed OTA, this reduction in transconductance is restored by using novel quasi-bulk floating gate MOSFETs as input transistors while maintaining the improved linearity. Both the OTAs are designed and simulated using 180 nm CMOS design library and powered with [Formula: see text]0.5[Formula: see text]V dual power supply. The process variation and mismatch effects on both the OTAs are examined using corner and Monte Carlo analysis. The layouts of the proposed OTAs are also presented and workability is confirmed using post-layout simulations.