Nonlinear Rule Research Articles

Methods of synthesis and formation of a system of nonlinear discrete signals for modern information and communication systems

The paper presents the results of solving the urgent problem of improving the performance indicators of information and communication systems (ICS), in particular, information security, noise immunity, secrecy, the speed of formation and processing of information. The use of the distributed spectrum technology (broadband noise-like signals) is a promising direction for ensuring the security of information resources. The methods used for data formation and processing, as well as the classes of broadband signals used as physical data carriers, do not allow providing the necessary (especially for critical infrastructure facilities) indicators of information security and noise immunity. In this case, as discrete sequences (DS) that expand the spectrum (manipulate the carrier frequency), should be used DS based on nonlinear construction rules and having improved correlation, ensemble and structural properties. Methods for the synthesis and formation of nonlinear discrete complex signals, namely, the so-called cryptographic signals, are proposed. The first method, presented in the article, uses random (pseudo-random) processes. Another method is based on the implementation of the operation of decimation of the original discrete sequence of symbols obtained from the results of the implementation of the first method; it provides the synthesis of an ensemble of signals for a certain signal duration. Analytical expressions are obtained for determining the synthesis time of an ensemble of signals using the proposed methods. It is shown that the speed of the signal generation method based on the decimation operation for a certain signal duration is more than three orders of magnitude higher than the speed of the method based on the random (pseudo-random) processes used. At the same time, based on the carried out computer simulation, it is shown that the signals obtained using the proposed methods have identical correlation, ensemble, and structural properties.

Influence of a nearby conductor on shape and length of a microwave plasma jet.

This Rapid Communication reports on the observation of an interesting phenomenon: the shape, especially the length, of a microwave plasma jet (MPJ) can be clearly influenced by simply placing a conductor near the plasma source, particularly when the nearby conductor is in contact with the external conductor of the coaxial microwave plasma generator, accompanied by a significant change in microwave reflection power from the terminal. To further investigate this discovery, the relationships between the length of the plume and some important factors, such as the conductivity and length of the nearby conductor, microwave input power, and gas flow velocity, are analyzed, and we find nonlinear rules of influence of these factors on the jet. Measurements of the electric potential around the jet reveal the nonuniform and non-neutral charge distribution inside the visible plasma plume, which plays a vital role in uncovering the mechanism underlying this phenomenon. The results are helpful for providing a deeper understanding of microwave plasma jet characteristics. More importantly, it provides guidelines to control the MPJ using simple structures.

Adaptive control strategy for velocity control of a linear switched reluctance motor

A new adaptive control strategy for a double-sided linear switched reluctance motor is proposed in this work. Switched reluctance motors inherently have non-linear dynamics that complicates their analysis and control. The Takagi–Sugeno fuzzy logic system has been used in this work to achieve an appropriate adaptive control system for the proposed linear motor. The fuzzy system has been heightened by non-linear rule consequences and a time-varying parameter. Updated laws have been designed to refresh the amount of the parameter consequently the suggested control system shows a stable performance in control of switched reluctance motors. The proposed control strategy is independent of the uncertainties of the motor dynamics and has an acceptable adaptability. This control method along with a conventional fuzzy logic based system have been studied on the proposed linear switched reluctance motor and their performances were compared in different performance conditions. An appropriate evaluation method has been used to compare the obtained results. The efficiency of the proposed method in different velocity commands has been examined and confirmed using appropriate simulation and experimental results.

IS THE TUNISIAN CENTRAL BANK FOLLOWING A LINEAR OR A NONLINEAR AUGMENTED TAYLOR RULE?

The political transition in the Arab Spring countries has been accompanied by a deterioration of economic and financial indicators like in the Tunisian case. This paper aims to get a deeper understanding of the nature of the rule that reflects the behavior of the Tunisian monetary authority in the current dominance of economic and financial instability. In particular, this paper assesses whether the Tunisian Central Bank is indeed following a linear or a non linear augmented Taylor rule. For our purpose, we use a forward looking version of Taylor rule augmented by including the effect of exchange rate to estimate the linear and the nonlinear models. A smooth transition regression model is used to estimate the nonlinear rule. The results obtained imply that the Tunisian Central Bank follows a nonlinear Taylor rule in the conduct of monetary policy. In addition, our evidence suggests that the reaction of monetary authority in Tunisia to the deviation of forecasts of inflation rate, output gap and exchange rate changes in terms of magnitude and statistical significance across the high and low interest rate regimes. In particular, when the lagged interest rate is above the threshold level of 4.76%, the main objective of the policy makers is to fight the inflation rate and to limit the depreciation of exchange rate rather than to boost the economic activity.Keywords: Taylor rule, smooth transition regression model, interest rate reaction function, nonlinearityJEL Classifications: C22, E17, E43, E52, E58DOI: https://doi.org/10.32479/ijefi.8975

Is The Tunisian Central Bank following a linear or a nonlinear augmented Taylor rule ?

Is The Tunisian Central Bank following a linear or a nonlinear augmented Taylor rule ?

A new method for mining information of co-expression network based on multi-cancers integrated data

BackgroundGene co-expression network is a favorable method to reveal the nature of disease. With the development of cancer, the way to build gene co-expression networks based on cancer data has been become a hot spot. However, there are still a limited number of current node measurement methods and node mining strategies for multi-cancers network construction.MethodsIn this paper, we introduce a new method for mining information of co-expression network based on multi-cancers integrated data, named PMN. We construct the network by combining the different types of relevant measures (linear and nonlinear rules) for different nodes based on integrated gene expression data of multi-cancers from The Cancer Genome Atlas (TCGA). For mining genes, we combine different properties (local and global characteristics) of the nodes.ResultsWe uncover more suspicious abnormally expressed genes and shared pathways of different cancers. And we have also found some proven genes and pathways; of course, there are some suspicious factors and molecules that need clinical validation.ConclusionsThe results demonstrate that our method is very effective in excavating gene co-expression genes of multi-cancers.

Nonlinear stationary subdivision schemes reproducing hyperbolic and trigonometric functions

In this paper we introduce a new family of interpolatory subdivision schemes with the capability of reproducing trigonometric and hyperbolic functions, as well as polynomials up to second degree. It is well known that linear, non-stationary, subdivision schemes do achieve this goal, but their application requires the practical determination of the parameters defining the level-dependent rules, by preprocessing the available data. Since different conic sections require different refinement rules to guarantee exact reproduction, it is not possible to reproduce a shape composed, piecewisely, by several trigonometric functions. On the other hand, our construction is based on the design of a family of stationary nonlinear rules. We show that exact reproduction of different conic shapes may be achieved using the same nonlinear scheme, without any previous preprocessing of the data. Convergence, stability, approximation, and shape preservation properties of the new schemes are analyzed. In addition, the conditions to obtain $\mathcal {C}^{1}$ limit functions are also studied, which are related with the monotonicity of the data. Some numerical experiments are also carried out to check the theoretical results, and a preferred nonlinear scheme in the family is identified.

Does the Reserve Bank of Australia follow a forward-looking nonlinear monetary policy rule?

ABSTRACTThe conventional monetary policy rule describes a simple linear relationship between the domestic interest rate, inflation rate and output gap. An important extension to this rule is to incorporate the forward-looking behaviour of central banks, where it is assumed that they target an expected level of inflation instead of its current realised value. Using quarterly observations for the period 1993:1-2018:2, this paper investigates whether the conduct of monetary policy in Australia can be described by a forward-looking linear monetary policy rule, or by a nonlinear forward-looking monetary policy rule. In particular, the nonlinear forward-looking monetary policy rule is analysed in a regime-switching framework using a smooth logistic transition regression model. While the results show that the conventional forward-looking linear monetary policy rule describes the application of monetary policy in Australia reasonably well, the interest rate setting behaviour of the RBA is best described by a nonlinear forward-looking monetary policy rule.

Nonlinear dynamic analysis of low viscosity fluid-lubricated tilting-pad journal bearing for different design parameters

To reveal nonlinear dynamic rules of low viscosity fluid-lubricated tilting-pad journal bearings (TPJBs), the effects of design parameters on journal center orbits and dynamic minimum film thicknesses of water-lubricated TPJBs with and without static loads are investigated. The hydrodynamic bearing force used in the nonlinear dynamic analysis is an approximate analytical solution including the turbulence effect. The results reveal the methods for vibration suppression and load capacity improvement and give an optimal pivot offset and clearance ratio that can maximize the minimum film thickness. The results also show that four-pad TPJBs with loads between pads are preferred due to good dynamic performance and load capacity. This study would provide some guidance for nonlinear design of low viscosity fluid-lubricated TPJBs under dynamic loads.

Designing Reactive Power Control Rules for Smart Inverters Using Support Vector Machines

Smart inverters have been advocated as a fast-responding mechanism for voltage regulation in distribution grids. Nevertheless, optimal inverter coordination can be computationally demanding, and preset local control rules are known to be subpar. Leveraging tools from machine learning, the design of customized inverter control rules is posed here as a multi-task learning problem. Each inverter control rule is modeled as a possibly nonlinear function of local and/or remote control inputs. Given the electric coupling, the function outputs interact to yield the feeder voltage profile. Using an approximate grid model, inverter rules are designed jointly to minimize a voltage deviation objective based on anticipated load and solar generation scenarios. Each control rule is described by a set of coefficients, one for each training scenario. To reduce the communication overhead between the grid operator and the inverters, we devise a voltage regulation objective that is shown to promote parsimonious descriptions for inverter control rules. Numerical tests using real-world data on a benchmark feeder demonstrate the advantages of the novel nonlinear rules and explore the trade-off between voltage regulation and sparsity in rule descriptions.

Using fuzzy controller for improvement of power decoupling performance in PV systems

ABSTRACTIn photovoltaic systems in order to ensure the stable operation of the module, ripple value of the input voltage should be mitigated to a small value; for this purpose, the power decoupling circuit can be used. In this work, considering the four-switch-based power decoupling circuit developed, the conventional Proportional-Integral (PI) controller has been replaced with well-known fuzzy controller, which enjoys a wide range of control gain variation, both linear and nonlinear rules' capability, robustness and more flexibility. The operating modes of the circuit are addressed and accordingly the space state model is derived. Then, the proposed controller has been replaced and the performance of the system will be analysed. The power decoupling circuit along with the proposed controller is implemented by MATLAB/Simulink software. The simulation results show the ability of the proposed fuzzy controller to improve the performance of the system in comparison to the conventional PI controller. A deeper comparison of two controllers confirms that the system would experience more accuracy, faster response and lower total harmonic distortion (THD) in presence of the proposed fuzzy controller.

Elasto-Plastic Contact Stress Analysis of Hardened Elements under Repeated Contact Loading

An elastic-plastic contact stress analysis is presented to study cyclic plastic deformation of surface hardened rolling elements under repeated contacts. The rolling contact is simulated by a Hertz contact loading moving across an elastic-plastic half-space. An exponential model with hardness varying with depth is employed for the surface hardened components, and the Chaboche nonlinear hardening rule is used to model cyclic plastic behavior of contact elements. Numerical results show that the hardened layer can effectively reduce the plastic deformation near contact surface. The contact elements with sufficient surface hardness may reach elastic shakedown state under repeatedly rolling contact. As the hardened layer reaches a certain depth, e.g. two times of half contact length, however, the effects of case depth on plastic strain and residual stress become negligible after hundred contact cycles.

Titrating the neuroplastic effects of cathodal transcranial direct current stimulation (tDCS) over the primary motor cortex

Transcranial direct current stimulation (tDCS) non-invasively induces polarity-dependent excitability alterations in the human motor cortex lasting for more than an hour after stimulation. Clinical applications with encouraging results have been reported in several pilot studies, but the optimal stimulation protocols remain to be determined. This is also important because the efficacy and directionality of tDCS effects follow non-linear rules regarding neuroplastic effects for the stimulation parameters duration and intensity. In this study, we systemically explored the association between tDCS, these parameters and induced after-effects on motor cortex excitability. Cathodal tDCS was applied in four different intensities (sham, 1, 2 and 3 mA) and three durations (15, 20 and 30 mins) in 16 young healthy subjects and the after-effects were monitored with TMS-induced motor evoked potentials (MEP) until the next day evening after stimulation. The results of the repeated measures ANOVA conducted to disentangle the effects of tDCS intensity and duration show a main effect of intensity in which 1 mA and 3 mA stimulation induced a reduction of MEP amplitudes, but 2 mA resulted in excitability enhancement. The results of a secondary ANOVA conducted to compare if active stimulation effects differ from those of sham stimulation revealed a significant main effect of tDCS condition in which 1 mA–15 min, 1 mA–30 min and 3 mA–20 min cathodal tDCS induced LTD-like plasticity, while LTP-like plasticity was observed after 2 mA–20 min stimulation. Our study thus provides further insights on the dependency of tDCS -induced neuroplasticity from the stimulation parameters, and therefore delivers crucial information for future applications.

Cue Combinatorics in Memory Retrieval for Anaphora.

Many studies have shown that memory retrieval for real-time language processing relies on a cue-based access mechanism, which allows the cues available at the retrieval site to directly access the target representation in memory. An open question is how different types of cues are combined at retrieval to create a single retrieval probe ("cue combinatorics"). This study addresses this question by testing whether retrieval for antecedent-reflexive dependencies combines cues in a linear (i.e., additive) or nonlinear (i.e., multiplicative) fashion. Results from computational simulations and a reading time experiment show that target items that match all the cues of the reflexive are favored more than target items that mismatch these cues, and that different degrees of mismatches slow reading times in comparable amounts. This profile is consistent with the predictions of a nonlinear cue combination and provides evidence against models in which all cues combine in a linear fashion. A follow-up set of simulations shows that a nonlinear rule also captures previous demonstrations of interference from nontarget items during retrieval for reflexive licensing. Taken together, these results shed new light on how different types of cues combine at the retrieval site and reveal how the method of cue combination impacts the accessibility of linguistic information in memory.

Comparative Study of Nonlinear Cumulative Creep Damage Model and Time Fraction Rule to Predict Residual Creep Life of Pressure Vessels - A Review

Comparative Study of Nonlinear Cumulative Creep Damage Model and Time Fraction Rule to Predict Residual Creep Life of Pressure Vessels - A Review

Nonlinear Damage Accumulation Rule for Solder Life Prediction Under Combined Temperature Profile With Varying Amplitude

Due to a mismatch of the coefficient of thermal expansion, electronic solder joints experience cyclic shear strain, which ultimately leads to fatigue failure. Traditional predictions of solder joint thermal fatigue life that use the experimental data or the physics-of-failure model often assume a regular profile. For complex temperature profiles, the linear accumulation rule is typically used to integrate the superposition effect. However, the linear rule was proved not applicable to most of the complex loading or temperature conditions. Based on the damage curve theory and the fatigue crack propagation theory, a novel nonlinear accumulation rule has been deduced for solder joint life predictions under irregular profiles, which were composed of two standard temperature cycles and may be experienced by phased-mission system. Four groups of experiments were conducted for ball grid array package solder joints with different dimensions and materials to determine parameters of the proposed nonlinear accumulation rule. The finite-element simulation method was used to extend this rule to more general cases for application. Compared to Miner’s linear accumulation rule, prediction of solder joint thermal fatigue life via the proposed nonlinear accumulation rule is closer to the accelerated life test results of real-world electronic solder joints under a combined temperature profile.

Quantifying Interactions in Nonlinear Feedback Dynamics: A Time Series Analysis

In this paper, we further study the dynamics of the Kyrtsou model composed of heterogeneous nonlinear feedback rules. For various levels and types of underlying nonlinearity, we analyze the resulting time series by means of the largest Lyapunov exponent. Our results highlight that the observed interaction among feedback mechanisms cannot lead to a univocal interpretation of system complexity.

Voice conversion for emotional speech: Rule-based synthesis with degree of emotion controllable in dimensional space

This paper proposes a rule-based voice conversion system for emotion which is capable of converting neutral speech to emotional speech using dimensional space (arousal and valence) to control the degree of emotion on a continuous scale. We propose an inverse three-layered model with acoustic features as output at the top layer, semantic primitives at the middle layer and emotion dimension as input at the bottom layer; an adaptive-based fuzzy inference system acts as connectors to extract the non-linear rules among the three layers. The rules are applied by modifying the acoustic features of neutral speech to create the different types of emotional speech. The prosody-related acoustic features of F0 and power envelope are parameterized using the Fujisaki model and target prediction model separately. Perceptual evaluation results show that the degree of emotion can be perceived well in the dimensional space of valence and arousal.

Nontrivial temperature behavior of the carrier concentration in graphene on ferroelectric substrate with domain walls

This work explores a nontrivial temperature behavior of the carriers concentration, which governs the conductance of the graphene channel on ferroelectric substrate with domain walls that is a basic element for field effect transistors of new generation. We revealed the transition from a single to double antiferroelectric-like hysteresis loop of the concentration voltage dependence that happens with the temperature increase and then exist in a wide temperature range (350–500) K. We have shown that the double loops of polarization and concentration can have irregular shape that remains irregular as long as the computation takes place, and the voltage position of the different features (jumps, secondary maxima, etc) changes from one period to another, leading to the impression of quasi-chaotic behavior. It appeared that these effects originate from the nonlinear screening of ferroelectric polarization by graphene carriers, as well as it is conditioned by the temperature evolution of the domain structure kinetics in ferroelectric substrate. The nonlinearity rules the voltage behavior of polarization screening by graphene 2D-layer and at the same time induces the motion of separated domain walls accompanied by the motion of p-n junction along the graphene channel. Since the domain walls structure, period and kinetics can be controlled by changing the temperature, we concluded that the considered nano-structures based on graphene-on-ferroelectric are promising for the fabrication of new generation of modulators based on the graphene p-n junctions.

Simulation Analysis on Water’s Micro Seepage Laws under Different Pressure Gradients Using Computed Tomography Method

The aim of this paper was to develop a model that can characterize the actual micropore structures in coal and gain an in‐depth insight into water’s seepage rules in coal pores under different pressure gradients from a microscopic perspective. To achieve this goal, long‐flame coals were first scanned by an X‐ray 3D microscope; then, through a representative elementary volume (REV) analysis, the optimal side length was determined to be 60 μm; subsequently, by using Avizo software, the coal’s micropore structures were acquired. Considering that the porosity varies in the same coal sample, this study selected four regions in the sample for an in‐depth analysis. Moreover, numerical simulations on water’s seepage behaviors in coal under 30 different pressure gradients were performed. The results show that (1) the variation of the simulated seepage velocity and pressure gradient accorded with Forchheimer’s high‐velocity nonlinear seepage rules; (2) the permeability did not necessarily increase with the increase of the effective porosity; (3) in the same model, under different pressure gradients, the average seepage pressure decreased gradually, while the average seepage velocity and average mass flow varied greatly with the increase of the seepage length; and (4) under the same pressure gradient, the increase of the average mass flow from the inlet to the outlet became more significant under a higher inlet pressure.