Nonlinear Parameters Research Articles

Entanglement between two charge qubits taking account the Kerr media

Background. The need to implement controlled coupling between qubits, which are the logical elements of quantum devices such as quantum computers and quantum networks, requires, along with the use of traditional methods, the development of new, more effective ways to organize the interaction of qubits with the microwave fields of resonators used to generate and control the entanglement of qubits. As one of these methods, a method based on the influence of frequency-regulated radio frequency signals on a superconducting Josephson qubit connected by a large Josephson junction to a free qubit has been proposed.
 Aim. The influence of the Kerr medium of the resonator, in which one of the two qubits is placed, on their entanglement induced by the coherent or thermal frequency-regulated radio frequency field of the resonator is considered.
 Methods. To analyze the dynamics of the system under consideration, the solution of the quantum Liouville equation for the full density matrix is studied. An exact solution o this equation is found in the case of initial separable and entangled states of qubits. The exact solution of the evolution equation is used to calculate the criterion of qubit-qubit entanglement – cconcurrence. Numerical modeling of the concurrence was carried out for various states of qubits, coherent and thermal fields of the resonator, as well as various values of the intensity of the resonator field and the Kerr nonlinearity parameter.
 Results. It is shown that for separable initial states of qubits, the inclusion of Kerr nonlinearity reduces the maximum degree of entanglement of qubits. For an entangled initial state of qubits, the possibility of creating long-lived entangled states in the presence of Kerr nonlinearity is shown.
 Conclusion. The type of initial states of qubits and the range of values of the intensities of the resonator fields and the Kerr nonlinearity parameters have been established, for which the most effective control and operation of the evolution of qubits, as well as the degree of their entanglement, in the physical system under consideration, is possible.

Relativistic energy density functional from momentum space to coordinate space within a coherent density fluctuation model

In this theoretical study, we have derived a simplified analytical expression for the binding energy per nucleon as a function of density and isospin asymmetry within the relativistic mean-field model. We have generated a new parameterization for the density-dependent DD-ME2 parameter set using the Relativistic-Hartree-Bogoliubov approach. Moreover, this work attempts to revisit the prior polynomial fitting in Kumar A. et al. Phys. Rev. C, 103 (2021) 024305 for the non-linear NL3 force parameter to provide a simplified set of equations for the energy density functional which is used for calculating the surface properties of finite nuclei. The current study improves the existing fitting procedure by effectively proposing a simpler model that provides comparably precise results while lowering the computational expense. To study the surface properties of finite nuclei with these parameterizations, we have adopted the coherent density fluctuation model, which effectively translates the quantities of nuclear matter from momentum space to coordinate space at local density. The isospin properties, such as symmetry energy and its surface and volume components, slope parameter, finite nuclear incompressibility, and surface incompressibility for even-even nuclei, are calculated for different mass regions. Moreover, we have studied the effect of density, weight function, and choice of relativistic force parameters on the surface properties. The significance of this work will help to determine the properties of nuclei along the nuclear landscape and can facilitate an improved understanding of the island of stability, heavy-ion collision, and nucleosynthesis, among others.

Modeling and Calibration of Gaia, Hipparcos, and Tycho-2 Astrometric Data for the Detection of Dark Companions

Hidden within the Gaia satellite’s multiple data releases lies a valuable cache of dark companions. To facilitate the efficient and reliable detection of these companions via combined analyses involving the Gaia, Hipparcos, and Tycho-2 catalogs, we introduce an astrometric modeling framework. This method incorporates analytical least-square minimization and nonlinear parameter optimization techniques to a set of common calibration sources across the different space-based astrometric catalogs. This enables us to discern the error inflation, astrometric jitter, differential parallax zero-points, and frame rotation of various catalogs relative to Gaia Data Release 3 (DR3). Our findings yield the most precise Gaia DR2 calibration parameters to date, revealing notable dependencies on magnitude and color. Intriguingly, we identify submilliarcsecond frame rotation between Gaia DR1 and DR3, along with an estimated astrometric jitter of 2.16 mas for the revised Hipparcos catalog. In a thorough comparative analysis with previous studies, we offer recommendations on calibrating and utilizing different catalogs for companion detection. Furthermore, we provide a user-friendly pipeline (https://github.com/ruiyicheng/Download_HIP_Gaia_GOST) for catalog download and bias correction, enhancing accessibility and usability within the scientific community.

Combined vibration analysis of a top tensioned riser with the geometrical nonlinearity

A coupling model representing the interactions between the riser and vortices is proposed, of which the time-varying top tension and the internal nonlinear axial force due to the bending of the riser are considered. In addition, the van der Pol oscillator is introduced to simulate the time-varying characteristic of the vortices. The motion equations are derived and the first-order mode approximation is obtained with the Galerkin approach. The multiple scale method is applied to study the steady-state solutions of the system. Effects of system parameters (the structural damping, nonlinearity, the amplitude ratio of the varying-tension, the shedding frequency) on the responses are investigated in detail. The synchronous and non-synchronous motions between the structure and wake oscillator are studied. The bifurcation diagrams for the responses in terms of the amplitude ratio and the nonlinear parameter are obtained in the large parameter ranges. The results show that responses with different topological properties including quasi-periodic, periodic and chaotic solutions can occur under different parameter conditions. A pair of chaotic attractors can be found for the large parameter range of the amplitude ratio. The joint effects of the amplitude ratio and the nonlinear parameter on the responses in the large parameter range are studied as well, which are further verified by the phase projections and Poincaré sections. The results show that the topological properties of responses can be controlled by the amplitude ratio. These results can be helpful to the dynamic design of the riser in practice.

Prediction of Production-Inflow Profile of a Well Producing Single-Phase Flow of Slightly Compressible Fluid from Multilayer Systems by Temperature and/or Pressure Transient Data

Summary This study focuses on the prediction of the production-inflow profile of a well producing a single-phase flow of slightly compressible fluid (water or oil flow) in a multilayered system using the layer permeability and skin values estimated by history matching spatial and temporal temperature and/or pressure data sets along the completion interval. Such data may be acquired by wireline formation testing, production-logging-tool (PLT), or distributed temperature sensing (DTS) fiber-optic cables. We use an in-house thermal, transient coupled reservoir/wellbore simulator developed during this study. It solves transient mass, momentum, and energy conservation equations simultaneously for both reservoir and wellbore. The effects of the Joule-Thomson (J-T), adiabatic expansion, conduction, and convection are all included for predicting the flow profiles across the wellbore. The results from our in-house simulator are verified with the results from a commercial simulator for the single-phase fluid flow of a vertical well producing geothermal brine and oil in a two-zone multilayer system. We also compare the results from our rigorous transient coupled wellbore/reservoir model with the results from a model assuming steady-state thermal wellbore model used in the previous studies. We find that the steady-state thermal wellbore model used in the previous studies that ignore accumulation terms in mass, momentum, and thermal energy balances is a reasonably accurate model for predicting wellbore pressures and temperatures when it is coupled with a nonisothermal reservoir model for slightly compressible fluid because the transient effect in the wellbore is less important with the slightly compressible fluid. We investigate the nonlinear parameter estimation problem based on the use of single or multiple observed temperature and/or pressure (if available) profiles recorded spatially inside the wellbore and at the sandface. The purpose is to identify if the wellbore or sandface data profiles are more useful to accurately estimate the permeability and skin information and predict a production-inflow profile of the well depending on the representation of an actual multilayer system by a reduced-layered or fine-layered model. We show that using an upscaled-layered model (e.g., representing each heterogeneous layer with a lumped single layer with uniform permeability and skin) provides estimates that are more toward the thickness-average permeability and skin factors of the layers and may not provide a good prediction of the well’s production-inflow profile. We show that including the sandface temperature data in regression worsens, while the use of wellbore temperature data sets improves the quality of parameter estimation if an upscaled multilayered model is used. We also show that regressing on multiple temperature profiles, preferably at the sandface, alone could be used to predict the production-inflow profile accurately if a “fine” multilayered heterogeneous model is used. We also investigate if including or excluding the temperature and/or pressure measurements at the nonperforated sections along the completion interval could help enhance the parameter estimation problem. The results show that when multiple profiles of temperatures including the data at nonperforated zones at different production rates are regressed, reliable estimates of the individual layer properties that predict the production-inflow profile accurately can be obtained, though layer permeability and skin factors may often exhibit wide 95% confidence intervals and high correlations among them. Adding sandface or wellbore pressure data, if available, into observed data sets in history matching always improves the quality of parameter estimation.

Particle Filter based on Jaya optimisation for Bayesian updating of nonlinear models

Particle filter (PF) is a powerful and commonly used filtering technique based on Sequential Monte Carlo framework. The main challenge in using PF for nonlinear state and parameter estimation is the degeneracy of particles. Although resampling techniques can solve this to some extent, it would still result in particle impoverishment when a limited number of particles are used thereby affecting the accuracy. Hence, a hybrid metaheuristic optimisation algorithm that combines the PF with Jaya optimisation, (PF-JAYA) has been proposed and implemented for joint state and parameter estimation for geotechnical engineering problems. The performance of PF-JAYA has been compared against the traditional Particle Filter with Sampling Importance Resampling (PF-SIR) technique. The synthetic examples show that PF-JAYA outperforms PF-SIR in terms of accuracy, rate of convergence, parameter identification and particle diversity. Furthermore, the performance of PF-JAYA is independent of the choice of prior distribution and due to its superior convergence proves to be efficient when working with sparse monitoring information. The performance of PF-JAYA on Bayesian updating of state and parameters of an elastoplastic model for a synthetic embankment case has also been evaluated where, along with PF-SIR, the Ensemble Kalman Filter (EnKF) is also chosen for comparison. Finally a further evaluation using the Lorenz ‘63 model, shows the superior performance of PF-JAYA in terms of accuracy and precision over the classical Data Assimilation techniques.

Impact of Arrhenius activation energy on magnetic nanofluid flow over a slendering stretchable sheet with nonlinear radiative heat transfer: A machine learning algorithm

Thermal systems in the contemporary world need effective cooling and heating methods. Heat transfer technology plays a vital role in various industries, including aerospace, electronic equipment, automobiles, and transportation. Considering the importance of effective cooling and heating processes, this framework explores the hydromagnetic stagnation point flow with binary chemical reactions, ohmic heating, Arrhenius activation energy, nonlinear thermal radiation, thermophoresis, and Brownian motion. At first, the flow equations are determined in a formal way as dimensional partial differential equations. Then, they are transformed into simpler, dimensionless ordinary differential equations using self-similar variables. The present study describes a novel approach to intelligent numerical computing, utilizing a Levenberg-Marquard algorithm-based MLP (Multi-Layer Perceptron) feed-forward back-propagation ANN (Artificial Neural Networks) implementation. The collection of data was conducted to facilitate the evaluation, validation, and instruction of the artificial neural network model. The utilization of appropriate self-similarity variables has facilitated the conversion of fluid transport equations into ordinary differential equations. The Runge–Kutta–Fehlberg (RKF) technique was used to solve these equations. The numerical results are presented visually for numerous constraints of the governing parameters. The increased values of the velocity ratio enhanced the fluid velocity. The nonlinear thermal radiation and temperature differential characteristics significantly raise the temperature of the fluid. Increasing the nonlinear radiation and magnetic field parameters improves the rate of heat transfer. The temperature of the fluid decreases as the size of stagnation increases. The skin friction coefficients decrease as the wall thickness and magnetic parameters increase.

Bright soliton of the third-order nonlinear Schrödinger equation with power law of self-phase modulation in the absence of chromatic dispersion

In this article, we are interested in two principal topics. First, the bright optical soliton solutions of the third-order (1+1)-nonlinear Schrödinger equation including power law nonlinearity with inter-modal and spatio-temporal dispersions are perused by taking advantage of the new Kudryashov method. Second, the impacts of power law nonlinearity parameters on soliton attitude are investigated for acquired bright soliton form. With the proposed technique, the bright optical soliton solution is acquired, and 3D, contour, and 2D plots are depicted. Then, the impact of power law nonlinearity parameters on the soliton attitude has been successfully demonstrated. As is clear from this perusal power law parameters have an important impact on the soliton attitude, and this impact alters based on the soliton form. As regards our investigation, this form of the equation has not been studied with the power law nonlinearity in the absence of the chromatic dispersion for nonlinear models and the proposed method has not been applied the introduced equation before. It is expected that the consequences which are acquired in this study will shed light on the studies in this field.

Comparative analysis of the optical and electrical properties of PVA/PVP blended polymer with ZnCo2O4/CdS nanocomposites for optoelectronic and dielectric capacitor applications

Polymer nanocomposite blends were produced using solution casting, hydrothermal and thermolysis techniques. The blends were composed of a polymer blend consisting of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as the organic host matrix with (1−x)ZnCo2O4–xCdS as filler samples. The current study investigated the morphological, structural, optical, and dielectric features of PVP/PVP/(1-x)ZnCo2O4/xCdS blends. The crystallite size and the phases formed in the fillers were obtained using Rietveld method. The structure and morphology of blended samples were studied using X-ray diffraction and scanning electron microscope techniques. The results of the optical properties imply that the linear and nonlinear optical parameters were affected by the amount of CdS in the (1-x)ZnCo2O4/xCdS filler samples. The direct allowed, indirect allowed, direct forbidden and indirect forbidden transitions values were reduced to 5.09, 4.55, 4.67 and 4.12 eV, respectively, as (1-x)ZnCo2O4/xCdS with x = 0.05 was incorporated into the PVA/PVP blend. The nature of electronic transitions in all blends were also studied. The fluorescence intensity, emitted colors and purity of the doped PVA/PVP blend are affected by the amount of CdS in the fillers and the excitation wavelength. The energy density of the host blend was improved as it loaded with fillers contained 5 and 10 % CdS in the frequency range beyond 1 kHz. The relaxation times of all doped blends were diminished except blend contained 25% CdS, the relaxation time rose slightly as compared with the relaxation time of undoped blend. The obtained properties indicates potential utility of the doped blends in photocatalytic, photonic, storage energy and optoelectronic applications.

Synthesis, structural elucidation and characterization of a new organic single crystal Guanidinium adipate monohydrate (GuAM) for nonlinear optical applications

A slow evaporation solution growth process was employed to grow a new organic single crystal Guanidinium adipate monohydrate (GuAM) at room temperature. The structure refinement and cell specifications were elucidated using the X-ray diffraction method. Single crystal XRD study revealed that the grown crystal crystallized in the monoclinic system with unit cell dimensions a = 4.948 (9) Å; b = 16.770 (2) Å; c = 13.554 (2) Å; α and γ = 90.00⁰; β = 95.302⁰ (3), V = 1120.1(3) Å3 and Z = 4. The structure of the crystal was solved by direct method and refined by full matrix least-square method using SHELXL-2018/3 program. The crystalline nature of the sample was evaluated by powder X-ray diffraction (PXRD) study. Fourier transform infrared (FTIR) spectral study was employed to recognize the diverse functional groups present in the synthesized crystal. Optical attributes such as absorbance and emission nature of the GuAM were explored using UV–visible-NIR absorbance study and photoluminescence study respectively. The laser damage threshold value of the formed crystal has been determined by employing an Nd-YAG laser with a wavelength of 1064 nm. The mechanical nature of the GuAM was examined utilizing Vicker's microhardness test and other related parameters were also calculated. TGA-DTA analysis was utilized to estimate the title crystal's thermal stability. The Z-scan technique has been employed to gain insight into the third order nonlinear (NLO) parameters of the GuAM. These findings imply that guanidinium adipate monohydrate (GuAM), a grown single crystal, may be a viable choice for NLO applications.

Slip Flow Via Nonlinearly Stretching/Shrinking Sheet in A Carbon Nanotubes

This study is to analyze the problem of slip flow via nonlinearly stretching/shrinking sheet in carbon nanotubes (CNTs) with suction/injection. The governing partial differential equations are transformed into nonlinear ordinary differential equations via the transformation of similarity. The bvp4c solver in Matlab is then used to resolve them numerically. Water is used as the base fluid together with single-wall and multi-wall CNTs. Both velocity slip and thermal slip are considered in this study. The flow parameters effect is investigated, shown in the form of a graph, and physically evaluated for the dimensionless velocity, temperature, skin friction, and Nusselt numbers. The results show that there are unique solutions for stretching sheets and non-unique solutions for shrinking sheets. In addition, increasing the velocity slip parameter , suction/injection parameter and nonlinear parameter widens the range of solutions, meanwhile increasing the thermal slip causing the rate of heat transfer to decrease.

Impact of weak nonlocal nonlinearity on modulational instability and chirp-free soliton trains in parabolic law optical fiber

This study considers the generation and evolution of chirp-free soliton trains in a focusing cubic-quintic nonlinear optical fiber media (by utilizing experimental parameters), under the influence of weak nonlocal nonlinearity. Analysis of modulational instability (MI) reveals that the MI gain exist only in the anomalous dispersion regime, with the quintic nonlinear term increasing the maximum gain and sideband frequencies. The nonlocal nonlinearity parameter generally suppresses the impact of MI, because the maximum gain is greatly reduced with increase in nonlocality. By using the subsidiary ordinary differential equation method, stationary periodic soliton trains are obtained; with the intensity of the optical beam greatly reduced and frequency increased as nonlocality is gradually stepped up. However, an increase in nonlocality instead reduces the frequency of the traveling optical signals; derived via an efficient transformation method. Our results strongly suggest that nonlocal nonlinearity has potential applications in the control of laser beams; as nonlinear periodic optical signals can be easily transformed to very weak quasi-plane waves.

Spectroscopic investigation demonstrating the enhancement of the linear/nonlinear optical properties of PVA: BSA blend films

The aim of this study was to prepare novel blend films of poly(vinyl alcohol):bovine serum albumin at different concentrations (96:4, 92:8, 88:12, and 94:16 wt/w%) for use in optoelectronic applications. Linear optical parameters were determined from transmittance and reflectance spectra using spectroscopic data in the range 400–2500 nm. Absorption coefficient analysis gives the type of bandgap transition. The calculated values of absorption edge and optical bandgap energy were increased when the BSA content increased to 8 wt% and then decreased when BSA increased to 16 wt%. The values of Urbach energy and bandgap energy have opposite behavior to each other. Absorption and refraction indices and related parameters were calculated. The data showed significant variations that lead to improved optical parameters and confirm that photon-electron interactions in the films change. The Wemple-DiDomenico model was used to evaluate the dispersion energies and related parameters. The dispersion energy values increase from 3.412 to 12.206 eV, while the oscillator energy values decrease from 6.104 to 4.696 eV and then increase to 6.677 eV with increasing BSA content to 16 wt%. The Eo/(Eg)d ratio is found in the range 1.82–2.82 which may coincide with the prediction of a single oscillator model. Other important dielectric-optical parameters were discussed. Some nonlinear optical properties were also evaluated. Increasing the amount of BSA increased the nonlinear parameters which is beneficial for enhancing local polarization of the blend. All studied parameters are discussed and linked together. The results obtained from this study suggest that these prepared blends can be used in numerous optical applications.

Photogrammetric Investigation of Storm-Induced Erosion Process on Sandy Beach Profile in Medium-Scale Flume

In this study, laboratory experiments were conducted to investigate the influence of changes in storm wave height and water level on beach response in a medium-scale wave flume. A schematic storm was simulated (rising, apex, and waning phases). A non-intrusive photogrammetric method was used to collect high-resolution and synchronous data regarding the free surface water elevation and bed level, from which shoreline location, sandbar position, cross-shore sediment transport rates, and nonlinear wave parameters were derived. The cross-shore sediment transport was in agreement with previous laboratory measurements, including the monotonous exchange from foreshore erosion to shoaling zone accretion in most stages of the storm simulation. The surf zone was the main region supplying sediment for beach morphology modification and sandbar generation. The degree of storm erosion was not completely determined by the largest wave height and water level or the cumulative wave power of the apex phase. The largest gradients of the wave parameter sequence change occurred in the rising phase, and this was the main factor generating efficient beachface erosion. It induced an increase in sandbar size, accompanied by the cross-shore motion of maximum velocity amplitude, more violent disturbances of wave nonlinearity, and increased surf zone erosion, with these factors increasing beach instability and leading to more severe storm erosion. The large wave height and water level resulted in shoreline retreat, with a more significant swash zone erosion under a higher runup. The offshore sediment transport turned toward the onshore direction as the original large sandbar deteriorated under the decreasing wave parameter sequence in the waning phase.

Unveiling of novel synthesized coumarin derivative for efficient self-driven hybrid organic/inorganic photodetector applications

During this study, a novel organic semiconductor material comprising coumarin and chromone moieties was synthesized via a facile route. Thin films of the synthesized powder were thermally deposited under vacuum conditions. The structural and morphological properties were investigated using X-ray diffraction and scanning electron microscope techniques, respectively. With increasing the film thickness, a relative crystallinity enhancement was observed, besides improving the surface features and uniformity. Furthermore, the UV–vis–NIR spectral transmittance and reflectance of the grown films were measured. The variation of film thickness induced significant changes in the optical parameters either dispersive or electronic such as energy gap (3.67–3.8 eV), oscillator energy (4.25–4.56 eV), and dispersion energy (4.61–10.31 eV). In addition, the nonlinear optical parameters and PL emission spectra of the prepared films were measured and analyzed in detail. Then, these films were exploited integrally with p-Si for the fabrication hybrid junction for light sensing. The optimized film thickness based on the optical, structure results, and electronic performance under dark conditions was ∼124 nm. Such a device showed a pronounced self-driven photodetection performance under different illumination intensities. The photoelectronic parameters including responsivity (∼5.17 mA/W), detectivity (∼2.64 × 1010 Jones), linearity (∼72.72 dB), and rise/fall times(∼51.48 ms/47.75 ms) were extracted and compared to other organic/p-Si devices and showed a high superiority.

Investigation of a Spatio-Temporal Fractal Fractional Coupled Hirota System

This article aims to examine the nonlinear excitations in a coupled Hirota system described by the fractal fractional order derivative. By using the Laplace transform with Adomian decomposition (LADM), the numerical solution for the considered system is derived. It has been shown that the suggested technique offers a systematic and effective method to solve complex nonlinear systems. Employing the Banach contraction theorem, it is confirmed that the LADM leads to a convergent solution. The numerical analysis of the solutions demonstrates the confinement of the carrier wave and the presence of confined wave packets. The dispersion nonlinear parameter reduction equally influences the wave amplitude and spatial width. The localized internal oscillations in the solitary waves decreased the wave collapsing effect at comparatively small dispersion. Furthermore, it is also shown that the amplitude of the solitary wave solution increases by reducing the fractal derivative. It is evident that decreasing the order α modifies the nature of the solitary wave solutions and marginally decreases the amplitude. The numerical and approximation solutions correspond effectively for specific values of time (t). However, when the fractal or fractional derivative is set to one by increasing time, the wave amplitude increases. The absolute error analysis between the obtained series solutions and the accurate solutions are also presented.

On the proximity between the wave dynamics of the integrable focusing nonlinear Schrödinger equation and its non-integrable generalizations

The question of whether features and behaviors that are characteristic to completely integrable systems persist in the transition to non-integrable settings is a central one in the field of nonlinear dispersive equations. In this work, we investigate this topic in the context of focusing nonlinear Schrödinger (NLS) equations. In particular, we consider non-integrable counterparts of the (integrable) focusing cubic NLS equation, which are distinct generalizations of cubic NLS and involve a broad class of nonlinearities, with the cases of power and saturable nonlinearities serving as illustrative examples. This is a notably different direction from the one explored in other works, where the non-integrable models considered are only small perturbations of the integrable one. We study the Cauchy problem on the real line for both vanishing and non-vanishing boundary conditions at infinity and quantify the proximity of solutions between the integrable and non-integrable models via estimates in appropriate metrics as well as pointwise. These results establish that the distance of solutions grows at most linearly with respect to time, while the growth rate of each solution is chiefly controlled by the size of the initial data and the nonlinearity parameters. A major implication of these closeness estimates is that integrable dynamics emerging from small initial conditions may persist in the non-integrable setting for significantly long times. In the case of zero boundary conditions at infinity, this persistence includes soliton and soliton collision dynamics, while in the case of nonzero boundary conditions at infinity, it establishes the nonlinear behavior of the non-integrable models at the early stages of the ubiquitous phenomenon of modulational instability. For this latter and more challenging type of boundary conditions, the closeness estimates are proved with the aid of new results concerning the local existence of solutions to the non-integrable models. In addition to the infinite line, we also consider the cubic NLS equation and its non-integrable generalizations in the context of initial-boundary value problems on a finite interval. Apart from their own independent interest and features such as global existence of solutions (which does not occur in the infinite domain setting), such problems are naturally used to numerically simulate the Cauchy problem on the real line, thereby justifying the excellent agreement between the numerical findings and the theoretical results of this work.

Tuning the optical, and dielectric properties of PVC/PEO/NiMoO4/MWCNTs/x wt %PANI blended polymers for optoelectronic applications

Nanoparticles of nickel molybdate (NiMoO4) have attracted significant interest for their application as electrode materials. Here, new hybrid blended polymers, poly (vinyl chloride)/polyethylene oxide/nickel molybdate/multi-walled carbon nanotubes/polyaniline (PVC/PEO/NiMoO4/MWCNTs/x wt %PANI) were prepared. Several techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance, fluorescence and LCR meter were used to investigate the impact of the different fillers on the structure, electrical and optical features of the PVC/PEO blend. The structures of NiMoO4 and different blends were explored using XRD technique. The linear and nonlinear optical properties and the emitted colors of host blend are found to be affected by NiMoO4, MWCNTs and different amounts of PANI fillers. The T values of PVC/PEO were reduced as it loaded with NiMoO4/MWCNTs/x wt %PANI and it reached its minimum value (21–37% in the visible range) in NiMoO4/MWCNTs/x 0.4 %PANI blend. The minimum direct and indirect optical band gap values (4.09, 4.9) eV and (1.92, 3.47, 3.94) eV, respectively, were obtained as the amount of PANI became 0.4 wt % in the doped blend. The doped PVC/PEO blend with NiMoO4 has the highest refractive index value (2.11) at 600 nm. The highest nonlinear optical parameters were acquired exclusively in the visible spectrum when PVC/PEO was doped with NiMoO4.The maximum energy density value (6.03 × 10−3 J/m3) was obtained when the host blend loaded with NiMoO4/MWCNTs. Thus, PVC/PEO/NiMoO4/MWCNTs/x wt %PANI blends are recognized as a good prospect for UV blocking, solar cell, optoelectronic, nonlinear optical devices and energy storage innovation.

Influence of the Plan Structural Symmetry on the Non-Linear Seismic Response of Framed Reinforced Concrete Buildings

Seismic-resistant design incorporates measures to ensure that structures perform adequately under specific limit states, focusing on seismic forces derived from both the equivalent static and spectral modal methods. This study examined buildings on slopes in densely built urban areas, a common scenario in Latin American cities with high seismic risks. The adjustment of high-rise buildings to sloping terrains induces structural asymmetry, leading to plan and elevation irregularities that significantly impact their seismic response. This paper explores the asymmetry in medium-height reinforced concrete frame buildings on variable inclines (0°, 15°, 30°, and 45°) and its effect on their nonlinear response, assessed via displacements, rotations, and damage. Synthetic accelerograms matched with Chile’s high seismic hazard design spectrum, scaled for different performance states and seismic records from the Chilean subduction zone, were applied. The findings highlight structural asymmetry’s role in influencing nonlinear response parameters such as ductility, transient interstory drifts, and roof rotations, and uncover element demand distributions surpassing conventional analysis and in earthquake-resistant design expectations.

Pitch angle control of wind turbines using model-free auto-tuned fractional order proportional derivative ATFOPD controller

The nonlinear dynamics of wind power plants, in addition to uncertainties such as unknown nonlinear disturbances and parameter variations make the design of a robust controller a difficult task. This paper proposes a robust fractional-order controller for the pitch angle control of a variable-speed wind turbine system. An auto-tuned fractional order proportional-derivative controller ATFOPD is designed taking the objectives of reducing pitch actuator fatigue, limiting output mechanical power and speed at their rated values above the rated wind speed. The phase, phase slope and modulus of the pitch actuator process at the fixed gain crossover frequency are needed in order to tune the fractional order controller parameters. These values are usually derived using a mathematical model of the system, such as a transfer function. A model-free auto-tuning technique that can calculate the controller's parameters from measured variables is used in this work in order to design a robust FOPD controller. Simulation results of the ATFOPD controlled system are compared to integer order proportional-derivative IOPD and IOPID controllers, which show that the ATFOPD controller is more effective than the other controllers and its robustness is verified in the presence of disturbances in addition to system parameters and wind speed variations.