Wave Period Research Articles

Epidemiological, clinical and biological profile of COVID-19 in patients hospitalized at the Avicenne Military Hospital in Marrakech

In late December 2019, a series of cases of viral pneumonia caused by a novel coronavirus emerged in Wuhan, China, and quickly spread to all continents. This coronavirus, identified in respiratory tract samples, was named SARS-CoV-2 for Severe Acute Respiratory Syndrome Coronavirus-2 by the ICTV (International Committee on Taxonomy of Viruses). The disease it causes was designated COVID-19 for Coronavirus Disease 2019 by the Word Health Organization. Most often, SARS-CoV-2 infection is responsible for a mild or moderate form, with the most typical clinical presentation being that of a febrile respiratory infection with dry cough, dyspnea, fatigue, and myalgia. Approximately 10-15% of cases are severe, and 5% are critical. Cases of reinfection have been described. Treatment for COVID-19 is currently symptomatic, relying on supportive care. The present study aims to investigate the demographic, clinical, and diagnostic aspects, as well as the study of risk factors associated with SARS-CoV-2 infection among 318 patients admitted to the Avicenne Military Hospital in Marrakech during the first wave of the pandemic. This is a retrospective descriptive and analytical study involving 318 cases of SARS-CoV-2 infection, diagnosed at the microbiology-virology department, and followed up in various non-intensive care units of the Avicenna Military Hospital in Marrakech, during the period of the first wave of the epidemic in Morocco, schematically between March 22, 2020, and July 19, 2020. For patients who developed pneumonia, 20% were diabetic and 13.3% were hypertensive. A quarter of patients with pneumonia experienced desaturation upon admission. In the multivariate logistic regression model, risk factors associated with the development of pneumonia and the various disease outcomes included advanced age and absence of a history of contact with a confirmed case. In the univariate analysis, hyperleukocytosis, neutrophilia, lymphopenia, eosinopenia, anaemia, hyperferritinaemia with elevated aspartate aminotransferase, hyponatraemia and fasting hyperglycaemia were significantly associated with a higher risk of an unfavourable outcome. Patients who presented with pneumonia on admission had an unfavourable outcome during their hospitalisation compared with patients who did not develop pneumonia. The statistically significant risk factors associated with an unfavourable outcome were advanced age (>60 years) with p <0. 001: OR=1.194; 95%IC= [1.114-1.278], absence of contact with a confirmed case (p <0.001 : OR= 43.138; 95%IC= [8.893-209.263]), presence of comorbidity (P<0.001 : OR=11. 503; 95%CI= [3,306-40,028]), mainly diabetes (P<0.001: OR=16,971; 95%CI= [4,267-67,504]) and arterial hypertension (P<0.001: OR=18,812; 95%CI= [3,977-88,954]). The study of the epidemiological, clinical and biological characteristics of COVID 19 at the Avicenne military hospital in Marrakech has enabled us to gain a better understanding of the profile of our patients with SARS-CoV-2 infection, and then to detect shortcomings in terms of prophylaxis, diagnosis and management, in order to be able to provide the necessary solutions aimed at further improving the quality of care for this population.

Dynamics of transformed nonlinear waves for the (2+1)-dimensional pKP-BKP equation: interactions and molecular waves

Abstract In this paper, the dynamical behaviors of transformed nonlinear waves for the (2+1)-dimensional combined potential Kadomtsev-Petviashvili and B-type Kadomtsev-Petviashvili (pKP-BKP) equation are investigated, which can be used to reveal the nonlinear wave phenomena in nonlinear optics, plasma physics and hydrodynamics. The breath-wave and the lump solutions are constructed by means of the soliton solutions. The conversion mechanism for the breath-waves is systematically analyzed, which leads to several new kink-shaped nonlinear waves. The gradient relationships of these transformed waves are revealed by a Riemannian circle. Through the analysis of the nonlinear superposition between the periodic wave component and the kink solitary wave component, the dynamical characteristics including the formation mechanism, oscillation and locality for the nonlinear waves are investigated. The time-varying properties of transformed waves are showed by the study of time variables. By virtue of the two breath-wave solution, several interactions including elastic and inelastic collisions between two nonlinear waves are studied. In particular, some transformed molecular waves encompassing the non-, semi- and full-transition modes are presented with the aid of velocity resonance. The results can help us further understand the complex nonlinear waves existing in the integrable systems.

Proposal of a New Control System Making Use of AI Tools to Predict a Ship’s Behaviour When Approaching the Synchronism Phenomenon

In spite of the IMO’s efforts to improve the safety of intact stability on ships, synchronous rolling still causes large rolling angles, resulting in a very dangerous situation on board. The implementation of automatic tools to predict this undesirable situation has not been widely implemented. Furthermore, the safety of ship stability is not the only responsibility of people involved in the design process, so ship operators must have enough knowledge to predict and avoid these dangerous situations well in advance. Therefore, from a theoretical point of view, in the first part, this paper aims to present a valuable guiding tool for ship operators in order to predict synchronous rolling and avoid undesirable situations on board by making use of only empirical observations of the wave profile and moments. With this purpose, mathematical models are first proposed, with the ship sailing in the worst condition, i.e., with and without considering the damping factor, at zero speed and considering the influence of any pure beam and trochoidal waves. Relevant results shown provide the exact time and wave profile at which the maximum rolling angles are reached. In the second part of the paper, a new control system making use of AI tools is proposed in order to be used by ship operators on board, avoiding dangerous situations. Finally, the results are validated using a set of ship rolling simulations for the most common and representative ship loading conditions and wave periods.

Dynamics of invariant solutions of the DNA model using Lie symmetry approach

The utilization of the Lie group method serves to encapsulate a diverse array of wave structures. This method, established as a robust and reliable mathematical technique, is instrumental in deriving precise solutions for nonlinear partial differential equations (NPDEs) across a spectrum of domains. Its applications span various scientific disciplines, including mathematical physics, nonlinear dynamics, oceanography, engineering sciences, and several others. This research focuses specifically on the crucial molecule DNA and its interaction with an external microwave field. The Lie group method is employed to establish a five-dimensional symmetry algebra as the foundational element. Subsequently, similarity reductions are led by a system of one-dimensional subalgebras. Several invariant solutions as well as a spectrum of wave solutions is obtained by solving the resulting reduced ordinary differential equations (ODEs). These solutions govern the longitudinal displacement in DNA, shedding light on the characteristics of DNA as a significant real-world challenge. The interactions of DNA with an external microwave field manifest in various forms, including rational, exponential, trigonometric, hyperbolic, polynomial, and other functions. Mathematica simulations of these solutions confirm that longitudinal displacements in DNA can be expressed as periodic waves, optical dark solitons, singular solutions, exponential forms, and rational forms. This study is novel as it marks the first application of the Lie group method to explore the interaction of DNA molecules.

Wave retrieval for Sentinel-1 synthetic aperture radar under complex sea state

ABSTRACT In this paper, sea surface waves during complex sea state (i.e. tropical cyclones (TCs) and Kuroshio current) are inverted from dual-polarized (vertical – vertical (VV) and vertical – horizontal (VH)) synthetic aperture radar (SAR) images using an existing algorithm, namely, the parameterized first-guess spectrum method (PFSM). In particular, the wind term is included in two modulation transfer functions (MTFs), i.e. tilt modulation and velocity bunching. More than 3000 Sentinel (S-1) images acquired in interferometric wide (IW) mode and extra wide (EW) mode are collected, and the operational CyclObs wind product provided by the French Research Institute for Exploitation of the Oceans (IFREMER) is collected corresponding to the TC images. Note that these images are located within 500 km away from TC eyes. The wave spectra during the TCs are then inverted using the PFSM algorithm and the SAR-derived wind product. Simultaneously, the 0.05° gridded wave spectra collocated with these images are simulated using a third-generation numeric wave model, called WAVEWATCH-III (WW3), in which the reconstructed wind based on the European Centre for Medium-Range Weather Forecasts (ECMWF), the Copernicus Marine Environment Monitoring Service (CMEMS) current, and the CMEMS sea level are treated as the forcing field. Comparison of the SAR wave retrievals and simulations reveals that the root mean square errors (RMSEs) of the significant wave height (SWH) and mean wave period (MWP) are 0.55 m and 0.43 s, their correlation coefficients (COR) are 0.94 and 0.92, and their scatter index (SI) values are 0.17 and 0.07. These results demonstrate the better performance of the PFSM algorithm using theoretical MTFs, i.e. an RMSE of 0.68 m and COR of 0.90 for the SWH and an RMSE of 0.60 s and a COR of 0.87 for the MWP. Although the accuracy of the wave retrieval from the SAR image under complex sea state is improved when implementing the tilt and velocity bunching MTFs with the strong wind term, SWH retrievals by algorithm PFSM suffer saturation problem at SWH > 8 m.

Simulation of LNG-Battery hybrid tugboat under the influence of environmental loads and manoeuvre

This paper presents a system modelling approach aimed at designing and simulating real-time conditions, with a specific focus on extreme scenarios to assess the impact on the annual CO2 emissions and the consumption of LNG and batteries in a hybrid tugboat. Environmental variables such as wave period, wave height, current speed, and wind speed are considered. The tugboat system model is validated using manually logged historical operational data from a similar tugboat profile using both AMESIM and MATLAB\Simulink to simulate diverse environmental conditions and estimate annual fuel operational costs and emissions. A comparative analysis of the different system configurations is then conducted between traditional diesel, LNG and several control configurations of LNG-battery hybrid. Results demonstrate a significant reduction of 96.5% in CO2 emissions and a 95.3% decrease in annual fuel operational costs with the adoption of LNG-battery hybrid propulsion with the rule-based control system. The study notes a slight increase in vessel operational time by 10.8% due to higher wave heights and a 0.97% rise in added resistance from increased wind speed. Insignificant differences are observed in variations of wave period and current speed. Additionally, the CII ratings of the different system configurations were then compared and concluded with the LNG-battery hybrid with a rule-based control system being the most environmentally and economically sustainable.

A novel analytical technique for analyzing the (3+1)-dimensional fractional calogero- bogoyavlenskii-schiff equation: investigating solitary/shock waves and many others physical phenomena

This work presents a thorough analysis of soliton wave phenomena in the (3+1)-dimensional Fractional Calogero-Bogoyavlenskii-Schiff equation (FCBSE) with Caputo’s derivatives through the use of a novel analytical technique known as the modified Extended Direct Algebraic Method (mEDAM). By converting nonlinear Fractional Partial Differential equations (FPDE) into integer-order Nonlinear Ordinary Differential equations (NODE), and then using closed-form series solutions to translate the NODE into an algebraic system of equations, this method allows us to derive families of soliton solutions, which include kink waves, lump waves, breather waves, and periodic waves, exposing new insights into the behavior and distinctive features of soliton waves in the FCBSE. By including contour and 3D graphics, the behaviors of a few selected soliton solutions are well depicted, showcasing their amplitude, shape, and propagation characteristics. The results enhance our understanding of the FCBSE and show that the mEDAM is a valuable tool for studying soliton wave phenomena. This work creates new opportunities for studying wave phenomena in more intricately constructed nonlinear FPDEs (NFPDEs).

Painlevé Analysis of the Traveling Wave Reduction of the Third-Order Derivative Nonlinear Schrödinger Equation

The second partial differential equation from the Kaup–Newell hierarchy is considered. This equation can be employed to model pulse propagation in optical fiber, wave propagation in plasma, or high waves in the deep ocean. The integrability of the explored equation in traveling wave variables is investigated using the Painlevé test. Periodic and solitary wave solutions of the studied equation are presented. The investigated equation belongs to the class of generalized nonlinear Schrödinger equations and may be used for the description of optical solitons in a nonlinear medium.

Derivation of optical solitons for perturbed highly dispersive conformable fractional nonlinear Schrödinger equation with sextic-power law refractive index

In this article, the modified extended direct algebraic method is applied for the perturbed highly dispersive nonlinear Schrödinger equation with conformable fractional derivative and sextic-power law refractive index. Various types of solutions are extracted such as bright solitons, dark solitons, combo bright-dark solitons, singular solitons, singular periodic wave solutions, exponential wave solutions and rational solutions. The impact of the fractional derivative is illustrated graphically using examples of some of the retrieved solutions with various values of fractional order.

Leaky wave antenna loaded complementary elements with dual-stopband suppression

Abstract In this paper, a periodic leaky wave antenna (PLWA) using complementary elements is proposed. The complementary elements of the transverse slot (horizontal magnetic current) and the monopole pairs (vertical electric current) in the substrate integrated waveguide (SIW) is employed as the radiation element, which can simultaneously suppress closed stopband β0p=π and open stopband (OSB) β-1p=0 to enhance the forward scanning of the LWA. Additionally, the gain and cross-polarization of the element are improved due to the loading of the monopole pairs. The LWA achieves forward and backward scanning from -73° to 10° when operating at the n=-1 spatial harmonic (SH), with corresponding gains of 11.5 to 15.4 dBi. When operating at the n=0 SH, it achieves forward scanning from 58° to 72°, with corresponding gains of 5.2 to 7.5 dBi. Moreovere, due to the element and its symmetrical structure, the cross-polarization within the entire operating frequency range is less than -35 dB. The design concept is validated through processed, fabricated, and tested.

Soliton structures for the (3 + 1)-dimensional Painlevé integrable equation in fluid mediums

The (3 + 1)-dimensional Painlevé integrable equation are a class of nonlinear differential equations with special properties, which play an important role in nonlinear science and are of great significance in solving various practical problems, such as many important models in fields such as quantum mechanics, statistical physics, nonlinear optics, and celestial mechanics. In this work, we utilize the Hirota bilinear form and Mathematica software to formally obtain the interaction solution among lump wave, solitary wave and periodic wave, which has not yet appeared in other literature. Additionally, using the (G′/G)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(G'/G)$$\\end{document}-expansion method, we provide a rich set of exact solutions for the (3 + 1)-dimensional Painlevé integrable equation, which includes two functions with arbitrary values. This method is the first to be applied to the (3 + 1)-dimensional Painlevé integrable equation. By giving some 3D graphics and density maps, the dynamic properties are analyzed and demonstrated, which is beneficial for promoting understanding and application of the (3 + 1)-dimensional Painlevé integrable equation.

Wave type fiber SPR sensor for rapid and highly sensitive detection of hyperoside

The fiber surface plasmon resonance (SPR) sensor used for the detection of active ingredients in traditional Chinese medicine has the problems of low sensitivity and difficult specific recognition. This paper proposed a wave type fiber SPR sensor, which reduced the mode of transmitted light through a periodic wave structure and caused concentrated and total reflection of the transmitted beam at the interface between the bent peak cladding and the air. A 50 nm gold film was coated on the surface of the cladding in the wave structure area to form the SPR sensing area. By controlling the width and height of the wave structure to control the total reflection angle of the transmitted light, i.e., the SPR incidence angle, the sensitivity of the fiber SPR sensor was effectively improved to 4972 nm/RIU. Furthermore, HSP90AA protein was modified on the gold film of the sensor to achieve specific detection of hyperoside. The longest single detection time was only 3 minutes, and the detection sensitivity was 0.53 nm/(µg/ml), with a detection limit as low as 0.68µg/ml, which is comparable to liquid chromatography. The proposed wave type fiber SPR sensor is fast in production and has high structural mechanical strength, providing a new approach for the rapid, highly sensitive, and specific detection of active ingredients in traditional Chinese medicine.

Exact solutions and bifurcations for the (3+1)-dimensional generalized KdV-ZK equation

Abstract In this paper, a class of (3+1)-dimensional generalized Korteweg-de Vries-Zakharov-Kuznetsov (KdV-ZK) equation is studied by utilizing the bifurcation theory of the planar dynamical systems and the Fan sub-function method. This model can be used to explain the effects of magnetic fields on weakly nonlinear ion-acoustic waves investigated in plasma fields composed of cold and hot electrons. Under the different parameter conditions, the phase portraits and bifurcations are derived, and new exact solutions including soliton, periodic, kink and breaking wave solutions for the model are constructed. Moreover, some exact solutions, which contain soliton, kink, trigonometric function, hyperbolic function, Jacobi elliptic function solutions, are derived via the improved Fan sub-function method. The types of solutions obtained completely correspond to the types of the orbits acquired
above, which verifies the validity of the method. Finally, the physical structures of some exact solutions are analyzed in graphical forms.

Lattice Boltzmann simulation of breaking waves

Water wave breaking at the ocean’s surface is a turbulent phenomenon and encompasses a wide range of physical processes such as generation of bubbles/drops with different spatio-temporal scales. In the present study, breaking of periodic waves in deep water regime has been simulated using phase-field lattice Boltzmann method (LBM). Compared to direct Navier–Stokes equation based numerical models, the present LB model is Poisson-free and explicit in time integration. Both the flow field and interface are solved using LBM with two sets of distribution functions. The normalized pressure-velocity formulation is used for the flow field, whereas the conservative Allen–Cahn equation is used to capture the interface. An impulsively started wave approach with Stokes third order wave profile has been used to initiate the breaking process. Through systematic variation of Weber number and initial steepness, the effect of surface tension on the kinematic, geometric, and energy dissipation characteristics has been studied for three breaker types, viz., spilling, weak plunging, and plunging breakers. The results are in good agreement with the past experimental observations and direct numerical simulation. In particular, the obtained breaking strength for different Weber numbers agrees well with the semi-empirical relation used in a wind-wave forecasting models.

Constructing the soliton wave structure to the nonlinear fractional Kairat-X dynamical equation under computational approach

In this paper, the nonlinear fractional Kairat-X equation is investigated on the basis of computational simulation. The nonlinear fractional Kairat-X equation is an integrable equation and is used to explain the differential geometry of curves and equivalence aspects. Several kinds of solitary wave structures of the nonlinear fractional Kairat-X equation are established successfully via the implantation of the extended simple equation method. Here, we explore the interesting, novel and general solutions in trigonometric, exponential, and rational types, which represent periodic wave solitons, mixed solitons in the shape of bright–dark solutions, kink wave solitons, peakon bright and dark solitons, anti-kink wave solutions, bright solitons, dark solitons, and solitary wave structure. The physical structures of secured results, aided by numerical simulation, have numerous applications in applied sciences such as optical fiber, geophysics, laser optics, mathematical physics, nonlinear optics, nonlinear dynamics, communication system, and engineering. This study explores the physical behavior of models through the visualization of solutions in contour, 2D and 3D plots by revealing that these solutions yield profitable results in the field of mathematical physics. The study demonstrates that the proposed technique is more reliable, efficient, and powerful in analyzing nonlinear evolution equations in various domains of science.

Continuous Wave Measurements Collected in Intermediate Depth throughout the North Sea Storm Season during the RealDune/REFLEX Experiments

High-resolution wave measurements at intermediate water depth are required to improve coastal impact modeling. Specifically, such data sets are desired to calibrate and validate models, and broaden the insight on the boundary conditions that force models. Here, we present a wave data set collected in the North Sea at three stations in intermediate water depth (6–14 m) during the 2021/2022 storm season as part of the RealDune/REFLEX experiments. Continuous measurements of synchronized surface elevation, velocity and pressure were recorded at 2–4 Hz by Acoustic Doppler Profilers and an Acoustic Doppler Velocimeter for a 5-month duration. Time series were quality-controlled, directional-frequency energy spectra were calculated and common bulk parameters were derived. Measured wave conditions vary from calm to energetic with 0.1–5.0 m sea-swell wave height, 5–16 s mean wave period and W-NNW direction. Nine storms, i.e., wave height beyond 2.5 m for at least six hours, were recorded including the triple storms Dudley, Eunice and Franklin. This unique data set can be used to investigate wave transformation, wave nonlinearity and wave directionality for higher and lower frequencies (e.g., sea-swell and infragravity waves) to compare with theoretical and empirical descriptions. Furthermore, the data can serve to force, calibrate and validate models during storm conditions.

Linear asymptotic stability of small-amplitude periodic waves of the generalized Korteweg–de Vries equations

We extend the detailed study of the linearized dynamics obtained for cnoidal waves of the Korteweg–de Vries equation by Rodrigues [J. Funct. Anal. 274 (2018), pp. 2553–2605] to small-amplitude periodic traveling waves of the generalized Korteweg–de Vries equations that are not subject to Benjamin–Feir instability. With the adapted notion of stability, this provides for such waves, global-in-time bounded stability in any Sobolev space, and asymptotic stability of dispersive type. When doing so, we actually prove that such results also hold for waves of arbitrary amplitude satisfying a form of spectral stability designated here as dispersive spectral stability.

The soliton and periodic solutions for the perturbed sine–cosine–Gordon equation

In the paper, the existence of soliton and periodic solutions is studied for the perturbed sine–cosine–Gordon equation. The corresponding traveling wave system is converted to a regularly Hamilton system via using bifurcation theory of differential equations and the geometric singular perturbation theory. Then by using Melnikov's method and symbolic computation, periodic wave solutions, solitary solutions, and kink and antikink solutions are obtained. The wave speed selection principles are given, respectively. Numerical simulations are performed to illustrate our theoretical analysis.

Experimental study on water replenishment holes in offshore monopiles

Adequate replenishment of water within the monopile foundations of offshore wind turbines is essential to ensure the effective performance of cathodic protection measures applied inside the monopile to combat internal corrosion. This study presents experimental results for the process of replenishing water within a monopile with one opening below the still water level. The results are presented as (1) the relative wave height and set-down inside the monopile under various regular wave conditions and (2) head loss coefficient for the flow in and out of the water replenishment opening in the monopile. The study demonstrates a clear link between the ratio of the wave height of the internal and external surface elevations, the relative wave height, and the dimensions of the opening in the monopile as well as the wave period. Furthermore, a simple predictive model is proposed based on linear wave theory and static energy loss considerations. The orientation of the opening with respect to the wave direction has limited effect on the relative wave height, however it has a distinct effect on the mean surface level (MSL) inside the monopile. The lowest MSL occurred when the opening hole was positioned perpendicular (at a 90-degree angle) to the direction of wave propagation. Geometric considerations suggest that the flow in and out of the cylinder is slightly asymmetric and the results also show a small difference in the head loss coefficient for the flow in and out of the monopile, respectively. On average, however, the head loss coefficient was found to be ζ=2.0.

Experimental study on wave damping potential of seaweed aquaculture systems on the Portuguese coast

The sea-level rise and intensification of extreme weather events pose a significant threat to coastal regions and their communities worldwide. With significant wave heights reaching over 5 m, and wave periods over 10 s (Mendes & Oliveira, 2021), the Portuguese coastline is exposed to major coastal erosion, due to the marine harsh conditions of the North Atlantic. In the last decades the preferred strategy to protect the coastline from coastal hazards has been the construction of hard-engineering structures such as seawalls and breakwater, which tend to be expensive and unsustainable, often becoming obsolete and were not designed to account for the increasing sea level. As such, there has been a growing trend over the adoption of soft, adaptative, and nature-based coastal protection measures (Pranzini et al., 2015). Longline seaweed aquaculture systems have long been identified as a nature-based, soft structure with wave damping potential by several studies performed by Mork (1996), Liu et al. (2015) among others. The AquaBreak Project aims at exploring the synergetic applications of seaweed aquaculture systems on food production, coastal protection, and sea decarbonization on the Portuguese coast with the creation of the AOS - the AquaBreak Offshore System (Miranda et al., 2023; Proença et al., 2023). However, in order to create a strategic and effective implementation plan for the AOS, it is important to assess the wave damping potential of such structure exposed to the common maritime conditions of the Portuguese Coast.