Wave Impact Research Articles

Evolución de la seroprevalencia de COVID-19 en bancos de sangre durante la pandemia en la región Lima, Perú

Introduction. Peru was one of the countries most affected by the COVID-19 pandemic, with more than 220,000 deaths recorded due to SARS-CoV-2 infection. Given the constant mutations of the virus and registered variants, it is important to carry out research that reflects the evolution of the humoral immune state. Objective. Measure the seroprevalence of COVID-19 during the pandemic in the department of Lima in the period between April 1, 2020 and June 30, 2022, in donor samples from 6 hospital blood banks public of Lima, Peru. Methods. A descriptive, transversal, observational and retrospective study was carried out evaluating the presence of IgM/IgG antibodies against SARS-CoV-2 using lateral flow chromatographic immunoassay in samples from healthy and asymptomatic donors from blood banks of 6 health facilities in the department of Lima. Results. A progressive increase in the seroprevalence of IgG and total reactivity of IgM/ IgG antibodies against SARS-CoV-2 will be observed as follows: 22,6% - 32,7% during 2020; 53,9% - 58,1% during 2021; 88,9% - 93,3% during the first half of 2022. Conclusions. The reactivity and presence of anti- SARS-CoV-2 antibodies progressively increase during the COVID-19 pandemic from 11,2% to 98,4% in the samples evaluated, possibly with the impact of the pandemic waves and the active vaccination campaign against COVID-19.

Opinion Instability and Measurement Errors: A G-Theory Analysis of College Students

ABSTRACT This study examines opinion instability among individuals from different ethnic groups (White, Latino, and Asian Americans) by analyzing measurement errors in survey measures. Using a multi-wave panel dataset of college students and employing generalizability theory, the study uncovers significant patterns. The results reveal that White students exhibit higher attitude reliability, characterized by larger variances in true opinions and smaller measurement errors. In contrast, Latino and Asian American students display lower attitude stability, with lower variances in true opinions and higher variances in both item-specific and measurement errors. Disparities in political socialization and issue concerns contribute to the observed attitude instability among Latino and Asian American students. Moreover, Asian American and Latino respondents require a greater number of survey items to mitigate measurement error compared to their White counterparts. However, the impact of multiple waves of surveys on improving reliability is limited for Latino and Asian American students compared to White students. These findings deepen our understanding of attitude stability across ethnic groups and underscore the importance of further research in this area.

Experimental study of sloshing flows in a rectangular tank under coupled pitch and heave excitations

Sloshing in partially filled containers under external forces has significant implications across industries like aerospace and oil and gas transportation. The present study aims to explore the influence of the first and second order Faraday waves on both resonant and non-resonant pitch sloshing, as well as the effects of coupled resonance. Laboratory experiments were conducted to analyze sloshing impact pressures and record wave elevations, delving into how Faraday waves alter wave shapes and impact pressure dynamics, especially in shallow water conditions. Key findings reveal significant effects of Faraday waves on both resonant and off-resonant pitch excitation. In shallow water, the presence of the first mode Faraday wave leads to reduced pressure through upward-deflected breaking impact waves, while the second mode Faraday wave intensifies impact pressure by generating flip-through waves carrying substantial energy before impacting the sidewall. Furthermore, the study explores the interaction between pitch and heave excitations, revealing how combined resonance affects sloshing behavior. Coupled-resonant sloshing waves induce periodic pressure behavior due to energy dissipations, providing insights into the complex dynamics of sloshing flows under various excitations, crucial for optimizing design and ensuring safety in engineering applications.

Advances of the in-house developed SWLBM framework in simulating large-scale three-dimensional violent free surface flow with intense splashing

The accurate and efficient simulation for violent free surface flow with intense splashing is import in engineering. The purpose of this paper was to extend and validate the capabilities of Sunway Lattice Boltzmann Method code (SWLBM, our in-house developed CFD framework) in simulating large-scale three-dimensional violent free surface flow. The lattice Boltzmann method was employed to solve the fluid dynamics. The interface was captured by the single-phase free surface model. For parallel computing, the computational domain was divided into parallel blocks and overlap layers were designed for inter-block communications. Several typical dam-break problems were selected for validating the ability of reproducing splashing details, where finest spatial resolution was up to about 0.6 billion cells. The numerical results were in good agreement with experimental results. The present results revealed more plentiful splashing details than various published results with relatively coarser spatial resolution. The efficiency of SWLBM was over 100 times higher than that of OpenFOAM in the testing example. It was demonstrated that SWLBM is capable of simulating large-scale violent free surface flow and reproducing splashing details with sufficient accuracy and efficiency. SWLBM has the potential to be applied in real engineering problems including simulating wave impact on decks.

Assessing the impact of waves and platform dynamics on floating wind-turbine energy production

Abstract. Waves have the potential to increase the power output of a floating wind turbine by forcing its rotor to move against the wind. Starting from this observation, we use four multi-physics models of increasing complexity to investigate the role of waves and platform movements in the energy conversion process of four floating wind turbines of 5–15 MW in the Mediterranean Sea. Progressively adding realism to our simulations, we show that large along-wind rotor movements are needed to increase the power output of a floating wind turbine; however, these are prevented by the current technology of spar and semi-submersible platforms. Wind turbulence is the main cause of power fluctuations for the four floating wind turbines we examined and is preponderant over the effect of platform motions due to waves. In a realistic met-ocean environment, the power curve of the floating wind turbines we studied is lower than that obtained with a fixed foundation, with reductions in the annual energy production of 1.5 %–2.5 %. The lower energy production is mainly ascribed to the platform mean tilt, which reduces the rotor's effective area.

Relative energy and perceived impact of vessel-generated waves in fetch-limited environments

Houser C, Carswell A, Chittle B, Johnson G, Caschera A, Smith A. 2024. Relative energy and perceived impact of vessel-generated waves in fetch-limited environments. Lake Reserv Manag. 40:285–302 Vessel-generated waves (or wakes) are perceived as an important stressor in both marine and freshwater systems, and they are an increasingly important focus of coastal management. Recent studies suggest that wakes account for a significant portion of the total wave energy in fetch-limited environments and in turn have the potential to resuspend sediment, erode shorelines, degrade water quality, damage infrastructure, and disrupt aquatic ecosystems, in addition to being considered a safety hazard and a nuisance. To assess the relative contribution of wakes to the total wave energy, monitoring was completed at 32 sites across 7 fetch-limited lakes in Ontario, Canada between 2020 and 2023. The percent wake energy was inversely related to the average fetch length, with deviations to the relationship dependent on whether the site was open, an embayment or along a narrow section of the lake. A survey of property owners and residents suggests that the perceived impact of wakes also varies with the fetch length. Shoreline erosion and degraded water quality were identified as primary impacts of wakes in lakes with the smallest average fetch, but very few respondents provided direct evidence of boat wake impacts. Most respondents described vessel operation, experience of the vessel operator and conflict over different boating uses as the primary issues associated with wakes. While boat wakes may contribute a significant portion of the wave energy in fetch-limited lakes, further research is required to determine when and where they may represent a physical and ecological stressor rather than being just a nuisance.

Impact of current density, TiO2 NPs, and ultrasonic waves on the physical and friction properties of Ni–Zn–TiO₂

In the present study, a nickel-zinc (Ni–Zn) alloy coating has been selected as the foundational coating, and the formation of a composite Ni–Zn-titanium dioxide (Ni–Zn–TiO2) coating, along with the factors influencing its development, has been thoroughly examined. The influential factors explored in this research encompass applying ultrasonic waves, current density, and incorporating varying concentrations of TiO2 nanoparticles (NPs). X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, and a wear test apparatus were utilized to assess the characteristics of these coatings. The findings indicate that the concentration of TiO₂ NPs in the plating bath profoundly impacts the morphology and coating properties. An increased TiO₂ concentration in the plating bath led to a finer morphology. Applying ultrasonic waves during the plating process enhanced the dispersion and finer distribution of NPs within the coating, resulting in improved wear resistance due to the confinement of irregularities. Applying ultrasonic waves up to 60 W improved the properties; however, a reduction in elemental levels was observed when the ultrasonic waves were increased to 120 W. This decrease in elemental levels can be attributed to the high-intensity ultrasonic waves, resulting in diminished wear resistance.

Spatio-Temporal Variation in Suspended Sediment during Typhoon Ampil under Wave–Current Interactions in the Yangtze River Estuary

Suspended sediment plays a major role in estuary morphological change and shoal erosion and deposition. The impact of storm waves on sediment transport and resuspension in the Yangtze River Estuary (YRE) was investigated using a 3D coupling hydrodynamic-wave model with a sediment transport model during Typhoon Ampil. This model has been validated in field observations of water level, current, wave, and sediment concentration. The model was run for tide only, tide + wind, tide + wind and wave forcing conditions. It was found that: (1) typhoons can increase the suspended sediment concentration (SSC) by enhancing bed shear stress (BSS), especially in the offshore area of the YRE, and there is hysteresis between SSC and BSS variation; (2) exponential and vertical-line types are the main vertical profile of the SSC in the YRE and typhoons can strengthen vertical mixing and reconstruct the vertical distribution; and (3) waves are the dominating forcing factor for the SSC in the majority of the YRE through wave-induced BSS which releases sediment from the seabed. This study comprehensively investigates the spatio-temporal variation in SSC induced by Typhoon Ampil in the main branch of the YRE, which provides insights into sediment transport and resuspension during severe storms for estuaries around the world.

A multicountry analysis of local government financial vulnerability during the 2020 pandemic considering systemic factors

AbstractThe COVID‐19 pandemic cut across geographical, sectorial, and policy boundaries and imposed difficult health, economic, and social challenges. Among many learnings, after the 2007–2008 global financial crisis and the austerity period that followed it, the economic and health crises forged by the COVID‐19 pandemic in 2020 offer an important experience to make local governments (LGs) more financially resilient and ready to deal with similar shocks.This paper builds on a recent framework to investigate the impact of the first wave of the COVID‐19 pandemic on LG financial vulnerability looking at both contingent and systemic aspects. It addresses the need for a multicountry perspective on the effects of the pandemic and responds to calls to test existing models. Seven countries were chosen to represent different administrative contexts and traditions to understand what factors impact the local level in a time of crisis. Results demonstrate that not only contingent aspects but also systemic factors and the initial level of financial vulnerability influenced the responses to the pandemic, confirming findings about the importance of initial conditions and “path dependency” by previous studies.

Wytwarzanie ochronnych struktur kompozytowych za pomocą technologii infuzji w celu zapewnienia odporności na fale uderzeniowe

The paper presents the results of experiments on the use of infusion of polymer binders into a pre-constructed skeleton of reinforcing structures. Currently, three-layer structures with an average layer of aluminum honeycombs are considered to be one of the effective structural elements that ensure the damping of the blast wave. As an alternative middle layer, it is possible to offer elements of various shapes (cylinders, cubes, etc.) and geometries made of modern composites that are well-proven under the impact of a shock wave. These are, as is known, metal-polymer composites, i.e. materials containing, in addition to polymer binder and fabric filler, thin layers of metal. In order to form a solid structure that perceives an explosive load, an attempt was made to use RFI technology to obtain individual elements with which two steel sheets are connected. Aramid, glass fabrics and aluminum thin (0.5, 0.15, 0.05 mm) plates were used in the experiments. For the implementation of the infusion process, an epoxy resin was used, suitable in its technological parameters for this process. The use of this resin leads to the minimization of non-nourished areas and pores. In this case, the uniformity of the product obtained from the composite material is achieved. It should be added that RFI technology differs from other polymer processing technologies in the following significant advantages: the possibility of abandoning expensive equipment, reducing energy costs for equipment and its maintenance, and complete rejection of the use of prepregs. However, there are a number of difficulties that are associated with the technological process of infusion, these primarily include the rheological requirements of the binder: at room temperature, the resin should have a low viscosity, and in the practice of fillers, the viscosity should have rather low values. Below are some preliminary plans for the development of this technology in order to obtain a product that provides attenuation of the blast wave.

Secondary Organic Aerosol Formation from Ambient Air in Summer in Urban Beijing: Contribution of S/IVOCs and Impacts of Heat Waves

Secondary Organic Aerosol Formation from Ambient Air in Summer in Urban Beijing: Contribution of S/IVOCs and Impacts of Heat Waves

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Data from the current study was used to analyse the impact of marine heat waves on the quantity and distribution patterns of Iraqi marine fisheries following the recent change in the climate of the northwestern Arabian Gulf. The average annual water temperature and salinity were 26◦C and 38.6 psu, respectively, higher than the averages recorded during previous decades. The dissolved oxygen average was 8.65 psu, and the pH was 8.23. Principal components analysis (PCA) showed that temperature and salinity accounted for 66.93% of the effect of the studied factors, while the percentage of dissolved oxygen was 32.81% and the pH was 0.27%. The results showed a decrease in the weight, numbers, and diversity of the fish during the summer compared to the data from previous decades. Supplementary variable analysis showed that the number of species, individuals, and weights of commercial marine fisheries' catches were inversely correlated to water temperature and salinity. Autocorrelation analysis revealed temporal changes in the effect of temperature and salinity on the decline in the number of fish during the summer. It is extremely important that significant progress be made in understanding marine heat waves and the risks they pose to marine ecosystems in order to predict how these systems and the products they provide will be affected.

Impacts of regular head waves on thrust deduction at model self-propulsion point

The results obtained from the self-propulsion simulations using Computational Fluid Dynamics (CFD) in the current study, for a ship free to heave, pitch and surge with the means of a weak spring system, are combined with the formerly executed CFD results of the bare hull and propeller open water simulations to investigate the impacts of regular head waves on the propeller-hull interactions in comparison to calm water, at the self-propulsion point of the model. Despite a rather significant dependency of the nominal wake on the wave conditions, the Taylor wake fraction remains almost unchanged in different studied waves which is around 12% lower than the calm water value. The thrust deduction factor in waves is reduced (12.8%–26.1%) in comparison to the calm water value. The change of thrust deduction factor is found to be associated with the boundary layer contraction/expansion and vortical structure dynamics, originating from the wave orbital velocities as well as the significant shaft vertical motions and accelerations that resulted in a modified propeller action, and consequently diminished suction effect on the aft ship. The altered thrust deduction factor and wake fraction in waves in comparison to calm water underlines the significance of waves on the propulsive factors and propeller design.

Study on fuel injection stability improvement in marine low-speed dual-fuel engines

Pressure waves within the fuel injection system exert a significant influence on the fuel injection process. This study investigated the impact of pressure waves on injection quantity stability. To quantify the influence of pressure waves on injection quantity stability, the relative standard deviation (RSD) was introduced as a metric. Through computational analysis under various operating conditions, the following results were obtained: when the target rail pressure is constant, the RSD tends to diminish as the injection quantity increases. The elevated RSDs observed during small injection quantities are predominantly attributed to the short power-on period of the solenoid valve. Subsequently, parameter optimization and structural improvements were carried out on the injector to address this problem. The results indicate that optimizing structural parameters alone has a limited effect on reducing RSD. However, by adding a block in the control chamber above the needle to improve the structural layout of the injector, the maximum RSD has been reduced from 21.08% to 4.58% under the action of pressure waves caused by fuel injection, and from 29.24% to 6.67% under the action of given random high-frequency pressure waves. The proposed improvement idea for existing injectors enhances injection stability across the entire operating condition range, thereby improving fuel utilization efficiency.

Analysis of the Dynamic Behavior of Multi-Layered Soil Grounds

The ground consists of many layers of soil with different properties. The propagation speed and path of seismic waves are affected by different soil layers. It is necessary to understand that layered soil exhibits different dynamic behaviors and responses under the action of seismic waves. This study utilized weathered soil and silica sand as materials to create multi-layered soil conditions with varying degrees of compaction. By conducting a 1 g shaking-table test on multi-layered soil, the interactions and influences between different soil layers under different earthquake conditions were observed. The approach of our numerical analysis aimed to complement the experimental results and provide an in-depth understanding of the dynamic behavior of multi-layered soil surfaces during seismic events. The acceleration results achieved with the ABAQUS and DEEPSOIL models for multi-layered soil were in good agreement with the experimental results. By comparing the stress–strain curves, the deformation mechanisms under different constitutive models in the numerical analysis were studied. The results of this study show that the amplification effect of seismic waves is related to the number of soil layers and the degree of compaction of the soil layers. This indicates that multi-layered soil ground and the behavior of the soil layers play an important role in the propagation and impact of seismic waves, and this amplification effect is of great significance in the design of actual seismic disaster risk assessments.

Regulating flow to maximize riverine nitrogen removal by riparian zones downstream of reservoirs

Flood waves generated by reservoir discharge play a crucial role in the potential for riparian denitrification downstream. The efficiency of nitrogen (N) removal from river water by riparian zones is typically enhanced with greater wave amplitude (A) and duration (T). However, a knowledge gap exists with respect to the impact of flood waves on N removal when considering a fixed-value integral over time of flood waves (IOFW). This study explored N transport and transformation in the riparian zone downstream of the dammed Inbuk River, Korea under various wave conditions with a fixed IOFW. The results revealed a logarithmic enhancement in solute infiltration into the riverbank with an increasing wave amplitude/duration ratio (A/T ratio). The solute residence time within the riparian zone displays an initial increase followed by a decrease with the increment in the A/T ratio. We identified a threshold for the wave A/T ratio that maximizes riverine N removal by the riparian zone, a phenomenon observed across various dammed rivers. Our findings indicated that riparian denitrification is reaction time-limited when the wave A/T ratio exceeds the threshold; contrarily, it becomes transport capacity-limited. Additionally, we observed a significant relationship between the net nitrate removal and the return/infiltration time ratio of water (r2 = 0.93, p < 0.05). The research results contribute to a better understanding of the impact of water level fluctuations on the N cycle in riparian zones, and provide valuable insights for developing sustainable reservoir operation strategies.

Bandgap tunability and impact mitigation enhancement of hybrid graded origami-inspired metamaterials with multiple resonators

Origami structure has become an important design source of metamaterials because of its extremely rich form and infinite design space. In order to improve the wave attenuation and impact mitigation ability of origami structure, a hybrid graded origami-inspired metamaterials with multiple resonators is proposed. The bandgap characteristics, transmission spectrum and impact resistance of the proposed metamaterials are analyzed in detail by numerical simulation. The results show that multiple local resonance mechanisms can open two new bandgaps compared to the single local resonance case, and the bandgap boundary is very sensitive to the dimension of resonance units. In particular, the resonance peaks of the origami metamaterials are substantially weakened due to the presence of dimensional gradients, which allows multiple bandgaps to merge into an ultra-wide bandgap (bandwidth up to 8.9 kHz), about five times than the original bandwidth. According to the time domain and frequency domain analysis results, it can be found that the amplitude of reaction force is significantly reduced in the bandgap range, and the ultra-wide frequency domain (2.9–10 kHz) with sustainable-low peak appears. Moreover, the asymmetry and graded design of unit-cell also affects the ability of dissipate and attenuate wave energy and delay the wave transmission time. In addition, the local-resonant origami metamaterials are fabricated by 3D printing technology, and the experimental results are in good agreement with the numerical simulation results. This study is expected to provide valuable ideas in crashworthiness design and impact wave protection of important equipments.

Investigation into the relationship between wave forces and characteristic velocity during wave impact on the deck structures

Deck structures, whose safety is threatened by catastrophic waves, are widely used in offshore and coastal engineering. This study aims to enhance the understanding of the impact of waves on deck structures through a combined approach of hydrodynamic experimentation and numerical simulations. In this study, the wave impact forces and pressure on a deck structure, which was simplified as a rectangular box model, were experimentally measured. The numerical model based on smoothed particle hydrodynamics was validated using experimental data due to its capacity to compute the wave force exerted on the box structure accurately. A characteristic velocity parameter was defined to explore the relationship between the wave-slamming forces and the wave velocity field. It was found that the characteristic velocity was highly correlated with the wave impact forces, which could be fitted using a negative exponential curve. In addition, the characteristic velocity can be roughly calculated using Stokes’ second wave theory, which offers a preliminary method for estimating wave impact loads on deck structures.

The Impact of a Strong Electromagnetic Wave on the Quantum Hall Effect in Cylindrical Quantum Wires

The impact of strong electromagnetic waves Hall effect is studied theoretically in a Cylindrical Quantum Wire (CQW) with infinitely high potential inside the wire and elsewhere subjected to a dc electric field , a magnetic field and a laser radiation . By using the quantum kinetic equation method for electrons interacting with Acoustic Phonon (AP) at low temperatures, we obtain analytical expressions for the conductivity tensor and the Hall Coefficient (HC), which are different from in comparison to those obtained for a rectangular quantum wire (RQW) or two-dimensional (2D) electron systems. Numerical calculations are also applied for GaAs/GaAsAl CQW to show the nonlinear dependence of the HC on the electromagnetic wave (EMW) frequency, and the radius, the length characteristic parameters of CQW. Wave function and energy spectrum in a CQW are dissiminar to those in Quantum Wires (QWs). Therefore, all numerical results are different from those in the case of QWs. The most important result is that the HC reaches saturation as the radius, the length of CQW or the EMW frequency increases.

Exploring structural and optical properties of shock wave-loaded polycrystalline picric acid: implications for molecular engineering applications

Abstract The shock wave impact on hydrogen-bonded organic materials’ structural properties and their responses with respect to their associated functional properties is one of the most prevalent research topics because of the possible emergence of unusual functional properties. Presently, we intend to examine the structural response of the poly-crystalline picric acid samples under shocked conditions. The crystallographic structural responses and the linear optical properties of the test samples have been examined by powder XRD analysis, ultra-violet diffused reflectance spectroscopy (UV-DRS) and Raman spectroscopy, respectively. Under shocked conditions, a considerable modification in the diffraction peak positions and their intensity changes could be witnessed. Notably, linear optical transmittance profiles show remarkable changes according to the number of applied shock pulses, such that the 150-shocked sample has the highest optical transmittance of 53.9 % at 350 nm, whereas the control sample has an optical transmittance of 6.6 %. The Raman spectrum shows the vibrational groups of material that are stable in shocked conditions with similar intensity changes. Based on the obtained XRD, UV-DRS and Raman results, shock wave-induced picric acid samples have remarkably improved characteristics of optical transmittance, which is highly favorable for non-linear optical applications.