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Particle tracking (PT) is a popular technique in microscopy, microfluidics and colloidal transport studies, where image analysis is used to reconstruct trajectories from bright spots in a video. The performance of many PT algorithms has been rigorously tested for directed and Brownian motion in open media. However, PT is frequently used to track particles in porous media where complex geometries and viscous flows generate particles with high velocity variability over time. Here, we present an evaluation of four PT algorithms for a simulated dispersion of particles in porous media across a range of particle speeds and densities. Of special note, we introduce a new velocity-based PT linking algorithm (V-TrackMat) that achieves high accuracy relative to the other PT algorithms. Our findings underscore that traditional statistics, which revolve around detection and linking proficiency, fall short in providing a holistic comparison of PT codes because they tend to underpenalize aggressive linking techniques. We further elucidate that all codes analyzed show a decrease in performance due to high speeds, particle densities, and trajectory noise. However, linking algorithms designed to harness velocity data show superior performance, especially in the case of high-speed advective motion. Lastly, we emphasize how PT error can influence transport analysis. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel dual guided PCF design capable of supporting the transmission of 68 OAM modes. The innovative design features a specialized structure with multiple layers composed of pure silica and SF57 material arranged alternately. To enhance physical strength and minimize loss, the fiber is enclosed by a perfectly matched layer (PML). Air holes are strategically added and optimized in the third and fifth layers. Through numerical analysis, we observed that the proposed design yields excellent results across all evaluated parameters. The maximum confinement loss recorded is 10–12 dB/m. The effective refractive index values range from 1.444 to 1.8, with effective refractive index difference values in the order of 10–2. Furthermore, the modal purity and power fraction values exceed 99% for all modes. Dispersion values are maintained below 9.87 ps/THz/cm, and crosstalk values are less than − 12 dB. These results demonstrate the potential of our dual guided PCF design in meeting the increasing demands for high-speed and reliable communicating systems. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) is a potential biopolymer and can replace petroleum-based plastic. PHB accumulated by bacteria needs a supply of carbon source whereas cyanobacteria are capable of synthesizing PHB by carbon fixation using sunlight energy. Since PHB is an intracellular product the polymer recovery cost is about 50 % of production cost. Apart from these, cyanobacterial pigments also affect the purity and recovery yield. In the present study, Chlorogloea fritschii TISTR 8527 was chosen as a PHB cell factory which accumulated 28 % of biopolymer. The hypochlorite-chloroform dispersion method could remove the pigments along with PHB extraction with 95.51 ± 3.164 % of the recovery in a single step. In addition to this, PHB extraction was performed with various halogenated solvents and green non-halogenated solvents with hypochlorite pretreatment. Selected solvents were unable to recover more than 90 % of polymer yield due to unsuitable operating conditions. Besides this, the green solvent dimethyl carbonate (DMC) was employed for PHB recovery with prior pigment removal from biomass using chilled methanol. DMC was capable of 83.34 ± 0.76 % biopolymer recovery with a purity of 75 %. PHB recovered using DMC has improved thermal and material characteristics. [ABSTRACT FROM AUTHOR]

Deforestation poses a significant environmental challenge that demands global efforts to address, aiming to preserve forest ecosystems and promote sustainable development worldwide. This study investigates the global phenomenon of deforestation convergence from 1990 to 2020 across 149 countries, employing state transition probabilities assessed using Markov chains, dispersion indicators, and average deforestation rates. The analysis indicates a consistent decrease in dispersion indicators and average deforestation rates observed across the studied countries over three decades, coupled with high probabilities of maintaining current forest ecosystem states. These findings suggest the presence of sigma and beta convergence phenomena in the shift towards sustainable development, akin to patterns observed in economic growth. Furthermore, our research identifies the emergence of a Kuznets curve based on deforestation growth rates and dispersion indicators relative to GDP per capita since 2010. This also suggests a potential global convergence in sustainable forest-related activities. Hence, it is clear that coordinating environmental development policies among countries is crucial for achieving global ecological stability. This underscores the necessity for proactive measures to ensure worldwide forest conservation and sustainable management. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) storage sites are potential and overlooked contributors to microplastic (MP) pollution. Herein, the distribution and dispersion characteristics of MPs at MSW storage sites were investigated through modeling, sampling analysis, and prediction methodologies. The results indicated a notable adsorption phenomenon of MPs on smooth surfaces within such sites, achieving high saturation levels and making MPs prone to re-release by airflow disturbance. Quantitative analysis revealed that the MP concentrations on these surfaces varied from 4.48 × 105 to 1.90 × 106 n/m2 and that MPs predominantly accumulated in the corner areas. Notably, MP accumulation on wall surfaces can be reduced by 76.4% using washing procedures. The majority of MPs were under 50 µm in size and were primarily in fragment form. Operational activities such as ventilation and waste handling were identified to amplify the airborne spread of MPs. The atmospheric concentrations of MPs peaked seasonally, with concentrations of 28.25 n/m3 in summer and 3.90 n/m3 in winter, and the spatial dispersion ranged from 14.98 to 124.08 km2 per station. This study highlights that MSW storage sites are substantial yet overlooked sources of MP pollution, where wall surfaces play a critical role in MP adsorption and dispersal. The implementation of robust management and cleaning protocols is essential to mitigate the environmental footprint of MPs emanating from these locations. This study also provides a typical case for the precise prevention and control of MPs in the environment. [ABSTRACT FROM AUTHOR]

The design of band gap metamaterials, i.e., metamaterials with the capability to inhibit wave propagation of a specific frequency range, has numerous potential engineering applications, such as acoustic filters and vibration isolation control. In order to describe the behavior of such materials, a novel integral micromorphic elastic continuum is introduced, and its ability to describe band gaps is studied in the one-dimensional setting. The nonlocal formulation is based on a modification of two terms in the expression for potential energy density. The corresponding dispersion equation is derived and converted to a dimensionless format, so that the effect of individual parameters can be described in the most efficient way. The results indicate that both suggested nonlocal modifications play an important role. The original local micromorphic model reproduces a band gap only in the special, somewhat artificial case, when the stiffness coefficient associated with the gradient of the micromorphic variable vanishes. On the other hand, the nonlocal formulation can provide band gaps even for nonzero values of this coefficient, provided that the penalty coefficient that enforces coupling between the micromorphic variable and nonlocal strain is sufficiently high and the micromorphic stiffness is sufficiently low. [ABSTRACT FROM AUTHOR]

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Lignosulphonate-based azo pigments are synthesized by functionalizing industrial waste lignosulphonate material through a diazo coupling reaction. It has dispersion and metal surface protection function by coating. Aniline, 4,4′-bis(4-aminophenoxy) biphenyl (BAP-Biphenyl), and o-dianisidine were used to synthesize three lignosulphonate-based azo pigments. 1H-NMR, FT-IR, HRMS, and UV spectroscopic methods confirm the pigment formation through the diazo coupling reaction of lignosulphonate and products. By using TGA and DSC analysis, the thermal behaviour of azo pigments was examined. Successive increase in mass also suggests successful diazo coupling reaction. The light scattering technique gives particle size of azo pigments for aniline-azo-LS, BAP-Biphenyl-azo-LS and o-dianisidine-azo-LS were found to be 1578, 2387, and 1917 nm, respectively. Additionally, the negative zeta potential was noticed indicating the pigments' dispersion ability. This dispersible ability was utilized for paint formulation, and chemical resistance of metal coating was observed. The formulation has good mechanical stability, and TGA suggests the thermal stability over 200 °C. This lignin-based functional pigment will find new forms of an environmentally friendly and sustainable method for a cleaner utilization of lignin in metal coatings. [ABSTRACT FROM AUTHOR]

Dust storms and dry haze are an unfavorable meteorological factor for the cities of the Aral Sea Region. The mean annual number of days with haze in Central Asian cities ranges from 10 to 20. Dust makes poorer the aspect of areas, but its impact on urban planning has been incompletely studied and the content of fine dust particles in the air of cities has not been monitored. The Afghan wind (garmsil: fiery, hot, dry wind with dust), which attracts particular attention, is a dust storm that suddenly starts in the deserts of Afghanistan and on the dried bottom of the Aral Sea (it is now called Aralkum (the Turkish kum signifies sand)). This is a real salt desert, containing pesticides and chemicals dangerous for human health. They penetrated rivers as fertilizers used by people and then flowed into the sea. They now cause significant damage to the cities and to the economy of Central Asian countries. Wind transport of dust from natural sources and, as a result, the dustiness of the urban environment are analyzed in this article. This problem is particularly urgent for most large cities in Central Asia, but has not been studied sufficiently. The dust factor is not sufficiently taken into account, when making urban planning decisions even in areas with intensive wind and dust activity, such as the Aral Sea Region, where it is related to natural and climatic conditions. More and more cool agricultural lands are now destroyed and used for building construction in many cities, which may exert a strong effect on the quality of life in the next few years. Not long ago, dustiness was considered only as a factor that creates uncomfortable conditions, but today, it is associated with morbidity and mortality of the population. A high dust content in the air harms landscaped areas, along highways and streets in particular. The protection of buildings from direct sunlight and dust consists in the use of sun protection devices, panels, and ventilated facades. One of the modern trends in architecture consists in the introduction of the technology of kinetic facades, which are formed of elements of different shapes and materials. When the proposed methods are implemented, there is a real opportunity to improve the quality of atmospheric air in cities located in complicated landscape conditions, which will directly affect the improvement of human health. [ABSTRACT FROM AUTHOR]

On-chip light generation in the mid-infrared (mid-IR) region of the electromagnetic spectrum is gaining considerable attention due to its various potential applications in free-space communication, mid-IR spectroscopy, sensing, and thermal Imaging. In this work, we have designed a dispersion-engineered silicon nitride (SiN)-coated tellurium oxide (TeO2) hybrid waveguide on silica (SiO2) substrate with barium fluoride (BaF2) as cladding for nonlinear applications. Strong modal confinement, broad dispersion characteristic, and high nonlinearity were achieved in the proposed hybrid waveguide design, which are important features for obtaining desired nonlinear applications. Through numerical simulations, we found that the dispersion curve is nearly flat within the dispersion range of −40.60 ps/nm/km to 33.15 ps/nm/km for a spectral bandwidth of 1.55–4.25 µm with a zero-dispersion wavelength (ZDW) around 1.80 µm, which is suitable for generating nonlinear effects such as four-wave mixing, self-phase modulation, and Raman scattering. Such types of on-chip hybrid waveguide devices can be pumped using a commercially available fiber laser operating at a wavelength of 2 µm. The design of the hybrid waveguide was optimized to achieve very low modal confinement loss ranging from 0.1 × 10−4 to 35 dB/cm, with a spectral bandwidth of 1.5–4 µm. Additionally, a high nonlinear coefficient value of 1372 W−1 km−1 was achieved at a pumping wavelength of 1.5 µm in hybrid waveguide. The results of such hybrid waveguides can be helpful to experimentalists working in this field for developing nonlinear hybrid waveguide devices. These nonlinear hybrid waveguide devices have potential nonlinear applications, including four-wave mixing, Raman scattering, and supercontinuum spectrum spanning the near-IR to mid-IR. Further, the on-chip hybrid waveguide structure can be significantly help to expand the functionality of future photonics integrated circuits. [ABSTRACT FROM AUTHOR]

The Airy phase is the frequency at which group velocity of a surface acoustic wave (SAW) attains a stationary value. In turn, a stationary value of the group velocity causes SAW to propagate with a lesser attenuation than at other frequencies. At present, no conditions for the appearance of stationary values of the group velocity are known for dispersive modes of Lamb waves propagating in stratified plates. Herein, the closed form solutions are derived for double zero group velocity (ZGV) belonging to the same Lamb mode. It is also found that the double ZGV leads to the appearance of the Airy phase located between the twofold ZGV. The analysis relies on the Cauchy formalism and the exponent fundamental matrix method. [ABSTRACT FROM AUTHOR]

The paper aims at studying dispersion of elastic waves in a sandwich plate with the parameters, characteristic of aerogel core and hard skin layers, typical for aerospace applications including optimal design of fuselage structural components. The proposed approach relies on multiparametric analysis, taking into account the effect of strong transverse inhomogeneity. It is demonstrated that both an additional low-frequency propagating wave and a slowly decaying evanescent one appear due to a high contrast in geometric and mechanical parameters of the layers. The key findings include the derivation of two-mode asymptotic expansions of the full dispersion relation at the low-frequency limit, as well as elucidation of the non-trivial link between long-wave evanescent and propagating modes. A sophisticated composite nature of the obtained expansions involving various shortened forms is investigated. The range of validity for each of these forms over frequency and wave-number domains is evaluated. Comparison of asymptotic results with the numerical solution of the full dispersion relation is presented. [ABSTRACT FROM AUTHOR]

Single-isotherm n(p, T90) results are reported for the gases Ar, N2, H2O, and D2O at vacuum wavelength λ = 1542.383 (1) nm. The argon and nitrogen isotherms were measured near 303 K; the water isotherms were measured near 373 K. Combined with the two previous articles of this series, the present results beget several insights via dispersion analyses. The argon result is highly consistent with static measurement plus ab initio calculation of dispersion polarizability. The nitrogen result is nominally consistent with one recent experiment and the dipole oscillator strength distributions, but the present work offers a refined estimate of the molar refractivity at optical wavelengths. For ordinary and heavy water, the dispersion trend is nominally consistent with existing liquid measurements. However, water's absorption features in the near-infrared preclude a reliable comparison of the present result with literature. [ABSTRACT FROM AUTHOR]

The traditional craft villages in Vietnam in general and in Bac Ninh province in particular have been exposing many negative impacts on the environment. The heavy metal-rich wastes from the metal recycling casting craft villages in the field of metal recycling and metal casting are causing severe heavy metal pollution not only to the air, soils, and sediments but also to the groundwater resources. In Da Hoi iron recycling craft village in Chau Khe ward, Tu Son town, Bac Ninh province, Vietnam, the Holocene aquifer is exposed to the Ngu Huyen Khe River's sediments contaminated with heavy metals Lead, Cadmium, Nickel, and Zinc. Freundlich isotherm parameters of the Holocene aquifer have been selected for finite element modeling of heavy metal transport with high temporal and spatial varying retardation factors to get reliable quantitative heavy metals' distribution in depth and time. Initial and boundary conditions have been augmented to be established. The retardation factors of the advection and dispersion transport in the Holocene aquifer for heavy metals Pb, Zn, Cd, and Ni are very highly none-linear and very much varying in time and space: 8.7–66.4 for Pb, 2.0–12 for Zn, 1.7–4.8 for Cd and 1.1–5.9 for Ni. The results of the numerical modeling show that heavy metal transport in the Holocene aquifer is very fast and the entire aquifer thickness has equilibrium aquifer formation and aquifer water heavy concentrations after around 2–2.5 years for Cd and Ni, around 4 years for Zn and around 27 years for Pb. The heavy metals' fluxes from the Holocene aquifer to the Pleistocene aquifer are maximal and more or less constant from the equilibrium time and would cause severe contamination of the Pleistocene aquifer. [ABSTRACT FROM AUTHOR]

We have developed a new type of hybrid-structured Photonic Crystal Fiber (H-PCF) that includes a sectored core-cladding configuration. It's composed of a cladding with a regular circular sectored lattice structure and a core with a hexagonal sectored lattice structure. To extensively design, analyze, and calculate the fiber's properties, the finite element method has been used. The results provide validation for the superior performance of this novel fiber design. It simultaneously achieves extremely low effective material loss and confinement loss equal to 0.0145 cm⁻1 and 1 × 10⁻14 cm⁻1, respectively, at the 1 THz frequency. Furthermore, the fiber demonstrates nearly zero flattened dispersion (− 0.45 ± 0.55 ps/THz/cm) across the 0.9–1.3 THz frequency range, along with important attributes such as a large core power fraction (50%) and an effective area of 5 × 105 µm2. The suggested PCF design is practical for manufacturing utilizing currently available technologies. Moreover, the proposed PCF design, employing common structured regions in the circular and hexagonal patterns for the sectored cladding and core regions, respectively, is feasible for fabrication using existing technologies. Overall, this H-PCF shows significant potential for various THz applications, especially in THz wave guidance. [ABSTRACT FROM AUTHOR]

The article is devoted to the study of the process of removing moisture from capillary-porous materials by its dispersion during the collapse of cylindrically-shaped cavitation bubbles formed in the capillaries of the material under ultrasonic exposure. A model has been proposed and developed that made it possible to explain the mechanism of dispersion during realization of the life cycle of a bubble in a capillary — slow growth, rapid expansion with deformation, and subsequent collapse. The range of sound pressure levels at which dispersion begins (from 150 dB) to the level at which bubbles reach the size of the capillary and the increase in the drying efficiency stops (170 dB) has been determined theoretically. It was also shown that for maximum efficiency in moisture removal, the size of the dehydrated sample must correspond to the ultrasonic wavelength in air. The mechanism of ultrasonic dispersion of liquid during drying has been confirmed experimentally and it has been established that to reduce the drying time by more than 40%, exposure with a level in the range of 165–170 dB is necessary, and the dried materials must be placed in the form of particles or layers having dimensions or thicknesses corresponding to the ultrasonic wave length. The practical implementation of ultrasonic drying using the example of food products (red beets) confirmed the effectiveness of the proposed mechanism and ensured a reduction in drying time by 1.9 times on reducing energy demand by 1.6 times. [ABSTRACT FROM AUTHOR]

External transient impact loads widely exist in the service environment of various engineering structures, and urgent engineering and military application requirements call for research on the theory and method of impact identification. This manuscript proposes a method to identify the impact event. By employing the dispersive property of wave propagation through the waveguides, a dispersion-based average power spectral density (PSD) curve for quantitative representation of the dispersion is established, and its evolution law is investigated to apply the identification of impact events. The critical parameters of the average PSD curve are obtained by analyzing the response of the structure from the perspective of mechanics. The effectiveness of this method is verified through the development of the triple-successive-impact split Hopkinson bar and the triple-successive-impact experiment. Through the method proposed in this manuscript, a kind of impact identification under multiple impact loads, which is not convenient to measure directly by the sensor, is realized, especially in the case of highly transient external impact. [ABSTRACT FROM AUTHOR]

This research studies rogue wave solutions with center parameters of a generalized (3+1)-dimensional KdV-type equation in plasma physics. Using a direct generalized formula and symbolic technique, it creates rogue waves with adjustable dynamical characteristics controlled by the center parameters. Our investigation produces rogue wave solutions up to the third order with Painlevé transformation through direct computation, considering a range of center-controlled and other parameters within the investigated equation. To facilitate our analysis, we derive an equation for the function f in bilinear form, utilize the Cole-Hopf transformation for the wave function u, and introduce the transformed variable ζ . It obtains the rogue wave solutions using a generalized form for N-rogue waves generated from Hirota's N-soliton approach. Through the powerful symbolic computation tool Mathematica, we provide visualizations of the dynamic behavior of rogue waves across diverse center parameters. This research highlights the prevalence of massive rogue waves within nonlinear phenomena, showcasing their dominance over their smaller counterparts. The investigated equation offers insights into the evolution of longer waves characterized by smaller amplitudes, which is particularly relevant in plasma physics, fluid dynamics, and dispersive media. Rogue waves have applications in diverse scientific fields, including oceanography, nonlinear dynamics, fluid dynamics, fiber optics, dusty plasma, and complex nonlinear systems [ABSTRACT FROM AUTHOR]

Most species-rich communities consist of a limited number of common species and many rare species. This widespread ecological pattern can arise due to the predominance of either niche-based or neutral-based processes in community structuring. We tested two hypotheses related to this pattern for an anuran metacommunity composed of 35 species distributed in 187 ponds in the South Brazilian grasslands: (1) for common species, niche processes should prevail over neutral ones because common species evolved under a wider range of ecological filters than rare species; (2) for rare species, neutral processes should prevail because rare species are more prone to ecological drift and dispersion limitation. We found that the densities of both common (i.e., the 25% higher density ones) and rare (i.e., the 75% lower density ones) species depended mostly on pond structure and land use, indicating a similar response to niche-based processes in both groups of species. The importance of pond descriptors and type of land use, however, differed between the two groups, confirming that common and rare species represent ecologically distinct groups within the metacommunity. In addition, neutral processes—related to dispersion limitation or not—influenced both species groups, but the spatial filters selected explained a smaller portion of the variation in species densities compared to environmental descriptors. Our findings showcase the prevalence of niche processes in structuring communities of common and rare species of anurans in subtropical grasslands and indicate the variables of pond structure and land use that are relevant to guide conservation practices for the metacommunity of anurans in the South Brazilian grasslands. [ABSTRACT FROM AUTHOR]

A systematic study has been performed for the effect of nonionic surfactants (NSs), i.e., ethoxylated higher fatty alcohols with different ethoxylation degrees, on the ultrasonic dispersion of carbon nanotubes in aqueous solutions and on the colloid-chemical properties of the resulting dispersions, namely, their optical density and the sizes and electrokinetic potentials of the particles in the colloidal systems. A non-linear dependence of the characteristics of dispersions on the ethoxylation degree has been revealed. This dependence is associated with structural transformations in NS molecules. The most efficient ethoxylation degree and concentration of nonionic surfactants in a solution, which have the highest disaggregating and stabilizing effects upon the preparation of carbon nanotube (CNT) dispersions, have been determined. The influence of the ethoxylation degree of the ethoxylated higher fatty alcohols on the electrokinetic properties of CNT dispersions has been revealed. It has been shown that carbon nanotube dispersions can be used to modify the rheological and electrical properties of gel systems based on rarely crosslinked poly(acrylic acid). The effects of NSs and CNTs on the viscosity, shear yield stress, consistency index, mechanical stability, relaxation time, and viscous flow activation energy of the polymer gels have been studied. It has been shown that the incorporation of nanotubes increases the electrical conductivity of the gels. The ultrastructure of the gel samples has been studied by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

It is known that Lamb waves in homogeneous traction-free plates can propagate with arbitrary phase velocity, spanning the admissible speed interval (0; + ∞) . However, as the current research shows, Lamb waves propagating in two-layered traction-free plates may have 'forbidden' phase velocities, at which no Lamb waves can propagate. The analysis is based on the approach comprising Cauchy complex formalism and the exponential fundamental matrix method. [ABSTRACT FROM AUTHOR]

The native savanna ecosystem of the Orinoquia region is the habitat of 50% of the wild ungulate species reported for Colombia. Over the last 20 years, this high species diversity has been strongly threatened by the human transformation of the natural land cover causing connectivity loss of the habitats. The Orinoquia region lacks a biological connectivity analysis with a multi-species approach involving species groups that are representative of the savanna ecosystem such as the ungulates. Understanding the spatial distributions of suitable areas and the main habitats that act as primary habitats for ungulate species in these landscapes is fundamental for the design of conservation strategies. We use an occurrence dataset for lowland tapir (Tapirus terrestris), white-tailed deer (Odocoileus virginianus), and white-lipped peccary (Tayassu pecari) in the development of species' potential distribution models, binarization process, and morphological spatial pattern analysis. This information was used for the modeling of dispersal corridors connecting the core habitats of the ungulate focal species using the randomized shortest path algorithm and quantifying the weighted global connectivity metrics. Our results suggest an integral corridor with potential least-cost dispersal routes between the native savanna landscape on the middle basins of the savanna rivers and the Meta River. These areas associated with the fluvial dendritic systems are connected, while the core habitats in the eastern part of the savanna landscape are disconnected. We discuss how the application of such knowledge on the spatial ecology of ungulate focal species might improve the management of the metapopulations in the Orinoquia region. [ABSTRACT FROM AUTHOR]

Rapid urbanisation has led to a remarkable increase in travel demand as well as the number of vehicles globally. Inadequate road networks, especially in developing countries fail to serve this increasing vehicle population resulting in frequent traffic congestion. Proportional vehicular emissions are found to be responsible for serious consequences on human health and the environment. The nature and impact of these emissions depend on the traffic, environmental and meteorological factors. The present study focuses on vehicular emissions in a typical identified urban road stretch. The dispersion of vehicular pollutants in the selected urban stretch was studied using Fluidyn PANACHE version 5.2.6 software. The analysis of dispersion revealed that the highest concentration of pollutants is observed along the road sections, with a gradual decrease in concentration as you move away from the streets in both directions. From the vertical profile plotted, the maximum concentration is found to be on the ground and decreases as the height increases, which reveals the influence of meteorological parameters on urban air quality. These results indicate the significant influence of vehicular emissions and meteorological characteristics on ambient air quality. [ABSTRACT FROM AUTHOR]

One option for solving the scientific and applied problem of increasing the efficiency of finishing quartz crystal elements (QCEs) through controlling the structural, mechanical, and rheological characteristics of abrasive suspensions is presented. The finishing technology for manufacturing QCEs is flat finishing on machines using an abrasive suspension of fine Al2O3 particles. The dispersion medium in the abrasive suspension during finishing of QCEs ensures uniform distribution of abrasive grains over the lap, minimizes the sticking of separating quartz particles, and facilitates its dispersion. Control of the structural and mechanical characteristics of the abrasive suspension is achieved by introducing into the dispersion medium (water) stabilizers such as protective colloids, which prevent the approach of abrasive particles and the destruction of quartz. The problem of QCE finishing has been solved by the authors for the first time ever. [ABSTRACT FROM AUTHOR]

This study aimed to identify ascidians in the coastal area of Chabahar Bay and assess their biodiversity in three stations (University, Tiss, Lipar) and four seasons for the first time. Sampling was carried out in the intertidal zone from July 2019 to May 2020, and samples were counted using the quadrate method. After narcotizing (in menthol crystal solution) and fixing (in formaldehyde solution), ascidians were identified using identification keys. The assessment of ascidians in Chabahar Bay led to the identification of Phallusia nigra, Cnemidocarpa sp., and Styela plicata. Results showed that P. nigra had the highest density in Lipar station (6.01 ± 0.72 individuals m−2) and during winter (6.65 ± 0.87). On the other hand, Cnemidocarpa sp. had the highest density in the University station (6.93 ± 0.84) and during fall (6.03 ± 0.96). The dispersion index showed that all ascidians identified in Chabahar Bay had an aggregated dispersion pattern. Moreover, the sustainability index showed that P. nigra and Cnemidocarpa sp. are more sustainable than Styela plicata. Assessment of each species in various seasons and stations showed that their abundance fluctuates based on their biology and effective physical factors. On the other hand, the assessment of their biodiversity using usual biodiversity indices (Shannon-Weiner index, the Simpson index, and Margalef index) showed a significant effect (P < 0.05) of seasons and stations on these indices. The discernible impact of seasonal variations becomes more pronounced, underscoring the dynamic fluctuations in ascidian biodiversity within Chabahar Bay over the course of a year. [ABSTRACT FROM AUTHOR]

Owing to the high fluid content, most incompressible soft structures typically exhibit viscosity, which has a significant influence on wave characteristics, especially attenuation. Meanwhile, they are inevitably prestressed owing to the volume-preserving deformations. Therefore, it is essential to investigate acoustoelastic and viscoelastic effects to better understand guided wave characteristics in a pre-stressed soft plate. To this end, a hyperviscoelastic model concerning viscoelasticity, acoustoelasticity, and nonlinearity is established to deduce the governed equations. An analytical integration orthogonal polynomial method is employed to solve complex solutions of wave equations. The dispersion, attenuation, and wave shapes are illustrated. The acoustoelastic and viscoelastic effects are analyzed. Some new wave phenomena are revealed: The pre-stretching inhibits wave attenuation, and the pre-compression promotes attenuation; As the pre-stress increases, high-frequency phase velocity and incremental displacement amplitudes increase. The results lay a theoretical foundation for guided wave elastography, quantitative characterization, and disease diagnosis of biological soft tissue. [ABSTRACT FROM AUTHOR]

Reliable reactive transport models require careful separation of mixing and dispersion processes. Here we treat displacing and displaced fluids as two separate fluid phases and invoke Whitman's classical two-film theory to model mass transfer between the two phases. We use experimental data from Gramling's bimolecular reaction experiment to assess model performance. Gramling's original model involved just three coupled PDEs. In this context, our new formulation leads to a set of seven coupled PDEs but only requires the specification of two extra parameters, associated with the mass transfer coefficient and its dependence on time. The two film mass transfer model provides a simple and theoretically based method for separating mixing from dispersion in Eulerian continuum-scale methods. The advantage of this approach over existing methods is that it enables the simulation of equilibrium chemical reactions without having to invoke unrealistically small reaction rate coefficients. The comparison with Gramling's experimental data confirms that our proposed method is suitable for simulating realistic and complicated bimolecular reaction behaviour. However, further work is needed to explore alternative methods for avoiding the need of a time-dependent mass transfer rate coefficient. [ABSTRACT FROM AUTHOR]

A functional hybrid nano-hydroxyapatite (carboxymethyl cellulose-phytic acid-n-HA, CMC-PA-n-HA) was prepared by adding CMC and PA. The results of Fourier transformation infrared spectra, X-ray diffraction, thermal gravimetric analysis and dispersion experiments indicated that the addition of CMC and PA affected the morphology, crystallinity and crystal size of hybrid n-HA, and CMC endowed hybrid n-HA with excellent dispersion. Scanning electron microscope results showed that CMC-PA-n-HA nanoparticle could be uniformly dispersed in chitosan (CS) matrix to obtain composite membrane by casting technology, so that the highest tensile strength of CMC-PA-n-HA/CS composite membrane was 69.64% and 144.45% higher than that of CS membrane and n-HA/CS composite membrane, respectively. Contact angle test showed that CMC-PA-n-HA effectively improved hydrophilicity of the CS membrane. The simulated body fluid immersion results indicated that the CMC-PA-n-HA/CS composite membrane not only exhibited good degradability but also promoted bone-like apatite deposition. The cell proliferation experiments proved that the introduction of PA made the composite membrane have better cell adhesion and proliferation ability. Antibacterial tests demonstrated that PA could effectively improve the antibacterial properties of the composite membrane, which is expected to be applied as guide bone tissue regeneration membrane. [ABSTRACT FROM AUTHOR]

In this work, a measuring system was developed according to the scheme of an AC bridge, with the help of which a constant voltage was applied to polymer-dispersed liquid-crystal films doped with silicon dioxide nanoparticles. For these cells with different content of silicon dioxide nanoparticles, capacitance-voltage measurements were carried out at different frequencies of the alternating voltage generator. For these cells, a memory effect was found, which manifests itself in the hysteresis behavior of the capacitance of these cells. The largest hysteresis area and the largest shift of the cell capacitance in the absence of an external field are observed at 10 kHz. In the entire region under study, with a minimum at a frequency of 10 kHz, the perpendicular component of the permittivity has a pronounced dispersion. It has been established that the content of silicon dioxide nanoparticles affects the permittivity of a polymer-dispersed liquid-crystal cell. The data obtained can be used in the development of energy-independent nanostructured data storage systems. [ABSTRACT FROM AUTHOR]

A new method for the preparation of hydrodesulfurization catalysts based on the mechanochemical treatment of molybdenum under cryogenic conditions was proposed. The results of direct one-stage mechanochemical grinding of molybdenum at 77 K in gaseous media of He and H2 and in liquid N2, as well as in the presence of solid Ar, are reported. The physicochemical properties of the cryopowders and their catalytic activity in the model hydrodesulfurization reactions of dibenzothiophene and diesel fraction were examined. [ABSTRACT FROM AUTHOR]

In this study, two groups of functionalized aliphatic and aromatic ILs with the same anions were synthesized and used as asphaltene dispersants. The quartz crystal microbalance and ultraviolet spectroscopy were used in this study, and the results obtained from these two techniques were in relatively good agreement with each other. The results showed that aromatic ILs generally possess better inhibitory performance than aliphatic ones. The molecular structure of IL anions also greatly influenced the dispersion of asphaltenes in a toluene solution. It seems that π-π interactions between asphaltene molecules and aromatic cations represent the main cause of the better performance of aromatic ILs. This hypothesis was also confirmed by observing the high dispersion ability of a maleate anion, which has a carbon-carbon double bond, compared to other studied anions. [ABSTRACT FROM AUTHOR]

Polymer-based dry and flexible electrodes are becoming increasingly popular in wearable healthcare for long-term electrocardiography (ECG) monitoring due to their comfort, biocompatibility, and gel-free operation. In this study, electrodes are prepared for ECG measurement using a polydimethylsiloxane (PDMS) and multi-walled conductive carbon nanotube (CNT)-based composite. The homogeneous dispersion of CNTs in PDMS is crucial for determining the electrical performance of the composite, and to accomplish this uniform dispersion, a combination of ultrasonication and a high-shear homogeneous dispersion technique is employed. This combination approach resulted in a rapid composite preparation method that took approximately 2–3 h to complete. The performance of the fabricated ECG electrodes was evaluated by measuring the ECG signal and compared to commercially available wet Ag/AgCl ECG electrodes. The ECG signal of the CNT/PDMS composite electrode with CNT content of 6 wt.% demonstrated optimal correlation of 0.9729 with the ECG signal measured from the Ag/AgCl electrode. The CNT/PDMS composite-based dry electrodes can be easily fabricated by manufacturing techniques, suggesting a possible benefit of cost and time reduction in mass production. [ABSTRACT FROM AUTHOR]

Air pollution is one of the most pressing environmental threats worldwide, resulting in several health issues such as cardiovascular and respiratory disorders, as well as premature mortality. The harmful effects of air pollution are particularly concerning in urban areas, where mismanaged anthropogenic activities, such as growth in the global population, increase in the number of vehicles, and industrial activities, have led to an increase in the concentration of pollutants in the ambient air. Among air pollutants, particulate matter is responsible for most adverse impacts. Several techniques have been implemented to reduce particulate matter concentrations in the ambient air. However, despite all the threats and awareness, efforts to improve air quality remain inadequate. In recent years, urban vegetation has emerged as an efficient Nature-based Solution for managing environmental air pollution due to its ability to filter air, thereby reducing the atmospheric concentrations of particulate matter. This review characterizes the various mitigation mechanisms for particulate matter by urban vegetation (deposition, dispersion, and modification) and identifies key areas for further improvements within each mechanism. Through a systematic assessment of existing literature, this review also highlights the existing gaps in the present literature that need to be addressed to maximize the utility of urban vegetation in reducing particulate matter levels. In conclusion, the review emphasizes the urgent need for proper air pollution management through urban vegetation by integrating different fields, multiple stakeholders, and policymakers to support better implementation. [ABSTRACT FROM AUTHOR]

A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition. The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible, however, theoretical explanation regarding the effect of the trigger system is insufficient. This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation. Subsequently, based on the new theoretical explanation, an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed. Two active surface wave testing cases are considered to validate the theory and method. The results indicate that (1) an accurate trigger system is not necessary for surface wave data acquisition, and (2) it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis. [ABSTRACT FROM AUTHOR]

Ceratium furcoides is a dinoflagellate that exhibits invasive behavior in the aquatic ecosystems of South America and has been expanding its range in recent years. In this study, we monitored 151 municipalities in southern Brazil between 2012 and 2019 with the objective of detecting and recording the species' occurrence and abundance in the state of Rio Grande do Sul, as well as to examine its expansion and persistence pattern. Ceratium furcoides was recorded in 84.1% of the monitored municipalities, in all three of the state's hydrographic regions (HR). Spatially, the Guaiba HR showed the highest density for the species (10,912 cells mL−1); in temporal scales, 2014 and 2015 displayed density peaks, usually in the summer. The cumulative area invaded by C. furcoides gradually increased, reaching 266,625 km2 in 2018, corresponding to about 94% of the state; however, the highest expansion rate (3142 km year−1) and longest distance covered (40.4 km) occurred in 2012, during its introduction. The expansion varied over the studied years, initially heading toward HR Littoral and Guaiba (between 2012 and 2014), followed by a steady period (2015–2017), and subsequently a progression toward HR Uruguay (2018). The frequency analysis showed that persistence was short in most of the municipalities. The results indicate that local environmental characteristics, especially temperature and precipitation, could be key for the invasion and development of the species. Given its rapid expansion, statewide dispersibility, and extremely large bloom formation, Rio Grande do Sul looks to be C. furcoides' second home. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to investigate the influence of inertia of nonlinear springs on the dispersion behavior of discrete monoatomic chains with lumped and distributed masses. The developed model can represent the wave propagation problem in a non-homogeneous material consisting of heavy inclusions embedded in a matrix. The inclusions are idealized by lumped masses, and the matrix between adjacent inclusions is modeled by a nonlinear spring with distributed masses. Additionally, the model is capable of depicting the wave propagation in bi-material bars, wherein the first material is represented by a rigid particle and the second one is represented by a nonlinear spring with distributed masses. The discrete model of the nonlinear monoatomic chain with lumped and distributed masses is first considered, and a closed-form expression of the dispersion relation is obtained by the second-order Lindstedt-Poincare method (LPM). Next, a continuum model for the nonlinear monoatomic chain is derived directly from its discrete lattice model by a suitable continualization technique. The subsequent use of the second-order method of multiple scales (MMS) facilitates the derivation of the corresponding nonlinear dispersion relation in a closed form. The novelties of the present study consist of (i) considering the inertia of nonlinear springs on the dispersion behavior of the discrete mass-spring chains; (ii) developing the second-order LPM for the wave propagation in the discrete chains; and (iii) deriving a continuum model for the nonlinear monoatomic chains with lumped and distributed masses. Finally, a parametric study is conducted to examine the effects of the design parameters and the distributed spring mass on the nonlinear dispersion relations and phase velocities obtained from both the discrete and continuum models. These parameters include the ratio of the spring mass to the lumped mass, the nonlinear stiffness coefficient of the spring, and the wave amplitude. [ABSTRACT FROM AUTHOR]

This paper examines the short-term or transient dynamics of SIR infectious disease models in patch environments. We employ reactivity of an equilibrium and amplification rates, concepts from ecology, to analyze how dispersals/travels between patches, spatial heterogeneity, and other disease-related parameters impact short-term dynamics. Our findings reveal that in certain scenarios, due to the impact of spatial heterogeneity and the dispersals, the short-term disease dynamics over a patch environment may disagree with the long-term disease dynamics that is typically reflected by the basic reproduction number. Such an inconsistence can mislead the public, public healthy agencies and governments when making public health policy and decisions, and hence, these findings are of practical importance. [ABSTRACT FROM AUTHOR]

The dynamics of swarm robotic systems are complex and often nonlinear. One key issue is to design the controllers of a large number of simple, low-cost robots so that emergence can be observed. This paper presents a sensor and computation-friendly controller for swarm robotic systems inspired by the mechanisms observed in algae. The aim is to achieve uniform dispersion of robots by mimicking the circular movement observed in marine algae systems. The proposed controller utilizes binary sensory information (i.e., see or not see) to guide the robots' motion. By moving circularly and switching the radii based on the perception of other robots in their line of sight, the robots imitate the repulsion behavior observed in algae. The controller relies solely on binary-state sensory input, eliminating the need for additional memory or communication. Up to 1024 simulated robots are used to validate the effectiveness of the dispersion controller, while experiments with 30 physical robots demonstrate the feasibility of the proposed approach. [ABSTRACT FROM AUTHOR]

Results of studying the process of producing reactive alumina in the presence of a complex additive, including polycarboxylate ester (PCE) and polyethylene glycol (PEG), are presented. The effect of such reactive alumina on rheotechnological properties of matrix systems and low-cement refractory castables is evaluated. The synergetic effect of combined introduction of PEG and PCE during fine milling of raw alumina is established. It is shown that the deflocculating effect of polycarboxylate ester and the intensity of the milling process are strengthened. [ABSTRACT FROM AUTHOR]

Lead-based water pipelines pose a significant public health risk in the US. The challenge lies in locating these pipelines, as current identification technologies have limitations. This study discusses potential and challenges of identifying the water Service Line (SL) material through a stress wave propagation methodology. Since buried service lines are surrounded by soil and contain water, the stress wave propagation is non trivial. This work presents numerical simulations to investigate the applicability of the proposed method. First, authors consider wave propagation properties that could be used in a stress wave approach to identify buried lead based pipelines. For instance, dispersion curves are quite different for steel, copper, Lead, and PVC pipes filled with water. While the soil surrounding pipes causes a decrease in wave propagation energy due to the energy leakage into the soil medium, this phenomenon can enable the detection of leaked waves with sufficiently sensitive sensors installed near the soil surface. The received signals vary for different types of pipe materials, allowing to differentiate among service line materials. This study's numerical simulations and lab experiments suggest that stress wave propagation could become a valuable tool for identifying buried lead-based water SL materials. [ABSTRACT FROM AUTHOR]

Integrated photonics have been growing at an exponential rate. The related technologies are advancing with numerous research works on integrated devices offering Complementary Metal–Oxide–Semiconductor (CMOS) compatibility. Various compact waveguides are also exploited for different applications. In this paper, we report an unconventional 5 mm long air-clad SiN suspended core channel waveguide that is CMOS compatible. The hollowed-out Silica (SiO2) rectangular substrate serves as the lower cladding for the Silicon Nitride slab on which the rectangular core is suspended. The envisioned waveguide is engineered to be numerically pumped at 1.55 μm wavelength with a pulse that is 20 kW in power and 50 fs in duration. The generated Supercontinuum spanning from 0.8 to 6 μm has a great potential in bio-medical and imaging applications. [ABSTRACT FROM AUTHOR]

We prove upper and lower bounds on the minimal spherical dispersion, improving upon previous estimates obtained by Rote and Tichy in (Anz Österreich Akad Wiss Math Nat Kl 132:3–10, 1995). In particular, we see that the inverse N (ε , d) of the minimal spherical dispersion is, for fixed ε > 0 , linear in the dimension d of the ambient space. We also derive upper and lower bounds on the expected dispersion for points chosen independently and uniformly at random from the Euclidean unit sphere. In terms of the corresponding inverse N ~ (ε , d) , our bounds are optimal with respect to the dependence on ε . [ABSTRACT FROM AUTHOR]

A metamaterial wave absorber (MWA) optimized for high-performance absorbers to harvest electromagnetic energy is designed for operation within the terahertz (THz) frequency range using renewable palm oil frond graphitic carbon (POFGC). The structural composition of the MWA consists of double split-ring resonators configured in rotational symmetry. The fundamental component of the design has three distinct layers: (1) the bottom layer, composed of a metallic substance with gold that exhibits a lossy metal characteristic; (2) the middle layer, made of a lossy dielectric material referred to as silicon dioxide (SiO2); and (3) the top layer crafted from POFGC. The findings reveal that the absorber achieves a broad absorption spectrum, with simulated results from CST software indicating absorption peaks at 414, 708, 981, and 1242 THz. These results demonstrate high absorption levels of 99.989, 99.999, 99.988, and 99.999% for typical incident electromagnetic waves. The structural dimensions (590 × 590 nm2) are designed to deliver remarkable performance across the visible spectrum and infrared frequency ranges. The energy harvester exhibits independent polarization at various angles, including 0°, 45°, 90°, 135°, 180°, and 225°. It has excellent harvesting capabilities across multiple angles of incidence from 0° to 80°, including the whole operational spectrum. A comparative investigation of the circuit indicates enhanced performance of the metamaterial wave absorber, demonstrating its potential for exceptional functionality inside the advanced design system (ADS) software. Furthermore, the structures under consideration, which were simulated using the HFSS (high-frequency structure simulator) tool, demonstrate strong agreement with the highest level of absorption seen at each resonance peak in the CST simulation outcomes. This paper introduces an alternative protocol, expressed in terms of the phase velocity of the mode, for use with the restricted asymmetric structure to find optimum dispersion. The study highlights the exceptional properties of POFGC, including its high absorption capacity, insensitivity to angles, and effective dispersion properties. [ABSTRACT FROM AUTHOR]

In recent years, the power conversion efficiency (PCE (%)) of perovskite solar cells (PSCs) has improved to over 26%. To enhance the photovoltaic properties of PSCs, several materials for the electron transport layer (ETL) have been investigated. Zinc oxide (ZnO) is a significant ETL due to its high electron mobility and optical transparency in PSCs. As a result of various deposition methods, ZnO ETL can be processed at low temperatures. On the other hand, based on several studies, metal-doped ZnO can facilitate electron transfer, thereby improving the performance of un-doped ZnO ETL-based PSCs. Here, to improve the PCE (%) and long-term stability of un-doped ZnO ETL-PSCs, silver (Ag)-doped ZnO 1wt% as a buffer layer is examined. In this paper, with the addition of an organic solvent (ethanol) to the dispersion of Ag-doped ZnO 1 wt% nanoparticles (NPs) in deionized (DI) water, the morphology of the buffer layer (Ag-doped ZnO 1 wt%) can be controlled. This approach focuses on reducing the wettability of the ZnO/Ag-doped ZnO 1 wt% bilayer ETLs and enhancing the stability of un-doped ZnO ETL-PSCs. According to the results, the ZnO/H2O-ethanol mixtures-Ag-doped ZnO 1 wt% bilayer ETL leads to the formation of high-quality perovskite with low defects, reducing the recombination rate, and long-term stability of un-doped ZnO ETL-PSCs in ambient conditions. [ABSTRACT FROM AUTHOR]

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable, which offers an approximate framework for the asymptotic homogenization analysis of the motion equation. However, in this framework, the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order increases. In such a context, a compact, fast, and accurate asymptotic paradigm is developed. This work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be determined. Remarkably, the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor, which is demonstrated by representative one- and two-dimensional cases. The numerical results show that (1) the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites, (2) the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation, and (3) the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results. [ABSTRACT FROM AUTHOR]

Urbanization is a major form of landscape alteration characterized by the extent of impervious structures. For urban vegetation, dispersal is key for allowing plants to reach and occupy spaces that offer conditions for germination. Here, we investigated (i) the effect of urbanization intensity on the variation in plant height, quantity, size and weight of fruits and seeds of spontaneous plants; (ii) the presence of variation in the traits for species with different dispersive syndromes and invasion status; and (iii) the effect of urbanization on the proportion of species with different dispersive syndromes. We collected plants from the herbaceous and shrub strata in different intensities of urbanization, in Lavras-MG, Brazil. Data were analyzed using generalized linear mixed-effect models. A total of 88 plant species were identified. We observed a decrease in the values of the functional traits with increasing urbanization intensity. Plant height decreased with increased urbanization. Anemochorous plants showed a decrease in fruit size, and zoochoric plants showed a decrease in fruit and seed weight. There was a reduction in the number and size of fruits of native plants and in the number of seeds of naturalized exotic plants. There was no variation in the proportion of species by dispersive syndromes. The tendency of smaller dispersive structures illustrates the filtering of functional traits caused by urbanization. [ABSTRACT FROM AUTHOR]

Purpose: The shear wave propagation due to a point source disturbance in a piezo-electro-magnetic medium (PEMM) has been studied analytically by Green's function technique. The composite structure comprises a PEMM layer coated with viscoelastic film, resting over a functionally graded half-space. Methods: The dispersion equation of the shear wave has been derived utilizing Green's function in combination with Fourier transformation. Results: Relating the dependence on complex wavenumber, the complex form of the dispersion equation is obtained to define the phase velocity and attenuation characteristics of shear wave. The impact of various parameters, such as functional grading, viscoelasticity, piezo-electro-magnetic coupling parameter, etc. on the phase velocity and attenuation coefficient has been analyzed through numerical simulations and graphical illustrations. Conclusion: The viscoelastic coating significantly influences the velocity and attenuation of the wave. [ABSTRACT FROM AUTHOR]

Studies on the wetting effect reveal that slip is prevalent at the fluid–solid interface, and its influence cannot be disregarded in microscopic systems. The traditional understanding of the propagation rules and characteristics of elastic waves in fluid-saturated porous media are challenged by the introduction of slip boundary effect. In this paper, the influence of slip boundary effect on the dispersion and attenuation of both shear horizontal guided waves and Love waves in a fluid-saturated porous media is investigated. The virtually enlarged pore model is employed to characterize the degree of slip and the wetting effect with the slip length. It is found that both velocity and attenuation of shear horizontal guided waves in monolayer are sensitive to slip boundary effect, while only attenuation shows sensitivity for Love wave with no significant impact observed on its velocity. The research results fill a gap in understanding how slip boundary effect affects the propagation of shear horizontal and Love waves in fluid-saturated porous media, which is of great significance for the identification of sediment type, physical property inversion and reservoir evaluation. [ABSTRACT FROM AUTHOR]

We numerically investigate a promising mid-infrared supercontinuum (SC) source through the design of an on-chip complementary metal oxide semiconductor compatible 3-mm-long inverse tapered waveguide made using stoichiometric silicon nitride (Si 3 N 4 ) as the core and silica (SiO 2 ) glass as both the upper and lower claddings. The proposed waveguide is designed for pumping only in the anomalous dispersion regime. To explore SC generation in terms of spectral flatness and mid-infrared expansion, three different types of inverse tapered geometry are analyzed. These are inverse linear tapering, hyperbolic tapering, and parabolic tapering approaches. The proposed structures are optimized by varying their width based on the tapering variation coefficient along the pulse propagation direction. Keeping the waveguide thickness (height) constant at 2 μ m, each geometry is engineered by varying widths between 1.2 and 0.75 μ m in the mode of inverse tapering approach. Using a pump at 1.55 μ m with a peak power of 8 kW, SC generation is explored in all tapering geometries with an ultrashort pulse of 50 fs. The largest SC spectra covering a region from 0.76 μ m to beyond 6.67 μ m have been realized with a good spectral flatness by the parabolic-type taper among the three tapering geometries considered here. To the best of the authors' knowledge, this is the first time report of broadband SC coverage through numerical study in the region of mid-infrared by Si 3 N 4 planar design through a tapering approach. After spectral broadening up to 3.5 μ m with a conventional uniform design, a dip has been observed at the middle of the spectra which gradually becomes large with further dimensional variations of a typical uniform waveguide. However, such spectral dip problems can largely be eliminated through selective spectral enhancement by applying an inverse tapering approach. The coherence calculation of the predicted SC coverages also shows a high coherence at the proposed tapers output. The proposed inverse tapered planar designs show a significant improvement not only in mid-infrared spectral expansion but also in spectral flatness compared to the axially unvarying waveguide design. [ABSTRACT FROM AUTHOR]

In this paper, mixed integer nonlinear programming (MINLP) optimization algorithm integrated with kriging surrogate-model is newly formulated to optimize the dispersion characteristics of photonic crystal fibers (PCFs). The MINLP is linked with full vectorial finite difference method (FVFDM) to optimize the modal properties of the PCFs. Through the optimization process, the design parameters can take real and/or integer values. The integer values can be used to selectively fill the PCF air holes to control its dispersion characteristics. However, the other optimization techniques deal with real design parameters where the PCF can be optimized using none or predefined infiltrated air holes. The MINLP algorithm is used to obtain an ultra-flat zero dispersion over a broadband of wavelength range from 1.25 to 1.6 μm using silica PCF selectively infiltrated with Ethanol material. To show the superiority of the proposed algorithm, nematic liquid crystal selectively infiltrated PCFs are also designed with high negative flat dispersion over wide range of wavelengths from 1.25 to 1.6 μm for the quasi transverse magnetic (TM) and the quasi transverse electric (TE) modes. Such designs have negative flat dispersions of − 163 ± 0.9 and − 170 ± 1.2 ps/Km nm, respectively over the studied wavelength range. Therefore, the MINLP algorithms could be used efficiently for the design and optimization of selectively filled photonic devices. [ABSTRACT FROM AUTHOR]