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This study investigates a bifunctional cloak composed of concentric metamaterials arranged in 4N thin layers, where N denotes the number of periodic layer pairs within the structure. The structure includes an inner circular domain, an outer domain, and alternating sequences of 2N layers between them. We explore two models: one using isotropic materials and another one using anisotropic materials. The anisotropic model demonstrates superior cloaking performance for both electrical and thermal fields. Analytical solutions based on the Effective Medium Theory and boundary-value problems reveal the structure’s response under quasi-static conditions. Numerical simulations using COMSOL validate these findings, highlighting the cloak’s and concentration’s ability to manipulate external thermal and electric fields efficiently. [ABSTRACT FROM AUTHOR]

This paper brings out an innovation in fabricating porous magnesia‐stabilized zirconia components by infiltrating free‐flowing suspension into polyurethane foam. The process enables the production of samples with different levels of porosity and pore structure by easily controlling the amount of slurry infiltrated into the foam. The process uses Isobam, a nontoxic binder, which makes the fabrication simple and environment‐friendly. Samples with five different levels of total porosity ranging from 41.7% to 62.4% were fabricated. Microstructural studies revealed multimodal pore structure comprising both open and closed porosities. Measurements on thermal properties and compressive strength of the samples showed that the sample with the lowest porosity exhibited a thermal conductivity of 0.495 W/mK and a compressive strength of 45.7 MPa. The measured values of thermal conductivity of the samples with different porosity levels could be described by modified effective medium theory. Present work opens up enormous possibilities for economical industrial production of porous magnesia‐stabilized zirconia components for biomedical and thermal insulation applications. [ABSTRACT FROM AUTHOR]

Although light‐matter interaction and topology of photonic systems have been extensively studied, the topology induced novel light‐matter interaction phenomena in deep‐subwavelength region remain unexplored. Here, based on the non‐trivial topological singularity of 1D photonic crystals (PhCs), novel photonic spin Hall effects and abnormal beam behaviors are revealed in deep‐subwavelength region for the beams with nearly normal incidence, which beyond effective medium theory. The huge photonic spin Hall shift (PSHS) is observed around the singularity in the deep‐subwavelength region. The shape of reflected beam undergoes dramatic changes near the singularity, especially at the singularity, the reflected field is split as dipole‐like distribution for both polarizations. Physically, such a phenomenon is resulted from the destructive interference between the spin‐maintained beam and spin‐flipped beam. Based on these theoretical researches, super‐subwavelength thickness detecting, in which the wavelength is six orders of magnitude larger than the detecting scale, can be designed. Such sensitive detecting can also be applied to dielectric permittivity of PhC and background. Further more, by tuning the distance between two singularities in the deep‐subwavelength region, multi‐frequency channels sensitive detection and broadband platform with huge PSHS can be achieved. This system could be a platform to explore nontrivial light‐mater interaction in deep‐subwavelength region and to design of extremely sensitive detection devices. [ABSTRACT FROM AUTHOR]

In this study, a rapid water content detection method for donkey-hide gelatin was established based on terahertz time-domain spectroscopy in reflection mode. Notably, the effective medium theory, informed by the double-Debye relaxation for free water, was employed to predict the water content in the sample. The water content obtained through effective medium theory was lower than that of the traditional thermogravimetric method due to the existence of bound water. Bound water is invisible in THz spectroscopy due to its slower dynamics. In the frequency range of 0.22–0.48 THz, the offset in measured values between the thermogravimetric method and the THz-based method was fitted by a polynomial function. The results of THz-based method calibrated by polynomial fitting were consistent with the findings of the thermogravimetric method. The water content detection results derived by these two methods demonstrated high correlation values (R2) of 0.9860, 0.9160, and 0.9784, and small root mean square errors (RMSE) of 4.5584, 4.4887, and 5.3657 for three samples, respectively. Moreover, the proposed water content detection method needs to be calibrated only once by the thermogravimetric method. Overall, this study provides a rapid water content detection method and demonstrates the potential of real-time water content detection in donkey-hide gelatin. [ABSTRACT FROM AUTHOR]

The development of bend‐induced effectively single‐mode fiber with a square cross‐section and flat top‐hat intensity distribution is reported using core topology nanostructuring dedicated to femtosecond laser ablation systems. The fiber's core comprises 5419 silica and germanium‐doped silica nanorods with a diameter of 430 nm each arranged into a hexagonal lattice. The distribution of the rods is calculated using in‐house developed code based on the Monte Carlo algorithm to obtain a target shape of mode and intensity distribution. As a proof‐of‐concept, a silica nanostructured fiber with a 24 µm core is developed and verified against the purity of mode guidance, bending, and guiding losses. It is shown that for a wavelength of 1030 nm, the fiber is effectively single‐mode with 96% mode purity when bending with a radius of 20 cm is applied. The fiber has a measured mode area of 360 µm2, numerical aperture of 0.03, and total losses of 0.07 dB m−1. [ABSTRACT FROM AUTHOR]

Since the initial discovery of Dyakonov surface waves at a flat infinite interface of two dielectrics, at least one of which is positively anisotropic, extensive research has been conducted towards their theoretical and experimental studies in materials with positive anisotropy. The potential applications of these waves were initially limited due to the stringent conditions for their existence and the requirement for position anisotropy. In our study, we present the theoretical prediction and experimental observation of a novel type of Dyakonov surface waves that propagate along the flat strip of the interface between two dielectrics with negative anisotropy. We demonstrate that the conditions for surface waves are satisfied for negatively anisotropic dielectrics owing to the specific boundaries of the strip waveguide confined between two metallic plates. We study such modes theoretically by using the perturbation theory in the approximation of weak anisotropy and demonstrate that the electromagnetic field distribution in these modes is chiral. Experimental verification of theoretical predictions is made in the microwave range using 3D-printed negatively anisotropic water-dielectric metamaterial slabs. The existence of Dyakonov surface waves in negative crystals prompts a reassessment of the list of materials suitable for practical realization of these waves in the visible and infrared ranges. Due to the ability of the considered modes to transmit chiral light, they have potential in the sensing of chiral organic molecules. [ABSTRACT FROM AUTHOR]

Surface modified ZnS nanoparticles / poly (methylmethacrylate) - (PMMA) nanocomposites were prepared by the solution casting method. The ZnS nanoparticles, as starting materials in the present study, were synthesized mechanochemically and their crystallite size was estimated as 2.3 nm. Surface modification of obtained nanoparticles was performed by 3-Mercaptopropyltrimethoxysilane. We investigate thin samples of the nanocomposite material and pure PMMA (about 290 μm) with a strong interference effect, and corresponding thick samples, as reference. The optical properties of this material were studied by far-infrared spectroscopy. The analysis of the far-infrared reflectivity spectra was made by the fitting procedure, according to the model for a thin plate of nanocomposites in the air. The dielectric function of the nanocomposites was modeled as a mixture of homogenous surface modified ZnS spherical inclusions in PMMA, by the Maxwell-Garnet formula. In the case of a PMMA thin sample, intense, well-defined interference was registered in the range of 90 to 200 cm− 1, while significantly weaker and less well-defined interference was registered in the range around 450 cm− 1. In the thin composite sample, in addition to the interference induced by sample thickness, interference induced by the existence of ZnS nanoparticles was also observed, located between the TO and LO phonons of ZnS. This opens the possibility of applying nanocomposites in interferometry. [ABSTRACT FROM AUTHOR]

With the advancement of urbanization, super high-rise buildings have become an integral part of modern cities. However, these structures face significant challenges due to thermal expansion effects in complex environments, especially considering the substantial impact of temperature-induced thermal expansion of concrete on the stability and safety of buildings. Although existing research has made some progress in exploring thermal expansion effects and their control strategies, traditional methods have limitations in addressing the complexities of super high-rise buildings. This study first solves the thermal expansion coefficient of concrete in super high-rise building structures based on an effective medium theory, providing a more precise calculation method from a microscopic perspective. Secondly, it proposes and validates a set of thermodynamic control strategies for super high-rise building structures to effectively manage the stress and deformation issues caused by temperature changes. The findings of this study will offer scientific support for the design and maintenance of super high-rise buildings, enhancing their overall safety and economic efficiency. [ABSTRACT FROM AUTHOR]

O-rings made from foam rubber are often used in sealing applications. Foam rubber have low (macroscopic) elastic modulus E 0 resulting in a low nominal contact pressure when squeezed against a countersurface. In most cases the foam rubber is covered by a thin surface film with the effective elastic modulus E 1 > E 0 . We show that the nominal contact pressure may not be high enough for the contact area to percolate and the O-ring seal will leak. For the leakage calculations we use the Persson multiscale contact mechanics theory, and the (modified) Bruggeman effective medium theory for the fluid flow conductivity. The experimental input for the theory are surface roughness power spectrum, which was obtained from stylus topography measurements, and the elastic properties ( E 0 and E 1 ) of the rubber O-ring. As an application of this calculation method, we have used the preliminary as well as the final results of the laboratory gas tightness tests of the 136 New Small Wheel Micromegas Quadruplets performed at CERN, from February 2019 to May 2021, in the framework of the ATLAS Experiment upgrade. In the integration quality control, a novel method for gas tightness measurement, that we have called "Flow Rate Loss", has been used as a baseline method. [ABSTRACT FROM AUTHOR]

This study unveils an advanced methodology for characterizing various types of cow's milk based on their optical properties, aiming to establish a straightforward yet comprehensive method. This study uses fundamental principles such as Snell's Law and Fresnel coefficients to determine and demonstrate critical angles for total internal reflection and reflectance at p polarization. Notably, milk composition, particularly fat content, significantly and remarkably influences its refractive index, with higher fat content leading to elevated values. Additionally, the extinction coefficient, derived through the Beer–Lambert law, provides valuable and essential information regarding light absorption and scattering within the milk samples. The significance of this research relies upon its ability to comprehensively analyze various optical properties of milk, including critical angles, reflectance, and extinction coefficients. By doing so, it offers an exhaustive and detailed understanding of how milk responds to light across different wavelengths and angles of incidence. Moreover, the technique effectively distinguishes milk types based on their fat content and particle characteristics. This novel characterization technique holds promise for various applications within the dairy industry, such as milk quality control, classification, and adulteration detection, which is crucial for maintaining consumer trust and safety. [ABSTRACT FROM AUTHOR]

Polymer thermal conductivities play an important role for their potential use in industrial applications. Therefore, great efforts have been made to investigate fundamental structure–property relationships to understand and predict thermal conductivities for polymers and their composites. The review summarizes selected well-proven microscopic theoretical approaches to calculate thermal conductivities such as EMD, NEMD, EMT, and BTE, and cites examples to focus on different qualitative aspects of recent polymer theoretical research. Examples other than polymer materials are given as supplemental information to support the general discussion of heat transport phenomena in solid materials. [ABSTRACT FROM AUTHOR]

Directional control of thermal emission over its broad wavelength range is a fundamental challenge. Gradient epsilon-near-zero (ENZ) material supporting Berreman mode has been proposed as a promising approach. However, the bandwidth is still inherently limited due to the availability of ENZ materials covering a broad bandwidth and additional undesired omnidirectional modes in multilayer stacking with increased thickness. Here, we show that broadband directional thermal emission can be realized beyond the previously considered epsilon-near-zero and Berreman mode region. We then establish a universal approach based on effective medium theory to realizing ultra-broadband directional thermal emitter. We numerically demonstrate strong (emissivity >0.8) directional (80 ± 5°) thermal emission covering the entire thermal emission wavelength range (5–30 μm) by using only two materials. This approach offers a new capability for manipulating thermal emission with potential applications in high-efficiency information encryption, energy collection and utilization, thermal camouflaging, and infrared detection. [ABSTRACT FROM AUTHOR]

Polymer thermal conductivities play an important role for their potential use in industrial applications. Therefore, great efforts have been made to investigate fundamental structure–property relationships to understand and predict thermal conductivities for polymers and their composites. The review summarizes selected well-proven microscopic theoretical approaches to calculate thermal conductivities such as EMD, NEMD, EMT, and BTE, and cites examples to focus on different qualitative aspects of recent polymer theoretical research. Examples other than polymer materials are given as supplemental information to support the general discussion of heat transport phenomena in solid materials.

The representation of three-dimensional integrated photonic structures in two-dimensional designs has been investigated through finite element analysis using COMSOL Multiphysics. The accuracy of the effective index method for various waveguide designs is studied. An alternative to the effective index method, here named the inverse effective index method, is derived in this paper. The results indicate that the commonly used effective index method has a deviation in propagation constant up to 17%, where the error is largest for low-confinement factor waveguides. The inverse effective index method vastly reduces this error to $< $0.01% for low confinement-factor geometries. This enables an accurate simulation in two-dimensions while retaining the waveguiding properties of the third dimension. As with the effective index method, the inverse effective index method does not require proprietary software.

The development of a flexible and robust metamaterial absorber is a great motivation for the new generation of microwave absorbers covering any conformal shape. Ceramic–polymer composites with variable dielectric constant within the microwave frequencies are proposed as a flexible middle dielectric spacer (MDS) layer to provide an additional degree of design freedom for metamaterial absorber applications. By varying the dielectric constant of the MDS layer, the resonance band of the metamaterial absorber can be tuned while retaining a low profile in addition to enhancing its electromagnetic performance for transverse magnetic (TM) polarized waves. To formulate these composites, tetragonal structured barium titanate (BaTiO3) powder is selected as an excellent candidate when mixed with elastomer polydimethylsiloxane (PDMS), resulting in high mechanical strength substrates. Experimentally, samples with a range of dielectric permittivity from 2.81 to 5.67 were obtained for a 0%–20% volume fill fraction of BaTiO3 in PDMS. The obtained dielectric permittivities are consistent with the Bruggeman effective medium theory. Utilizing an optimized composition (10% BaTiO3), resulting in ϵ r = 4 substrate, an X-band flexible absorber is designed and fabricated to absorb more than 90% of incident electromagnetic waves within a frequency band of 8.16–12.12 GHz. [ABSTRACT FROM AUTHOR]

Particle shape variability is a key to understanding the rich behavior of granular materials. Polyhedra are among the most common particle shapes due to their ubiquitous origins in nature such as rock fragmentation and mineral crystallisation. Because of their faceted shape, polyhedral particles tend to assemble in jammed structures in which face-face and face-edge contacts between particles control the packing-level properties. In this paper, we use tri-periodic particle dynamics simulations to derive for the first time a generic analytical expression of the elastic moduli of polyhedral and spherical particle packings subjected to triaxial compression as a function of two contact network variables: (1) a "constraint number" that accounts for the face-face and edge-face contacts between polyhedra and is reduced to the coordination number in the case of spherical particles, and (2) the contact orientation anisotropy induced by compression. This expression accurately predicts the simulated evolution of elastic moduli during compression, revealing thereby the origins of the higher elastic moduli of polyhedral particle packings. We show that particle shape affects the elastic moduli through its impact on the contact network and the level of nonaffine particle displacements is the same for the simulated shapes. Its nearly constant value during compression underlies the constant values of our model parameters. By connecting the elastic moduli to the contact network through parameters that depend on particle shape, our model makes it possible to extract both the connectivity and anisotropy of granular materials from the knowledge of particle shape and measurements of elastic moduli. [ABSTRACT FROM AUTHOR]

The severe climate and energy issues require more environmentally friendly and efficient cooling methods. Radiative cooling offers a cooling solution with significant advantages. However, current radiative cooling technologies focus primarily on seeking perfect materials to achieve complete wavelength absorption. However, numerous research studies have shown that achieving such a perfect scenario is not feasible. Here, inspired by the surface of the Cerambycini Latreille, the inherent mechanism of radiative cooling functionality in the unique structure of these hairs is revealed using effective medium theory and Finite Difference Time Domain (FDTD) optical simulation analysis. Through alkaline etching and template methods, a biomimetic radiative cooling film (BRCF) was successfully fabricated. The BRCF not only efficiently reflects solar radiation but also enhances absorption in the atmospheric window wavelength range. The radiative cooling mechanism proposed in this study and the BRCF presented here may inspire researchers to further explore the field of structural radiative cooling. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive theoretical framework for understanding surface-enhanced Raman scattering (SERS) measurements in both solution and thin-film setups, focusing on electromagnetic enhancement principles, was presented. Two prevalent types of SERS substrates found in the literature were investigated: plasmonic colloidal particles, including spherical and spheroid nanoparticles, nanoparticle diameters, and thin-film-based SERS substrates, like ultra-thin substrates, bundled nanorods, plasmonic thin films, and porous thin films. The investigation explored the impact of analyte adsorption, orientation, and the polarization of the excitation laser on effective SERS enhancement factors. Notably, it considered the impact of analyte size on the SERS spectrum by examining scenarios where the analyte was significantly smaller or larger than the hot spot dimensions. The analysis also incorporated optical attenuations arising from the optical properties of the analyte and the SERS substrates. The findings provide possible explanations for many observations made in SERS measurements, such as variations in relative peak intensities during SERS assessments, reductions in SERS intensity at high analyte concentrations, and the occurrence of significant baseline fluctuations. This study offers valuable guidance for optimizing SERS substrate design, enhancing SERS measurements, and improving the quantification of SERS detection. [ABSTRACT FROM AUTHOR]

In this paper, a narrowband optical absorber with an absorption peak of 99.9% at the telecommunication wavelength of 1310 nm is presented. It consists of nanowires composed of five periods of Ag-Ge-Si disks on a Si substrate. The design of the stacks is based on epsilon-near-zero (ENZ) metamaterials, which causes this structure to have a relatively small thickness (i.e., thickness < 5λ, where λ is the working wavelength). By adjusting the thickness of the stacks using the effective medium theory (EMT) model, we have achieve the desired ENZ wavelength. The perfect absorption feature has been obtained by the synergy of resonances of surface plasmon polaritons (SPP) and ENZ modes. The proposed structure has been simulated using the finite difference frequency domain method. The simulation results indicate that the absorption rate remains almost 90% up to an angle of 75° and is insensitive to polarization. Furthermore, by changing the arrangement of the neighboring stacks, we see an increase in the sensitivity of the absorption peak to the refractive index variations of the environment. In general, narrowband absorbers have good potentials for applications such as filtering, sensing, and detecting, which underlines the significance of this work. [ABSTRACT FROM AUTHOR]

This paper presents a cross-scale prediction of the dielectric properties of long-term-cured tricalcium silicate (C3S) paste specimens and investigated the effect of different phase geometry models on the prediction results. Firstly, the dielectric properties of C3S paste specimens cured for 180 days were tested. Based on tests such as X-ray diffraction (XRD) and mercury intrusion porosity (MIP), the types of phases and the volume fractions of individual phases in the C3S paste specimens were determined. Subsequently, the dielectric performance of the phases was measured. The dielectric performance linkage between each phase and the C3S paste specimen was established based on the effective medium theory. The effects of three morphological models of the phase on the predicted results were dissected. The results showed that the volume fraction and dielectric constant of calcium silicate hydrates (C-S-H) gel were significantly higher than those of other phases in the C3S paste specimens. Among the three computational models of phase geometry, the standard spherical phase model produced the best prediction. The prediction results of the standard spherical model improved the accuracy by more than 45.8% compared with that of the oblate phase model and the prolate phase model. Among the phases, the trend of the dielectric constant of C-S-H gels with frequency was the most similar to the results obtained by the three prediction models. [ABSTRACT FROM AUTHOR]

In this paper, the problem of scattering of a plane harmonic electromagnetic wave on a double wire array is solved accurately. The array consists of two identical infinite wire gratings arranged in a free space. Each of the grids consists of parallel thin, infinitely long metal cylinders of circular cross section. The study considers the case when the electric vector of the incident wave is parallel to the wires. The expression for the total reflection coefficient is obtained in the dipole approximation for the case of s -polarization. Analysis of the spectrum of the total reflection coefficient in the subwavelength part of the microwave frequency range was carried out. The paper proposes a new approach for determining the effective relative permittivity and permeability, as well as the effective refractive index of the grating. The approach does not depend on the number of grating layers and allows to taking into account near-field couplings in homogenizing the grating. This approach also allowed us to describe the behavior of the reflectivity and obtain expressions for the effective parameters of the grating at and near the resonant frequency. The validation of all the approximations obtained in the study was carried out using a finite-difference time-domain electromagnetic simulator. [ABSTRACT FROM AUTHOR]

The fractal characteristic of cement paste has been investigated for decades. In this paper, a systematic study referring to analysis, modeling as well as application is presented with respect to the pore size-dependent fractality of the porous structure in cement paste. In particular, the multiscale fractal dimensions other than the traditional single fractal dimension are analyzed for a measure of incomplete fractality. Then, the multiscale solid mass fractal model is introduced and implemented. It is demonstrated that the modeled pore size distribution agrees well with that obtained from the experimental measurement. Moreover, in combination with other analytical (the effective medium theory) and/or numerical (the finite element method) tools, such a pore size-dependent fractality could provide a fast assessment of some basic mechanical and physical properties. [ABSTRACT FROM AUTHOR]

The dielectric constant of an electrolyte solution, which determines electrostatic interactions between colloids and interfaces, depends nonlinearly on the salinity and also on the type of salt. The linear decrement at dilute solutions is due to the reduced polarizability in the hydration shell around an ion. However, the full hydration volume cannot explain the experimental solubility, which indicates the hydration volume should decrease at high salinity. Volume reduction of the hydration shell is supposed to weaken dielectric decrement and thus should be relevant to the nonlinear decrement. According to the effective medium theory for the permittivity of heterogeneous media, we derive an equation which relates the dielectric constant with the dielectric cavities created by the hydrated cations and anions, and the effect of partial dehydration at high salinity is taken into account. Analysis of experiments on monovalent electrolytes suggests that weakened dielectric decrement at high salinity originates primarily from the partial dehydration. Furthermore, the onset volume fraction of the partial dehydration is found to be salt-specific, and is correlated with the solvation free energy. Our results suggest that while the reduced polarizability of the hydration shell determines the linear dielectric decrement at low salinity, ion-specific tendency of dehydration is responsible for nonlinear dielectric decrement at high salinity. [ABSTRACT FROM AUTHOR]

In a 3 D bounded and C 1 , α -smooth domain Ω, α ∈ (0 , 1) , we distribute a cluster of nanoparticles enjoying moderately contrasting relative permittivity and permeability which can be anisotropic. We show that the effective permittivity and permeability generated by such cluster is explicitly characterized by the corresponding electric and magnetic polarization tensors of the fixed shape. The error of the approximation of the scattered fields corresponding to the cluster and the effective medium is inversely proportional to the dilution parameter c r : = δ a , where a is the maximum diameter of the nanoparticles and δ is the minimum distance between them. The constant of the proportionality is given in terms of a-priori bounds on the cluster of nanoparticles (i.e. upper and lower bounds on their permittivity and permeability parameters, upper bound on the dilution parameter c r , the used incident frequency and the domain Ω). A key point of the analysis is to show that the Foldy-Lax field appearing in the meso-scale approximation, derived in [17] , is a discrete form of a (continuous) system of Lippmann-Schwinger equations with a related effective permittivity and permeability contrasts. To derive this, we prove that the Lippmann-Schwinger operator, for the Maxwell system, is invertible in the Hölder spaces. As a by-product, this shows a Hölder regularity property of the electromagnetic fields up to the boundary of the inhomogeneity. [ABSTRACT FROM AUTHOR]

Recently, ternary solar cells have developed as a vital photovoltaic-technology since they combine the advantages of both single junction and tandem solar cells with their processing simplicity, mechanical flexibility, and lightweight. In this paper, we have investigated the role of domain size and the weight ratio of fullerene and non-fullerene acceptor on the performance of ternary blended PM6:Y6: PCBM organic solar cell. Using the effective medium approach and assuming the ternary blend of donor/acceptor1/acceptor2 nanocomposite as an effective integrated active layer, along with augmented Drift-diffusion formalism for the active layer of the organic solar cell, we have modeled the performance parameters of the device. The results show that the conversion efficiency of ternary solar cells depends on the distribution and size of both fullerene and non-fullerene acceptor domains. There are some optimal domain sizes where the optimum solar cell performance occurs. The obtained model results are in good agreement in comparison with experimental studies. [ABSTRACT FROM AUTHOR]

Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering, such as tunnels and mines. The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature. Based on effective medium theory, this paper presents the governing equation of the “elastic modulus” for combined and single bodies under triaxial compressive tests. A binary effective medium model is then established. Based on the compressive experiment of concrete-granite combined bodies, the feasibility of determining the stress threshold based on crack axial strain is discussed, and the model is verified. The model is further extended to coal-rock combined bodies of more diverse types, and the variation laws of the compressive mechanical parameters are then discussed. The results show that the fitting accuracy of the model with the experimental curves of the concrete-granite combined bodies and various types of coal-rock combined bodies are over 95%. The crack axial strain method can replace the crack volumetric strain method, which clarifies the physical meanings of the model parameters. The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering.

Fundamental effects in nanophotonic resonance systems focused on singular states and their properties are presented. Strongly related to lattice geometry and material composition, there appear resonant bright channels and non-resonant dark channels in the spectra. The bright state corresponds to high reflectivity guided-mode resonance (GMR) whereas the dark channel represents a bound state in the continuum (BIC). Even in simple systems, singular states with tunable bandwidth appear as isolated spectral lines that are widely separated from other resonance features. Under moderate lattice modulation, there ensues leaky-band metamorphosis, merging modal bands and resulting in offset dark states and reflective BICs along with transmissive BICs within a high-reflectance wideband. Rytov-type effective medium theory (EMT) is shown to be a powerful means to describe, formulate, and understand the collective GMR/BIC fundamentals in resonant photonic systems. Particularly, the discarded Rytov analytical solution for asymmetric fields is shown here to predict the dark BIC states essentially exactly for considerable modulation levels. The propagation constant of an equivalent EMT homogeneous film provides a quantitative evaluation of the eminent, oft-cited embedded BIC eigenvalue. The work concludes with experimental verification of key effects.

In this paper, features of generation of two types of surface plasmon-polaritons (SPPs) in optical anisotropic hyperbolic metamaterials formed by a periodic lattice of metal nanocylinders embedded in a dielectric matrix are considered. The dependencies of the group velocity and the penetration depth inside metamaterial of the generated plasmon-polaritons on filling ratio are established and analyzed. Based on the effective medium theory, the surface plasmon-polaritons generation at interface of hyperbolic metamaterials is analytically calculated and discussed. [ABSTRACT FROM AUTHOR]

This study unveils an advanced methodology for characterizing various types of cow’s milk based on their optical properties, aiming to establish a straightforward yet comprehensive method. This study uses fundamental principles such as Snell’s Law and Fresnel coefficients to determine and demonstrate critical angles for total internal reflection and reflectance at p polarization. Notably, milk composition, particularly fat content, significantly and remarkably influences its refractive index, with higher fat content leading to elevated values. Additionally, the extinction coefficient, derived through the Beer–Lambert law, provides valuable and essential information regarding light absorption and scattering within the milk samples. The significance of this research relies upon its ability to comprehensively analyze various optical properties of milk, including critical angles, reflectance, and extinction coefficients. By doing so, it offers an exhaustive and detailed understanding of how milk responds to light across different wavelengths and angles of incidence. Moreover, the technique effectively distinguishes milk types based on their fat content and particle characteristics. This novel characterization technique holds promise for various applications within the dairy industry, such as milk quality control, classification, and adulteration detection, which is crucial for maintaining consumer trust and safety.

Heterogeneous composites consisting of Bi6Cu2Se3.6Cl0.4O6 and Bi2O2Se are prepared according to the concept of modulation doping. With prominently increased carrier mobility and almost unchanged effective mass, the electrical transport properties are considerably optimized resulting in a peak power factor ≈1.8 µW cm−1 K−2 at 873 K, although the carrier concentration is slightly deteriorated. Meanwhile, the lattice thermal conductivity is lowered to ≈0.62 W m−1 K−1 due to the introduction of the second phase. The modified Self‐consistent Effective Medium Theory is utilized to explain the deeper mechanism of modulation doping. The enhancement of apparent carrier mobility is derived from the highly active phase interfaces as fast carrier transport channels, while the reduced apparent thermal conductivity is ascribed to the existence of thermal resistance at the phase interfaces. Ultimately, an optimized ZT ≈0.23 is obtained at 873 K in Bi6Cu2Se3.6Cl0.4O6 + 13% Bi2O2Se. This research demonstrates the effectiveness of modulation doping for optimizing thermoelectric properties once again, and provides the direct microstructure observation and consistent theoretical model calculation to emphasize the role of interface effects in modulation doping, which should be probably applicable to other thermoelectrics. [ABSTRACT FROM AUTHOR]

Stokes polarimetry was used to evaluate the birefringence of nanoporous alumina films. The transmittance of the film and the degree of polarization of the transmitted radiation were measured for angles of incidence at which the phase difference of the orthogonal polarized components of the transmitted radiation was λ/4 or λ/2. The porosity and film pore radii were estimated using the Maxwell–Garnet model. The possibility of creating achromatic phase plates based on nanoporous alumina film with a variable phase difference of the orthogonal polarized components of the transmitted radiation that can function as quarter-wave and half-wave plates is shown. [ABSTRACT FROM AUTHOR]

The physicochemical transformations and electromagnetic properties of a composite based on the dust of electrical arc steel-making furnaces and a carbon-containing material (hydrolysis lignin) have been studied. The complex dielectric permittivity of the studied material was measured by the resonator method during heating to 800°C. At room temperature, the effective values of the magnetic permeability and loss of the composite mixture were calculated by solving the Bruggeman equation according to the effective medium theory. The magnetic permeability during heating was found by orthogonal regression. The numerical model of heating a dense packing from several layers of studied material grains was constructed by the finite element method with consideration of the real properties and physicochemical transformations. [ABSTRACT FROM AUTHOR]

Optical anisotropy of α-MoO3 in its reststrahlen (RS) bands provides exciting opportunities for constructing the polarization-dependent devices. However, achieving broadband anisotropic absorptions through the same α-MoO3 arrays is still challenging. In this study, we demonstrate that selective broadband absorption can be achieved by using the same α-MoO3 square pyramid arrays (SPAs). For both the x and y polarizations, the absorption responses of the α-MoO3 SPAs calculated by using the effective medium theory (EMT) agreed well with those of the FDTD, indicating the excellent selective broadband absorption of the α-MoO3 SPAs are associated with the resonant hyperbolic phonon polaritons (HPhPs) modes assisted by the anisotropic gradient antireflection (AR) effect of the structure. The near-field distribution of the absorption wavelengths of the α-MoO3 SPAs shows that the magnetic-field enhancement of the lager absorption wavelength tends to shift to the bottom of the α-MoO3 SPAs due to the lateral Fabry–Pérot (F–P) resonance, and the electric-field distribution exhibits the ray-like light propagation trails due to the resonance nature of the HPhPs modes. In addition, broadband absorption of the α-MoO3 SPAs can be maintained if the width of the bottom edge of the α-MoO3 pyramid is large than 0.8 μm, and excellent anisotropic absorption performances are almost immune to the variations of the thickness of the spacer and the height of the α-MoO3 pyramid. [ABSTRACT FROM AUTHOR]

The insight into the composition of iron corrosion products is critical for corrosion studies. A novel and non-destructive method is proposed in this paper to quantitatively analyse the binary iron oxides mixtures based on the terahertz time-domain spectroscopy combined with the effective medium theory. The utility of this method is exemplified by analysing the THz refractive index for a set of samples, including hematite, magnetite, and their mixtures at several volume ratios. The effective medium theory is applied to the raw data of single-component samples to remove the dielectric influence of dilution polymer matrix and trapped air voids. The refractive index of hematite and magnetite is determined to be 4.01 ± 0.04 (1.00%) and 5.6 ± 0.2 (3.6%). The measured refractive index of two iron oxides is further adopted to construct an effective medium model for the binary mixture. The analytical model can predict the volume ratios of two iron oxides within the mixture. Comparison between the theoretical predictions and experimental measurements reveals a relative difference of less than 10.0%. [ABSTRACT FROM AUTHOR]

We propose a quantitative effective medium theory for two types of acoustic metamaterials constituted of a large number N of small heterogeneities of characteristic size s, randomly and independently distributed in a bounded domain. We first consider a "sound-soft" material, in which the total wave field satisfies a Dirichlet boundary condition on the acoustic obstacles. In the "sub-critical" regime sN = O(1), we obtain that the effective medium is governed by a dissipative Lippmann–Schwinger equation which approximates the total field with a relative mean-square error of order O(max((sN)2N-1/3, N-1/2)) O (max ((sN) 2 N - 1 3 , N - 1 2 )) $ O(\mathrm{max}(({sN}{)}^2{N}^{-\frac{1}{3}},{N}^{-\frac{1}{2}}))$. We retrieve the critical size s ~ 1/N of the literature at which the effects of the obstacles can be modelled by a "strange term" added to the Helmholtz equation. Second, we consider high-contrast acoustic metamaterials, in which each of the N heterogeneities are packets of K inclusions filled with a material of density much lower than the one of the background medium. As the contrast parameter vanishes, δ → 0, the effective medium admits K resonant characteristic sizes (si(δ))1≤i≤K and is governed by a Lippmann–Schwinger equation, which is diffusive or dispersive (with negative refractive index) for frequencies ω respectively slightly larger or slightly smaller than the corresponding K resonant frequencies (ωi (δ))1≤i≤K. These conclusions are obtained under the condition that (i) the resonance is of monopole type, and (ii) lies in the "subcritical regime" where the contrast parameter is small enough, i.e. δ = o(N−2)), while the considered frequency is "not too close" to the resonance, i.e. Nδ1/2 = O(|1 - s/si(δ)|) N δ 1 2 = O (| 1 - s / s i (δ) |) $ N{\delta }^{\frac{1}{2}}=O(|1-s/{s}_i(\delta)|)$. Our mathematical analysis and the current literature allow us to conjecture that "solidification" phenomena are expected to occur in the "super-critical" regime Nδ1/2|1 - s/si(δ)|-1 → + ∞ N δ 1 2 | 1 - s / s i (δ) | - 1 → + ∞ $ N{\delta }^{\frac{1}{2}}|1-s/{s}_i(\delta){|}^{-1}\to +\mathrm{\infty }$. [ABSTRACT FROM AUTHOR]

• A mixing rule for imaginary parts of refractive indices is derived. • This Rayleigh Mixing Rule is valid for small particles in the Rayleigh regime. • In certain limits, it is in good agreement with established mixing rules. • The Rayleigh Mixing Rule retrieves imaginary parts of refractive index spectra. • Retrieved imaginary parts of refractive indices are weakly dependent on morphology. A Rayleigh mixing rule that relates the effective imaginary part of the refractive index of a composite medium, such as an aerosol or colloid, to the complex refractive index of the Rayleigh particles is derived using Rayleigh scattering theory. The derivation is simple, straightforward, and only weakly dependent on particle morphology. The Rayleigh mixing rule offers an opportunity to derive the imaginary part of refractive index spectra of Rayleigh particles, suspended in a non-absorbing medium with known refractive index spectrum, from an extinction spectrum of the composite medium. However, for this application, the real refractive index spectrum of the particle must be known reasonably well and the imaginary part must be known well enough to decide between two mathematical solutions for it. The Rayleigh mixing rule is compared with widely used mixing rules (i.e., volume, Maxwell Garnett, and Bruggeman mixing rules) and we show that in the small volume fraction regime both the Maxwell Garnet and Bruggeman mixing rules agree with the Rayleigh mixing rule. [ABSTRACT FROM AUTHOR]

Silica-based membranes exhibit significant promise for the separation of hydrogen from other larger gas molecules based on size sieving mechanism, particularly when employed in membrane reactors. Nevertheless, the migration of silanol bonds (Si–OH) formed under hydrothermal conditions leads to alterations in pore size, ultimately compromising the performance of the membrane. Therefore, this study focuses on determining the pore size of cobalt-doped silica membranes before and after hydrothermal treatment by the apparent activation energy of gas permeation. The Oscillator model and the effective medium theory are employed to estimate the potential pore size distribution, as well as to calculate the apparent activation energy and permeability. The calculated apparent activation energy is compared with experimental data to identify the most probable pore size distribution, which showed the minimum activation energy error to the experimental value. The calculated permeability based on the identified pore size distribution is in line with experimental permeability, which validated the identified pore size distribution. Since silica-based membrane is generally applied in hydrothermal conditions, our model successfully identifies the changes in pore size of silica-based membranes after hydrothermal treatment. The results demonstrated that hydrothermal treatment significantly impacts the pore size of silica-based membranes. Specifically, 5-membered rings are prevalent in the intact membrane, but after hydrothermal treatment, there is a gradual shift of the pore size distribution towards larger pores, potentially leading to a decrease in sieving performance. This methodology presents a promising approach for determining intriguing pore size information of porous materials. [Display omitted] • The relationship between permeation activation energy and PSD was interpreted. • The pore size change before and after hydrothermal treatment was confirmed. • The superior hydrothermal stability of Co3+Si over Co2+Si arises from the more rigid PSD. [ABSTRACT FROM AUTHOR]

The optical and dielectric properties of opals with different water contents were investigated using terahertz time-domain spectroscopy. The refractive indices and absorption coefficients showed different trends due to the different water contents. The effective medium theory was used to extract the intrinsic dielectric permittivity of opal from opal–polytetrafluoroethylene mixtures. The extracted dielectric permittivities were fitted using a double Debye model to analyze the microscopic relaxation mechanism. [ABSTRACT FROM AUTHOR]

The modeling of fluid transport in nanoporous materials has long attracted attention because of the numerous industrial applications of such materials, particularly in membrane-based separations, and others such as adsorptive gas separation and storage, catalysis, and the emerging area of nanofluidics. While effective medium theory has been widely used in modelling this transport, a critical approximation that all pores have the same length is commonly made, whose adequacy is unknown. Here we apply effective medium theory to a randomly overlapping capillary model having an inherent pore length distribution related to the pore radius distribution, and compare the network transport properties with those of the commonly used uniform pore length random network. We find that the consideration of nonuniform pore length distribution leads to significantly higher effective diffusivity and lower associated apparent tortuosity, mediated by the lower mean pore length of large pores due to their higher probability of overlap. The decrease in pore length with an increase in pore radius and the competing effects of adsorption and diffusion, lead to more complex behaviour of the transport properties with variation in temperature and relative standard deviation of the pore radius distribution. Our results clearly demonstrate the importance of considering nonuniformity of pore length, as the conventional uniform pore length approximation leads to significantly different and therefore misleading results. [Display omitted] • Comparison of transport properties of two different pore networks using effective medium theory. • A network of overlapping randomly oriented long capillaries has an inherent pore length distribution. • Effective diffusivity and tortuosity of membranes is strongly affected by pore length nonuniformity. • Nonuniformity in pore length enhances effective diffusivity compared to uniform pore length. [ABSTRACT FROM AUTHOR]

Carbonate rocks have a wide variety of pore shapes and different types of grains, which greatly affect the elastic properties and characteristics of the reservoir. This causes certain difficulties in petroelastic modeling. One of the problems is the scale of the input data, which is then used to build the rock physics model. The paper presents the results of studying three core samples of carbonate rocks of the Upper Devonian and Lower Carboniferous age, which are located in the South Tatar arch (Volga-Ural oil and gas basin (Russia)). To evaluate the structural characteristics of the pore space, the effective medium theory is used. The input data are the results of laboratory studies that include measurements of the velocities of longitudinal and transverse waves, porosity, and thin section and computed tomography analysis. When using the computed tomography, the core samples are analyzed at different resolution (12–37 µm/voxel). The tomography studies of pore space at different scales provide rather different values of porosity and pore aspect ratio. The tomography-based porosity estimations also differ from the experimentally measured porosity (up to 10%). The pore space characteristics provided by different datasets are used to build a rock physics model for the studied rocks that helps to estimate the elastic wave velocities with three different methods of effective medium theory (self-consistent approximation, differential effective medium (DEM), and the Kuster–Toksöz method). A comparison of the velocity estimations with their experimental analogs for dry rocks may indicate the presence of microcracks whose size is beyond the tomography resolution. Improved rock physics models incorporating both pores and microcracks are then used to predict the elastic wave velocities of fluid-saturated rock in a wide porosity range. It is demonstrated that the predicted values significantly differ (up to 30%) from those provided by the rock physics (RP) models constructed without the support of the tomography results. Moreover, other types of models are considered in which the difference in experimental and theoretical velocities is attributed to changes in the host matrix properties as compared to the calcite polycrystal, which are caused by various reasons. [ABSTRACT FROM AUTHOR]