Property Of Medium Research Articles

Characteristics of hollow micron zero valent iron and its transport properties in groundwater: Effect of key engineering parameters and retention mechanism

In this study, a hollow micron zero-valent iron (H-mZVI) was synthesized, and its transport and retention property in saturated porous media was determined via a series of column experiments. Furthermore, the maximum migration distance (Lmax) and sedimentation rate coefficient (Kdep) models of H-mZVI in saturated porous media were established using statistical methods. The results revealed a distinct hollow structure in H-mZVI, with a density of 1.03±0.03 g/cm3, significantly lower than solid micron zero-valent iron (4.57±0.15 g/cm3). FTIR and XRD analyses indicated no formation of new functional groups on H-mZVI's surface, with iron being the main component. The column experiment demonstrated that the Lmax of H-mZVI in saturated porous media was 4.15 times that of solid micron zero-valent iron (mZVI) under the same conditions. The prediction model of Lmax aligned with the linear model, where Lmax correlated positively with particle size, injection velocity, and H-mZVI concentration, but inversely with ionic strength. Medium particle size and injection velocity were the main engineering parameters to control H-mZVI. The prediction model of Kdep accorded with the quadratic model, and an interaction was observed between medium particle size and injection velocity, which jointly affected the deposition rate of H-mZVI. Moreover, the single particle capture coefficient (η0) was hereby calculated and analyzed using the T-E theory. Interception primarily governed the precipitation of H-mZVI in saturated porous media, with gravity sedimentation contributing minimally to η0.

A Novel Finite Element-Based Method for Predicting the Permeability of Heterogeneous and Anisotropic Porous Microstructures.

Permeability is a fundamental property of porous media. It quantifies the ease with which a fluid can flow under the effect of a pressure gradient in a network of connected pores. Porous materials can be natural, such as soil and rocks, or synthetic, such as a densified network of fibres or open-cell foams. The measurement of permeability is difficult and time-consuming in heterogeneous and anisotropic porous media; thus, a numerical approach based on the calculation of the tensor components on a 3D image of the material can be very advantageous. For this type of microstructure, it is important to perform calculations on large samples using boundary conditions that do not suppress the transverse flows that occur when flow is forced out of the principal directions. Since these are not necessarily known in complex media, the permeability determination method must not introduce bias by generating non-physical flows. A new finite element-based method proposed in this study allows us to solve very high-dimensional flow problems while limiting the biases associated with boundary conditions and the small size of the numerical samples addressed. This method includes a new boundary condition, full permeability tensor identification based on the multiscale homogenization approach, and an optimized solver to handle flow problems with a large number of degrees of freedom. The method is first validated against academic test cases and against the results of a recent permeability benchmark exercise. The results underline the suitability of the proposed approach for heterogeneous and anisotropic microstructures.

Introducing the area under stress–velocity curve: Theory, measurement and association with rock properties

AbstractSince many years ago, ultrasonic velocity has been used to investigate the physical and mechanical behaviour of rocks, thereby playing an important role in reservoir characterization and seismic interpretation. In order to develop the knowledge of ultrasonic tools, we performed a noble analysis on the ultrasonic behaviour of rocks under confining stress and evaluated a distinctive property of porous media that is measured as the area under the stress–velocity curve (here defined as S*). We further investigated its relationship with elastic and mechanical behaviours of rock. To validate the theoretical framework developed in this work, 20 core plugs from various rock units with complex microstructures were subjected to triaxial compressional tests to calculate their area under the curve. Calculations were made for crack‐closing, elastic and post‐elastic stages (e.g. pore collapse) along the ultrasonic velocity–stress curve. Moreover, the selected samples had their microstructure investigated by thin‐section studies to quantify their porosity and pore type. The results were analysed to check for the effect of pore type on S* in different stages of the stress–velocity curve. Based on the outputs of the analysis of variance and Pearson's correlation coefficient analysis, the curve had its shape and underlying area closely related to the porosity and pore geometry. Indeed, the results showed that the shale and sandstone with micro cracks and carbonate with stiff pores correspond to smaller and larger areas under the curve in crack‐closing and inelastic stages, respectively. Cross‐correlating the results to compressibility (inverse of bulk modulus), it was figured out that the calculated area under curve was well consistent with the compressibility. In addition, S* represents both static and dynamic behaviours of the rock, and the results revealed that the shape and curvature of the stress–velocity curve give valuable information about the rock microstructure. Another finding was the fact that the type of fluid and wave velocity seemingly affect the S*. Our findings can help interpret wave velocity behaviour in reservoir rocks and other stressful porous media.

Converted wave tomography based on inverse level set and adjoint formulation

SUMMARY Shear wave velocity (Vs) is a fundamental property of elastic media whose estimation from PS converted waves is challenging and requires modelling the boundary where P to S conversion occurs. This paper presents a PS tomography where seismic wave conversion/reflection points correspond to reflectors modelled with the level-set function set to zero [ϕ(x, z) = 0]. The proposed method aims for stable Vs inversion in a seismic acquisition setting using multicomponent receivers. Synthetic models simulating true Vs, Vp and the location of the geological reflector are used in the study. The inversion starts by locating a flat reflector, ϕ(x, z) = 0, which defines the zone Ω1 between the surface and the reflector, where the initial Vs and Vp fields are also set. To calculate the traveltimes of incident PT (P wave that propagates in Ω1 from source to the reflector), converted PS and reflected PP waves, for both observed and modelled data (forward problem), the methodology proposed by Rawlinson and Sambridge is adopted. This method uses the arrival times of the P waves, Tpt, from the seismic source at each reflector point as secondary sources generating the times Tps and Tpp. These times are calculated as a solution to the eikonal equation by using the Fast Marching method. The PS and PP residual times are minimized by updating Vs, Vp and ϕ(x, z) = 0 through adjoint variables designed from a formulation using Lagrange Multipliers in a variational context. The performance of the algorithm is evaluated for models with synclinal, sinusoidal and monoclinal reflector geometries using numerical tests considering the inversion of: (1) ϕ, given the true values of Vs and Vp; (2) ϕ and Vs, given the true value of Vp; (3) ϕ and Vp, given the true value of Vs and (4) the three parameters ϕ, Vs and Vp, simultaneously. Good results are obtained by inverting Vs and ϕ, given the true value of Vp. The simultaneous inversion of the three parameters exhibits promising results, despite the illumination problems caused by the different distribution of the PS, PP and PT time gradients due to the geometry of the reflectors and the acquisition setting (sources–receivers in the same plane). The proposed tomography estimates Vs and reflector positions which could help in statics corrections and improve the lithological characterization of near surface.

Reflection modulation generated by scale-free network resonator periodic structure

The pattern of resonator in a periodical array is decisive for its response under impinging electromagnetic wave. A scale-free network resonator is proposed by connecting sub-units in the form of scale free network. Scale-free network resonator array’s reflectivity near resonant frequency could be modulated at arbitrary value between zero and unity, which is different from known resonator array or frequency selective surface. Reflection amplitude modulation could generate rich behaviors, as effective medium property in wide band could be maintained near zero constant, which means zero phase shift and is favorable in radar radome structure. S-parameter analysis indicates amplitude modulation is owing to polarization conversion generated by network links. Scale-free network resonator array has application potentials in future radar radomes, electromagnetic wave lens and microwave antenna panels.

Complexes GET 17/1–KVI and GET 17/2–KVN from GET 17–2018 State Primary Standard of Dynamic and Kinematic Liquid Viscosities

Viscosity is the most important property of liquid medium, determining the quality, as well as the possibility of their processing and transportation. Viscosity measurements are performed in many industries to control technological processes in which viscosity is one of the controlled parameters of the final product. Accuracy of viscosity measurements is also necessary in medicine and biology to organize research for new materials.This review article raises issues of measuring liquid viscosity using the capillary method, reveals the factors and reasons justifying the emergence of the capillary method as the main method of high-precision measurements used in many countries.The author describes two standard complexes from GET 17–2018 State Primary Standard of Dynamic and KinematicLiquid Viscosities. The first is EK GET 17/1-KVI designed for reproducing, storing, and transmitting a unit of kinematic viscosity in the temperature range from 20 to 40 °C. The second is EK GET 17/2-KVN designed for reproducing, storing, and transmitting a unit of kinematic viscosity in the temperature ranges from –40 to +20 °C and from 40 to 150 °C. The focus is on the operating principle and main metrological characteristics of these reference complexes, as well as the results of international key comparisons involving them.In the future, the research materials may influence the development vector of means and methods for measuring liquid viscosity.

Reciprocal action of natural bianisotropy and artificial chirality on electromagnetic propagation in medium

Background. The present article investigates the reciprocal action of specific medium effects on electromagnetic waves propagation. The object of study is a moving dielectric, which at rest already demonstrate bianisotropic properties, i. e., it is a synthetic material, e. g., chiral media with Ω-particles. Bianisotropic material equations are the most general for describing the effects of electromagnetic waves interaction with complex medium. Studying and analyzing them is proving to be a notable scientific problem. Natural bianisotropy is a property of simple media under special conditions (state of motion, internal currents and diffusion processes), whereas artificial bianisotropy is an inherent property of the synthetic material itself (composite material, material with different metaparticles).
 Aim. The main goal of the work is to generalize the already available data. On it basis, then, obtain analytical expressions, which can be effectively used for the experiments designing, creating new computational techniques for solving direct and inverse electromagnetic diffraction problems.
 Methods. In this paper, analytical methods are applied to obtain the resulting close-form expressions.
 Results. Three classes of effects have been identified that have a significant reciprocal effect on each other: gyrotropy, spatial dispersion, and temporal dispersion. In this article it was shown that the gyrotropy of the medium has not only a simple additive effect, but under some, specific conditions, can be related to the system emergence.
 Conclusion. The reciprocal action of the spatial dispersion of the moving chiral medium, generally has different scales in range. Temporal dispersion was investigated, which does not have a simple additive property, because even an isotropic medium acquires fundamentally new material properties of bianisotropy when it moves.

An Adaptive PML Finite Volume Algorithm for the Scattering by Periodic Gratings

In this paper, we studied the finite volume formulations for solving the diffraction grating problem that is truncated by the perfectly matched layer (PML) technique. Based on a reliable the a-posteriori error estimate, an adaptive PML finite volume method is discussed for the numerical approximation of the diffraction grating problem. The PML parameters are obtained numerically by sharp a-posteriori error estimates of the PML finite volume method such as the thickness of the layer and the medium property. It is worth mentioning in the a-posteriori error estimates that we derive the error representation formula and use a [Formula: see text]-orthogonality property of the residual similar to the Galerkin orthogonality used in the finite element method. Furthermore, the lower bound is established to demonstrate the efficiency of the a-posteriori error estimates. Numerical experiments are given to illustrate the accuracy and robustness of our adaptive algorithm.

Intrinsic and scattering attenuations of the Sichuan-Yunnan region in China from S coda waves

Seismic attenuation is a fundamental property of the Earth's media. Attenuation structure for the complicated geological structures with strong seismicity in the Sichuan-Yunnan region is poorly studied. In this study, we collected 108,399 waveforms of 11,517 local small earthquakes with magnitudes between 1.5 and 3.5 from January 2014 to September 2021 in the Sichuan-Yunnan region and its adjacent areas. We employed an envelope inversion technique for separating the intrinsic and scattering attenuations of the S coda wave, and obtained the intrinsic and scattering attenuation structures for frequencies between 0.25 and 8.00 Hz. The attenuation structures correlate well with the geological units, and some major faults mark the attenuation variations where historic large earthquakes have occurred. The regional average attenuation shows a negative frequency dependence. The average scattering attenuation has a faster descending rate than the average intrinsic attenuation, and is dominant at low frequencies, while at high frequencies the average intrinsic attenuation is stronger. The lateral variation in the intrinsic attenuation is consistent with the variation in heat flow, the scattering attenuation may be related to the scatter distribution and size. The total attenuation is consistent with the previous studies in this region, and the separate intrinsic and scattering attenuation may be useful in understanding regional tectonics and important in earthquake prevention and disaster reduction.

On gravity as a medium property in Maxwell equations

On gravity as a medium property in Maxwell equations

Peculiarities of using the hypothesis of S.O. Kulon for soil dispersed sediments

The publication is devoted to the outstanding French scientist Charles Auguste Coulomb, who 250 years ago (1773) proposed a hypothesis that relates tangential and normal stresses through the angle of internal friction of soils. This hypothesis provides reliable results while maintaining Hooke's law. Beyond this law, it is necessary to take into account the property of the soil medium, namely the change in volume during shearing or displacement of soils, which requires the introduction of additional dilatancy parameters.
 It is known that there are two types of friction in nature: sliding and rolling friction. At certain values of deformation in the soil medium, sliding friction, which is characterised by the traditional value of the internal friction angle, initially appears in certain zones of the soil medium at low deformations. Further increase in deformation causes rolling friction, which is characterised by a different value of the internal friction angle, almost one third less than the traditional value of the internal friction angle of the soil. This fact must be taken into account when performing numerical modelling of a dispersed soil medium from the beginning of loading to its failure. In this publication, we discuss the methodology for finding the parameters of the dilatancy theory to reveal the elastic-plastic deformation of cohesionless soils based on experimental results. Recommendations are given on the use of the Coulomb hypothesis in engineering calculations and on the relationship between tangential and normal stresses through the angle of internal friction of soils. For a correct description of the nonlinear process of soil deformation, it is necessary to use the parameters of the dilatancy theory, which can be investigated on an axisymmetric shear tester.
 The results of tests of sand of medium size, medium density, low-moisture, homogeneous on several devices showed that the values of the angle of internal friction of soils differ depending on the design of the device. This fact is recommended to be taken into account when designing geotechnical facilities.

Medium transmission property of the interfacial transition zone between MK-GGBFS geopolymer mortar and aggregate

In this study, metakaolin (MK)–ground granulated blast furnace slag (GGBFS) was used to prepare geopolymer mortar, and concrete was prepared using prismatic-shaped basalt or aged cement mortar block as coarse aggregate. The pore structure characterization of the mortar, chloride binding capacity of the corresponding paste and the micro dimension of the interfacial transition zone (ITZ) in concrete were analysed by using a mercury intrusion porosimeter, the chloride adsorption equilibrium method and scanning electron microscopy-energy dispersive spectroscopy, respectively. The medium transmission properties of the concrete and corresponding mortar were analysed through a moisture diffusion test, chloride migration test, and chloride natural diffusion test. On this basis, the permeability resistance of the ITZ in geopolymer concrete was studied by manipulating the parameters for the basalt aggregate. The result shows that the geopolymer mortar exhibits higher porosity compared to cement mortar with similar strength, while the most probable pore size is significantly smaller, with more than 80% of the pores showing a pore size of less than 50 nm. The chloride binding mechanism for geopolymer paste primarily involves physical adsorption, and shows a greater binding capacity than cement paste at a chloride ion concentration greater than 1 mol/L. The medium transmission coefficient for geopolymer concrete is found to be 55.1–79.0% of that of cement concrete for the same parameters of the coarse aggregate. The impermeability of geopolymer concrete and its ITZ is found to be always better than that of cement concrete for varying parameters of the coarse aggregate.

Mode attraction, rejection and control in nonlinear multimode optics

Novel fundamental notions helping in the interpretation of the complex dynamics of nonlinear systems are essential to our understanding and ability to exploit them. In this work we predict and demonstrate experimentally a fundamental property of Kerr-nonlinear media, which we name mode rejection and takes place when two intense counter-propagating beams interact in a multimode waveguide. In stark contrast to mode attraction phenomena, mode rejection leads to the selective suppression of a spatial mode in the forward beam, which is controlled via the counter-propagating backward beam. Starting from this observation we generalise the ideas of attraction and rejection in nonlinear multimode systems of arbitrary dimension, which paves the way towards a more general idea of all-optical mode control. These ideas represent universal tools to explore novel dynamics and applications in a variety of optical and non-optical nonlinear systems. Coherent beam combination in polarisation-maintaining multicore fibres is demonstrated as example.

A study of kinematic viscosity approach with air as a gas medium for turbine flowmeter calibration

Calibrating a gas flowmeter requires a suitable working medium that represent its use in the real operating condition. However, factors like installation conditions, costs, and safety considerations may necessitate to utilize a different medium for calibration. The accuracy of measuring fluid flow by a flowmeter is greatly influenced by the kinematic viscosity property of the gas medium. In this particular study, a turbine flowmeter for compressed natural gas (CNG) application was calibrated using air as a substitute with an approach that simulated the kinematic viscosity property of CNG. Here, the pressure and temperature of the air were calculated to achieve the same kinematic viscosity value as CNG during the calibration process, which was accomplished by adjusting the setting of a regulating instrument in the calibration installation. Furthermore, argon (Ar) was also used for comparison with air, with a modification in working pressure to attain similar kinematic viscosity properties for both gases. The calculation results showed that the working pressure setting for the air used was 4.5 bars, while for argon was 3.38 bars to achieve similar kinematic viscosity. By utilizing air instead of CNG, a minimum and maximum volume flowrate difference of −0.0242 m3/h and 0.0016 m3/h, respectively, was observed, with an absolute average of 0.0086 m3/h or 0.8 %. This study reveals the effectiveness of the kinematic viscosity approach in calibrating a turbine flowmeter under working pressure of up to 4.5 barg. This process results in uncertainty measurement of under 1 % when calibrating gas flowmeters, using air as the medium.

Maxwell equations in curved spacetime

In curved spacetime, Maxwell’s equations can be expressed in forms valid in Minkowski background, with the effect of the metric (gravity) appearing as effective polarizations and magnetizations. The electric and magnetic (EM) fields depend on the observer’s frame four-vector. We derive Maxwell’s equations valid in general curved spacetime using the fields defined in the normal frame, the coordinate frame, and two other non-covariant methods used in the literature. By analyzing the case in the generic frame we show that the EM fields, as well as the charge and current densities, defined in non-covariant ways do not correspond to physical ones measured by an observer. We show that modification of the homogeneous part is inevitable to any observer, and such a modification is difficult to interpret as the effective medium property. The normal frame is the relevant one to use as it gives the EM fields measured by an Eulerian observer.

Marketing Strategy of Property Sector Crowdfunding Company of PT Esa Dana Unggul

The demand for housing needs in Indonesian society is still quite large and this is positively welcomed by housing developers to compete in providing the best housing for the community. From the data on available housing units above compared to the housing needs (backlog) by the community, there is still a very large gap. For example, the need for houses in West Java in 2021 is 2,638,153 units, while the available housing units in 2021 are only 11,115 units. In fulfilling the provision of residential houses, small and medium scale property developers need capital both for purchasing land and building units. This is where crowdfunding exists to help developers take advantage of opportunities to provide housing by supporting the availability of developer capital. From the investor side, Securities Crowdfunding is also a new alternative as a choice of investment instruments. The increase in the number of people who are aware of investment currently is also accompanied by an increasing number of investment instruments that are growing in society. Through the SCF scheme, investors and parties who need funding will be brought together through a digital-based platform or application. This is where property developers need capital and the desire of investors to look for investment instruments that are safe and with attractive investment profit sharing can be filled with the presence of SCF.Research method using STP and Marketing Mix (NICE and 4 P) strategies.Result This analysis can help the securities crowdfunding companies in property in Indonesia use their marketing strategy.

Wettability modification effects on relative permeability end-points: Comparative analysis of surfactant agents for enhanced oil recovery

This research examines the impact of wettability alteration on the end points of relative permeability, a crucial property of fluids and porous media that influences the displacement processes of immiscible fluids through such media. The estimation of the mobility ratio for oil recovery relies on these end points, which are influenced by connate water saturation and residual oil saturation. To investigate this relationship, carbonate rock is generally subjected to wettability alteration using surfactant agents, and core flooding is employed to determine the relative permeability before and after the alteration. The wettability of the rock is commonly assessed through contact angle measurements. Two surfactants, TritonX-100 (Tx-100) and Cedar, were tested in reducing the wettability of the porous media for oil. The contact angle measurements revealed that Tx-100 was more effective for this purpose than Cedar. Furthermore, the relative permeability tests indicated that both surfactants decreased residual oil saturation, but Tx-100 also improved system pressure. In contrast, Cedar reduced residual oil saturation but increased system pressure, possibly because of its high viscosity. The results also demonstrate that injecting Tx-100 leads to a 14% increase in ultimate oil recovery compared with water injection, while Cedar injection increased the recovery factor by 5%. This difference may be attributed to the incomplete coverage of the pore wall by Cedar or its weaker chemical structure than Tx-100. Notably, in carbonate cores, neither non-ionic surfactant enhanced oil recovery.

Seismic Characterization of the Blue Mountain Geothermal Field

Subsurface characterization is crucial for geothermal energy exploration and production. Yet hydrothermal reservoirs usually reside in highly fractured and faulted zones where accurate characterization is very challenging because of low signal-to-noise ratios of land seismic data and lack of coherent reflection signals. We perform an active-source seismic characterization for the Blue Mountain geothermal field in Nevada using active seismic data to reveal the elastic medium property complexity and fault distribution at this field. We first employ an unsupervised machine learning method to attenuate groundroll and near-surface guided-wave noise and enhance coherent reflection and scattering signals from noisy seismic data. We then build a smooth initial P-wave velocity model based on an existing magnetotellurics survey result, and use 3D first-arrival traveltime tomography to refine the initial velocity model. We then derive a set of elastic wave velocities and anisotropic parameters using elastic full-waveform inversion, and obtain PP and PS images using elastic reverse-time migration. We identify major faults by analyzing the variations of seismic velocities and anisotropy parameters, and reveal mid- to small-scale faults by applying a supervised machine learning method to the seismic migration images. Our characterization reveals complex velocity heterogeneities and anisotropies, as well as faults, with a high spatial resolution. These results can provide valuable information for optimal placement of future injection and production wells to increase geothermal energy production at the Blue Mountain geothermal power plant.

Direct prediction of relative permeability curve from 3D digital rock images based on deep learning approaches

The relative permeability curve is one of the key features to evaluate the flow property of a porous medium, which is important in petroleum and gas industry, yet it is not easy to obtain. In this study, we proposed a new intelligent way to predict the relative permeability curves directly from 3D digital rock images, compared with other existing artificial intelligence (AI) methods that usually used indirect geometrical parameters as inputs. The inputs of our AI model are the digital rock images and fluid/rock physical properties such as wettability and interfacial tension; the outputs (relative permeability curves) are obtained by an improved pore-network model. We test three deep learning methods (CNN, ConvLSTM-FC, and ConvLSTM-CNN) and compare their accuracy in the predictions for both sandstone and volcanic rock types. The results show that the overall prediction accuracy of the deep hybrid ConvLSTM-CNN method is the highest, reaching 95%. The well-trained model is further applied to successfully predict the effects of wettability and interfacial tension on the relative permeability curves of a Berea sandstone.

Multiscale model reduction of finite-difference frequency-domain wave modelling in acoustic media

SUMMARY Frequency-domain wave modelling can easily describe the visco-acoustic behaviour of wave propagation using frequency-dependent velocities. Conventional finite-difference (FD) modelling in the frequency domain is computationally prohibitive for solving the acoustic Helmholtz equation in complicated and large geological models. To reduce the computational cost of traditional FD Helmholtz solvers, we develop a multiscale FD frequency-domain method that uses multiscale basis functions to significantly reduce the dimension of system matrices associated with the Helmholtz equation. Due to the insufficient accuracy of the first-order multiscale basis functions in the case of strongly heterogeneous models, we introduce the multinode coarse-element scheme into the scalar Helmholtz equation, a scheme previously developed in the extended multiscale finite-element method for vector problems. This multinode scheme enables multiscale basis functions to capture accurate fine-scale medium property variations. We use one homogeneous model and two heterogeneous models to validate our multiscale method for accuracy and computational cost. Numerical results demonstrate that our new approach can significantly reduce the time and memory costs of acoustic wave modelling while maintaining accuracy, indicating the great potential of our multiscale method in large-scale modelling applications.