Layered Model Research Articles

Anti-plane waves in a liquid-loaded piezo-flexo-electric layered model with interface energy

The basic design of a Love wave (LW) bio-sensor contains the loading of a viscoelastic liquid on top of a layered structure with distinct viscoelastic properties. Changes in the characteristics of the propagating acoustic wave caused by biochemical interactions at the sensing area can be detected at the output Inter digital transducer (IDT). The propagation of the anti-plane (AP) wave is discussed in this work in a layered structure of piezo-flexo-electric (PFE) layer bonded with a PFE half-space having a soft reinforced layer at the interface. The free surface of the PFE layer is loaded with viscous liquid. The viscosity of the loaded liquid introduces losses and results in the damping of the wave. For the formulation of the problem with interface energy, the Gurtin–Murdoch approach is used. Using suitable conditions, a dispersion relation for propagating waves is derived in complex form. On separating the dispersion relation in real and non-real parts, the expressions relating the phase and damp velocities with wave number are derived. The obtained theoretical results are portrayed for the numerical data of PFE materials and distinct data of the interface layer. The obtained results are validated with pre-existing literature.

Residential differentiation characteristics based on “socio-spatial” coupling: A case study of Zhengzhou

Residential differentiation transcends its physical aspect, necessitating attention to deeper issues such as group-based disparities underlying spatial configurations. This paper based on multiple data sources, utilizes indicator dimensionality reduction, spatial clustering, and indices of dissimilarity to conducts clustering and matching analysis of social groups and residential spaces. It summarizes and distills the social-spatial coupling types of residential differentiation in Zhengzhou city under a layered model, focusing on social spatial polarization and solidification phenomena in China, and proposing optimization and control recommendations. Findings include: (1) Residential space differences primarily manifest in pricing, while social group distinctions focus on consumption capacity and age. Residential differentiation is a process of continuous differentiation and interaction between two dimensions; (2) Urban housing types do not strictly align with socio-economic attributes, with six typical coupling types observed within the “inner city - new city - outskirts” framework; (3) The “filtering” effect of high housing prices in Zhengzhou leads to wealthy clustering in new city outskirts, while low-income groups aggregate in peripheral and declining inner-city areas, resulting in pronounced spatial segregation; (4) Urban residential differentiation reflects the interaction between macro-controls in the housing market and individual residential choices, serving as a spatial representation of social stratification outcomes.

Geoelectrical image of the Sabalan geothermal reservoir from magnetotelluric studies

The magnetotelluric (MT) survey of the Sabalan geothermal zone, which includes 22 stations along three traverse profiles across the main prospect zone, was conducted in 2007. The geophysical investigation utilized sharp boundary inversion of processed MT data due to the high contrast of electrical resistivity between embedded layers. This method was preferred to suppress the smeared-out impact of the smooth inversion algorithm on retrieving geological layering. The analysis of MT data led to the use of a 2D inversion algorithm to visualize the geothermal reservoir. Additionally, the geoelectrical strike of the main geothermal target was determined, showing some inconsistency across the profiles. The simulation of synthetic numerical models is conducted to evaluate the effectiveness of sharp boundary inversion compared to a smooth algorithm in sharp gradient mediums, specifically in terms of electrical characteristics, for plausible geothermal scenarios. The Finite Element method (FEM) was employed to construct these models, followed by running the 2D forward and inversion processes. The meshing and initial parameters of the modeling were set based on information obtained from prior geological and geophysical investigations. A sharp boundary inversion can be accurately implemented by introducing layering constraints along each profile surrounding the probable sought geothermal reservoir target. These layering constraints encompass the conductive cap, topsoil, and basement rocks, which are the key components of a plausible geothermal configuration. The results of the comparison indicate that the sharp boundary inversion technique effectively restored the boundary between neighboring layers that had significant differences in electrical resistivity. This was achieved when the smoothing algorithm failed to produce an accurate representation of the layered model. Ultimately, conceptual geological models were developed to illustrate the plausible structures corresponding to each profile, focusing on the sought geothermal reservoir targets. It can be deduced that many misunderstandings in the smoothing inversion algorithm will be omitted if the sharp boundary algorithm is used in highly electrical gradient structures. Based on the outcomes, a trachyandesite, andesite, and altered andesite reservoir exists at an elevation of 1600 to −2000 m. The reservoirs were recovered precisely with sharp and discriminable interfaces. Therefore, accurate interfaces led us to determine the conductive cap, heat source, and topsoil stacking as the main components of the geothermal system.

A Layered Employee Recruitment Model and Strategy Considering Value Fitness

Based on the status and role of employees at different levels in the enterprise, a hierarchical employee recruitment model (3C model) and corresponding strategies based on the perspective of values are proposed. For enterprises, rather than striving to influence and change their employees' values, it is better to choose employees who align with the company's values during recruitment. Senior managers are the leaders and leaders of enterprises, and their value orientation in business management is closely related to the long-term development of the enterprise. When recruiting, emphasis should be placed on the compatibility of values, consciously forming heterogeneity in the management values of senior team members, and improving the effectiveness of team operation; Middle level managers are the backbone of the enterprise, playing an important role in connecting the past and the future. When recruiting, emphasis should be placed on consistency of values, and their value assessment standards can be determined based on the 3V model, with appropriate consideration given to the widely recognized life values of middle level managers; Grassroots employees are the specific executors of work, and recruitment should focus on the competence of values. Enterprise values can be integrated into the competency model of the position, and comprehensive consideration should be given to specific job characteristics. The hierarchical employee recruitment strategy based on the perspective of values provides a new perspective and method for the recruitment and selection of employees from a more detailed perspective.

Towards an interdisciplinary formalization of soundscapes.

Soundscapes have been studied by researchers from various disciplines, each with different perspectives, approaches, and terminologies. Consequently, the research field determines the actual concept of a specific soundscape with the associated components and also affects the definition itself. This complicates interdisciplinary communication and comparison of results, especially when research areas are involved which are not directly focused on soundscapes. For this reason, we present a formalization that aims to be independent of the concepts from the various disciplines, with the goal of being able to capture the heterogeneous data structure in one layered model. Our model consists of time-dependent sound sources and geodata that influence the acoustic composition of a soundscape represented by our sensor function. Using a case study, we present the application of our formalization by classifying land use types. For this we analyze soundscapes in the form of recordings from different devices at 23 different locations using three-dimensional convolutional neural networks and frequency correlation matrices. In our results, we present that soundscapes can be grouped into classes, but the given land use categories do not have to correspond to them.

Multilingual Program Code Classification Using $n$-Layered Bi-LSTM Model With Optimized Hyperparameters

Multilingual Program Code Classification Using $n$-Layered Bi-LSTM Model With Optimized Hyperparameters

Numerical Investigation of Layered Homogeneous Skull Model for Simulations of Transcranial Focused Ultrasound

Background and ObjectivesThe influence of the intracranial pressure field must be discussed with the development of a single-element transducer for low-intensity transcranial focused ultrasound because the skull plays a significant role in blocking and dispersing ultrasound wave propagation. Ultrasound propagation is mainly affected by the structure and acoustic properties of the skull; thus, we aimed to investigate the impact of simplifying the acoustic properties of the skull on the simulation of the transcranial pressure field to present guidance for efficient skull modeling in full-wave simulations. Materials and MethodsWe constructed a three-dimensional computational model for ultrasound transmission with the same structure but varying acoustic properties of the skull. The structural information and heterogeneous acoustic properties of the skull were acquired from computed tomography images, and we segmented the skull into three layers (3 L), including spongy and compact bones. We then assigned homogeneous acoustic properties to a single layer (1 L) or 3 L of the skull. In addition, we investigated the influence of different types of transducers and different ultrasound frequencies (1.1 MHz, 0.5 MHz, and 0.25 MHz) on the intracranial pressure field to provide a comparison of the heterogenous and homogeneous models. ResultsWe indicated the importance of numerical simulations in estimating the intracranial pressure field of the skull owing to beam distortions. When we simplified the skull model, both the 1 L and 3 L models showed contours of the acoustic focus comparable to those of the heterogeneous model. When we evaluated the peak pressure and volume of the acoustic focus, the 1 L model produced a better estimation of peak pressure with a difference <10%, and the 3 L model is suitable to obtain smaller errors in the volume of the acoustic focus. ConclusionsIn conclusion, we examined the possibility of simplification of skull models using 1 L and 3 L homogeneous properties in the numerical simulation for focused ultrasound. The results show that the layered homogeneous model can provide characteristics comparable to those of the acoustic focus in heterogeneous models.

DeepDet: YAMNet with BottleNeck Attention Module (BAM) for TTS synthesis detection

Spoofed speeches are becoming a big threat to society due to advancements in artificial intelligence techniques. Therefore, there must be an automated spoofing detector that can be integrated into automatic speaker verification (ASV) systems. In this study, we recommend a novel and robust model, named DeepDet, based on deep-layered architecture, to categorize speech into two classes: spoofed and bonafide. DeepDet is an improved model based on Yet Another Mobile Network (YAMNet) employing a customized MobileNet combined with a bottleneck attention module (BAM). First, we convert audio into mel-spectrograms that consist of time–frequency representations on mel-scale. Second, we trained our deep layered model using the extracted mel-spectrograms on a Logical Access (LA) set, including synthesized speeches and voice conversions of the ASVspoof-2019 dataset. In the end, we classified the audios, utilizing our trained binary classifier. More precisely, we utilized the power of layered architecture and guided attention that can discern the spoofed speech from bonafide samples. Our proposed improved model employs depth-wise linearly separate convolutions, which makes our model lighter weight than existing techniques. Furthermore, we implemented extensive experiments to assess the performance of the suggested model using the ASVspoof 2019 corpus. We attained an equal error rate (EER) of 0.042% on Logical Access (LA), whereas 0.43% on Physical Access (PA) attacks. Therefore, the performance of the proposed model is significant on the ASVspoof 2019 dataset and indicates the effectiveness of the DeepDet over existing spoofing detectors. Additionally, our proposed model is robust enough that can identify the unseen spoofed audios and classifies the several attacks accurately.

Analytical model for geotextile-enhanced horizontal drain vacuum consolidation of slurries

Horizontal drains are gradually introduced to the vacuum preloading method to improve dredged slurries by adding geotextiles to alleviate the blockage in the consolidation process. This study considers the consolidation of slurries enhanced by the vacuum preloading method with geotextile combined horizontal drains based on a double-layered consolidation model. The model approximates geotextile as a special soil layer possessing an equivalent consolidation factor. An analytical solution of the layered consolidation model is obtained using the Laplace transform and the finite Fourier transform method. The effectiveness of the solution is verified by comparing it with the one-dimensional double-layered consolidation solution and the one-dimensional consolidation with a partially permeable boundary. Through comparison with laboratory experiments, the model shows good fitness with the test results in the literature. The influences of related parameters, including the drain arrangement densities, soil parameters, and geotextile parameters, are discussed on average consolidation degree and pore water pressure. The influence mechanism is explained regarding drainage path and vacuum pressure transfer. Findings demonstrate that geotextile facilitates vacuum transfer and promotes soil consolidation, especially when the smaller density of drains’ deposition and lower soil permeability are applied.

The Effects of Layer-Induced Elastic Anisotropy on Microseismic Monitoring Records in Underground Coal Mines

Real-time microseismic observations are extensively used in underground hard rock mines. However, microseismic monitoring in coal mines is not common. In this study, the features of microseismic (MS) event waveforms were discussed under conditions of thin-layered sedimentary media. The possibility of source mechanism evaluation was considered for the MS event recorded in coal mine. Moment tensor (MT) inversion of the waveforms can be challenging due to influence of thin-layered medium structure. Splitting of shear SH- and SV-waves is one of the characteristic features that affect MS records in coal mines. The effect of splitting was demonstrated using real microseismic data collected by an underground seismic array installed in the Polosukhinskaya coal mine, Russia. Velocities of shear SH- and SV-waves were estimated from travel times. The results reveal significant variations in shear wave velocities composed of a radial anisotropy of 75%, thus confirming the importance of a thin-layered model for moment tensor inversion. The thin-layered model was built for geological conditions at the Polosukhinskaya coal mine and synthetic seismograms were generated using QSEIS (Pyrocko OS). A full moment tensor of a single typical event was found employing the layered 1D velocity model.

Enhancing Security in Internet of Things (IoT) Architecture through Defense-in-Depth Mechanism: A Comprehensive Study

The Internet of Things (IoT) has revolutionized various domains, offering connectivity and data sharing among diverse devices and services. However, this interconnectedness poses significant security challenges, primarily centered around confidentiality, integrity, and availability. This paper investigates the security issues embedded in the layers of IoT architecture, ranging from the perception layer to the application layer. By leveraging the Defense-in-Depth security mechanism, we propose a comprehensive approach to fortify IoT systems against cyber threats. The Defense-in-Depth strategy is illustrated through a layered model, addressing security concerns at the perimeter, host, OS/application, and data layers. The study explores various security measures applicable to each layer, emphasizing the need for a multi-faceted approach to ensure the robustness of IoT security. Keywords: Internet of Things (IoT), Security Issues, Defense-in-Depth Mechanism, Perception Layer, Network Layer, Data Processing Layer, Application Layer, Confidentiality, Integrity, Availability

Trans-dimensional joint inversion of modal amplitude and arrival- time data for geoacoustic properties in layered muddy sediments

Long-range sound fields in a shallow-water waveguide can be expressed as a summation of several dispersive propagating modes. Modal arrival times as a function of frequency, extracted via warping time-frequency analysis, have been used by many researchers to estimate sound speeds and densities for layered models of the seabed sediments. This paper explores joint inversion of modal amplitude spectra together with arrival times to also estimate sediment-layer attenuations. To consider the common case in underwater-acoustic applications where the source amplitude spectrum is unknown, we include this spectrum as unknown parameters in the inversion, formulated implicitly within the likelihood function. Trans-dimensional Bayesian inversion is applied to estimate marginal probability profiles of the geoacoustic properties, providing quantitative uncertainties. The data considered here were collected on the New England Mud Patch during the 2017 Seabed Characterization Experiment. [Work supported by the Office of Naval Research.]

Adaptive-Coefficient Finite Difference Frequency Domain Method for Solving Time-Fractional Cattaneo Equation with Absorbing Boundary Condition

The time-fractional Cattaneo (TFC) equation is a practical tool for simulating anomalous dynamics in physical diffusive processes. The existing numerical solutions to the TFC equation generally deal with the Dirichlet boundary conditions. In this paper, we incorporate the absorbing boundary condition as a complex-frequency-shifted (CFS) perfectly matched layer (PML) into the TFC equation. Then, we develop an adaptive-coefficient (AC) finite-difference frequency-domain (FDFD) method for solving the TFC with CFS PML. The corresponding analytical solution for homogeneous TFC equation with a point source is proposed for validation. The effectiveness of the developed AC FDFD method is verified by the numerical examples of four typical TFC models, including the different orders of time-fractional derivatives for both the homogeneous model and the layered model. The numerical examples show that the developed AC FDFD method is more accurate than the traditional second-order FDFD method for solving the TFC equation with the CFS PML absorbing boundary condition, while requiring similar computational costs.

Retrieval of chromophore concentration changes in a digital human head model using analytical mean partial pathlengths of photons.

Continuous-wave functional near-infrared spectroscopy has proved to be a valuable tool for assessing hemodynamic activity in the human brain in a non-invasively and inexpensive way. However, most of the current processing/analysis methods assume the head is a homogeneous medium, and hence do not appropriately correct for the signal coming from the scalp. This effect can be reduced by considering light propagation in a layered model of the human head, being the Monte Carlo (MC) simulations the gold standard to this end. However, this implies large computation times and demanding hardware capabilities. In this work, we study the feasibility of replacing the homogeneous model and the MC simulations by means of analytical multilayered models, combining in this way, the speed and simplicity of implementation of the former with the robustness and accuracy of the latter. Oxy- and deoxyhemoglobin (HbO and HbR, respectively) concentration changes were proposed in two different layers of a magnetic resonance imaging (MRI)-based meshed model of the human head, and then these changes were retrieved by means of (i)a typical homogeneous reconstruction and (ii)a theoretical layered reconstruction. Results suggest that the use of analytical models of light propagation in layered models outperforms the results obtained using traditional homogeneous reconstruction algorithms, providing much more accurate results for both, the extra- and the cerebral tissues. We also compare the analytical layered reconstruction with MC-based reconstructions, achieving similar degrees of accuracy, especially in the gray matter layer, but much faster (between 4 and 5 orders of magnitude). We have successfully developed, implemented, and validated a method for retrieving chromophore concentration changes in the human brain, combining the simplicity and speed of the traditional homogeneous reconstruction algorithms with robustness and accuracy much more similar to those provided by MC simulations.

The effects of the acoustic resonance induced in the atmosphere

After strong earthquakes and volcanic eruptions, geomagnetic oscillations with frequencies of 3.5–4.0 mHz have sometimes been observed. In this paper, we theoretically study the probable cause of these phenomena, which is related to the vertical acoustic resonance arising between the Earth’s surface and the thermosphere due to the propagation of the atmospheric wave corresponding to the acoustic branch generated by surface displacements. In the plane layered model of the atmosphere and ionosphere with inclined geomagnetic field, we analyze the propagation of two-dimensional (2D) harmonic acoustic wave. The height of the reflecting atmospheric layer corresponds to the region of sharp temperature change close to the thermosphere boundary ∼80–90 km. In this case, the calculated fundamental resonant frequency is close to the frequencies of the observed oscillations. The solution of this problem is used to calculate currents and electromagnetic perturbations in the atmosphere and ionosphere. The ionospheric E-layer is considered in the thin layer approximation. In this approximation, the formulas describing the geomagnetic perturbations (GMP) in the ionosphere and on the Earth’s surface are derived. The GMP spectrum contains a sharp maximum at the frequency corresponding to the acoustic resonance. According to the calculations, close to the resonance frequency, the spectral powers of GMPs on the ground can reach 5–30 nT2/Hz, which is consistent with the results of ground-based measurements.

Joint wave-equation inversion of Rayleigh and Love dispersion curves

Wave-equation dispersion (WD) inversion techniques for surface waves have proven to be a robust way to invert the S-wave velocity model. Unlike 1D dispersion curve inversion, WD method obviates the need for a layered model assumption and reduces the susceptibility to cycle-skipping issues in surface wave full-waveform inversion. Previous WD inversion experiments conducted on Rayleigh and Love waves have highlighted that inverting Love waves yields better stability due to their independence from the P-wave velocity model. Nevertheless, Rayleigh waves possess the advantage of greater penetration depth compared with Love waves with similar wavelengths. Therefore, combining the two types of surface waves is a feasible way to improve the accuracy of S velocity tomograms. In light of this, we develop a novel approach: a joint WD inversion encompassing Rayleigh and Love waves. This innovative technique adjusts the weighting of individual WD gradients using the sensitivity factor of an equivalent layered model, offering a significant advancement in subsurface characterization. Synthetic model tests demonstrate that the joint WD inversion method can generate a more accurate S-wave velocity model, particularly in the presence of complex low-velocity layers or high-velocity layers, when compared with individual wave WD inversion techniques. Simultaneously, the results of field tests validate the effectiveness of the proposed joint WD inversion strategy in producing a more dependable S-wave velocity distribution that aligns closely with the actual geologic structure.

A Virtual Battlefield for Embassies: Longitudinal Network Analysis of Competing Mediated Public Diplomacy on Social Media

ABSTRACT Mediated public diplomacy is a critical way of strategic communication for governments to influence global public opinion, especially during international conflicts. Based on the theories of mediatization and digitalization as well as the layered model of communicative space, this study investigates how the United States and Iranian embassies competed on the Chinese social media platform Sina Weibo over 13 months. Following a network ethnography approach, this study conducts longitudinal network analysis and textual analysis. The findings suggest that the macro-layer function (i.e. hashtag) facilitated horizontal dissemination of news about the US-Iran conflict from mainly China’s state-media accounts, increasing public awareness of the issue within a short time. The meso-layer (repost and follower network) and micro-layer (mention and comment) functions helped establish vertical communication facilitated by opinion leaders and crowd-enabled leaders that perpetuated public attention on relevant issues. The two embassies engaged with the Chinese public in different communicative layers. The US embassy interacted with the Chinese publics through reposts and replies, while the Iranian embassy constructed their posts in the form of replies. The Iranian embassy leveraged China’s state media agendas as narrative agency to conduct diplomatic communication by incorporating relevant hashtags in their posts. A layered model of mediated public diplomacy is proposed. The findings deepen our understanding of competing mediated public diplomacy, and contribute to the field of international communication of international conflicts.

Lithofacies Characteristics of Gulong Shale and Its Influence on Reservoir Physical Properties

The lithofacies characteristics of the Qingshankou Formation (K2qn) shale in the Gulong Depression are crucial for oil exploration and development. This study investigates the K2qn shale lithofacies characteristics and their impact on reservoir physical properties using scanning electron microscopy (SEM), high-pressure mercury injection (HPMI), and logging quantification. The results indicate that the main minerals in K2qn shale are quartz, plagioclase, and clay. The sedimentary structures are classified into three types: laminated, layered, and massive. The K2qn shale lithofacies can be categorized into 12 types based on a combination of lithology and sedimentary structure. The main types are laminated clayey shale, layered clayey shale, and layered felsic shale. The larger the average pore size of the K2qn lithofacies, the stronger the heterogeneity of pore size distribution in space and the better the pore-to-throat connectivity. The impact of K2qn shale lithofacies on reservoir physical properties is mainly due to differences in lithology, complemented by variations in the sedimentary structural model. Under certain diagenetic or tectonic conditions, a layered sedimentary structural model of lithofacies may not increase reservoir permeability. Generally, felsic and carbonate rocks in tidal flat environments promote the development of shale with high permeability and porosity, while lithofacies deposited in static water environments below the wave base in lake basins typically exhibit low permeability and porosity. The physical properties of a reservoir are primarily influenced by the differences in pore throat characteristics resulting from variations in lithology.

On the eigenvalues and eigendisplacement of the critical mode in horizontally layered media

Wave propagation in horizontally layered media is a classical problem in seismic-wave theory. In semi-infinite space, a nondispersive Rayleigh wave mode exists, and the eigendisplacement decays exponentially with depth. In a layered model with increasing layer velocity, the phase velocity of the Rayleigh wave varies between the S-wave velocity of the bottom half-space and that of the classical Rayleigh wave propagated in a supposed half-space formed by the parameters of the top layer. If the phase velocity is the same as the P- or S-wave velocity of the layer, which is called the critical mode or critical phase velocity of surface waves, the general solution of the wave equation is not a homogeneous (expressed by trigonometric functions) or inhomogeneous (expressed by exponential functions) plane wave, but one whose amplitude changes linearly with depth (expressed by a linear function). Theories based on a general solution containing only trigonometric or exponential functions do not apply to the critical mode, owing to the singularity at the critical phase velocity. In this study, based on the classical framework of generalized reflection and transmission coefficients, the propagation of surface waves in horizontally layered media was studied by introducing a solution for the linear function at the critical phase velocity. Therefore, the eigenvalues and eigenfunctions of the critical mode can be calculated by solving a singular problem. The eigendisplacement characteristics associated with the critical phase velocity were investigated for different layered models. In contrast to the normal mode, the eigendisplacement associated with the critical phase velocity exhibits different characteristics. If the phase velocity is equal to the S-wave velocity in the bottom half-space, the eigendisplacement remains constant with increasing depth.

The Impact of Fine-Layering of Tailings Dam on the Variation Pattern of Infiltration Lines

The type of soil and its compactness significantly influence its permeability coefficient, which in turn affects the drainage difficulty of soil pore water and the distribution of the infiltration line. However, current tailings dam models typically consider only a single soil layer instead of taking into account the differences in soil types and compactness, resulting in a deviation between simulated results and actual conditions. To address this issue, this study proposes three models with a gradually increasing degree of layering refinement based on soil type and compactness. These models aim to simulate the variations in the infiltration line under three different strategies: constant head, rainfall, and drainage. The simulation results indicate that the average increase in the infiltration line of the three schemes after rainfall is 46.2%, 65.88%, 83.52%, respectively; the fitting percentages for each scheme of infiltration line after 720 days of drainage and the constant head stage are 72.38%, 88.27%, and 93.61%, respectively. It can be seen that the higher the refinement level of the layered model, the more sensitive it is to changes in the infiltration line. Furthermore, as the refinement level of the layered model increases, the simulation effect on the changes in the infiltration line improves, and the simulated results become more consistent with the actual situation. This finding provides a strategy and possibility for the study of the tailings dam’s infiltration lines, safety, and stability.