Layered Model Research Articles

Modeling Borehole Resistivity Logs with Exponentially Graded Multilayered Soil Inversion for Electrical Engineering Applications

In this paper, we present the application of a special soil resistivity model, the Exponentially Graded Multilayered Soil model, to the interpretation of Borehole Resistivity Logging surveys. The model, which was recently introduced by the authors, offers an alternative to the interpretation provided by constant resistivity layer models. The model is applied to synthetic soil surveys as well as to a real survey that is not satisfactorily interpreted using conventional models. This model aids in the design and calculation of grounding systems in electrical engineering, providing an alternative to calculations performed by traditional layered models.

Pharmacogenomics concierge service as an opportunity for pharmacist reimbursement and practice-based learning

ObjectiveTo assess the feasibility of a pilot pharmacogenomics concierge service that incorporates student practice-based learning opportunities and a survey to determine patients’ interest and willingness to pay. MethodsParticipants in the pilot study (n=34) completed a survey to determine their willingness to pay for concierge services. Six participants indicating the highest level of interest were selected to participate in the program free of charge. Students conducted preliminary genetic testing to assess the potential value of a pharmacogenomics service. For the subset of participants (n=6) invited to the concierge service, confirmatory genetic testing was completed by a third-party lab. A layered learning model allowed senior students to mentor and train junior students in the area of pharmacogenomics. ResultsSix invited participants completed the concierge program and third party pharmacogenomic testing, and the majority (83%) received pharmacogenomic consultation with the pharmacist. Completed surveys from participants in the pilot program (n=34) indicated a willingness to pay $25-50 a month to have continued access to a pharmacist. Surveyed individuals rated their likelihood of utilizing the concierge service at a mean rating of 8.6 (SD=1.88) on a scale of 1 to 10 although this rating dropped significantly if insurance did not cover the cost. The pilot program offered opportunities for practice-based learning through a layered learning model. ConclusionThis pilot concierge program presented several successes and challenges which may help others avoid common pitfalls and spur discussion on optimal ways to develop new pharmacy services and experiential opportunities for students.

Experimental study on mechanical properties of 3D Printed layered rock like materials

Layered rocks are prevalent in the Earth’s crust and are frequently encountered in underground engineering construction. Due to their pronounced anisotropy, the deformation and failure mechanism of layered rock are complex. Laboratory tests are an effective way to study these mechanisms. However, natural layered rocks present challenges, such as difficult sampling and large discreteness. Additionally, current methods for creating layered rock models are often costly or lack precision, limiting research into their mechanical properties. In this study, a 3D printing process using wet material extrusion was adopted, with a wide range of material options and low production costs. Five layered model samples with bedding dip angles of 0°, 30°, 45°, 60° and 90° were printed using this method. Uniaxial compression tests were conducted, supplemented by digital image correlation (DIC) to capture detailed stress–strain data and failure patterns. The results demonstrate that the mechanical properties of the 3D-printed samples closely resemble those of natural layered rocks and exhibit significant anisotropy. This approach presents a new cost-effective method for studying the mechanical behavior of layered rock.

3D Controlled‐source electromagnetic modelling in anisotropic media using secondary potentials and a cascadic multigrid solver

AbstractQuantitative interpretation of the data from controlled‐source electromagnetic methods, whether via forward modelling or inversion, requires solving a considerable number of forward problems, and multigrid methods are often employed to accelerate the solving process. In this study, a new extrapolation cascadic multigrid method is employed to solve the large sparse complex linear system arising from the finite element approximation of Maxwell's equations using secondary potentials. The equations using secondary potentials are discretized by the classic nodal finite element method on nonuniform rectilinear grids. The resulting linear systems are solved by the extrapolation cascadic multigrid method with a new prolongation operator and preconditioned Stabilized bi‐conjugate gradient method smoother. High‐order interpolation and global extrapolation formulas are utilized to construct the multigrid prolongation operator. The extrapolation cascadic multigrid method with the new prolongation operator is easier to implement and more flexible in application than the original one. Finally, several synthetic examples including layered models, models with anisotropic anomalous bodies or layers, are used to validate the accuracy and efficiency of the proposed method. Numerical results show that the extrapolation cascadic multigrid method improves the efficiency of 3D controlled‐source electromagnetic forward modelling a lot, compared with traditional iterative solvers and some state‐of‐the‐art methods or software (e.g., preconditioned flexible generalized minimal residual method, emg3d) in the considered models and grid settings. The efficiency benefit is more evident as the number of unknowns increases, and the proposed method is more efficient at low frequencies. The extrapolation cascadic multigrid method can also be used to solve systems of equations arising from related applications, such as induction logging, airborne electromagnetic, etc.

Layered Graph Models for the Electric Vehicle Routing Problem With Nonlinear Charging Functions

AbstractElectric vehicle routing problems (EVRPs) involve the routing of a fleet of electric vehicles (EVs) to visit a set of customers while typically minimizing the total travel and charging time. Due to their limited autonomy, EVs may need to recharge their batteries en‐route at charging stations (CSs). Thus, routing decisions also include which CSs to visit, and how much energy to charge during those visits. These decisions are compounded by the fact that charging times follow a nonlinear charging function with respect to the EV's state of charge (SoC). We propose a layered graph representation for the EVRP with nonlinear charging functions (EVRP‐NL). Specifically, the layers correspond to discretized SoC values. Therefore, the arcs' energy consumption is approximated to match those values. We develop two compact formulations based on the layered graph. Furthermore, we introduced two charging policies that facilitate aligning charging duration with practical considerations. Computational results demonstrate the effectiveness of our formulations. Our best formulation effectively handles instances with up to 40 customers. On those instances, compared to the state‐of‐the‐art compact formulation, our formulation solves 13 more instances to optimality with less than half of the computational time. Considering instances solved by both formulations to optimally, the approximation entailed by our formulation yields a 0.94% deviation on average. Since our best performing formulation is compact, it may be readily used by a broad audience. Furthermore, as the majority of algorithms for the EVPR and its variants are heuristics, our formulation could be beneficial in evaluating the performance of these methods.

An Indoor-Outdoor Layered HD Map Construction for Unmanned Ground Vehicles

Abstract. High-Definition Maps (HD Maps) are lane-level 3-dimensional road network models that ensure the safe operation of autonomous vehicles and drive the continuous advancement of autonomous driving technology to higher levels. However, HD Maps currently face challenges regarding limited coverage and description of indoor environments (e.g. underground parking), as well as the lack of uniformity between indoor and outdoor map formats. Therefore, this paper proposes a Layered HD Map model for both indoor and outdoor environments. The map model consists of 6 layers, allowing effective representation of indoor and outdoor environments, as well as transitional areas. The paper also establishes an Unmanned Ground Vehicle (UGV) to collect and update map data using LiDAR (Light Detection and Ranging) SLAM (Simultaneous Localization and Mapping) and autonomous exploration technology, aiming to enhance the efficiency and automation of HD Map acquisition. In order to verify the validity of the proposed map model, this paper conducted a navigation experiment in a double decker parking lot containing entrances and exits. The results of the experiments demonstrate that the Layered HD Map generated through autonomous LiDAR SLAM can effectively describe the indoor and outdoor environments, and enable successful navigation of UGVs.

Study on ground-penetrating radar wave field characteristics for earth dam disease considering the medium randomness

Ground-Penetrating Radar (GPR) has been widely used for non-destructive testing of earth dam disease. However, the forward simulation of GPR for earth dam disease often employs layered homogeneous models, neglecting the influence of medium randomness on its wave field characteristics. Therefore, considering the randomness of the medium, a geoelectrical model for earth dam disease is established, which is based on the mixed-type autocorrelation function and the finite element time-domain method. The influence of random medium model parameters on the single-channel wave of GPR is analyzed. The electromagnetic wave propagation characteristics under different medium models are explored. The forward simulation of GPR for earth dam disease such as panel voiding, concentrated seepage, and loosening are performed. The differences in propagation characteristics for earth dam disease between uniform medium model and random medium model are compared. Compared to the calculation results of the uniform medium model, the propagation speed and amplitude of electromagnetic waves in the random medium model changes, and a number of diffraction waves are present. When performing forward simulation of GPR for earth dam disease, considering medium randomness can deepen the understanding of the GPR section view and help improve the accuracy of image interpretation.

Magnetization in the zig-zag layered Ising model and orthogonal polynomials

Magnetization in the zig-zag layered Ising model and orthogonal polynomials

Novel brittleness index construction and pre‐stack seismic prediction for gas hydrate reservoirs

AbstractReservoir transformation is essential for developing gas hydrate reservoirs. Predicting sediment brittleness is key to optimizing drilling design and evaluating engineering sweet spots. Constructing a brittleness index reflecting the brittle mineral content of a rock based on elastic parameters and predicting it using seismic data is a feasible solution for assessing reservoir brittleness. In addition, the elastic brittleness index can characterize the effect of complex pore types, fractures and pore fillings on rock brittleness. With the shallow hydrate reservoir in the sea as the research target. First, a novel brittleness index characterized by multiplying the Lamé parameter () by Poisson's ratio () is proposed. Its superiority in indicating brittle mineral content is verified by a rock‐physics model. Second, a reflection coefficient approximation equation including the novel brittleness index is derived, enabling direct estimation of reservoir brittleness from seismic data. The new brittleness index has proven to better reflect brittle mineral content and effectively indicate the high brittleness characteristics of hydrate reservoirs. The accuracy of the proposed approximate equation is verified by a layered medium model, and the viability of predicting the new brittleness index using seismic data is also theoretically supported by the model test. Finally, the proposed method has obtained favourable results in the application of hydrate work area data collected at the South China Sea, confirming its availability and practicality.

Two layered hidden Markov model for studying type 2 diabetes

Two layered hidden Markov model for studying type 2 diabetes

Stochastic Analysis of Epithelial/Absorbed Power Density in Multilayered Planar Skin Model With Uncertain Tissue Electric Properties

AbstractStochastic analysis of the absorbed power density (APD) on skin surface exposed to radiation of halfwave dipole at 10, 30 and 90 GHz and for different antenna‐body distances is presented. Skin tissue is modeled as a half‐space consisting of one layer (skin) or three layers (skin, fat and muscle) whose permittivities and conductivities are uncertain. Deterministic part is based on numerical solution of Pocklington equation via Galerkin Bubnov Indirect Boundary Element method (GB‐IBEM) and numerical integration of the corresponding field integrals. Uncertainty from tissue electric parameters is propagated to APD via non‐intrusive Stochastic Collocation method (SCM) in order to compute stochastic moments of APD. For 1‐layered model APD stochastic moments are computed with 3 deterministic simulations. On the other hand APD mean and variance for 3 layered model are successfully computed with 13 deterministic simulations while skewness and kurtosis require 85 deterministic simulations. The ratio of APD standard deviation and mean decreases with frequency thus indicating that the uncertainty in the tissue electric properties has smaller effect on APD uncertainty at higher frequencies. Finally, sensitivity analysis carried out for both 1‐layered and 3‐layered models indicates the same conclusions. At 10 GHz skin permittivity and conductivity are the two most important parameters. However, as frequency increases the impact of skin conductivity prevails. This indicates that in frequency range 10–90 GHz the APD uncertainty quantification and sensitivity analysis can be carried out by using only 2‐dimensional stochastic model.

Adaptive-coefficient finite difference frequency domain method for time fractional diffusive-viscous wave equation arising in geophysics

The diffusive-viscous wave (DVW) equation is a widely used model to describe frequency dependent attenuation of seismic wave in fluid-saturated porous medium. In this paper taking power law frequency dependent attenuation into account, we first introduce a modified DVW equation (time fractional DVW equation) in which the first order temporal derivative of viscous term is replaced with a fractional order temporal derivative. In consideration of that most of the existing numerical simulations for seismic wave equations are based on time domain methods and truncation with some specific boundary conditions, we incorporate the absorbing boundary condition as complex-frequency-shifted (CFS) perfectly matched layer (PML) into the time fractional DVW equation, and then develop an adaptive-coefficient (AC) finite difference frequency domain (FDFD) method for numerical simulation. The corresponding analytical solution for homogeneous time fractional DVW equation is provided for model validation, and the effectiveness of the developed AC FDFD method is verified by some numerical examples including the homogeneous model and the layered model. Numerical results show that AC FDFD method is more accurate than the traditional 2nd-order FDFD method for numerical modeling of time fractional DVW equation with CFS PML absorbing boundary condition, while requiring similar computational costs.

Expected constraints on Phobos interior from the MMX gravity and rotation observations

The origin of the Martian moons is still uncertain, and knowledge about their interior could provide support to some of its leading theories. In preparation for the JAXA Martian Moons eXploration (MMX) mission, we review our current knowledge on the interior of Phobos, and provide synthetic tests showing how the gravity and rotation determination could allow the detection of specific interior-structure properties. The inversion of the geodetic observables for the retrieval of the internal mass distribution of a set of synthetic interior models is performed via non-linear least-squares, where the interior parameterization is based on the level-set method. We additionally provide simple expressions allowing to relate some of these interior models to the geodetic observables of Phobos. The results, based on realistic measurement resolution and noise scenarios, show good retrievals for most of the models at the data resolutions expected from MMX. Specifically, we find the gravity information is realistically sufficient for the detection of mass anomalies below the Stickney crater, as well as large scale heterogeneous regions within plausible rubble-pile structures. Libration helps retrieve the more degenerate models for gravity, such as those with concentric layers or with density varying linearly with depth. The incremental improvement from further adding an hypothetical mean obliquity measurement is marginal. Finally, we apply the level-set inversion and the analytical formulas to estimate possible interior characteristics of the ‘real’ Phobos from the currently-available scarce geodetic observables. The level-set solutions for the real-data inversion generally converge to a higher mass concentration towards the surface in the equatorial region. Markov chain Monte Carlo estimations of parameters relative to a simple 2-layer model or a radial density distribution similarly hint at a lighter region inside of Phobos.

Insight into intracontinental deformation and crustal reworking of ancient continents implied by crustal structure imaging of the Yangtze Craton

The crustal imprints from multistage tectonic activities in cratons offer valuable insights into continental evolution. Utilizing seismic data from two densely deployed, nearly perpendicular linear arrays, and a newly developed stepwise joint inversion of depth-domain receiver function and surface wave dispersion, we constructed a detailed crustal layering model for the Yangtze Craton. Our analysis revealed elongated double velocity reversal zones as salient features of the crust, which likely record ancient crustal reworking and juvenile crustal growth associated with Neoproterozoic rift-related magmatic processes. The interlayering of low- and high-velocity structures may contribute to the enduring stability of the Yangtze Craton. Additionally, superimposed layers separated by east-dipping interfaces and abrupt changes in crustal thickness in the boundary belts surrounding the Yangtze Craton document the crust's structural responses to intracontinental deformation during continent assembly.

Stress transfer paths and damage modes of layered coal-rock mass under static loading

In order to explore the distribution characteristics of nonlinear mechanical behavior and the tendency of damage and failure of deep in situ coal-rock mass, a layered composite thin plate coal-rock mass model is established based on thin plate theory and finite element method. The continuity of interlayer stress and displacement is maintained by transfer matrix function, and the maximum shear stress is calculated by Mohr-Coulomb strength criterion. The distribution characteristics of stress, displacement, energy and maximum shear stress of coal-rock mass under static load are obtained. The analysis results are as follows : ① The torsional stress concentration areas of τxz and τyz are formed on the boundary of coal-rock interface, and the principal stress concentration areas of σx, σy and σz are formed in the center and center of the boundary, and the shear stress distribution of τxy is formed on the diagonal line. ② The maximum shear stress of the long axis has a strengthening effect on the shear failure, and each layer forms a stress state of alternating tension-shear-compression-shear. It first destroys in the middle of the coal-rock interface and boundary, and then destroys along the long side and short side. ③ The coal-rock mass presents a ′ X ′ -type shear zone along the radial and axial. The shear failure occurs first, followed by the principal stress compression failure. The cracks are preferentially developed in the direction perpendicular to the minimum principal stress, and the stepped ′ V ′ -shaped failure characteristics are formed under the action of shear and tensile stress.

Explore the Evolution of Computer Network Architecture

Since the invention of computer networks in the 1960s, their architecture has undergone many major innovations and evolutions. This review aims to sort out and analyze this evolution process and reveal its internal motivations and fundamental driving forces. We will analyze the development of network architecture from multiple dimensions such as network topology, protocol stack, and control mechanism, and reveal the internal logic of the architecture evolving with the times.First, the paper reviews the origins of computer network development, explains the original packet switching ideas and ARPANET architecture, and analyzes its influence on later generations. Then it focuses on the birth of the TCP/IP protocol family and its architecture, analyzing its design concepts and innovations. Subsequently, the paper will explore the rise of the Internet and the formation of its layered architecture model, commenting on the advantages and disadvantages of this model. We will also examine the ideas and attempts of the next generation Internet architecture, such as active networks and content-centric networks, and analyze their challenges and limitations.In addition, the paper will explore the new changes brought about by emerging network paradigms such as software-defined networking (SDN) and network function virtualization (NFV) to network architecture, and comment on their advantages and impacts. We will also focus on the driving role of emerging paradigms such as cloud computing and edge computing on network architecture. Finally, the paper will look forward to new trends and challenges in the development of future network architecture, such as the potential application prospects of cutting-edge technologies such as artificial intelligence, machine learning, and blockchain in network architecture. By comprehensively analyzing and summarizing the evolution of network architecture, the paper hopes to provide readers with a macro perspective and a deep understanding of the internal driving force and development logic of network architecture innovation. This will not only help us understand the past, but also provide inspiration and ideas for future network architecture innovation.

A layered microcircuit model of somatosensory cortex with three interneuron types and cell-type-specific short-term plasticity.

Three major types of GABAergic interneurons, parvalbumin-, somatostatin-, and vasoactive intestinal peptide-expressing (PV, SOM, VIP) cells, play critical but distinct roles in the cortical microcircuitry. Their specific electrophysiology and connectivity shape their inhibitory functions. To study the network dynamics and signal processing specific to these cell types in the cerebral cortex, we developed a multi-layer model incorporating biologically realistic interneuron parameters from rodent somatosensory cortex. The model is fitted to in vivo data on cell-type-specific population firing rates. With a protocol of cell-type-specific stimulation, network responses when activating different neuron types are examined. The model reproduces the experimentally observed inhibitory effects of PV and SOM cells and disinhibitory effect of VIP cells on excitatory cells. We further create a version of the model incorporating cell-type-specific short-term synaptic plasticity (STP). While the ongoing activity with and without STP is similar, STP modulates the responses of Exc, SOM, and VIP cells to cell-type-specific stimulation, presumably by changing the dominant inhibitory pathways. With slight adjustments, the model also reproduces sensory responses of specific interneuron types recorded in vivo. Our model provides predictions on network dynamics involving cell-type-specific short-term plasticity and can serve to explore the computational roles of inhibitory interneurons in sensory functions.

Source-independent Q-compensated viscoacoustic least-squares reverse time migration

The strong viscosity of the subsurface introduces amplitude absorption and phase-velocity dispersion. Incorrect compensation of the inherent attenuation (the strength of the seismic attenuation can be quantified by the inverse of the quality factor Q, which is defined as [Formula: see text] times the ratio of the stored energy to the lost energy in a single cycle of deformation) can significantly affect imaging quality. Although Q-least-squares reverse time migration ( Q-LSRTM) allows for the compensation of attenuation effects during the iterations, the traditional [Formula: see text]-norm minimization, which is highly sensitive to the source wavelet, poses a challenge in accurately estimating the source wavelet from the field data. Thus, we develop a source-independent Q-LSRTM, in which a convolutional objective function is introduced to replace the [Formula: see text]-norm constraint to mitigate the source wavelet effect. According to the Born approximation, we first linearize the constant-order decoupled fractional Laplacian viscoacoustic wave equation to derive the demigration operator and then construct the corresponding adjoint equation and gradient based on the convolutional objective function, iteratively estimating the reflectivity images. Our method relaxes the sensitivity to the wavelet compared with the conventional [Formula: see text]-norm scheme due to the convolutional objective function, which has the ability to construct the same new source for simulated and observed data. Numerical tests on a layered model, the Marmousi model, and field data demonstrate that our source-independent Q-LSRTM enables us to obtain high-quality reflectivity images even when using incorrect source wavelets.

Layered security model through integration of Vigenere and Hill Cipher in digital message encryption

The rapid development of digitalization has a significant impact on data and information protection. One approach to protecting data and information is through the use of cryptography. The research aims to combine the use of Vigenere and Hill Cipher algorithms in modeling to maintain the security and confidentiality of digital messages. The focus of this research is on the process of encrypting digital text messages. The layered security in this study takes advantage of the advantages of each algorithm. The combination of the two is designed to increase the complexity of encryption and reduce vulnerability to cryptanalytic attacks. The encryption process starts with using Vigenere Cipher for initial message encrypting, then the results are re-encrypted using Hill Cipher. Research shows that this layered security model can improve data security and make it more difficult for uninterested parties to decipher it. The combination of Vigenere's and Hill Cipher's algorithms could be one of the layered security alternatives to digital message encryption in an effort to protect information and data from security threats in the digital age.

Galerkin boundary element method for simulating lightning response of grounding grid in horizontal multilayered soil model considering soil ionization effect

AbstractThis work proposes a novel mathematical model based on the Galerkin time‐domain boundary element method for accurately calculating the lightning current distribution and lightning impulse response of the buried substation grounding grid, in a multi‐layer horizontal layered soil model, by taking into account the soil ionization effect. To improve computational efficiency, the quasi‐static complex image method and its closed form time‐domain Green's function have been introduced into the model that has the ability to analytically calculate the mutual inductance coefficient between the branch currents of any two conductor segments and the mutual resistance coefficient between the leakage currents. The Galerkin time‐domain boundary element method proposed in this work can simulate the transient lightning impulse response of a substation grounding grid buried in the multi‐layer horizontal layered soil.