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This work deals with fracture mechanisms in quasi-brittle materials, focusing on the characterization of the Fracture Process Zone (FPZ) of specimens under tensile load. Particularly, paper was used as model material. Experiments were conducted on notched and unnotched specimens. Based on an image analysis of these observations, a stochastic finite element model was developed, using both a nonlocal stress-based approach and a discretized random field modeling of the Young's modulus. The proposed methodology allowed characterizing the damage zone and the size of the FPZ, analyzing the influence of the mesostructure, composed of flocs (fiber aggregates where the basis weight is larger than the average one) and antiflocs (complement of flocs). The area of the active FPZ and the normalized stress drop were linked using a surface energy dissipated in the active FPZ. The stress drop, until limiting value, increased with the width of the active FPZ. Finally, a relationship between the surface energy and the nonlocal internal length was established. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

The aim of this Authors’ Reply is to examine critically certain assertions by Logo in a Discussion and in two conference papers about a publication by Rozvany and Maute on a reliability based benchmark example [ABSTRACT FROM AUTHOR]

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Data from natural sources show counter-intuitive distribution patterns for the leading digits to the left of the decimal point and the digit 1 is observed more frequently than all other numbers. This pattern, which was first described by Newcomb and later confirmed by Benford, is used in financial and tax auditing to detect fraud. Deviations from the pattern indicate possible falsifications. Anesthesiology journals are affected not only by ghostwriting and plagiarism but also by counterfeiting. In the present study 20 publications in anesthesiology known to be falsified by an author were investigated for irregularities with respect to Benford's law using the χ-test and the Z-test. In the 20 retracted publications an average first-digit frequency of 243.1 (standard deviation SD ±118.2, range: 30-592) and an average second-digit frequency of 132.3 (SD ±72.2, range: 15-383) were found. The observed distribution of the first and second digits to the left of the decimal point differed significantly (p< 0.01) from the expected distribution described by Benford. Only the observed absolute frequencies for digits 3, 4 and 5 did not differ significantly from the expected values. In an analysis of each paper 17 out of 20 studies differed significantly from the expected value for the first digit and 18 out of 20 studies varied significantly from the expected value of the second digit. Only one paper did not vary significantly from expected values for the digits to the left of the decimal. For comparison, a meta-analysis using complex mathematical procedures was chosen as a control. The analysis showed a first-digit distribution consistent with the Benford distribution. Thus, the method used in the present study seems to be sensitive for detecting fraud. Additional statements of specificity cannot yet be made as this requires further analysis of data that is definitely not falsified. Future studies exploring conformity might help prevent falsified studies from being published. [ABSTRACT FROM AUTHOR]

Abstract  A web is continuous, flexible materials such as paper, plastic film, metal foil, textiles, etc. Web wrinkle is a problem which plagues the process industries. Most webs are very thin and prone to buckle or wrinkle. The effects of wrinkling can range from compromised product quality to down time of a processing operation, leading to less profitability in the manufacturing operation. The web wrinkles which will be treated in this paper are those that can be affected by roller misalignment and friction characteristics between web and roller. In this paper, observation method is presented for paper-web wrinkling and the prediction model of wrinkling is proposed with experimental verifications. [ABSTRACT FROM AUTHOR]

In the recent paper [1], a new scaling theory of electron localization was proposed. We show that numerical data for the quasi-one-dimensional Anderson model do not support predictions of this theory. [ABSTRACT FROM AUTHOR]

Recently, Al-Odat and Al-Hussien presented consideration of the critical energy of a composite superconductor in this journal. Various numerical and other deficiencies have been identified in this paper. These problems are discussed and clarified in this Comment. [ABSTRACT FROM AUTHOR]

This study presents the dynamic capillary pressure model (Hassanizadeh and Gray, Adv Water Resour 13:169-186, ; Water Resour Res 29:3389-3405, ) adapted for the needs of paper manufacturing process simulations. The dynamic capillary pressure-saturation relation is included in a one-dimensional simulation model for the pressing section of a paper machine. The one-dimensional model is derived from a two-dimensional model by averaging with respect to the vertical direction. Then, the model is discretized by the finite volume method and solved by Newton's method. The numerical experiments are carried out for parameters typical for the paper layer. The dynamic capillary pressure-saturation relation shows significant influence on the distribution of water pressure. The behavior of the solution agrees with laboratory experiments (Beck, Fluid pressure in a press nip: measurements and conclusions, ). [ABSTRACT FROM AUTHOR]

As the main structural bodies of underground facilities such as subway stations, frame tunnel structures play an important role in urban development and construction. In recent years, with the frequent occurrence of explosions after vehicle impacts in tunnels, which have caused severe damage to frame tunnels, the lack of relevant papers makes it necessary to develop a dynamic response analysis of frame tunnels. In this paper, by optimizing the design of an original frame tunnel structure, a dynamic response numerical model of the frame tunnel considering the impact effect of a 3D solidified vehicle and the joint effect is investigated. The deformation trend and damage evolution of the frame tunnel are analysed under different collision masses (1.4, 2.4, 6 and 15 t), collision angles (5, 10, 15 and 75°), collision speeds (60, 80 and 100 km/h), blast delay times (10, 20 and 30 ms) and blast equivalents (50, 100 and 200 kg TNT). This paper improves the active and passive robustness of frame tunnels using both improved operational management and the optimal design of the tunnel structure as a way to ensure the structural safety and functional resilience of frame tunnels. [ABSTRACT FROM AUTHOR]

This paper discusses the design process toward new lumped chaotic systems that originates in higher-order ordinary differential equations commonly used as description of ideal oscillators. In investigated third-order case, two chaotic oscillators were constructed. These systems are dual in the sense of vector field geometry local to fixed points. The existence of robust chaos was proved by both standard routines of numerical analysis and practical measurement. For the fourth-order oscillatory equation, the concept based on interaction between superinductor and supercapacitor was examined in detail. Since both "superelements" are active, the nonlinearity essential to the evolution of chaos is fully passive. It is demonstrated that complex motion is robust and does not represent long transient behavior or numerical artefact. The existence of chaos was verified using standard quantifiers of the flow, such as the largest Lyapunov exponents, recurrence plots, approximate entropy and sensitivity calculation. A good final agreement between theoretical assumptions and practical results will be concluded, on a visual comparison basis. [ABSTRACT FROM AUTHOR]

Unidentified diseases are becoming more prevalent among humans due to various climatic factors, and some of these diseases originate in animals before spreading to humans. One virus that has been of particular concern is the avian influenza virus, which primarily infects bird and can subsequently transmit to humans. This article presents a mathematical model describing the spatio-temporal reaction-diffusion process involved in the transmission of avian flu in human population. The paper begins by studying the proposed model's well-posedness and the calculated basic reproduction number, which provides valuable insights into the dynamics of virus transmission. The paper also provides stability analysis for the disease-free steady state of the model. All theoretical studies are validated using computational results. [ABSTRACT FROM AUTHOR]

This paper shows the construction of a growth model that includes public infrastructure and a related externality and investigates the dynamic properties of the model for a specific endogenous time preference function. After suggesting a saddle-path stability for long-term equilibrium under an endogenous time preference, numerical analysis of the model then reveals an unexpected relation between the strength of the externality, the magnitude of the rate of time preference, and the growth rate of the economy. In addition, it is found that multiple equilibria are unlikely to be supported empirically by the model in this paper. [ABSTRACT FROM AUTHOR]

O. Einstein (2008) proved Bollobás-type theorems on intersecting families of ordered sets of finite sets and subspaces. Unfortunately, we report that the proof of a theorem on ordered sets of subspaces had a mistake. We prove two weaker variants. [ABSTRACT FROM AUTHOR]

Layered rock slope exists widely. Because of its special slope structure, it is prone to bending deformation and toppling failure, which is a serious threat to engineering construction and safety operation. At present, the research of layered rock slope still has great innovation potential. During the construction of Wudongde Hydropower Station on Jinsha River, safety and stability problems such as slope geological structure development, face rock unloading and relaxation, and even slip and large deformation were encountered. Through field exploration, it is found that the rock and soil stratification of the slope on both sides of Wudongde Hydropower Station is highly obvious. At present, there is a lack of research on-site long-term displacement monitoring of layered rock high-steep slope, especially for layered slope in complex hydrogeology and construction environment. In order to strengthen the research on the deformation and stability of layered rock slope, this paper analyzes the measured displacement data of Wudongde hydropower station slope, and establishes three-dimensional geological finite element model with the help of numerical simulation software. The stability of the slope is calculated by combining the finite difference method and the strength reduction method. Finally, the evolution mechanism of the deformation of the layered rock slope is explained according to the geological structure characteristics. The main conclusions of this paper are as follows: the layered slope in the dam reservoir area is prone to deformation under the combined action of long-term construction disturbance and fissure water seepage, and the construction disturbance has a strong influence on the artificial excavation area below 1070 m, and the maximum rock mass deformation and surface displacement in the artificial excavation area of the slope reach 92.2 mm and 312.5 mm, respectively. However, the influence of construction disturbance on the natural mountain above 1070 m is limited, the valley deformation of the natural mountain on the left bank of the reservoir area is higher than that on the right bank, and the cumulative deformation is still less than 20 mm. The influence of seepage on the displacement of the area with higher elevation at the top of the slope is more obvious, and the influence of excavation and other disturbances on the displacement of the artificial excavation area with lower elevation is more obvious. The deformation of the river valley in the water cushion pond behind the dam increases slowly, and the change trend of the field deformation data is mostly consistent with that of the numerical calculation. The horizontal shrinkage of the mountains on both sides shows a contraction trend on the whole, and the maximum horizontal shrinkage calculated by numerical simulation is close to 20 mm, which is located at the elevation of 990 m. [ABSTRACT FROM AUTHOR]

Clustered group nail connectors are key connecting components for the full lifecycle construction and safe operation of steel–concrete composite structural bridges. To thoroughly investigate the stress mechanism of clustered group nail connectors in steel–concrete composite structures, this paper conducts a detailed numerical analysis on 100 sets of such connectors. It analyzes the stress mechanism of individual nail connectors and quantitatively calculates the group nail effect under the coupled action of multiple factors (nail spacing between layers, number of nail layers, concrete strength). Based on clarifying the force transmission patterns of nails and concrete in different layers during the loading process, this paper proposes a method for calculating the average bearing capacity reduction coefficient and the load-slip curve of single nails in clustered group nail connectors under the coupled action of multiple factors, which has been validated by experimental data. This research provides a theoretical basis for the design and calculation of group nail connectors in steel–concrete composite structural bridges. [ABSTRACT FROM AUTHOR]

Nonsymmetric algebraic Riccati equations are a class of nonlinear matrix equations with wide applications. In this paper, numerical solution of nonsymmetric algebraic Riccati equations is studied. A generalized ALI iteration method is proposed to solve the equation, which is an extension of the ALI iteration method and the MALI iteration method. Theoretical analysis and numerical experiments show that the proposed method is feasible and is more effective than the ALI iteration method and the MALI iteration method. [ABSTRACT FROM AUTHOR]

Coal pillar is a crucial element formed during underground coal mining, playing a significant role in ensuring coal mining operations are conducted safely. Historically, research on coal pillars has primarily focused on regular-shaped pillars, with limited attention given to special-shaped pillars. Therefore, this paper aims to investigate the special-shaped coal pillar formed after the excavation of the newly constructed 3307 headgate in Dayang Coal Mine, China. The primary object of this paper is to elucidate the mechanism behind the instability failure of special-shaped coal pillars and verify the influence of various geological conditions on their stability. To accomplish these goals, numerical simulation techniques were employed to analyze the stress distribution patterns and plastic zone failure characteristics of special-shaped coal pillar. The investigation revealed the presence of stress concentration phenomena within special-shaped coal pillar, where the stress peak values were directly correlated with the width of the pillar. Moreover, it was observed that as the width of coal pillar decreased, the stress curve gradually transitioned from a bimodal shape to a unimodal shape. Additionally, the ratio of the plastic zone within coal pillar increased as the width decreased, with pronounced tensile failures occurring at sharp corners. Building upon theoretical analysis and numerical simulation results, the interior of special-shaped coal pillar was classified into four distinct zones: damaged zone, progressive zone, stable zone, and special zone. Based on this zoning approach, a stability control technology was developed, employing a combination of "pier pillar support + flexible formwork concrete + grouting reinforcement + high-strength cable and bolt + U-steel." Subsequently, an industrial experiment was conducted to validate the efficacy of this control technology. Field monitoring results demonstrated that the newly excavated roadway exhibited minimal deformation and damage, thereby satisfying the requirements for safe and efficient mine production over the anticipated service life. Highlights: The failure characteristics and bearing mechanism of special-shaped coal pillars were analyzed, and a mechanical model was established, allowing exploration of the influence of different geological conditions on pillar stability. The stress evolution and plastic zone development characteristics of special-shaped coal pillar during the whole cycle were studied. A zoning criterion for special-shaped coal pillar was proposed, along with corresponding control measures, which were successfully applied to the site, effectively controlled the deformation of roadway. [ABSTRACT FROM AUTHOR]

The segment misalignment is a common defect in the segment installation of a shield tunnel construction, due to the complexity and uncertainty of its construction conditions. This raises a concerning about the safety of the segment lining for the shield tunnel. In this paper, the integrated numerical models with surrounding rock, peastone grouting and segment lining were built using three-dimensional finite element method, by introducing two kinds of misaligned defects of segments. One was the misalignment that elongated the horizontal axis of the transversal ring section of segment lining, another was the misalignment between adjacent rings of segments. To eliminate the impact of boundary on numerical results, seven rings of segments are built for the three-dimensional finite element models, and the middle ring is dealt with for the results analysis under V-class surrounding rock, including the circumferential stress of outer and inner layers of the segment, the contact stress on joint surface between segments, and the stress of locating pins between adjacent rings. Results indicate that the two kinds of misaligned defects create pronounced impact on tensile stress of segment at the bottom and the crown segments, respectively, which produces a greater tensile stress to increase cracking risk even abrupt fracture of segment. However, the misaligned defects have a slight impact on the contact stress and the locating pins stress. Therefore, attention should be paid to the cracking of bottom or crown segments in the segment lining of shield tunnel. [ABSTRACT FROM AUTHOR]

Reservoir simulation is crucial for understanding the flow response in underground reservoirs, and it significantly helps reduce uncertainties in geological characterization and optimize methodologies for field development strategies. However, providing efficient and accurate solutions for the strong heterogeneity remains challenging, as most of the discretization methods cannot handle this complexity. In this work, we perform a comprehensive assessment of various numerical linearization techniques employed in reservoir simulation, particularly focusing on the performance of the nonlinear solver for problem dealing with fluid flow in porous media. The primary linearization methods examined are finite difference central (FDC), finite forward difference (FDF), and operator-based linearization (OBL). These methods are rigorously analyzed and compared in terms of their accuracy, computational efficiency, and adaptability to changing reservoir conditions. The results demonstrate that each method has distinct strengths and limitations. The FDC method is more accurate particularly in complex simulations where strong heterogeneity are introduced but is generally slower in convergence. The OBL on the other hand, is more efficient and converges quickly, which makes it suitable for scenarios with limited computational resources and simple physics, while the FDF method provides a balanced combination of precision and computational speed, contingent upon careful step size management of the derivative estimations. This paper aims to guide the selection of appropriate linearization techniques for enhancing nonlinear solvers' accuracy and efficiency in reservoir simulation. [ABSTRACT FROM AUTHOR]

When river channels or foundation pits are excavated above the existing subway tunnels, ground soil unloading will have a disturbance effect on the safety of the existing tunnel structure. Based on a typical river-channel excavation project, this paper designs a total of 25 comparison schemes considering the influence of five major factors: the relative distance between the river channel and the existing tunnel, river-channel excavation width, tunnel's embedment depth, grouting reinforcement thickness and grouting reinforcement range. This paper conducts a numerical simulation study on the river-channel excavation above the existing subway tunnels under different working conditions, and carries out comparative analysis on disturbance effect laws of different working conditions on deformation of the ground soil and the existing tunnel structure. On this basis, this paper constructs sensitivity evaluation indexes for disturbance effect on the existing tunnels, identifies the influence sensitivity of the above five major factors, and provides engineering suggestions and measures. Finally, based on the numerical simulation results, we carried out a field verification test. The research work in this paper can provide some reference for design and risk prevention of excavation engineering adjacent to the existing subway tunnels. [ABSTRACT FROM AUTHOR]

Micro-mixers and piezoelectric pumps have been studied as independent parts, which achieves only single mixing or pumping functions. A new valveless piezoelectric mixing pump (VPMP) driven by a sinusoidal signal is proposed in this paper to achieve a structure with both pumping and mixing functions. It accomplishes this by placing obstacles in the pump chamber and in the flow channel then adding active mixing. Because it is small in size, has a simple structure and is easy to control, it can be used in micro mixing applications. In this study, numerical simulation analysis using the Fluent software tests if the new VPMP has good mixing and pumping performance, and analyzes the effect of the obstacles. Simultaneously, the results of numerical simulation are verified with experiments. It was proven that the flow rate of the VPMP can reach 12.26 mL/min, and that the liquid can achieve uniform mixing. Moreover, the obstacle placed in the pump chamber has a more obvious impact on the mixing capability, and the obstacle placed in the channel has a more obvious impact on the flow rate. In addition, with the increase of the amplitude of driving signal, the flow rate of the VPMP increased correspondingly. With the increase of the frequency, the flow rate first increased and then decreased. The capability of mixing increased with an increase of working frequency. The experimental results showed that the VPMP can achieve good pumping and mixing performance, and that one structure can possess both mixing and pumping functions. [ABSTRACT FROM AUTHOR]

This paper presents simple numerical solutions for electromagnetic plane waves in spatially homogenous time varying medium. The solution is based on converting the resulting second order differential equation into two combined ordinary differential equations which are solved numerically by using the built-in ode113 function in Matlab. By using this method, the time domain responses of the electric and magnetic fields at fixed point in space are obtained. The proposed method is applied on two cases: linearly time varying medium and sinusoidally time varying medium. The corresponding frequency domain response is obtained by using inverse Fourier transformation of the obtained time domain response. The proposed method is compared with FDTD solution. It is found that the proposed method has the same accuracy of FDTD with much less computational time. [ABSTRACT FROM AUTHOR]

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced vibrations. However, complicated finite element (FE) modeling, together with repetitive and computationally intensive nonlinear time-history analyses (NTHAs) are generally required in conventional design methods. To streamline the preliminary design process, this paper developed a simplified longitudinal double degree of freedom model (DDFM) for single and symmetric twin-tower cable-stayed bridges. Based on the proposed simplified longitudinal DDFM, the analytical equations for the relevant mass- and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy methods. Modeling of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization method. Additionally, the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were derived. Based on the developed simplified DDFM and suggested analytical equations, this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper parameters. Moreover, the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed bridge. Finally, the results indicated the following. 1) For the obtained fundamental period and longitudinal stiffness, the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05% and 1.5%, respectively. 2) Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%. 3) The equivalent damping ratio of nonlinear viscous dampers and the applied loading frequency had significant effects on the longitudinal seismic responses of the bridge. Findings of this study may provide beneficial information for a design office to make a simplified preliminary design scheme to determine the appropriate nonlinear damper parameters and longitudinal seismic responses for long-span cable-stayed bridges. [ABSTRACT FROM AUTHOR]

The simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers also have to be taken into account in the rheological model. A disadvantage of such a description is time-consuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows the fast generation of input data based on uniaxial static and dynamic tensile tests at different strain rates. Unloading, i.e. forming a hysteresis loop, can also be modeled easily based on a damage formulation. We show the theoretical background and algorithmic setup of our model that has been implemented in the explicit finite element program LS-DYNA [1-3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under loading and subsequent unloading at different strain rates is shown. [ABSTRACT FROM AUTHOR]

This paper deals with precipitation events, particularly the problem of recognising events individually, of distinguishing one local meteorological/precipitation event from another. The final aim was to arrive at a more appropriate conceptualization of "distance" between individual annual events. A criterion for identifying annual precipitation events, inside a 5 min-timestep series of pluviometric data, was proposed. Using this numerical criterion, a series of annual distances between events were obtained and compared with those obtained by other two known and applied statistical methods. This comparison would be important for linking the so-called statistical methods to the real data of the series, analysed through a numerical process. This would make it possible to provide a kind of "measure" for the understanding of real data via a statistical model. Results showed that distances between events, obtained through numerical analyses, are almost always different from those obtained by statistical methods. The supposed Poisson-process, generally matched to, and widely applied in the field of rainfall data, showed some contradiction with the analysis conducted in this paper. The so-called Lag method shows a numerical method type distribution, but produces some important internal deviations from numerical results. It seems that the method proposed in this paper can reproduce the real distances between events more realistically compared to the statistical methods considered here. Exponential distribution does not seem highly performing, at least in the case of the annual analysis, with series of a 5-min time-step resolution, obtained from rain gauges installed in the Veneto Region of Italy. It is believed that the numerical criterion presented in this paper can be considered adequate for determining the distances between events, within an annual time-window. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of a single and a group of laterally loaded barrettes using a series of numerical models in a three-dimensional finite element software. The simulation of laterally loaded barrettes in both directions is verified by comparing numerical predictions to field measurements previously published in the literature. This paper defines the soil wedge around the barrette sheared at a strain equivalent to the minimum shear strain value at the barrette side or higher as the effective strain wedge. The results from a suite of numerical experiments show that the size of the effective shear strain wedge remains constant at different lateral loads, soil density, barrette shape (aspect ratio), and barrette stiffness. This paper also delineates the effect of spacing in a group of barrettes on the mobilized strain wedges and the associated lateral deformations. The paper then suggests equivalent dimensions for laterally loaded barrettes to be used as input parameters in analyses using p-y curves based on the shape of the effective strain wedge. The predictions from p-y analyses are improved in all the studied cases when equivalent dimensions are used compared to the finite element computations. The paper studies the appropriate design multipliers recommended in literature to be used in the p-y curves method for laterally loaded barrette groups in single and multiple rows. Comparisons with finite element results show the validity of employing the equivalent shape dimensions in determining suitable p-multipliers. [ABSTRACT FROM AUTHOR]

In this note we will show that finitely generated condition is necessary in Theorem 1.2 of the above mentioned paper. [ABSTRACT FROM AUTHOR]

Because of the increased mobility of vehicle users, it might be difficult to keep communication services in vehicle networks effective and dependable. Huge hurdles have been presented to vehicular networks as a result of the meteoric rise in the amount of data, which comes with the needs of high dependability and low latency. The deployment of access point servers at geographic locations that are closer to the vehicles in order to provide real-time service to applications that are based on the vehicles is one possible option. However, there is a limited amount of cache store space, and there is also a lack of a tractable access mode allocation method. As a result of these factors, it is very difficult to strike a compromise between the network transmission performance and fronthaul savings. Because the signal-to-interference-ratio (SIR) can be enhanced with switching mode in vehicular infrastructure, it may be possible to achieve higher levels of dependability. To serve all of the vehicles, the conventional allocation in vehicular network may not be sufficient on its own for two reasons: (1) the number of vehicles exceeds the number of paths, and (2) a vehicle may be located outside of the coverage path. Therefore, the implementation of switching mode allocation in vehicular communication is very necessary in order to increase the number of vehicles that can be supplied. In this paper, allocation using V2I, V2V, and V2X modes have been analyzed to provide dependable coverage for vehicles. These methods are used for communicating with other vehicles. In this paper, the numerical analysis has been performed such that SIR is optimized. In switching mode allocation, it has been shown that establishing a variable SIR threshold is helpful in achieving a path coverage that can be relied upon. It has been shown beyond a reasonable doubt that the coverage probability is likewise directly dependent on SIR thresholds. The theoretical analysis is verified, and it is confirmed that the suggested method is capable of achieving significant performance improvement in terms of coverage probability and data rate. [ABSTRACT FROM AUTHOR]

In the paper, a tunable split-ring based microstrip band-pass filter is proposed and the corresponding measurement and simulation results are presented. The proposed filter has a band-pass performance around 2.2 GHz. The prototype of the proposed filter is fabricated by using Arlon DiClad 880 substrate with an electrical permittivity of ϵ r = 2.2. There is a quite good agreement between the measurement and simulation results with a slight ( ∼ 0.3 GHz) discrepancies. Also, the frequency tuning performance is achieved by using a simplistic varactor diode model of SMV1247-079LF placed on one gap of the ring. By changing the capacitance on the model, the center resonance frequency of the filter can be adjusted in the range of 2.4–3.4 GHz band. The simulation results demonstrate tunable band-pass characteristics of the proposed design. Modelling and the numerical analysis of the filter design are carried out by using CST Microwave Studio simulator. An equivalent circuit modeling of the proposed filter is presented along with the corresponding simulations. The results of the analysis on the effects of the physical dimensions of the filter on the filter performance are presented. Also, the variation of the resonance frequency with respect to the voltage value on the varactor diode was summarized with cubic spline method and displayed. [ABSTRACT FROM AUTHOR]

The performance of a permissioned blockchain, namely, Hyperledger Fabric, is modeled and analyzed in a quantitative manner in this paper. Various types of nodes contribute to the performance of Hyperledger Fabric, and each of those is modeled and tracked along the operational flow of the permissioned blockchain. There are nodes for endorsement, ordering, and commitment to realize the due decentralized network operations. A quantitative model for each type of nodes has been proposed in Ke and Park (Performance study on various Hyperledger Fabric node types and transaction flow, IEEE BCCA, 2021) along with numerical analysis. Each type of the nodes is characterized in terms of transaction/block queue size and waiting time, and the transaction/block arrival rates and the transaction/block service rates are considered for simulation purposes. The analysis is extended beyond the analysis in Ke and Park (Performance study on various Hyperledger Fabric node types and transaction flow, IEEE BCCA, 2021) in this paper to particularly demonstrate how the arrival rates and the service rates co-influence the performance and how the number of channels impacts the performance, in order to ultimately facilitate a more dynamic way of optimization, taking the co-relation across different types of nodes into account. The major contribution of this paper to the field of computer science by creating a series of queuing models to evaluate the performance of different types of nodes: Chaincode Execution and Endorsement, Block Creation and Delivery, Transaction Validation and Block Committing, and Transaction Processing. [ABSTRACT FROM AUTHOR]

The convergence of the integral smoothed particle hydrodynamics (SPH) solution to the advection-diffusion equation in two dimensions in the particular case of a rigid rotation transport velocity field, is established in this paper. The approximation to the Laplacian operator is considered (Morris et al. 1997). The convergence of the SPH solution to the exact one is established in Fourier space. It is shown that convergence is guaranteed if a certain condition on the Fourier transform of the kernel, that we call positivity condition, is fulfilled. This condition is that the first moment of the radial profile of the kernel’s Fourier transform is positive. The analytical result is illustrated with a numerical verification. The numerical solutions obtained with different kernels, including those more commonly used by the SPH community (namely, the Wendland kernels and the cubic and linear spline kernels), are compared in terms of both the L2 norm and the norm of the maximum. In addition to that, a pathological kernel, for which the positivity condition is not satisfied, is presented and tested, leading to non convergent results. This fact suggests that the Positivity condition is not only a sufficient but a necessary condition for convergence, in the case of the advection-diffusion equation. Moreover, the derivation of the exact solution for one of the numerical examples discussed in the paper is presented in detail in an appendix. This is an interesting test case for the advection-diffusion equation due to its discontinuous nature, therefore, the authors consider it useful to thoroughly present the obtaining of its exact solution. The paper is closed with conclusions and future work. [ABSTRACT FROM AUTHOR]

The article focuses on the call for paper for special issue of the journal "Finance and Stochastics" on topic related to the probabilistic methods for solving computational problems in financial mathematics. The paper to be submitted to the journal could focus on new methods/algorithms or significant improvements in solving computational problems in financial mathematics. Furthermore, all submitted papers will be reviewed in the usual way so that only papers which meet the high standards of the journal.

Positive semidefinite kernels on spheres cross time are on demand in spatial statistics, machine learning and numerical analysis, motivated by applications in the climate, environmental and earth sciences. Most of the recent literature has focused on kernels that are isotropic on the sphere and stationary in time, but this assumption is often overly limited in quantifying spatial dependence properly. A broader class of kernels can be obtained by trading isotropy for axial symmetry, i.e., stationarity with respect to longitudes only. This paper challenges theoretical aspects by providing a spectral representation that uniquely characterizes space-time positive semidefinite kernels that are axially symmetric on the sphere and stationary in time. We also address the problem of partial Fourier inversion and show that it is feasible under mild technical conditions. The second part of the paper focuses on constructive methods to build nonseparable kernels having axial symmetry on the sphere and stationarity over time. [ABSTRACT FROM AUTHOR]

This paper presents results obtained using three numerical approaches for the basal heave analysis of a hypothetical circular shaft: the Finite Element Method (FEM), Numerical Limit Analysis (NLA), and the Material Point Method (MPM). The Strength Reduction Factor (SRF) methodology was used in conjunction with the MPM, NLA, and FEM to analyze the stability of this structure under dry and saturated conditions. In this paper, we introduced a methodology for applying the SRF technique within the framework of the MPM in a three-dimensional (3D) context. The paper compares and discusses results from the three analysis methods concerning the factor of safety and failure mechanisms. In particular, the failure surface and the run-out condition were also evaluated for a hypothetical case with large deformations using MPM. The results obtained from the three numerical methods exhibited good consistency. Regarding FEM, NLA required the least computational cost to get the safety factor, being a more appealing tool for its estimation, and the MPM allowed consideration of large deformations in the simulations without any additional numerical treatments like remeshing. The current work demonstrates a potential strategy for combining MPM, NLA, and FEM approaches to determine the failure mechanism and the post-rupture processes with large deformations. [ABSTRACT FROM AUTHOR]

From the literature it is known that orthogonal polynomials as the Jacobi polynomials can be expressed by hypergeometric series. In this paper, the authors derive several contiguous relations for terminating multivariate hypergeometric series. With these contiguous relations one can prove several recursion formulas of those series. This theoretical result allows to compute integrals over products of Jacobi polynomials in a very efficient recursive way. Moreover, the authors present an application to numerical analysis where it can be used in algorithms which compute the approximate solution of boundary value problem of partial differential equations by means of the finite elements method. With the aid of the contiguous relations, the approximate solution can be computed much faster than using numerical integration. A numerical example illustrates this effect. [ABSTRACT FROM AUTHOR]

Formerly the geometry was based on shapes, but since the last centuries this founding mathematical science deals with transformations, projections, and mappings. Projective geometry identifies a line with a single point, like the perspective on the horizon line and, due to this fact, it requires a restructuring of the real mathematical and numerical analysis. In particular, the problem of interpolating data must be refocused. In this paper, we define a linear structure along with a metric on a projective space, and prove that the space thus constructed is complete. Then, we consider an iterated function system giving rise to a fractal interpolation function of a set of data. [ABSTRACT FROM AUTHOR]

Livestreaming, now one of the most popular selling methods in e-commerce, affects consumers' shopping behaviors and firms' operations management. Compared with the traditional post-price strategy, livestreaming has many advantages such as strong interactivity, but it also has some defects, such as purchase time limits and the time cost of watching livestreams. This paper considers the characteristics of livestreaming and examines the strategic interaction with product line design. We find that the seller prefers to adopt livestreaming when the streamers' selling ability is high enough. In addition, the product line design can also affect the adoption of the livestream strategy. When the seller offers a single product, a high-quality product incentivizes the adoption of livestreaming; when the seller offers a product line, the upward-line extension can incentivize the adoption of livestreaming. We also test the robustness of our main results through numerical analysis and related extensions. [ABSTRACT FROM AUTHOR]

This paper deals with the mathematical analysis of Tuberculosis by using fractal fractional operator. Mycobacterium TB is the bacteria that causes tuberculosis. This airborne illness mostly impacts the lungs but may extend to other body organs. When the infected individual coughs, sneezes or speaks, the bacterium gets released into the air and travels from one person to another. Five classes have been formulated to study the dynamics of this disease: susceptible class, infected of DS, infected of MDR, isolated class, and recovered class. To study the suggested fractal fractional model’s wellposedness associated with existence results, and boundedness of solutions. Further, the invariant region of the considered model, positive solutions, equilibrium point, and reproduction number. One would typically employ a fractional calculus approach to obtain numerical solutions for the fractional order Tuberculosis model using the Adams-Bashforth-Moulton method. The fractional order derivatives in the model can be approximated using appropriate numerical schemes designed for fractional order differential equations. [ABSTRACT FROM AUTHOR]

The selection of materials for the protective coating of a crusher's feed chute significantly influences the mean time between failures (MTBF) and operational costs associated with the mass production of sulfuric acid at MMG/Kinsevere. Neglecting the condition of the protective coating can pose a serious challenge to production efficiency and result in increased downtime. This study focuses on enhancing industrial productivity in Sulfuric Acid production with minimal maintenance. The investigation explores the quality and type of materials used for the protective coating of the feed chute in the mining industry, particularly at MMG/Kinsevere, utilizing Ansys Fluent and SOLIDWORKS Software for analysis. The paper proposes a Ceramic protective liner for the crusher feed chute due to its superior resistance to erosion compared to other liners. Different feed chute models, constructed with materials like halogenated butyl rubber, 316 stainless steel, and ceramic, underwent analysis. The evaluation of the potential impact on the mean time between failures (MTBF) for different materials used in a protective coating, considering the rate of erosion through computational fluid dynamics (CFD) with ANSYS FLUENT software, is a central aspect of this study. The detailed modeling and simulation reveal that the ceramic material exhibits the most favorable protective coating characteristics, with an erosion rate density of 06.636753 kg/m2s, outperforming halogenated butyl rubber (3.326576 kg/m2s) and 316 stainless steel (2.186633 kg/m2s). The simulation yielded results corresponding to flow rates of 284.19 kg/s for the solid phase and 123.14 kg/s for the liquid phase. [ABSTRACT FROM AUTHOR]

Pile driving can trigger slope failure, specifically in sensitive soil deposits or marginally stable slopes. Cases of slope failure during pile installation have been reported in countries such as Norway, Sweden and Canada where soft sensitive clay deposits are prevalent. Although a few approaches have been suggested to assess the factor of safety of a slope during pile driving, there is currently no standard method recognized by the geotechnical society to account for the reduction of safety factor of a slope as an effect of pile installation. Some approaches suggest using the excess pore pressure generated during pile driving to account for the reduction in soil strength (by reducing effective stresses), neglecting the change in total stresses. This paper discusses the accuracy of stability analysis methods currently in use for this problem by looking at stress changes in the soil during pile driving as well as using numerical analysis results. Importantly, the paper identifies the shortcomings regarding these approaches, thus allowing geo-engineers to understand the limitations of their analysis and the uncertainties in the models. [ABSTRACT FROM AUTHOR]

Particle morphology is a crucial determining factor in the physicochemical properties of geological materials. Currently, there are still substantial challenges with the characterization and reconstruction of the morphology of irregular particles. Most currently used characterization and reconstruction methods were developed separately, and lack cohesive integration of parameters between the two processes. This limitation hinders the comprehensive characterization of the multiscale geometric features and impedes a clear relation between geometrical features and reconstruction parameters. Therefore, a unified 2D and 3D morphological characterization method for irregular particles is developed in this paper, enabling a systematic morphology quantification across three relative scales. Furthermore, a geometric parameters-driven particle reconstruction approach is proposed, which is the reverse of the quantification process, achieving precise and controllable 2D and 3D irregular morphology reconstruction. The proposed methods achieve, for the first time, an integrated quantification and reconstruction framework of irregular particle morphology, as well as a unified 2D and 3D morphology characterization. Notably, the proposed approach exhibits strong robustness and computational efficiency when performing 2D and 3D particle morphology quantification and precisely controllable virtual particle reconstruction, which are the bases for accurate mechanical analyses and numerical simulations. [ABSTRACT FROM AUTHOR]

This paper investigates an adapted loss function for the estimation of a linear regression with right censored responses. The adapted loss function could be used in composite quantile regression, which is a good method to handle the responses with high censored rate. Under some regular conditions, we establish the consistency and asymptotic normality of the resulting estimator. For estimation of regression parameters, we propose the MMCD algorithm, which generates satisfactory results for the proposed estimator. In addition, the algorithm can also be extended to the fused adaptive lasso penalized method to identify the interquantile commonality. The finite sample performances of the methods are further illustrated by numerical results and the analysis of two real datasets. [ABSTRACT FROM AUTHOR]

With the development of cloud computing, users are more inclined to outsource complex computing tasks to cloud servers with strong computing capacity, and the cloud returns the final calculation results. However, the cloud is not completely trustworthy, which may leak the data of user and even return incorrect calculations on purpose. Therefore, it is important to verify the results of computing tasks without revealing the privacy of the users. Among all the computing tasks, the polynomial calculation is widely used in information security, linear algebra, signal processing and other fields. Most existing polynomial-based verifiable computation schemes require that the input of the polynomial function must come from a single data source, which means that the data must be signed by a single user. However, the input of the polynomial may come from multiple users in the practical application. In order to solve this problem, the researchers have proposed some schemes for multi-source outsourced data, but these schemes have the common problem of low efficiency. To improve the efficiency, this paper proposes an efficient polynomial-based verifiable computation scheme on multi-source outsourced data. We optimize the polynomials using Horner's method to increase the speed of verification, in which the addition gate and the multiplication gate can be interleaved to represent the polynomial function. In order to adapt to this structure, we design the corresponding homomorphic verification tag, so that the input of the polynomial can come from multiple data sources. We prove the correctness and rationality of the scheme, and carry out numerical analysis and evaluation research to verify the efficiency of the scheme. The experimental indicate that data contributors can sign 1000 new data in merely 2 s, while the verification of a delegated polynomial function with a power of 100 requires only 18 ms. These results confirm that the proposed scheme is better than the existing scheme. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to analyzing the dynamics of COVID-19 using nonstandard finite difference (NSFD) schemes. Our model incorporates both asymptomatic and symptomatic infected individuals, allowing for a more comprehensive understanding of the epidemic's spread. We introduce an unconditionally stable NSFD system that eliminates the need for traditional Runge–Kutta methods, ensuring dynamical consistency and numerical accuracy. Through rigorous numerical analysis, we evaluate the performance of different NSFD strategies and validate our analytical findings. Our work demonstrates the benefits of using NSFD schemes for modeling infectious diseases, offering advantages in terms of stability and efficiency. We further illustrate the dynamic behavior of COVID-19 under various conditions using numerical simulations. The results from these simulations demonstrate the effectiveness of the proposed approach in capturing the epidemic's complex dynamics. [ABSTRACT FROM AUTHOR]

Enhancing information security has become increasingly significant in the digital age. This paper investigates the concept of physical layer security (PLS) within a relay-aided power line communication (PLC) system operating over a multiple-input multiple-output (MIMO) channel based on MK model. Specifically, we examine the transmission of confidential signals between a source and a distant destination while accounting for the presence of multiple eavesdroppers, both colluding and non-colluding. We propose a two-phase jamming scheme that leverages a full-duplex (FD) amplify-and-forward (AF) relay to address this challenge. Our primary objective is to maximize the secrecy rate, which necessitates the optimization of the jamming precoding and transmitting precoding matrices at both the source and the relay while adhering to transmit power constraints. We present a formulation of this problem and demonstrate that it can be efficiently solved using an effective block coordinate descent (BCD) algorithm. Simulation results are conducted to validate the convergence and performance of the proposed algorithm. These findings confirm the effectiveness of our approach. Furthermore, the numerical analysis reveals that our proposed algorithm surpasses traditional schemes that lack jamming to achieve higher secrecy rates. As a result, the proposed algorithm offers the benefit of guaranteeing secure communications in a realistic channel model, even in scenarios involving colluding eavesdroppers. [ABSTRACT FROM AUTHOR]

The rock mechanics parameters are important indicators for risk assessment in tunnel construction. However, rock mechanical parameters estimated by traditional mechanical testing in the field are subject to considerable uncertainties due to limitations testing technology, which can directly lead to unreliable risk assessment results. Deformation data for parametric back analysis is a reliable and efficient method for estimating mechanical parameters of rock masses. Deformation monitoring data used for parameter back analysis is an efficient and reliable method for estimating rock mechanical parameters, but the current research generally suffers from inaccurate constitutive models, confusing selection of input data, and failure to consider the intrinsic correlation of mechanical parameters. In this paper, a deformation-based back analysis method for rock mechanical parameters was proposed by XGBoost with RC. Taking the Changning Tunnel in Yunnan Province, China, as an example, the construction process of the back analysis model was described in detail. To improve the reliability of the sample data, the Ubiquitous-Joint constitutive model was used and a more characteristic deformed data selection method was proposed. Furthermore, the performance of the back analysis model was improved through Bayesian Optimization of hyperparameters and order filtering of Regressor Chain, and the intrinsic correlation of the parameters was effectively considered through the Regressor Chain. The results showed that applying the rock mechanics parameters obtained from the back analysis model to numerical simulation can effectively predict deformation during tunnel construction, and the error rate of deformation prediction was within 10%, which demonstrates the reliability of the method in this paper. This method can be extended to other heavily fractured tunnels. Highlights: Summarized the technical process of back analysis of mechanics parameters based on machine learning, analyzed the current research status, and put forward the existing problems. Through the spatial–temporal effect analysis of deformation of rock mass, a reasonable selection method of the surrounding rock deformation index in the sample data is proposed. The performance of the back analysis model of rock mechanics parameters is effectively improved by hyperparameter optimization of Bayesian and order filtering of Regressor Chains. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to investigate the hydrodynamic and vibrational behavior of the 2000 mm diameter Howell Bunger valve that will be installed in the Khodaafrin dam. The existence of a historical bridge downstream of this dam makes it important to investigate the vibration and hydrodynamic behavior of the valve, so that its design and operation should be in such a way that the historical bridge located downstream will not be damaged. In order to achieve this goal, the valves are considered to have submerged discharge, and this has raised the need to investigate the hydrodynamic behavior of the valve and compare it with the non-submerged state. To investigate the behavior of the valve, a 1:20 model of the valve, hood and discharge pool were designed and built. Then, the experimental rig was designed and equipped with measuring equipment, and the model valve was subjected to hydrodynamic and vibration tests with different opening percentages in non-submerged and submerged states with different downstream pool depths. These experiments have been repeated for the valve with hood and without hood and the results have been compared. Then, the finite element model of the 1:20 model valve was developed and hydrodynamically analyzed and the numerical results were compared with the experimental data. After ensuring the correctness of the numerical model, it was used to investigate the behavior of the valve in different conditions. The results show that there is not much change in the flow rate when the valve is submerged, but the range of vibrations decreases significantly. This decrease in the amplitude of vibrations becomes more dominant with increasing the depth of the pool. Also, it has been shown that the range of vibrations in the case without the hood is lower than the case with the hood. [ABSTRACT FROM AUTHOR]