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Thin-walled tubular deployable composite boom (DCB) has gained significant attention due to its lightweight, simple structure and high packaging efficiency. The experimental and numerical simulation methods were employed in this paper to investigate the folding behavior of the DCB. Using T700/epoxy unidirectional reinforced prepreg as raw material, DCB specimens were prepared by the vacuum bag method. To complete the folding experiments of DCB specimens, a folding mechanism was designed and manufactured. Folding experiments of DCB specimens were conducted and folding moment versus rotational displacement curves were measured. In addition, a Finite Element Model (FEM) was established to predict the folding behavior of the DCB. Different failure criteria were considered in the numerical analysis, including the Tsai‐Hill criterion and maximum stress criterion. Prediction results using the FEM were compared with experimental results, and both sets of results were in good agreement. It is shown that the DCB can achieve the folding function without failure. The research results in this paper are of great significance to the practical engineering application of the DCB. [Display omitted] • Six tubular deployable composite boom specimens and a precise folding mechanism were designed and prepared. • Folding experiments were conducted to measure the folding moment and rotational displacement curves. • A finite element model for predicting the folding behavior of the tubular deployable composite boom was established. [ABSTRACT FROM AUTHOR]

This paper employs a numerical approach to investigate the impact of liquidity shocks on European options in modeling markets. To accurately capture the behavior of European options under liquidity shocks, a coupled system of differential equations is employed, consisting of a degenerate parabolic equation and a diffusion-free equation. The primary focus is on developing and analyzing implicit-explicit methods for numerically simulating European option pricing, specifically considering the presence of liquidity shocks while ensuring the positivity of the solution. The paper also includes convergence analysis and establishes the discrete comparison principle for the developed methods. Numerical experiments are conducted using both uniform and nonuniform meshes to validate the theoretical findings, demonstrating the efficiency and accuracy of the proposed methods. [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 the development of a framework for the parametric design of tunnels using geographic information system (GIS) mapping and building information modelling (BIM). According to the framework, a parametric representation of each system component (e.g., layers of rock mass, size of excavation, topography, fault geometry, primary lining, secondary lining, rock bolts, etc.) can be incorporated in the GIS model with high levels of detail and used for the automatic generation of numerical models for the design of tunnel construction. This parametric evaluation allows the designer to consider several levels of detail for each component, for the efficient design and process optimization in conventional tunneling. Information between parametric analysis and numerical simulations can be freely exchanged with significantly reduced computational effort while results can be exported into BIM. It is anticipated that the proposed framework could lead to a comprehensive, yet efficient analysis of complex conventional tunneling project using parametric evaluations at the early design stages. [ABSTRACT FROM AUTHOR]

As a basic parameter of rock, the rock bridge angle plays an important role in maintaining the stability of rock masses. To study the size effect of rock bridge angle on the uniaxial compressive strength of rocks, this paper adopts the principle of regression analysis and combines numerical simulation to carry out relevant research. The research results indicate that: (1) the uniaxial compressive strength decreases with the increase of the rock bridge angle, showing a power function relationship; (2) The uniaxial compressive strength decreases with the increase of rock size and tends to stabilize when the rock size is greater than 350 mm, showing a significant size effect. (3) The fluctuation coefficient of compressive strength increases with the increase of rock bridge angle and decreases with the increase of rock size; When the rock size is 350 mm, the fluctuation coefficient is less than 5%; (4) The characteristic compressive strength and characteristic size both increase with the increase of the rock bridge angle. [ABSTRACT FROM AUTHOR]

Multi-material additive manufacturing using heterogeneous powders as raw materials is one of the important development directions of metal additive manufacturing technology. The evaporation behavior of heterogeneous powders in the selective laser melting (SLM) process has a significant influence on the accuracy of chemical composition control and the quality of the final product. In this paper, the fusion process of Fe20Mn (80 wt.% Fe and 20 wt.% Mn) heterogeneous powder, Fe and Mn elemental powders, and Fe20Mn pre-alloyed powder is numerically simulated using FLOW-3D® software and partially validated through SLM experimental results. The morphology and the characteristics of the flow field and temperature field in the melt pool for four kinds of powder materials are analyzed. The influence of the elemental evaporation behavior of different powders on the mass loss of the Mn element is discussed. The results show that the excessive accumulation of heat increases the maximum temperature of the melt pool, thus increasing mass loss. The Fe20Mn heterogeneous powder has a wider heat-affected zone and a higher peak value of temperature, nearly 400 K higher than that of the Fe20Mn pre-alloyed powders, which exhibits an intensive evaporation behavior. The mass loss of the Mn element obtained from the SLM experiment for Fe20Mn heterogeneous powders forming parts is more than the Fe20Mn pre-alloyed powders' forming parts for different laser powers, up to 17 wt.% at P = 120 W. This tendency is consistent with the numerical analysis of the effect of evaporation behavior of Fe–Mn heterogeneous powder during the SLM process. This study provides the necessary theoretical reference and process guidance for realizing the precise control of the SLM composition of a heterogeneous powder in multi-material additive manufacturing caused by evaporation behavior. [ABSTRACT FROM AUTHOR]

The present paper provides a brief overview of the existing methods for energy separation and an analysis of the possibility of the practical application of the Hartmann–Sprenger effect to provide quasi-isothermal pressure reduction of natural gas at the facilities within a gas transmission system. The recommendations of external authors are analyzed. A variant of a quasi-isothermal pressure regulator is proposed, which assumes the mixing of flows after energy separation. Using a numerical simulation of gas dynamics, it is demonstrated that the position of the resonators can be determined on the basis of calculations of the structure of the underexpanded jet without taking into account the resonator and, accordingly, without the need for time-consuming calculations of the dynamics of the processes. Based on the results of simulating the gas dynamics of two nozzle–resonator pairs installed in a single flow housing, it is shown that, in order to optimize the regulator length, the width of the passage between the two nearest resonators should be greater than or equal to the sum of diameters of the critical sections of the nozzles. Numerical vibroacoustic analysis demonstrated that the most dangerous part of the resonator is the frequency of its natural oscillations. [ABSTRACT FROM AUTHOR]

The urban underlying surface may affect the thunderstorm process. However, current research on this phenomenon is still in its infancy. This paper aimed to analyze the influence of the urban underlying surface on the evolution of thunderstorm organization through ground observation and numerical simulation. The results indicated that when the thunderstorm system with strong synoptic conditions passed through the built-up area of Beijing, it exhibited obvious bifurcation and detour. The dynamic field of near-surface cold pools could serve as diagnostic indicators for understanding how the urban underlying surface affects the thunderstorm process. The large-scale compact-rise clusters in the city center could alter the movement direction and path of the cold pool outflow, thereby influencing the thunderstorm organization process. In addition to the spatial configuration of the building complex, the city size might also be an important factor influencing the thunderstorm process. This study might provide a fundamental foundation and technical support for predicting and assessing urban thunderstorm disasters. [ABSTRACT FROM AUTHOR]

For all humanity, the sudden outbreak of Corona Virus Disease 2019 has been an important problem. Timely and effective media coverage is considered to be one of the effective approaches to control the spread of epidemic in early stage. In this paper, a Sentiment‐enabled Susceptible‐Exposed‐Infected‐Recovered (SEIR) model is established to reveal the relationship between the propagation of the epidemic and media coverage. The authors take the positive and negative media coverage into consideration when implementing the Sentiment‐enabled SEIR model. This model is constructed by parameterizing the number of current confirmed cases, cumulative cured cases, cumulative deaths, and media coverage. The numerical simulation and sensitivity analysis are conducted based on the Sentiment‐enabled SEIR model. The numerical analysis confirms the rationality of the Sentiment‐enabled SEIR model. The sensitivity analysis shows that positive media coverage acts a pivotal part in reducing the figure for confirmed cases. Negative media coverage has an effect on the figure for confirmed cases is not as significant as that of positive media coverage, but it is not negligible. [ABSTRACT FROM AUTHOR]

Upper protective layer (UPL) mining is extensively utilised as a pressure relief strategy to prevent outbursts and coal bursts. However, when the excavation height of the protected layer is substantial, the depressurisation efficacy of the protective layer may be diminished. This paper takes the Haishiwan coal mine in China as a case study and explores the stress evolution and influencing factors in the mining of extra-thick coal seam beneath the protective layer through theoretical analysis, numerical simulation, and field observation. The results indicate that increasing the excavation height of the coal seam will lead to the upward development of the collapse zone in the overburden of the goaf, with the "masonry beam" structure formed at a higher position by key strata blocks. The overburden above the masonry beam will be supported by the coal rock masse on both sides of the structure, leading to increased stress on the coal seam near the goaf and eliminating the depressurisation effect of the protective layer. Numerical simulation shows that factors such as faults, protective layers, interlayer spacing, and the height of coal seam excavation significantly affect the stress distribution in the protected layer. With the increase in interlayer spacing and the thickness of coal seam extraction, the stress reduction phenomenon of the UPL gradually decreases, especially with an abnormal stress concentration of the gob-side coal seam. Observations of Surface subsidence and the distribution of mining-induced seismic events corroborate the conclusions of theoretical analysis and numerical simulations. The results offer valuable guidance for the mining of extra-thick coal seams and the selection of the UPL. [ABSTRACT FROM AUTHOR]

In order to understand and master the diffusion mechanism and spatial concentration distribution of hydrogen leakage in the engine room, this paper studies the diffusion behavior and concentration distribution of hydrogen under the coupling effect of multiple factors, and further explores the optimal installation location of the sensors. The results indicate that when the ventilation rate increases by 1, 2, and 3 times, the diffusion volume of hydrogen decreases by about 0.4, 0.5, and 0.6 times. The harm of the increase in leakage diameter is greater than the leakage pressure. And the temperature has a greater impact on the hydrogen volume fraction in areas below 4 % and a smaller impact on areas above 4 %. In this environment, the sensors should be installed at or above 5.5 m in the rear of the engine room and above the axis of the hydrogen transport pipeline interface, valves and other places prone to leakage. • Taking a ship engine room as the research object. • The influence of various factors on hydrogen distribution is compared. • The spatial concentration distribution of hydrogen leakage is analyzed. • Explored the installation position of the sensors. [ABSTRACT FROM AUTHOR]

The aim of this paper is to establish a precise illustration for the structure of the nonconstant steady states for a Beddington–DeAngelis and Tanner predator–prey reaction–diffusion system with prey‐taxis. We treat the nonlinear prey‐taxis as a bifurcation parameter to analyze the bifurcation structure of the system. Furthermore, the exported global bifurcation theorem, under a rather natural condition, offers the existence of nonconstant steady states. In the proof, a priori estimates of steady states will play an important role. The local stability analysis with a numerical simulation and bifurcation analysis are given. Finally, some conclusions including biological meanings are performed to summarize our main analytic results and future investigations. [ABSTRACT FROM AUTHOR]

The mechanical properties of fractured rock have always been a focal point in the rock mechanics field. Based on previous research, this paper proposes improvements to the SPH method and applies it to the study of crack propagation in fractured rocks. By conducting uniaxial compression tests and simulating crack propagation on various specimens with different crack shapes, the characteristics of crack propagation were obtained. The comparison between the simulated results in this study and existing experimental and numerical simulation results confirms the validity of the SPH method employed in this paper. The present study utilizes the proposed methodology to analyze the influence of the crack angle, width, and orientation on crack propagation. The SPH method employed in this study effectively demonstrates the expansion process of fractured rock under uniaxial compression, providing valuable insights for the engineering applications of SPH. [ABSTRACT FROM AUTHOR]

This paper presents a coherent approach to evaluate the roll damping derivatives for the standard Basic Finner Model. The study compares and analyses the results obtained through a range of techniques, including experimental testing, numerical simulations and semi-empirical models. The study aims to evaluate the reliability and accuracy of these methods and to identify the factors that contribute to their sensitivity. The paper concludes by summarizing the findings of the study and discussing the implications of the results for the design and operation of rockets. The experimental and numerical analysis used in this study provides a robust and comprehensive evaluation of the roll damping coefficient. [ABSTRACT FROM AUTHOR]

In this paper, a small strain numerical procedure, the press-replace method (PRM), is adopted to model the monotonic, quasi-static installation of a jacked-in pile under an undrained condition. Numerical simulations are carried out using the small-strain geotechnical finite-element software PLAXIS 2D (version 20.03.00.60). The PRM implementation for modeling jacked-in pile installation is described. This paper aims to demonstrate and assess the prediction potential and limitations of the PRM for modeling the pile installation process followed by the subsequent load testing, using published information from two well-known field case studies. It is shown that the combination of the PRM with the modified Cam-clay constitutive model can not only capture the penetration resistance experienced by the pile during jacking but also simulate realistic stress and pore-pressure changes around the pile caused by the jacking process. The pore-pressure response during postinstallation consolidation, which leads to the pile setup phenomenon, can also be reasonably captured. Subsequently, the importance of incorporating installation effects in the numerical simulations of pile load tests is demonstrated, using a wished-in-place (WIP) pile model and another with the installation process simulated via the PRM. The PRM model predicts a significantly higher pile capacity than the WIP model. The different load-settlement behavior of the two piles can be attributed to the different soil states present in the two models at the start of the load test, in which the WIP model does not capture the changes occurring in the stresses, overconsolidation ratios, and void ratios of the surrounding soil caused by the pile jacking process. [ABSTRACT FROM AUTHOR]

This paper proposes an assembled X-shaped flexural steel damper. Welding is waived for the novel damper. As the kernel element of the damper, the X-shaped flexural steel plates have the advantages of ease of installation and replacement if necessary. In the analytical part, the effective height of the flexural steel plate was suggested, and then, the yield displacement, yield load and initial stiffness of the damper were derived. The proof-of-concept cyclic loading test was conducted using one reduced-scale specimen within a four-bar linkage experimental setup. The hysteretic performance indexes, including strength, stiffness and energy dissipation, were quantified. The high-fidelity finite element (FE) models were established by ABAQUS. The parametric study was further conducted based on the verified FE model. The considered parameters were the height and thickness of the steel plates. The testing results indicate that the proposed damper has plump hysteretic curve with good energy dissipation capacity and excellent ductility, although slight slip behavior can be found due to the gap caused by the assembling process. The results obtained from analytical method and numerical model are in good agreement with the experimental data. The results of parametric analysis show that the numerical results well agree with analytical predictions, indicating the numerical model can reflect the mechanical behavior of AXSFD. A benchmark frame building was selected to demonstrate the seismic control efficacy of the damper. The nonlinear time history analysis results indicate that the damper reduced both peak and residual interstory drift ratios for the protected structure. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) is being considered for use to enhance oil recovery and resource utilization and storage, with wide technical adaptability. In this paper, a numerical simulation method is used to study the adaptability of CO2 huff and puff in shale reservoirs. A fluid model introduces the nanoconfinement effect and reflects the nanoconfinement effect using the fluid p–T phase diagram. This method uses local grid refinement and changes the permeability near the grid to characterize the reservoir reconstruction volume (SRV) fracture network while considering the CO2 diffusion effect. The results indicate that by using the incremental recovery rate and oil change rate as references, adaptive charts can be obtained for different Kf/Km and oil saturation. When Kf/Km is 1000 and the increase in the CO2 recovery rate reaches 1.5%, the lower limit of oil saturation is 0.54. When Kf/Km is 1000 and the increase in the CO2 recovery rate reaches 2%, the lower limit of oil saturation is 0.57. When the oil saturation is 0.5 and the CO2 huff and puff oil change rate reaches 0.3, the lower limit of Kf/Km is 700. Finally, when the oil saturation is 0.548 and the CO2 huff and puff oil change rate reaches 0.6, the lower limit of Kf/Km is 10. The research results are significant and can guide the design and application of on-site CO2 throughput test plans. [ABSTRACT FROM AUTHOR]

In this paper, we propose an approach for describing wave propagation in finite-size microstructured metamaterials using a reduced relaxed micromorphic model. This method introduces an additional kinematic field with respect to the classical Cauchy continua, allowing to capture the effects of the underlying microstructure with a homogeneous model. We show that the reduced relaxed micromorphic model is not only effective for studying infinite-size metamaterials, but also efficient for numerical simulations and analysis on specimens of finite size. This makes it an essential tool for designing and optimizing metamaterials structures with specific wave propagation properties. The proposed model's efficiency is assessed through numerical simulations for finite-size benchmark problems, and shows a good agreement for a wide range of frequencies. The possibility of producing the same macroscopic metamaterial with different but equivalent unit cell "cuts" is also analyzed, showing that, even close to the boundary, the reduced relaxed micromorphic model is capable of giving accurate responses for the considered loading and boundary conditions. [ABSTRACT FROM AUTHOR]

In this paper, we propose and analyse a predator-prey model with disease in prey. We assume that a portion of healthy prey takes refuge to avoid predation. We find the biologically feasible equilibrium points and their stability criteria by using linearization technique. We also perform Hopf bifurcation analysis around the co-existing equilibrium point. We use substantial numerical simulation to verify our theoretical results and to investigate rich dynamics that are not possible to achieve analytically. We illustrate rich dynamics such as Hopf bifurcation. chaos, bistability, and others using one and two parameter bifurcation diagrams. We find that disease invasion in prey can produce chaos by inducing period-doubling bifurcation. but refuge can reduce chaos by causing period-halving bifurcation. We also observe that refuge can reduce the prevalence of disease in the Prey population. [ABSTRACT FROM AUTHOR]

The treelike structure links members and transfers loads via its solitary cast steel joint with branches. Therefore, the joint's bearing capacity significantly affects the treelike structure's stability, security, and economics. This paper utilized experimental verification and numerical modeling to examine the mechanical behavior of cast-steel joints with branches in the treelike structure under various loading conditions. Then, researchers investigated the failure process and mechanism of joints, and the three most common failure modes were outlined. Furthermore, the researchers proposed the bearing capacity calculation formula based on the common failure modes. The results show that the three common failure modes of the cast-steel joints with branches under different loading conditions are the failure in the joint core area under the axial load, the failure in the main pipe compression side under eccentric load, and the failure in the compression side of the single branch pipe root when the single branch pipe is under the uneven load. The suggested empirical calculation method can serve as a reference point for similar engineering practices design. [ABSTRACT FROM AUTHOR]

This paper reviews latest developments of substructures for offshore wind turbines focusing on investigations and applications of hybrid foundations. Model tests and numerical analyses were used to simulate the loading of hybrid piles in sand. The results of pile-soil interaction were investigated to confirm the changes in soil stiffness around the hybrid monopile head. The mechanism and factors affecting the change in lateral stiffness of the hybrid foundation were explained by analysing p-y curves for M+H loading conditions in sand. Based on this research, a new shape of p-y curves for hybrid monopiles was established and a method for determining key parameters was proposed. The effectiveness of new p-y curves was verified by comparing back-calculated results with those from numerical simulations. The conducted tests confirmed that the hybrid monopile displacement is 30-50% smaller when compared to a standard monopile with similar dimensions. The gained experiences can be useful for designers and researchers to enhance the design of foundations for offshore wind turbines. [ABSTRACT FROM AUTHOR]

Plasma gasification technology is a harmless and resourceful solid waste treatment method. As a hazardous waste, studying the plasma gasification treatment of oil-based drilling cuttings has practical significance. Therefore, this paper uses Aspen Plus to establish a plasma gasification model. Based on model validation, the effects of input power, oxygen equivalence ratio, and carrier gas type on the plasma gasification process of oil-based drilling cuttings were discussed. In addition, by designing a quadratic regression orthogonal experiment, a nonlinear quadratic regression equation was established between the three factors of gasification pressure, input power, and equivalence ratio, as well as different gasification indicators, namely gas yield, lower heating value, and gasification efficiency. By solving the equation, it was found that when the gasification power is 70 kW, the gasification pressure is 10 atm, and the equivalence ratio is 0.1, the gas yield reaches its maximum of 0.74 kg/m3; When the gasification power is 15 kW, the gasification pressure is 10 atm, and the equivalence ratio is 0.1, the lower heating value of gas production reaches its maximum of 9.68 MJ/m3; When the gasification power is 15 kW, the gasification pressure is 1 atm, and the equivalence ratio is 0.1, the gasification efficiency reaches its maximum of 37.6%. At the same time, it was found that the influence of gasification pressure, input power, and equivalence ratio on gasification indicators was ranked in descending order as equivalence ratio, input power, and gasification pressure. The above research provides certain reference values for the practical operation of plasma gasification of oil-based drilling cuttings. • Analyzed the effects of different factors on plasma gasification of OBDC. • Optimum parameters of plasma gasification of OBDC are studied. • Ranked the degree of influence of different factors on plasma gasification of OBDC. • Analyzed the efficiency of plasma gasification of OBDC. [ABSTRACT FROM AUTHOR]

HIV/AIDS-COVID-19 co-infection is a major public health concern especially in developing countries of the world. This paper presents HIV/AIDS-COVID-19 co-infection to investigate the impact of interventions on its transmission using ordinary differential equation. In the analysis of the model, the solutions are shown to be non-negative and bounded, using next-generation matrix approach the basic reproduction numbers are computed, sufficient conditions for stabilities of equilibrium points are established. The sensitivity analysis showed that transmission rates are the most sensitive parameters that have direct impact on the basic reproduction numbers and protection and treatment rates are more sensitive and have indirect impact to the basic reproduction numbers. Numerical simulations shown that some parameter effects on the transmission of single infections as well as co-infection, and applying the protection rates and treatment rates have effective roles to minimize and also to eradicate the HIV/AIDS-COVID-19 co-infection spreading in the community. [ABSTRACT FROM AUTHOR]

This paper introduces a new prefabricated recyclable double-row piles retaining system for excavations in silty clay ground. Laboratory model test and numerical simulation are conducted to study the system behavior upon excavation. The horizontal displacement (δh), Von Mises stress (σM), strain (ε), ground surface settlement (δv), and earth pressure are systematically investigated. Furthermore, the monitoring data of 13 excavation cases supported by double-row piles retaining system are presented and discussed. The experimental results can basically match the numerical results, and the maximum σM, maximum bending moment (Mmax), maximum horizontal displacement (δhm) of structural members are all less than the tolerance limits. The ground surface settlement model of double-row piles retaining system consists of three zones, i.e., rebound influence zone, primary influence zone and secondary influence zone. The dhm values are 0.07%-1.42% of the excavation depth (He). The maximum ground surface settlement (δvm) is generally less than δhm. The ratio of δvm/δhm varies between 0.09 and 0.76, with an average value of 0.5. The observed earth pressure on the retained side of front pile (paf) is about 0.53-0.57 γH below the excavation surface. Above the excavation surface, paf decreases dramatically when getting closer to the ground surface. [ABSTRACT FROM AUTHOR]

Coupler separation is among the serious accidents threatening the operation safety of heavy-haul trains. This paper reports a study on the formation mechanism and key influencing factors of middle coupler separation of a 20,000-tonne combined heavy-haul train during air-braking release by means of field investigation, theoretical analysis and numerical simulation. The interaction state between the connected coupler knuckles and the potential sensitive factors leading to the coupler separation are investigated based on field tests and theoretical analysis. The formation process of coupler separation and the related influencing factors are analysed through numerical simulations. The results show that the coupler separation between slave locomotives and connected wagons usually occurs in the switching process of the longitudinal coupler force from the buffing (compressive) state to the draw (tensile) state. The excessive initial height difference of connected coupler knuckles, dynamic braking force of locomotive, pitch angle of locomotive and wagon coupler as well as the too small friction coefficient of the coupler knuckles significantly increase the risk of coupler separation. [ABSTRACT FROM AUTHOR]

In recent years, the finite-difference time-domain (FDTD) method has been used to simulate a wide range of frequency dependent media. The accuracy of these simulations often depends on how accurately the complex dielectric constant is simulated in the sampled time domain used by FDTD. This paper describes the process of modelling the complex dielectric constant as a digital filtering problem and uses Z transforms to convert the frequency domain expression to a sampled time domain expression. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a new method to improve re performance of intra-field interpolation which is the mos~ important element of deinterlacing method. Traditional edge- based methods were poor at determining accurate edge iirection which decides interpolation performance. The 7roposed method decides the direction and slope of edge based on locally adaptive-thresholded binary image to mprove efficiency and accuracy, and it also increased the ~orizontal size of search window to 15 for better direction ietermination at gentle slope. Compared to traditional edge- based methods, interpolation based on binary image, which is ,`enerated using the proposed method, leads to great erformance improvement. With computer simulations for a ~`ariety of images, this paper shows the new approach is much ~etter than traditional methods.. [ABSTRACT FROM AUTHOR]

This paper presents an implementation of an ~daptive beamformer in a hands-free unit. The proposec~ ~daptive beamformer suppresses stationary noise an~ nterference sound. The adaptive beamformer and acoustic `cho canceller were implemented in a compact hands-free mit with a low-cost DSP. Experimental results demonstrate he noise reduction performance of the hands-free unit'. [ABSTRACT FROM AUTHOR]

A new approach using FIT-formulation (Finite Integration Technique) (T. Weiland, Electron. Commun., 31, 116–120 (1977); Int. J. Numer. Model., 9, 295–319 (1996)) for simulating waveguide propagation of optical pulses is presented. FIT-methods are widespread in use for broadband linear simulations. In recent years, several attempts have been made to describe different dispersive material-characteristics such as Drude, Debye or Lorentz dispersion. Today advanced FDTD-formulations (Finite Difference Time Domain) also consider non-linear effects (P. M. Goorjian and A. Taflove, IEEE Opt. Lett., 17(3), 180–182 (1992); D. M. Sullivan, IEEE Trans. Microwave Theory Techniques, 43(3), 676–682 (1995)). In the following presented method third-order non-linear effects were described, which can be observed in isotropic media in frequency ranges of optical pulses, by updating material polarization terms using classical descriptions of Lorentz dispersion, Raman scattering and the Kerr effect. The basic idea is transforming these description formulas into sets of linear differential equations and solving them with the help of the general exponential solution. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised [ABSTRACT FROM AUTHOR]

From the facts that numerous regions with initially similar economic conditions end up with different levels of entrepreneurial agglomeration, this paper constructs a model assuming that the sequential entrants make their career choices based on existing entrepreneurial ratio and describing the dynamics of entrepreneurial agglomeration formation. After mathematical analysis and numerical simulation using NetLogo, it is found that under social selection, a nonlinear Polya process with self-reinforcing and path-dependency characters will emerge, and the repeated entrants' career choices will lead to the agglomeration of entrepreneurship; the agent's risk compensation value, the initial population of agents, the number of role models in the early stage and the initial entrepreneurial ratio are determinants to the formation of entrepreneurial agglomeration. The findings confirm that entrepreneurship has "memory" and the entrepreneurial history could have influence on the future. In order to forge the entrepreneurial agglomeration, our suggestions include exerting influence on the determinants from an early age, and improving the individual's risk-taking abilities. [ABSTRACT FROM AUTHOR]

In the present paper, a new fractional order predator–prey model is considered. The applied fractional operator is a generalized Atangana–Baleanu–Caputo (ABC) derivative, which does not require any restrictions on the initial conditions as in the case of classical ABC fractional derivatives. On the theoretical aspect, we prove the existence, uniqueness, and Ulam–Hyers stability results by using some fixed point theorems and nonlinear analysis techniques. The numerical aspect discusses the approximation solutions for the proposed model by applying the generalized scheme of the Adams–Bashforth technique. At the end, we explain the behavior of the solution to the studied model through graphical representations and numerical simulations. [ABSTRACT FROM AUTHOR]

• The proposed method (P-SuS) generalises subset simulation from, to the capability of handling distributional responses. • P-SuS can be used in reliability analyses with partially-converged simulations, probabilistic and surrogate models. • The algorithm can be used in lieu of subset simulation in reliability analysis, optimisation, and pre-calibration. Reliability analysis can be performed efficiently through subset simulation. Through Markov chain Monte Carlo, subset simulation progressively samples from the input domain of a performance function (typically a computer model) to find the failure domain, that is, the set of input configurations that result in an output higher than a prescribed threshold. Recently, a probabilistic framework for numerical analysis was proposed, whereby computation is treated as a statistical inference problem. The framework, called probabilistic numerics, treats the output of a computer code as a random variable. This paper presents a generalisation of subset simulation, which enables reliability analysis for probabilistic numerical models. The advantages and challenges of the method are discussed, and an example with industrial application is presented. [ABSTRACT FROM AUTHOR]

Unconventional oil and gas formations are abundant, have become an increasingly important part of the global energy supply, and are attracting increasing attention from the industry. Predicting key reservoir properties plays a significant role in both geological science and subsurface engineering workflows. With the advent of horizontal well drilling and multiple-stage hydraulic fracturing, the Montney Shale formation is one of the most promising and productive shale plays in Canada. However, very few academic papers discuss its in situ stress, reservoir pressure, and permeability, which are essential for the development of the Montney Shale. The objective of this study is to analyze the geo-stress, the pore pressure, and several key reservoir properties by using diagnostic fracture injection test (DFIT) data from the Montney Shale. One horizontal well from the Wapiti field has been analyzed with a set of DFIT data, and its results show that the general pressure and Gdp/dG responses from Well-A indicate a signature of height recession/transverse storage. In the study, the Tangent Line method, the Compliance method, and the Variable Compliance method have been applied to estimate the key reservoir properties. As a result, the Well-A DFIT analysis estimates that the closure pressure is ranging from 34.367 to 39.344 MPa, contributing to the stress gradient from 14.09 to 16.13 KPa/m for the formation. The pore pressure is ranging from 20.82 to 24.58 MPa, contributing to the pore pressure gradient from 8.54 to 10.07 KPa/m for the formation. The porosity is ranging from 3% to 6%. These reservoir properties are contoured cross the Montney Shale formation. Using the DFIT's numerical simulation and history matching, the reservoir permeability is 0.024 md, fracture length is 13.44 m, and fracture geometries are analyzed by different models. Moreover, the physics behind the DFIT are analyzed and discussed in detail. For the first time, three different analysis methods have been applied to estimate a series of key reservoir properties for the case wells in the Montney Shale formation. This approach can not only reduce the potential prediction error caused by a single method application but also increase the persuasiveness of the assessment and save time, ensuring the efficient implementation of engineering operations. Given the significance of quantifying in situ stress and reservoir pore pressure in unconventional hydrocarbon exploration and development, this study could help the operator to quickly understand the stress regimes, the fracture geometry, and the formation properties of the Montney Shale formation in the Wapiti field. Furthermore, the interpreted results demonstrated in this paper are adding substantial business value to the asset, especially in terms of improving the hydraulic fracturing design and, thus, accelerating the cashflow from production. [ABSTRACT FROM AUTHOR]

After the excavation of an underground cavern, how the surrounding rock and the support work together to bear the excavation load is an important prerequisite to correctly analyze the joint force characteristics; effectively play the role of support; and ensure the safety, efficiency, and economy of underground cavern construction. Starting from the elastic-plastic load release characteristics of surrounding rock, this paper proposes a calculation method of the elastic load coefficient of surrounding rock and a graded release method of plastic load, which ensures the actual effect of the synergistic action of the first support and surrounding rock. Based on the elastic-plastic damage evolution characteristics of surrounding rock, a weighted iterative calculation method of elastic-plastic damage is proposed, and an evaluation method of load release ultimate bearing capacity of surrounding rock is determined. By monitoring the change law of rock acoustic wave velocity with surrounding rock damage, the relationship between the wave velocity and the damage coefficient of the surrounding rock in the excavation process is deduced, and it is proposed to determine the latest support time for first support by using the measured rock damage wave velocity. Through the numerical simulation analysis of a diversion tunnel excavation and support, the damage evolution law of the surrounding rock with the release of the excavation load is studied. The ultimate bearing capacity of various surrounding rocks and supporting opportunity is determined. The results demonstrate the validity and practicality of the analysis and calculation methods in this paper, which provide a new idea and analysis method for quantifying the bearing capacity of surrounding rock and determining the support timing in the excavation and support design of underground caverns. [ABSTRACT FROM AUTHOR]

The traditional numerical analysis method of deformation mechanics of bolt support has the problems of poor numerical simulation effect and accuracy. In this paper, the numerical simulation of deformation mechanics of bolt support in high stress mine roadway is studied. This paper analyzes the principle of bolt in high stress mine roadway, constructs the deformation concentration parameter model of bolt support in high stress mine roadway, and calculates the bearing capacity of bolt; The elastic deformation equation of bolt support in high stress mine roadway is obtained, the energy balance control of bolt support in high stress mine roadway is realized, and the numerical simulation of deformation mechanical characteristics of bolt support in roadway is realized. The experimental results show that when the impact time is 18 ms, the deformation force of the proposed method and the actual bolt support is 286 kn, which indicates that the proposed method can obtain the deformation force results of the bolt support, and the proposed method can accurately simulate the deformation mechanical characteristics of the bolt support. [ABSTRACT FROM AUTHOR]

This paper is devoted to the numerical analysis of a numerical scheme for the simulation of front advection. The scheme has been recently proposed and it is based on the ideas used for Glimm's scheme. It relies on a two-step approach: a convection step is followed by a projection step, which is based on a random choice. The main advantage of this scheme is that it is applicable to multidimensional problems. In the present paper, a convergence result for this scheme is provided for a particular class of multidimensional problems. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the behavior of a spherical absorber composed of two parts, an inner sphere and a supporting convex spherical dish in which the ball is placed. Considering only the planar behavior of the system, a set of governing nonlinear differential equations was derived and solved numerically. Firstly, the system is exposed to the harmonic excitation of the supporting bowl and its time response is analyzed for all time dependent variables. By gradually changing the angular frequency of the excitation, a resonance curve is obtained, which is examined in detail with respect to the changing amplitudes of the excitation force and the nonlinear behavior. The effect of internal damping and different settings of the absorber characteristics are also investigated. The effect of initial conditions without the presence of an external excitation force is also numerically analyzed by means of phase portraits for selected pairs of initial conditions. [ABSTRACT FROM AUTHOR]

River valley contraction (RVC) has increased continuously at the Xiluodu Dam site since the completion of the slope excavation that commenced on December 1, 2008. Previous studies on RVC only analyzed the displacement after reservoir impoundment. Since deformation is affected by many factors, it is difficult to determine the leading causes of RVC by merely studying the displacement after impoundment. This study examines, for the first time, the complete displacement process before and after impoundment. Four models that include poroelastic, thermo-poroelastic, poroelastic-plastic, and poroelastic-creep are used to simulate the RVC displacement using COMSOL multiphysics. It is observed that the creep of the basalt formation is the leading cause of RVC. Sloped excavation causes RVC, and the subsequent reservoir impoundment accelerates the RVC by changing the creep parameters. A poroelastic-creep model with two-stage creep parameters was applied to the numerical simulation. The simulation results are in good agreement with the field observations. The predicted results show that the convergence value of RVC is 187 mm, and an additional closure of 21.5 mm will occur in the next 14.5 years. This research provides a further assessment of the RVC by providing a model that is validated by existing data and leads to an estimation of future RVC. Highlights The paper presents a comprehensive investigation of the river valley contraction behavior at the Xiluodu reservoir. 2D simulation was performed to reveal the mechanism of the river valley contraction. Four models that include poroelastic, thermo-poroelastic, poroelastic-plastic, and poroelastic-creep were applied to the numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper, motivated by considerations of server utilization and energy consumption in cloud computing, we investigate a homogeneous queueing system with a threshold-based workload control scheme. In this system, a virtual machine will be turned off when there are no tasks in its buffer upon the completion of a service by the machine, and turned on when the number of tasks in its buffer reaches a pre-set threshold value. Due to complexity of this system, we propose approximations to system performance measures by mean field limits. An iterative algorithm is suggested for the solution to the mean field limit equations. In addition, numerical and simulation results are presented to justify the proposed approximation method and to provide a numerical analysis on the impact of the system performances by system parameters, which suggests that the proposed system saves about (1 − λ μ) × 100 % of the energy consumption compared to the ordinary supermarket models. [ABSTRACT FROM AUTHOR]

This paper takes the compact tensile specimens manufactured by glass fiber reinforced composites as the research object. Hopkinson tension bar experimental technique was used to study the dynamic fracture toughness. The dynamic fracture toughness of [0/90]n laminated and [45/− 45]n laminated compact tensile specimens was measured by Hopkinson tension bar experimental device; the simulation calculation under the same stress wave loading was carried out by ABAQUS, and the accuracy was verified by comparing with the experimental results; using the verified simulation model, the effect of specimen thickness and crack length on the dynamic fracture toughness of fiber reinforced composites was studied. [ABSTRACT FROM AUTHOR]

This paper is concerned with a reaction–diffusion–advection chemostat model with two species growing and competing for a single-limited resource. By taking the growth rates of the two species as variable parameters, we study the effect of growth rates on the dynamics of this system. It is found that there exist several critical curves, which may classify the dynamics of this system into three scenarios: (1) extinction of both species; (2) competitive exclusion; (3) coexistence. Moreover, we take numerical approaches to further understand the potential behaviors of the above critical curves and observe that the bistable phenomenon can occur, besides competitive exclusion and coexistence. To further study the effect of advection and diffusion on the dynamics of this system, we present the bifurcation diagrams of positive equilibrium solutions of the single species model and the two-species model with the advection rates and the diffusion rates increasing, respectively. These numerical results indicate that advection and diffusion play a key role in determining the dynamics of two species competing in a flow reactor. [ABSTRACT FROM AUTHOR]

In order to study the heat dissipation characteristics of lithium batteries, a staggered bi-directional flow cooling method is designed and numerical simulations are established using CFD in this paper with a circular battery as the research object. Since the optimal operating range of Li-ion battery is 293.15-313.15 K and the maximum temperature difference is not higher than 5 K, the maximum temperature and maximum temperature difference are selected as the optimized design objectives. Firstly, the temperature field of the round lithium battery with discharge multiplier 3C working at ambient temperature 308.15 K is studied, and an orthogonal test design is carried out for three factors: battery pack embedding distance, coolant flow rate and coolant temperature, and the best combination of orthogonal test is selected by extreme difference analysis and analysis of variance. Secondly, in order to further verify the heat dissipation efficiency of the battery pack, a back propagation neural network with multi-objective optimization algorithm is proposed, and the optimal heat dissipation method of the numerical simulation is obtained by parameter solution and simulation analysis using the parameter range of the orthogonal test as the constraints of the multi-objective optimization. The results show that this optimized way of battery pack heat dissipation has a significant improvement for the maximum temperature, and non-e of them will exceed its working range; compared with the 3.39 K obtained from the orthogonal test design, the maximum temperature difference of the battery pack calculated by the multi-objective optimization is 3.15 K, which is reduced by 7.08%. [ABSTRACT FROM AUTHOR]

In this paper, the stress-induced twin interface nucleation in single-crystalline NiMnGa alloys is studied through theoretical analyses and numerical simulations. First, the mechanical governing system for a single-crystalline NiMnGa sample is formulated, which contains the mechanical field equation and the twin interface movement criteria. To complete the governing system, the nucleations of twin interfaces in the NiMnGa sample under general mechanical loads are investigated. By considering the connection conditions of some physical quantities across a "fictitious" twin interface, the explicit expression of the configurational force on the twin interface is derived. Then, based on the twin interface movement criteria, a practical scheme for predicting the twin interface nucleation is proposed. This scheme can be integrated into the iterative numerical algorithm for solving the mechanical governing system. To demonstrate the efficiency of this scheme, some simulation results are presented for two typical deformations of a NiMnGa sample (i.e., the axial compression and the bending deformation), which show good consistency with the experimental results. By analyzing the evolution properties of the configurational forces on the possible nucleation interfaces, the mechanism responsible for twin interface nucleations under different loading conditions can be revealed. The results obtained in the current work would be helpful for the design of smart devices by utilizing NiMnGa alloys. [ABSTRACT FROM AUTHOR]

The coupled motion of roll and pitch is noticeable when trimaran sails in oblique head waves, which will lead to negative influence on the safety and comfort of navigation. In this paper, the numerical simulation of the trimaran's motion in oblique waves was carried out by open source CFD tool OpenFOAM, and the computed motion response was analyzed to study the characteristics of the torsional rolling. The OpenFOAM-based hybrid method used in this paper was briefly introduced first, and the numerical method was validated and verified by both the grid convergence test and the comparison with experimental result. Both the amplitude and the time history of the computed motion are used for analysis, and the influence of wave steepness, wave heading and forward speed of trimaran on the characteristics of torsional rolling was investigated. The result shows that the large wave steepness and the low forward speed will lead to dangerous torsional rolling motion of trimaran in oblique waves, and the dangerous condition is mainly caused by nonlinear rolling motion; the motion state is more sensitive and changing obviously with other factors at large wave steepness wave conditions. [ABSTRACT FROM AUTHOR]

This paper investigates the nonlinear dynamical behaviors of a time-delayed supercavitating vehicle system varying with the system parameters, and proposes control strategies to stabilize the trajectory. A simplified dynamical model of the supercavitating vehicle is firstly constructed and then analyzed on its local and global stability in terms of different parameter values and initial conditions. Due to the forces resulting from the fins and the afterbody plane causing one of the system parameters to become a piecewise constant function of position, the system is described as a linear switched one with time delay. Both theoretical analysis and numerical simulations are adopted to describe the system behaviors. Several special phenomena such as bifurcations, deviation behaviors and period-doubling processes emerging from the system for a given set of parameters are discussed in detail in this paper. Besides, the equilibrium and chaotic solutions are accurately located by plotting the Lyapunov exponent map. Chaotic attractors present different strange forms with the variation of the parameters. Finally, based on the system's global property, the control and anti-control strategies are proposed to stabilize the system or generate desirable chaos and it is shown that the system can be controlled by selecting appropriate control parameters. [ABSTRACT FROM AUTHOR]

Little seems to be considered about the globally exponentially asymptotical stability of parabolic type equilibria and the existence of heteroclinic orbits in the Lorenz-like system with high-order nonlinear terms. To achieve this target, by adding the nonlinear terms yz and x 2 y to the second equation of the system, this paper introduces the new 3D cubic Lorenz-like system: x ˙ = a (y - x) , y ˙ = b 1 y + b 2 y z + b 3 x z + b 4 x 2 y , z ˙ = - c z + y 2 , which does not belong to the generalized Lorenz systems family. In addition to giving rise to generic and degenerate pitchfork bifurcation, Hopf bifurcation, hidden Lorenz-like attractors, singularly degenerate heteroclinic cycles with nearby chaotic attractors, etc., one still rigorously proves that not only the parabolic type equilibria S x = { (x , x , x 2 c) | x ∈ R , c ≠ 0 } are globally exponentially asymptotically stable, but also there exists a pair of symmetrical heteroclinic orbits with respect to the z-axis, as most other Lorenz-like systems. This study may offer new insights into revealing some other novel dynamic characteristics of the Lorenz-like system family. [ABSTRACT FROM AUTHOR]

A reinforced concrete shear wall is an important building structure. Once damage occurs, it not only causes great losses to various properties but also seriously endangers people's lives. It is difficult to achieve an accurate description of the damage process using the traditional numerical calculation method, which is based on the continuous medium theory. Its bottleneck lies in the crack-induced discontinuity, whereas the adopted numerical analysis method has the continuity requirement. The peridynamic theory can solve discontinuity problems and analyze material damage processes during crack expansion. In this paper, the quasi-static failure and impact failure of shear walls are simulated by improved micropolar peridynamics, which provides the whole process of microdefect growth, damage accumulation, crack initiation, and propagation. The peridynamic predictions are in good match with the current experiment observations, filling the gap of shear wall failure behavior in existing research. [ABSTRACT FROM AUTHOR]

The squeezed multiple-branch pile is a variable section pile that was built by adding a bearing branch cavity to a constant section pile using expansion and extrusion equipment. It is widely used in engineering practice for its high bearing capacity, small settlement deformation, high economic benefits, strong adaptability, and simple pile forming process. In this paper, a new type of squeezed multiple-branch pile is proposed and its forming tool is invented. The forming tool of the pile has applied for an invention patent and is authorized by the China National Intellectual Property Administration. Multiple groups of comparison models of the new squeezed multiple-branch piles are established by using FLAC3D numerical simulation software to investigate the influence of the number and spacing of branches on the bearing mechanism in response to uplift load. The results indicated that the number and spacing of branches have a significant effect on the uplift bearing capacity, load–displacement curves, side friction resistance, and stress distribution law in the new pile and soil around the pile. The suitable number and spacing of branches maximize the uplift bearing capacity and minimize the settlement of a single pile. [ABSTRACT FROM AUTHOR]