Search

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]

In this paper, a distributed bearing-based formation control scheme with finite-time convergency is proposed for multiple underactuated surface vessels (USVs). By virtue of the guide point-based model transformation method, the dimension of underactuated tracking error dynamics can be reduced from three to two. This allows us to convert the actuator model to a fully form that matches dimension-reduced tracking error dynamics. Further, to reduce the computation complexity, a finite-time recruited filter is designed according to first-order Levant differentiator. At meanwhile, auxiliary error compensation signals are introduced to address unknowns stemming from filter process and system dynamics. Since merely relative-distances and inner bearings are utilized in the proposed bearing-based formation approaches, the proposed control scheme provides a feasible solution to achieve formation control under body-fixed frame. Finally, theoretical analysis and numerical simulations are presented to demonstrate the efficacy. • Bearing-based finite-time formation control. • Underactuated surface vessels. • Levant differentiator. • Command filtered backstepping with error compensation signals and compensated errors. [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]

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]

Deployable coilable booms have many advantages for use in space, but these kinds of structures sometimes experience a deployment failure mode called 'blossoming'. Blossoming of a coiled boom occurs when the boom stops deploying, and instead unwinds and expands within the deployer. This can occur even in the presence of sprung rollers used to constrain the coil. In the blossoming process, friction between the layers of the coil plays an important role that has only been briefly considered in previous work. In order to be able to model and predict the onset of this phenomenon more precisely, the pressure distribution between adjacent layers of the coil must be known. This paper establishes a numerical model to investigate the pressure distribution within a coiled open-section tape spring boom, then combines this result with theoretical analysis to produce an estimate of the maximum tip force that a deploying boom can withstand before the onset of blossoming. The effect of the roller springs' stiffness and the boom friction coefficient are also taken into account in the simulation. The results of the theoretical analysis and numerical simulation are compared with previous experimental results to provide some practical verification. [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]

Numerical simulations are used in this work to investigate aspects of microstructure and microsegregation during rapid solidification of a Ni-based superalloy in a laser powder bed fusion additive manufacturing process. Thermal modeling by finite element analysis simulates the laser melt pool, with surface temperatures in agreement with in situ thermographic measurements on Inconel 625. Geometric and thermal features of the simulated melt pools are extracted and used in subsequent mesoscale simulations. Solidification in the melt pool is simulated on two length scales. For the multicomponent alloy Inconel 625, microsegregation between dendrite arms is calculated using the Scheil-Gulliver solidification model and DICTRA software. Phase-field simulations, using Ni–Nb as a binary analogue to Inconel 625, produced microstructures with primary cellular/dendritic arm spacings in agreement with measured spacings in experimentally observed microstructures and a lesser extent of microsegregation than predicted by DICTRA simulations. The composition profiles are used to compare thermodynamic driving forces for nucleation against experimentally observed precipitates identified by electron and X-ray diffraction analyses. Our analysis lists the precipitates that may form from FCC phase of enriched interdendritic compositions and compares these against experimentally observed phases from 1 h heat treatments at two temperatures: stress relief at 1143 K (870 °C) or homogenization at 1423 K (1150 °C). [ABSTRACT FROM AUTHOR]

• A new stochastic evolutionary adaptive dynamics model. • Conditions for continuously stable strategy and evolutionary branching. • Influence of the stochastic disturbance on the evolutionary dynamics. • Rigorous numerical simulations for dimorphic coexistence and coevolution. This paper proposes a stochastic model for the evolutionary adaptive dynamics of species subject to trait-dependent intrinsic growth rates and the influence of environmental noise. The aim of this paper is twofold: (a) mathematically we make an attempt to investigate the evolutionary adaptive dynamics for models with noises; (b) biologically we investigate how the noises in environment affect the evolutionary stability. We first investigate the extinction and permanence of the population in the presence of environmental noises. Combining evolutionary adaptive dynamics with stochastic dynamics, we then establish a fitness function with stochastic disturbance and obtain the evolutionary conditions for continuously stable strategy and evolutionary branching. Our study finds that under intense competition among species, increasing stochastic disturbance can lead to rapidly stable evolution towards smaller trait values, but there is an opposite effect under weak competition among species. This yields an interesting evolutionary threshold, beyond which any increasing stochastic disturbance can go against evolutionary branching and promote evolutionary stability. We then carry out the evolutionary analysis and numerical simulations to illustrate our theoretical results. Finally, for demonstrating the emergence of high-level polymorphism we perform long-term simulation of evolutionary dynamics. [ABSTRACT FROM AUTHOR]

• A coupling mechanism model of an FSDB unit is developed and verified. • Mathematical analysis is explored to reveal the coupling mechanism of an FSDB system. • Rigid and elastic motions of disk and cyclic blades induce diagonal and cross-coupling terms. • The motion patterns of cyclic blades are classified and clarified. • Effects of motion patterns of cyclic blades on NFs and CSs are applied to interpret and validate the dynamic coupling. This paper focuses on the influence mechanism of cyclic blades on the dynamic coupling of a flexible shaft-disk-blade (FSDB) system through mathematical analysis and numerical simulation. Firstly, a coupling mechanism model of an FSDB unit is developed through a Lagrange method and the assumed mode method (AMM), after considering the coupling behavior among shaft bending, shaft torsion, disk vibration, and blade bending. The modal comparison results between the proposed model and FEM affirm the validity of the model. Then the analytical interpretation is explored by decomposing and discussing the diagonal coupling and cross-coupling matrices of the FSDB system. The mechanism discussion reveals that the coupling matrices originate from the rigid and elastic motions of flexible disk and cyclic blades, indicating that the motions of cyclic blades play an important role in dynamic coupling. Therefore, the motions of cyclic blades are classified and analyzed, and their effects on natural frequencies (NFs) and critical speeds (CSs) are applied to further interpret and validate the dynamic coupling through numerical simulation. The numerical results indicate that motions of cyclic blades can increase, decrease, and eliminate the magnitude of dynamic coupling significantly. [ABSTRACT FROM AUTHOR]

This paper represents a sequel to Jureczka and Ochal (2019) where numerical solution of a quasistatic contact problem is considered for an elastic body in frictional contact with a moving foundation. The model takes into account wear of the contact surface of the body caused by the friction. Some preliminary error analysis for a fully discrete approximation of the contact problem was provided in Jureczka and Ochal (2019). In this paper, we consider a more general fully discrete numerical scheme for the contact problem, derive optimal order error bounds and present computer simulation results showing that the numerical convergence orders match the theoretical predictions. [ABSTRACT FROM AUTHOR]

The seismic retrofit design of structures in which the bracings are compressed due to the presence of significant vertical loads shall take into account the strong asymmetric working conditions of the bracings induced by the seismic action. The initial compression and the consequent asymmetric cyclic loading lead, indeed, to poor global performances and drawbacks in the case of seismic retrofitting through the substitution of the existing bracings with dissipative ones. In order to overcome such issues, this paper presents the development of an asymmetric re-centering dissipative device characterized by a different behavior in tension and in compression and by a strong re-centering capacity, making it suitable to resist and dissipate the energy generated by asymmetric cyclic loadings. The paper firstly analyzes the specific issues of structures in which the bracings work in strong asymmetric loading conditions due to the presence of significant vertical loads, highlighting the main problems that can arise adopting traditional dissipative bracings. Then the proposed device is conceptually described and its behavior experimentally assessed. Finally, the structural behavior of a sub-system equipped with the proposed device is assessed through numerical analyses. The experimental and numerical results show the effectiveness of the proposed device in reducing the residual displacements and protecting the other structural elements demanded to resist to the vertical loads. • The development of a new re-centering device with asymmetric hysteretic behavior is presented. • The situations in which the proposed device is useful are analyzed in the paper. • The experimental results testifies the asymmetric and re-centering behavior of the proposed device. • The numerical simulations highlights the possibility of overcoming some of the drawbacks of classical dissipative devices. [ABSTRACT FROM AUTHOR]

What are the geometrical and mechanical properties ruling bistability of Kresling origami metamaterials? How can we tune the magnitude of their axial-torsional coupling? Complete answers to these compelling questions cannot be found in the scientific literature, as the intertwining between bistability, axial-torsional coupling and an other significant behaviour, namely transverse dilation/contraction, remains mostly uninvestigated. This contribution aims at shedding light on this intertwining, through the use of a discrete model of Kresling origami that takes into account folding resistance. The present study is mostly computational and involves both pre- and post-critical analyses. It is based on displacement controlled tests — shearing and axial shortening/lengthening. Single-storey Kresling origami's are first considered, preliminarly to multiple-storey tubes, where buckling is observed. Several parameters are taken into account such as the number of storeys, stretching and folding stiffnesses, and – for shearing tests – the prescribed displacement direction in the transversal plane. The ultimate goal of the paper is to provide evidence that can be useful in the construction of homogenised continuum models of Kresling origami metamaterials. • We present some numerical simulation concerning metamaterials based on Kresling tube pattern. • Numerical analyses of some selected tests clarifies the mechanical behaviour of metamaterials based on Kresling pattern. • Numerical simulations address the homogenised model of Kresling tubes. [ABSTRACT FROM AUTHOR]

• An in situ bitumen decomposition kinetic model is developed. • The significance of bitumen decomposition to oil recovery is discussed. • A green and economical recovery tech without steam additives injection from surface. • The tech has higher oil production, lower steam consumption and carbon emission. In the late stages of Steam Assisted Gravity Drainage (SAGD) development, the increase in steam chamber volume and greater heat losses result in elevated thermal losses, and increased CO 2 emissions, leading to reduced economic efficiency. To address this issue, this paper proposes a pioneering approach, termed the in situ solvent generation enhanced SAGD technique (ISSG-SAGD). Through a comprehensive review of Athabasca bitumen aquathermolysis, thermal cracking, and their phase behavior with solvents, a general reaction kinetic model and fluid model are established. Subsequently, the feasibility and recovery mechanism of ISSG-SAGD are elucidated by employing numerical simulation that compares SAGD with ISSG-SAGD. Results show that, in comparison to SAGD, ISSG-SAGD reduces steam consumption by 13.77 %, lowers carbon intensity by 18.12 % and increases oil production by 5.48 %. These advantages arise from the synergistic integration of recovery mechanisms characteristic of Expanding Solvent SAGD (ES-SAGD) and Steam and Gas Push (SAGP). Notably, non-condensable gas accumulation above the steam chamber diminishes heat loss while replenishing reservoir energy. Simultaneously, light hydrocarbons are strategically positioned at the drainage interface, leading to a reduction in residual oil saturation and an increment in drainage rates. Consequently, ISSG-SAGD emerges as an environmentally sustainable and economically viable trajectory for heavy oil development. [ABSTRACT FROM AUTHOR]

• Mechanical response characteristics of beam-column substructures exposed to fire are analyzed. • Explicit calculation formulas for determining the collapse resistance are derived in detail. • Proposed theoretical calculated formulas agree well with these from numerical simulations. • Error analysis is conducted to reveal deviation reasons between theoretical model and numerical simulations. This paper provides a simplified analytical model for the restrained steel beam-column substructure under a fire-induced progressive collapse scenario, which is applied to predict the collapse resistance of substructures under fire. The simplified model is formulated for axially and rotationally restrained two-span steel beam-column substructures under column-loss scenarios and involves rigid and semi-rigid connections. The response characteristics of restrained substructures exposed to fire under column-loss scenarios in each response stage are elaborately analyzed. A "negative" catenary stage, in consideration of the unique negative axial force effects induced by the temperature thermal expansion, was first introduced in the five-stage simplified model for restrained substructures exposed to fire against progressive collapse. Subsequently, the explicit calculation formulas for determining the vertical loads and deflection of both rigid and semi-rigid joint substructures exposed to fire were derived in a quantified way, based on rigid-plastic mechanisms and restraint coefficient methods. In addition, the corresponding numerical simulation analysis on a restrained two-span steel beam-column substructure with different end constraints and fire conditions was carried out to verify the applicability and reliability of established theoretical formulas. Comparisons of vertical load-deflection relationships between the calculation formulas and corresponding numerical simulation shows good accuracy. For more accurate prediction results, the error analysis was further conducted, and several theoretical formulas were modified, which were verified to be accurate and reliable after correction. With derived resistance functions, the resistance of steel beam-column substructures in fire-induced progressive collapse scenarios can be predicted. [ABSTRACT FROM AUTHOR]

This paper presents a quasistatic problem of an elastic body in frictional contact with a moving foundation. The model takes into account wear of the contact surface of the body caused by the friction. We recall existence and uniqueness results obtained in Sofonea et al. (2017). The main aim of this paper is to present a fully discrete scheme for numerical approximation together with an error estimation of a solution to this problem. Finally, computational simulations are performed to illustrate the mathematical model. [ABSTRACT FROM AUTHOR]

Abstract In this paper, compressive material tests on unconfined/confined resin and steel reinforced resin were experimentally evaluated in order to validate the numerical results. The uniaxial model which combines damage mechanics and Ramberg-Osgood relationship is proposed in this paper to describe the uniaxial compressive behaviour of resin and steel reinforced resin. Numerical homogenization is conducted to predict the tensile and shear behaviour of steel reinforced resin after validated by compressive material test results. The friction angle β , the ratio of the yield stress in triaxial tension to the yield stress in triaxial compression K, and the dilation angle ψ of the linear drucker-prager plastic model are obtained based on experiments and numerical homogenization simulation. The confinement effects on resin and steel reinforced resin could be effectively simulated by combing above parameters and uniaxial compressive model. Finite element simulations on unconfined/ confined resin and steel reinforced resin material tests were conducted to validate the material parameters proposed in this paper. A good agreement is observed, indicating the model and parameters proposed in this paper could be effectively used in the finite element simulation of injected bolts. [ABSTRACT FROM AUTHOR]

Highlights • Constitutive equations for a vertical rod bundle are reviewed. • Dependence of distribution parameter on flow conditions is discussed. • 1D momentum equation by considering void fraction distribution is discussed. • Effect of channel size on interfacial area concentration is discussed. Abstract In view of the quality assurance of two-phase flow simulations, CSAU (Code Scalability, Applicability, and Uncertainty) methodology and code V & V (Verification and Validation) have been proposed. The estimation of simulation uncertainty is indispensable in using best-estimate computational codes. A key of successful two-phase flow simulations is to use the state-of-the-art constitutive equations to close the mathematical system used in two-phase flow analyses. The advanced constitutive equations should be developed based on “physics” behind phenomena and should consider scaling parameters which enable their application beyond test conditions used for a code validation. Two-phase flow simulations in a rod bundle is important in various industrial apparatuses such as heat exchangers and nuclear reactors. Constitutive equations for two-phase flows in a vertical rod bundles have been advanced in recent five years. In view of this, this paper provides a comprehensive review of most advanced constitutive equations for two-phase flow analyses in a vertical rod bundle. The constitutive equations of two-phase flow parameters reviewed in this paper are flow regime map, void fraction, void fraction covariance and relative velocity covariance, interfacial area concentration and wall friction. In addition, an exact formulation of one-dimensional momentum equation in two-fluid model considering void fraction distribution is discussed. [ABSTRACT FROM AUTHOR]

Abstract As part of the LEAP-GWU-2015 exercise, a dynamic centrifuge test was conducted at the University of Cambridge on a 5° slope of medium dense Ottawa F-65 sand. The model preparation and saturation details are presented in this paper. This paper presents the experimental data recorded during small and large magnitude sinusoidal ground motions. After the experiment, numerical simulations of the experiment were performed using the finite element code Swandyne. The results from these numerical analyses are compared with the centrifuge test data and the deformations observed during the post-test investigations. The numerical analyses replicated many of the salient features of the test, such as the overall generation of excess pore pressures and attenuation of accelerations in the liquefying ground. More subtle results, such as the de-liquefaction shocks and the asymmetric response due to differences in upslope and downslope accelerations were less well captured in terms of the expected spikes in the dynamic excess pore pressures and accelerations. Overall, the combination of centrifuge testing and numerical analysis were found to complement each other well. Highlights • The effect of shaker translation on the model is explored in terms of accelerations and excess pore pressure generation. • Relative performance between the numerical analysis and experimental data are discussed for each earthquake loading. • The influence of high frequency components in the acceleration input were assessed using an additional numerical analysis. • Interpretation of the numerical analyses were guided by the discrepancies between predicted and measured pore pressures. [ABSTRACT FROM AUTHOR]

• The prostate tumor growth model. • An asymptotic analysis. • A generalized moving least squares technique. • Experimental data. This paper focuses on presenting an asymptotic analysis and employing simulations of a model describing the growth of local prostate tumor (known as a moving interface problem) in two-dimensional spaces. We first demonstrate that the proposed mathematical model produces the diffuse interfaces with the hyperbolic tangent profile using an asymptotic analysis. Next, we apply a meshless method, namely the generalized moving least squares approximation for discretizing the model in the space variables. The main benefits of the developed meshless method are: First, it does not need a background mesh (or triangulation) for constructing the approximation. Second, the obtained numerical results suggest that the proposed meshless method does not need to be combined with any adaptive technique for capturing the evolving interface between the tumor and the neighboring healthy tissue with proper accuracy. A semi-implicit backward differentiation formula of order 1 is used to deal with the time variable. The resulting fully discrete scheme obtained here is a linear system of algebraic equations per time step solved by an iterative scheme based on a Krylov subspace, namely the generalized minimal residual method with zero–fill incomplete lower–upper preconditioner. Finally, some simulation results based on estimated and experimental data taken from the literature are presented to show the process of prostate tumor growth in two-dimensional tissues, i.e., a square, a circle and non-convex domains using both uniform and quasi-uniform points. [ABSTRACT FROM AUTHOR]

In the recent paper entitled “Hopf bifurcation analysis and ultimate bound estimation of a new 4-D quadratic autonomous hyper-chaotic system” in [Appl. Math. Comput. 291 (2016) 323–339] by Amin Zarei and Saeed Tavakoli, they proposed the following new four-dimensional (4-D) quadratic autonomous hyper-chaotic system: x 1 ˙ = a ( x 2 − x 1 ) , x 2 ˙ = b x 1 − x 2 + e x 4 − x 1 x 3 , x 3 ˙ = − c x 3 + x 1 x 2 + x 1 2 , x 4 ˙ = − d x 2 , which generates double-wing chaotic and hyper-chaotic attractors with only one equilibrium point. Combining theoretical analysis and numerical simulations, they investigated some dynamical properties of that system like Lyapunov exponent spectrum, bifurcation diagram, phase portrait, Hopf bifurcation, etc. In particular, they formulated a conclusion that the system has the ellipsoidal ultimate bound by employing the method presented in the paper entitled “Ultimate bound estimation of a class of high dimensional quadratic autonomous dynamical systems” [Int. J. Bifurc. Chaos, 21(09) (2011), 2679–2694] by P. Wang et al. However, by means of detailed theoretical analysis, we show that both the conclusion itself and the derivation of its proof in [Appl. Math. Comput. 291 (2016) 323–339] are erroneous. Furthermore, we point out that the method adopted for studying the ultimate bound of that system is not applicable at all. Therefore, the ultimate bound estimation of that system needs further studying in future work. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of gain-scheduled controller design for parameter-varying discrete-time systems. In practice, the scheduling parameters are only available with limited accuracy due to the measurement errors. In the present paper, these uncertainties are systematically taken into account for the gain-scheduled controller synthesis to achieve improved performance in practical situations. It is assumed that all the matrices of the state-space model of the plant have a homogeneous polynomial dependency of arbitrary degree on the scheduling parameters. The merit of the proposed method is its capability in dealing with the measurement error less conservatively than available approaches while it can also encompass the traditional methods employing the exact scheduling parameters in a less conservative manner. A comprehensive numerical example demonstrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A numerical assessment study of tsunami attack on the rubble mound breakwater of Haydarpasa Port, located at the southern entrance of the Istanbul Bosphorus Strait in the Sea of Marmara, Turkey, is carried out in this study using a Volume-Averaged Reynolds-Averaged Navier-Stokes solver, IHFOAM, developed in OpenFOAM ® environment. The numerical model is calibrated with and validated against the data from solitary wave and tsunami overflow experiments representing tsunami attack. Furthermore, attack of a potential tsunami near Haydarpasa Port is simulated to investigate effects of a more realistic tsunami that cannot be generated in a wave flume with the present state of the art technology. Discussions on practical engineering applications of this type of numerical modeling studies are given focusing on pressure distributions around the crown-wall of the rubble mound breakwater, and the forces acting on the single stone located behind the crown-wall at the rear side of the breakwater. Numerical modeling of stability/failure mechanism of the overall cross-section is studied throughout the paper. The present study shows that hydrodynamics along the wave flume and over the breakwater can be simulated properly for both solitary wave and tsunami overflow experiments. Stability of the overall cross-section can only be simulated qualitatively for solitary wave cases; on the other hand, the effect of the time elapsed during tsunami overflow cannot be reflected in the simulations using the present numerical tool. However, the stability of the overall cross-section under tsunami overflow is assessed by evaluating forces acting on the rear side armor unit supporting the crown-wall of the rubble mound breakwater as a practical engineering application in the present paper. Furthermore, two non-dimensional parameters are derived to discuss the stability of this armor unit; and thus, the stability condition of the overall cross-section. Approximate threshold values for these non-dimensional parameters are presented comparing experimental and numerical results as a starting point for engineers in practice. Finally, investigations on the solitary wave and tsunami overflow experiments/simulations are extended to the potential tsunami simulation in the scope of both representation of a realistic tsunami in a wave flume and stability of the rubble mound breakwater. [ABSTRACT FROM AUTHOR]

Numerical simulation is more and more used in automotive industry to reduce design time and cost. Moreover, for high performance engines, the development of cylinder heads requires well known and adapted materials to ensure their reliability. The estimation of adapted fatigue criteria based on few experiments is thus an important challenge: to obtain more predictive model on more complex mechanical phenomena. This paper describes the methodology adopted by Renault to estimate fatigue life of a new aluminum-silicon alloy. A low copper aluminum-silicon alloy has been developed for a new generation of cylinder heads. Those kinds of alloys provide a good compromise between the two main failure modes encountered for cylinder heads: high cycle fatigue of water jacket and low cycle fatigue of fire deck. However, those materials are subjected to thermal ageing that can affect mechanical behavior, such as yield stress and hardening, but also fatigue mechanisms at higher temperatures. This article presents first the selected constitutive equations that introduce thermal ageing effect in a cyclic elasto-viscoplastic model. The low cycle fatigue criterion is then calibrated on the relevant database, which includes isothermal and non-isothermal tests. The fatigue criterion is a specific version of a classical model previously developed at Onera. The critical variables for the fatigue part are the stress amplitude and the mean stress, both of them being normalized by an ultimate stress which depends on temperature and ageing state. Finally, the constitutive and damage models have been applied on 3D cylinder head numerical analysis. The paper proposes a brief comparison of those results with more classical simulations made on cylinder heads and highlights the perspectives offered by this new aluminum-silicon alloy. [ABSTRACT FROM AUTHOR]

In this paper, two classes of efficient difference schemes for the simulation of the time-fractional Korteweg–de Vries equation are carried out. The temporal derivative is approximated with the help of the uniform/nonuniform L 1 formula and the uniform L 2 - 1 σ formula, respectively. The spatial derivative is done with the uniform centered difference scheme. Unique solvability, boundedness and convergence of the corresponding difference schemes are rigorously proved at length. As far as we know, the proposed schemes achieve the highest convergence order in space among all the difference methods for the time-fractional KdV equation. Several numerical examples confirm the theoretical results and demonstrate the dynamic behavior. • Numerical analysis of two classes of efficient difference schemes for the simulation of the time-fractional KdV equation. • The highest convergence in space among all the difference methods for the time-fractional KdV equation up to now. • Numerical confirmation of the accuracy of theoretical results and demonstration of the dynamic behavior of KdV equation. [ABSTRACT FROM AUTHOR]

• Proper quantification of joint rotational stiffness (JRS) of a flight intersection joint (FIJ) influences the dynamic characteristics of a flight vehicle. • JRS of an FIJ is often determined experimentally due to the lack of a right predictive model. • An analytical model is proposed to evaluate the JRS of a radial-type FIJ when subjected to an external bending moment. • Numerical analyses and experiments are performed on six different FIJ configurations. • JRS and moment-rotation behavior predicted by the proposed model are correlated with both experimental and numerical analyses. • Further, the effect of joint clearances on the behavior of FIJ is investigated through the present model. Joint rotational stiffness (JRS) of a flight intersection joint (FIJ) and its accurate quantification play an essential role in studying the dynamic modal characteristics of a flight vehicle. This JRS of a FIJ is mostly determined through elaborate experiments due to the non-availability of a reliable predictive model. Therefore, in this paper, an analytical model is proposed to evaluate JRS of a radial type FIJ when subjected to external bending moment. In this model, at first, the tensile and compressive part of the FIJ section is identified by determining the neutral axis position. The respective part's contributing stiffness is then estimated by employing a spring-mass model. Later, the JRS expression is derived from the moment equilibrium condition and expressed as a function of the stiffness of the tensile and compressive part and neutral axis position. Subsequently, finite element analysis (FEA) is conducted with different numbers of screws, followed by detailed experimental investigations. The proposed analytical model is validated with the results from FEA and experiments for different screw configurations of FIJ. Further, the proposed model is extended to account for the effect of joint clearances on the JRS and the corresponding moment-rotation characteristics of the FIJ. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Solidworks software is used to construct the geometric model of the heading face. • Temporal-spatial evolution laws of diesel particulate matter (DPM) was obtained. • DPM concentration variation along the heading face is obtained. • The reliability of numerical simulation was verified by field measurements. Diesel equipment used in underground production and transportation will produce a large amount of diesel particulate matter (DPM), which seriously pollutes the fresh air in underground and endangers the life and health of miners. In order to study the diffusion and distribution of DPM, this paper based on CFD numerical simulation technology, carries out numerical simulation of airflow and DPM field in heading face. The results show that from 15 s to 60 s, DPM continuously accumulates in the blind zone of the airflow and on both sides of the monorail locomotive, with the DPM concentration greater than 1.2 × 10−7 kg/m3. At this time, the DPM cloud is 60 m in the horizontal direction, and shows a distribution characteristic of high in the middle and low on both sides. When T = 90 s, part of DPM diffuses to the roadway exit. At this time, in the entire roadway, starting from a section of 23 m away from the heading face, the DPM concentration sharply increases, reaching a peak of 2.91 × 10-7 kg/m3 at 33 m. Then it begins to decline slowly. The research results are of great significance to clean production in mines. [ABSTRACT FROM AUTHOR]

The hydraulic network study is a real-life engineering problem extensively base on applied and computational approaches. Several numerical schemes are tested for defining of hydraulic pipe networks solution, such as, Hardy Cross Method, Newton Method and Modified Newton method are presented in this paper. Convergence analysis are also compared and deliberated by using a multi-loop hydraulic network. As a novelty, a Modified Newton method tabulated data, graphical results and comparisons are presented with the Hardy-Cross method and 2nd -order Newton–Raphson method. On other hand, we applied Ancient Chinese Algorithm and its modification for value of friction factor by using Colebrook-White relation. Numerical efficiency and comparison of Ancient Chinese Algorithm with Newton method and Bubbfil Algorithm I and Algorthm-II is presented and discussed quantitative approach to demonstrate the feasible result. [ABSTRACT FROM AUTHOR]

In this paper, a novel third-order autonomous memristor-based chaotic circuit is proposed. The circuit has simple topology and contains only four elements including one linear negative impedance converter-based resistor, one linear capacitor, one linear inductor, and one nonlinear current-controlled memristor. Firstly, the voltage-current characteristic analysis of the memristor emulator for different driving amplitudes and frequencies are presented. With dimensionless system, the symmetry, equilibrium point and its stability are analysed. It is shown that the system has two unstable saddle-foci and one unstable saddle. A set of typical parameters are chosen for the generation of chaotic attractor. Differing from the common period-doubling bifurcation route in smooth dynamical systems, this memristive system shows abrupt transition from the coexisting period-1 limit cycles to robust chaos when varying system parameters. Various dynamical behaviors are analysed using the numerical simulations and circuit verifications. • A novel current-controlled memristor-based chaotic circuit is proposed. • Dynamical behaviors of robust chaos and coexisting attractors are investigated. • Both numerical analyses and circuit simulation validated the feasibility of the chaotic oscillator. [ABSTRACT FROM AUTHOR]

The paper presents a numerical analysis of the resistance and stiffness of an aluminium-concrete beam with steel connectors. Aluminium-concrete structures are less known than steel and concrete composite structures, they do, however, have a lot of applications. In this paper, the resistance and midspan deflection of a composite beam calculated using the Abaqus program was compared with the results obtained in an experimental study. [ABSTRACT FROM AUTHOR]

This paper presents the basic methodologies used for Natural Smoke and Heat Ventilation Systems design under wind conditions, along with chosen numerical tools such as Computational Fluid Dynamics method and evacuation modelling as their supplement. First, results of comparison of different natural ventilation systems a series of transient CFD simulations are shown, illustrating potential problems in the system design with traditional approach. Later in the paper, authors focus on complete analysis of fire related phenomena in wind conditions, for a real historical shopping mall in Warsaw with vertical natural smoke ventilators. All of the steps of the analysis are described, together with some practical remarks. The reference analysis were carried in ANSYS Fluent CFD model, followed by evacuation study with building Exodus software. [ABSTRACT FROM AUTHOR]

Erosion and deposition are fundamental surface processes, and the Hairsine-Rose (HR) model describing these dynamic processes for individual particle size classes has increasingly been applied at a range of scales. There are no exact solutions of the HR equations for the dynamic erosion of multi-size-classed soil. For numerical solution, upwind explicit schemes which have been applied so far generally require extremely small time intervals (10 −2 –10 −3 s) for numerical stability, thus limiting the computational efficiency. The Preissmann scheme, which is flexible and can be fully implicit, has been widely used to simulate open-channel flows. The objective of the paper was to implement, for the first time, the Preissmann scheme to solve the HR equations, and to verify the accuracy and evaluate the efficiency of the scheme. The paper shows that (1) implementation of the Preissmann scheme, while complex, is straightforward, and the numerical solution of the HR equations can be reduced to a set of 2 I algebraic equations where I is the number of size classes, with no matrix operations or iteration involved; (2) the numerical solution is verified for steady state solutions, and for the only exact solution for uniform grain-sized soil known to exist; (3) for two benchmark tests to simulate dynamic erosion of multi-size-classed soil. The time interval using the Preissmann scheme can be much larger (∼1 s), and there is improvement in overall computational efficiency so long as the time interval for the Preismann scheme is at least 6 times larger than that for upwind explicit schemes for the case of flow-driven erosion. The improvement in computational efficiency can be even more pronounced for overland flows with rainfall where the water depth can be quite small near the upper end of the slope. [ABSTRACT FROM AUTHOR]

A numerical method is employed to investigate the fluid flowing dynamics in fractured reservoirs in this paper. Owing to the multi-scales and strong heterogeneity, description of fracture network systems plays a significant role for a successful fractured reservoir simulation model. Comparing to previous works, this paper proposes a combination of dual continuum and discrete fracture network (DFN) model, which is used to simulate the flow in reservoirs with multi-scale fractures and proved feasible. In the first part of the paper, implicit flow equations of oil and water phase in fractured reservoirs are established to consider the nonlinearity properties. And then the control volume finite element method based on the unstructured grid system and N-R iteration are used to obtain the numerical solution. Moreover, the accuracy of this simulator is proved to be reasonable by field data; Sensitivity analysis shows that the existences of complex multi-scale fracture networks have great impacts on water flooding. Compared with the homogeneous reservoir, natural fracture (micro and large scale) networks can change the direction and velocity of the waterfront, which finally leads to the more serious water breakthrough, higher water cut and less recovery. The research and the numerical results obtained in this paper can provide theoretical guidance for efficient and scale development of natural fractured reservoirs. [ABSTRACT FROM AUTHOR]

The first part of the paper presents a brief description of the material point method (MPM) including the governing equations, solution scheme and a benchmark problem of soil collapse simulated using the method. In the second and third part of the paper, the post-failure runout process of the Wangjiayan landslide is simulated and analyzed. The landslide's final topography and information from post-failure in-situ survey and laboratory tests are used to constrain the accuracy of computational results. The kinematic behaviors of the failure mass are investigated in terms of displacement, velocity, effective plastic strain fields and topography changes during the movement. Comparisons are made between conditions with and without buildings on the deposition area. Numerical computations demonstrate that the presence of buildings on the sliding path strongly governs the flow regime, run-out distance, velocity, strain field and final deposition topography of the landslide. So it is very essential to incorporate the effects of buildings in the modelling and analyses. Numerical results considering buildings show that the slide lasts about 30 s with the most rapid phase occurring between 6 and 12 s, and that the maximum simulated velocity among the sliding particles in the landslide is 43.5 m/s, indicates that the moving of the landslide mass was very fast. The run-out distance simulated with MPM matches the measured post-earthquake topography well, whereas the shape of the simulated deposition zone is a little differs. The buildings influence the sliding by shortening the overall run-out distance, decelerating the movement of the bottom layer, and increasing the internal deformation and mixing among deposition layers. [ABSTRACT FROM AUTHOR]

• A numerical simulation method for the multifactor coupling of stress field and temperature field is developed. • The numerical simulation method is in good agreement with the experiment results at elevated temperatures. • The numerical simulative description of the grout material failure and fracture of a steel bar. • Prediction of the yield point and the ultimate point of FGSC from 25 °C to 1000 °C. Fire is one of the main objects of study at the cutting edge of the research on disaster prevention and mitigation in structures. In the event of a fire, the mechanical properties of the structural material will be significantly reduced, resulting in serious consequences. This paper simulates the tensile properties of sleeve grouting members at five different temperatures, to contribute to the research here. The simulated member stress-strain curves fit well with the corresponding experimental results. The paper introduces constitutive models of concrete, steel, and sleeve. Beyond that, a feasible finite element model of the grouted sleeve is proposed. Two special points' (yield point, ultimate point) coordinate formulas which are related to different temperatures (25–1000 °C) are presented. It indicates the regularity of fully-grouted sleeve tensile force-displacement curves in various temperatures. Meanwhile, the research content provides the basis for further research on reinforcing bars spliced by grout-filled coupling sleeves. [ABSTRACT FROM AUTHOR]

Following the experimental study on EN 1.4003 ferritic stainless steel T-stubs in tension discussed in the companion paper, this study reports the development and validation of an advanced FE model that can predict the overall behaviour and failure modes of ferritic stainless steel bolted T-stubs subjected to tension. Key simulation strategies regarding the modelling of bolt geometry and overcoming numerical instabilities are discussed. Following the determination of material properties in the longitudinal, transverse and diagonal direction reported in the companion paper, the effect of allowing for anisotropy in the FE simulations is investigated and modelling recommendations for its inclusion in FE models are made. Moreover, the effect of bolt end and edge spacing on the joint plastic resistance, ultimate capacity, ductility as well as overall response is comprehensively discussed by inspecting the stress distribution through the plate thickness at various locations along the T-stub, thus revealing both the flexural and the membrane component of the load transfer mechanism. The numerical results were validated against the experimental results reported in the companion paper in terms of predicted plastic and ultimate resistance, ductility and obtained failure modes. On the basis of the obtained results and the discussion, modelling recommendations for the simulation of stainless steel T-stubs are made. • An advanced numerical study on austenitic, duplex and ferritic stainless steel bolted T-stubs under tension was reported. • The effect of material anisotropy on the plastic and ultimate resistance of stainless steel bolted T-stubs was reported. • Damage initiation model with instantaneous fracture was proposed and validated against the test results. • Membrane action on the ultimate resistance of stainless steel T-stubs have been examined. • Newly proposed design methods for predicting the ultimate resistance of stainless steel T-stubs have been verified. [ABSTRACT FROM AUTHOR]

In this paper the space-fractional Schrödinger equations with singular potentials are studied. Delta like or even higher-order singularities are allowed. By using the regularising techniques, we introduce a family of 'weakened' solutions, calling them very weak solutions. The existence, uniqueness and consistency results are proved in an appropriate sense. Numerical simulations are done, and a particles accumulating effect is observed in the singular cases. From the mathematical point of view a "splitting of the strong singularity" phenomena is also observed. [ABSTRACT FROM AUTHOR]

• The improved PSO was employed to calibrating the micro-parameters. • Different combinations of micro-parameters of DEM model can be obtained. • More macro-parameters should be used to calibrate the micro-parameters of DEM model. The discrete element method (DEM) is commonly used for simulating the mechanical characteristics of rock materials; however, constructing a DEM model requires the specification of a number of microparameters. In this paper, to obtain the microparameters of the DEM model, the improved particle swarm optimization (PSO) calibration method was presented. Based on numerical simulation examples, the new approach is considered valid for calibrating the microparameters of the DEM model. Moreover, it is concluded that different sets of microparameters can be determined when few macroparameters are used, which indicates that the empirical formula between microparameters and macroparameters is not reliable. From the analysis of the numerical simulation results, it is suggested that more macroparameters should be used to calibrate the microparameters of the DEM model, and the corresponding numerical simulation results could be more reliable; otherwise, the generated numerical model may not accurately simulate the mechanical characteristics of rock materials. [ABSTRACT FROM AUTHOR]

• A new sub-step time-marching procedure is proposed for linear and nonlinear dynamics. • Higher computation accuracy and desirable numerical dissipation are achieved by selecting appropriate algorithmic parameter. • Desirable performance on conserving energy and momentum is confirmed by theoretical and numerical analysis. • Simple formulation and good compatibility for various dynamic problems and commercial software. In this paper, an improved sub-step time-marching procedure is proposed for structural dynamics. The proposed procedure has two free parameters which can be adopted to control basic algorithmic properties including computation accuracy, algorithmic damping, period elongation, and overshooting behavior. The influences of the algorithmic parameters on these basic properties of the method are studied, and the optimal parameter value is thus obtained. Theoretical analysis and numerical simulations demonstrate that new procedure is desirable for linear and nonlinear dynamics due to its higher-order accuracy, desirable numerical dissipation, and high-efficient energy conservation. [ABSTRACT FROM AUTHOR]

This paper investigates the finite-time attitude tracking control problem for rigid spacecraft exposed to the external disturbance and unknown inertial parameters. Initially, the basic controller is developed under the assumption that the inertial parameters and the upper bound of external disturbances are available to the designer. However, this assumption is inapplicable in practical applications. Considering this limitation, adaptive laws and Minimum-learning- parameter (MLP) algorithm are employed in the second controller to estimate the unknown system dynamics. Finite-time stability for tracking errors is achievable under the proposed methods. Though theoretical analysis and numerical simulations, effectiveness of the proposed controllers has been validated. • Two finite-time attitude tracking controllers are proposed. • The proposed controller is inertia-free for implementation. • MLP Algorithm has been employed to reduce the computational burden. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lattice beam model extended to self-healing in cementitious materials. • A new rate dependent discrete damage-healing model is presented. • Healing response derived from healing-agent chemo-physical properties. • Detailed information is provided on the size and disposition of cracking and healing zones throughout a transient analysis. • The model provides valuable information required for designing a self-healing system. • Model validated using experiments with healing under fixed and moving crack conditions. • Nature and extent of damage-healing zones determined numerically. This paper describes the development of a discrete lattice model for simulating structures formed from self-healing cementitious materials. In particular, a new approach is presented for simulating time dependent mechanical healing in lattice elements. The proposed formulation is designed to simulate the transient damage and healing behaviour of structures under a range of loading conditions. In addition, multiple and overlapping damage and healing events are considered. An illustrative example demonstrates the effects of varying the healing agent curing parameters on the computed mechanical response. The model is successfully validated using published experimental data from two series of tests on structural elements with an embedded autonomic self-healing system. The meso -scale model gives detailed information on the size and disposition of cracking and healing zones throughout an analysis time history. The model also provides an accurate means of determining the volume of healing agent required to achieve healing for all locations within a structural element. The importance of the information provided by the model for the design of self-healing cementitious material elements is highlighted. [ABSTRACT FROM AUTHOR]