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This paper addresses the problem of lot splitting in the context of workload control (WLC). Past studies on WLC assumed that jobs released to the shop floor proceed through the different stages of processing without being split. However, in practice, large jobs are often split into smaller transfer sublots so that they can move more quickly and independently through the production process and allow operations overlapping relating to the same job. This paper assesses the performance of different lot splitting policies for job release and dispatching strategies under lot splitting. A new dispatching rule was designed to specifically take advantage of lot splitting and operations overlapping in the context of WLC. Discrete-event simulation is used to assess system performance in relation to the ability to provide shorter delivery times and on time deliveries. Results highlight the importance of releasing the sublots of the same job together and demonstrate that combining an effective lot splitting policy with an appropriate dispatching rule can enhance the performance of production systems. [ABSTRACT FROM AUTHOR]

Despite landfills having the potential to pollute the environment both during their operation and long after they have ceased to receive waste, they remain a dominant waste management option, particularly in the UK. In order to combat the environmental pollution caused by landfills, risk analysis is increasingly being employed through computer models. However, for a risk analysis process to be successful, its foundation has to be well established through a baseline study. This paper aims to identify knowledge gaps in software packages regarding environmental risk assessments in general, and especially those that have been developed specifically for landfills and landfill leachate. The research establishes that there is no holistic computer model for the baseline study of landfills, which risk assessors can use to conduct risk analyses specifically for landfill leachate. This paper also describes a number of factors and features that should be added to the baseline study system in order to render it more integrated—thereby enhancing quantitative risk analysis, and subsequently environmental risk management. [ABSTRACT FROM AUTHOR]

This paper describes visual servoing methods to align an end edge of a flexible sheet object such as paper to a specified line segment in 3D space. In order to manipulate the end edge pose which may be distant from a grasping point by a robot hand on the flexible sheet, we incorporate online estimation of the relative pose between the end edge and the robot hand into visual servoing control laws. Two types of feature values to be regulated, position-based and image-based ones, are defined. The position-based one consists of 3D pose parameters of the end edge, which are estimated by fitting a polynomial surface model to stereo-measured edge points around the sheet. The image-based one consists of image pixel values within narrow regions around the end edge. Through numerical simulations, we confirm that the position-based features are effective in achieving quick response while the image-based features are robust against measurement noise. In order to combine these contrasting behaviors, we introduce a weighted combination of the position-based and image-based features. Experimental results show both of the position-based method and the weighted combination method work well and suggest the possibility that the weighted combination method can reduce final alignment errors. [ABSTRACT FROM PUBLISHER]

In this paper, due to the special shape of the sandglass-type floating body, the characteristic of heave damping of the sandglass-type floating production, storage and offloading (FPSO) unit is mainly discussed by the computational fluid dynamics method. Firstly, the numerical model for free heave decay motion of the sandglass-type floating body was created, and the accuracy of the numerical model has been validated by the experimental data. Then, the scale effect on the heave damping of sandglass-type FPSO was further discussed. Furthermore, to provide a reference for the design criteria of sandglass-type floating body, the relationships between its heave decay coefficients and shape parameters were analysed based on the orthogonal test and single-factor analysis method. Finally, the estimation formula of the decay coefficients was obtained by means of the optimisation algorithm, which can be used for the preliminary design of the shape of the sandglass-type floating body. [ABSTRACT FROM AUTHOR]

This paper is concerned with the design of a robust finite-time observer for a class of uncertain nonlinear systems. The novelty of the proposed approach lies in estimating uncertainties accurately in a finite time as well as states at the same time, without any constraint on the structure of the matrices of the system. In the proposed method, in contrast to similar papers, considering the system in canonical form or triangular structure is not necessary. In this paper, sufficient conditions are given to guarantee the exact estimation of both state variables of the system and uncertainties in a finite time. Finally, the performance and robustness of the proposed observer are validated using a numerical simulation. [ABSTRACT FROM AUTHOR]

Computer simulations are used routinely in the automobile industry. The simulation algorithms and software are well developed for computations that are carried out on a small cluster of computers. To further reduce the design time and increase the fidelity of the computation, new algorithms and software are needed on larger computing systems with more processor cores. In this paper, we study a Newton–Krylov–Schwarz algorithm based 3D incompressible Navier–Stokes solver for solving unsteady, high Reynolds number flows around a car with realistic geometry and parameters. We also investigate the impact of the yaw angles and crosswind on the flow field. The numerical experiments show that the approach scales well with more than 8000 processor cores. [ABSTRACT FROM AUTHOR]

This paper addresses the finite-time consensus problem for multi-agent systems with nonlinear dynamics under Euler digraph. By pinning control technique, a nonlinear distributed protocol is proposed, which ensures that all the agents can be controlled to the pinner's trajectory in finite time. Furthermore, we solve the challenging and fundamental question that how many nodes should be pinned to reach finite-time consensus. A sufficient condition is proposed to achieve finite-time consensus for multi-agent systems with nonlinear dynamics under Euler digraph. It is found that adding communication connections or increasing feedback gains is an effective way to reduce the settling time. Finally, numerical simulations are presented to verify the effectiveness of the obtained theoretical results. [ABSTRACT FROM AUTHOR]

The diffusive Schnakenberg model with gene expression time delay is considered. In this paper, the stability, diffusion-driven instability, and time delay-induced Hopf bifurcation have been investigated. By linear stability analysis, we find the parameter areas where the unique positive equilibrium is stable and Turing instability can occur for a certain relationship of diffusion rates. Then we obtain a series of critical values for the time delay at which the spatially homogeneous and inhomogeneous periodic solutions may emerge. Based on the explicit formula determining the properties of the Hopf bifurcation, we employ numerical simulations for parameters both in the stable region and Turing instability region. The numerical simulations show that delay can destabilize the stability of the positive equilibrium solution and eventually induce spatially homogeneous and inhomogeneous periodic solutions. Furthermore, the spatiotemporal patterns in the two spaces dimension from the Turing instability regime provide an indication of the wealth of patterns that the delayed system can exhibit. [ABSTRACT FROM AUTHOR]

Two-component reaction–diffusion models in high dimensions involving space-fractional derivatives are used as a powerful modelling approach for understanding several aspects of spatial heterogeneity and nonlocality. In this paper, we propose an accurate, unconditionally stable, and maximum principle preserving fourth-order method both in space and time variables to study the complex dynamical processes of two-component nonlinear space-fractional reaction–diffusion systems posed in high dimensions. To achieve a fast fourth-order accurate method, we adapt the matrix transfer technique with a fast Fourier transform-based implementation in space and an exponential integrator in time. The main advantage of the method is that it avoids storing the large dense matrix resulting from discretizing the fractional operator with the matrix transform approach and significantly reduces the computational costs. Some numerical experiments are carried out in two and three space dimensions to demonstrate the accuracy and computational efficiency of the method. [ABSTRACT FROM AUTHOR]

Comparison of landscapes and patterns is a long-standing challenge in spatial analysis research. Recently, new models and tools developed for non-geographic image data are being used to study geographic problems involving classification or prediction. Specifically, computer vision models and artificial neural networks have been deployed in an ever-growing number of geographical analyses. In this paper, we review the use of these models in geographical analysis, focusing on the representation and comparison of spatial patterns. We review artificial neural networks and provide semantic linking across domains using similar model constructs through the lens of scale. We note that scale, a contextual element in geographical research, is typically considered a model parameter in computer vision. Scale impacts both computer vision techniques and traditional pixel-based or object-oriented analysis, yet computer vision methods such as CNNs are relatively robust to small-scale variations due to their capability to learn multiscale features via spatial filtering and the formation of scale-space tensors across layers. Parameterization of computer vision models to represent multiscale patterns however remains ad hoc. A typology of scales, therefore, provides a framework for mapping model constructs to develop guidelines for parameterizing and evaluating computer vision models in a geographic context. [ABSTRACT FROM AUTHOR]

The use of piles as settlement reducers in the design of artificial embankments on soft soil strata is nowadays very common. The design methods employed in the current engineering practice are based on simplified approaches not allowing the assessment of average and differential settlements at the top of the embankment. In this paper, a model to estimate both differential and average displacements at the top of the embankment is introduced. This, based on the choice of substructuring the spatial domain and employing a suitably conceived upscaling procedure, is an extension to the case of rough pile shafts of a model originally conceived by the authors for smooth piles. To conceive and calibrate the model, the authors performed a series of numerical simulations mainly aimed at highlighting the mechanical processes taking place at the pile shaft. From a practical point of view, this model can fruitfully be employed in displacement based design approaches and to optimize pile diameter and spacing. [ABSTRACT FROM AUTHOR]

Computer simulations are considered efficient in supporting exploratory learning. This paper highlights instruction challenges and undesirable consequences on student learning in exploratory learning with computer simulations in classroom situations. A classroom with students who explore using simulations contains ideas explicated on several communicative channels. We use the professional noticing paradigm to demonstrate how a teacher's ability to listen to students' thinking via a brief encounter in real classroom setups can yield misconstrued interpretation of students' activity and impede learning. We present a case study where a teacher listens to students' thinking in building a model with a dynamic mathematics environment. We show how the teacher's response exacerbated those local confusions in ways that compromised the lesson's goals. We reflect on how the lesson's design influenced these outcomes and survey technology and activity developments to support teachers' noticing. [ABSTRACT FROM AUTHOR]

This paper proposes a casting improvement process to enable the casting of Al-Cu alloy cylinder heads to achieve the required quality. The hot tearing defects generated in the fire face of the cylinder head during casting were simulated using MAGMA software. The simulation results show that the large wall thickness transition difference in the fire face of the cylinder head is the reason for the large temperature and stress gradient during solidification. Therefore, the first solution was optimised by forming the fire face as a whole into a flat plate, but the fire face centre area stress is still too high. The second optimisation option optimises the cold iron structure of the fire face, the probability of cracking in the fire face is reduced to 17%. These results have important reference significance for the optimisation of the Al-Cu alloy cylinder head hot tearing problem. [ABSTRACT FROM AUTHOR]

This paper addresses the leaderless and leader-followers flocking motion problems of multi-agent systems in a workspace with obstacles. We consider inertial agents with equally limited communication radius and heterogeneous input constraints. Using the notion of proximity graphs, we provide distributed controllers to induce the desired flocking behaviour. Unlike previous results, our controller designs do not require predicted states or a target determination scheme and allow edge deletions. Also, by taking advantage of the group's heterogeneity, our controllers allow agents with less restrictive input constraints to compensate for the control effort that their less capable neighbours cannot provide. We illustrate the effectiveness of our proposals through numerical simulations. [ABSTRACT FROM AUTHOR]

This paper proposes a decentralized navigation method with collision avoidance for a robotic swarm whose individuals possess heterogeneous abilities, such as sensing range and maximum speed. In this method, each agent distributedly constructs and maintains a local directed connection with another agent using only local information, which is relative distance. Moreover, all agents always maintain some distance from other agents to avoid collision. As a result, one leader robot can guide an entire swarm of robots to their destination, and the other robots can follow the leader while maintaining connectivity and not colliding with others. We prove the above mathematically, and we demonstrate the validity of the proposed method by numerical simulation and experimentation. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of feedback stabilisation of bilinear systems with discrete delay in a Hilbert space. We consider the decomposition of the phase space and we propose a bounded feedback control to study the weak, strong and exponential stabilisation. Firstly, we discuss the well possedness of mild solutions of the considered systems. Secondly, some sufficient conditions are given to guarantee the feedback stabilisation for the bilinear systems. The stabilisation results are given in term of observation estimates. Furthermore, an explicit decay estimate of the stabilised state is obtained in the strong stabilisation case. At the end, examples with numerical simulations are given to show the applicability of our theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the fold bifurcation, flip bifurcation and degenerate Neimark–Sacker bifurcation of a second-order rational difference equation. As we know, many scholars used the first-order Poincaré-Lyapunov constant σ to determine the type of Neimark–Sacker bifurcation. However, by computing, we find that σ = 0 which means this system undergoes a degenerate Neimark–Sacker bifurcation. Therefore, using the centre manifold theorem, the Normal Form theory and the bifurcation theory, we calculate the fifth-order term of this system and give the conditions of the degenerate Neimark–Sacker bifurcation. Simultaneously, the Neimark–Sacker bifurcation curve is not a traditional parabolic shape, but an unbounded extended line. Finally, the numerical simulations are provided to illustrate theoretical results. [ABSTRACT FROM AUTHOR]

Spark ignition by low-energetic electrical discharges in combustible fuel/air mixtures is a significant safety risk in various industries. In the present paper, OH-LIF measurements and numerical simulations of the ignition and early flame propagation of hydrogen/air, propane/air and ethene/air mixtures are reported. The experiments, carried out at four energy levels close to the respective minimum ignition energy (MIE), show that higher energy input leads to a wider flame radius, which is in agreement with one-dimensional numerical simulations. Further, the evaluation of the radial OH distribution reveals the highly stochastic nature of this process if the introduced energy is near the respective MIE. By utilizing the combined methodical approach of experiments and simulations, the key factors impairing the experimental repeatability are identified. The numerical results indicate at lower energies a longer time delay between source time and ignition, during which loss processes and perturbations may lead to extinction. One important influencing factor is the three-dimensional flow induced by the discharge, effectively increasing the experimental scatter. The presented work facilitates a detailed view on the complex physiochemical mechanisms dominating ignitions of explosive gas mixtures by low-energetic electrical discharges. [ABSTRACT FROM AUTHOR]

This paper considers the passivity-based boundary control for stochastic delay reaction–diffusion systems (SDRDSs) with boundary input–output. Delay-dependent sufficient conditions are obtained in the sense of expectation for SDRDSs by the use of Lyapunov functional method, for the input strict passivity and the output strict passivity, respectively. Then delay-dependent sufficient conditions are presented to ensure the uncertainty SDRDSs to achieve the robust passivity. Moreover, by utilising the techniques of Green formula and Poincare's inequality, the difficulty is handled caused by the boundary input and boundary controller. Besides, the troubles brought by the existence of the stochastic term and uncertain parameters are resolved by stochastic inequality techniques. Finally, numerical simulations are provided to show the validity of our theoretical results. [ABSTRACT FROM AUTHOR]

In this work, the results of a detailed art technological investigation of the icon Last Supper from the Russian Memorial Church in Leipzig (Germany) are presented. The icons of the iconostasis of the church were made in the workshop of N.S. Emelyanov in Moscow in 1912. The investigation showed that the painter in principle technologically adhered to the traditional way of making icons. The panel is made of boards of lime wood with two crossbars on the reverse. The paint was applied to a chalk ground over a textile layer. The traditional iconographer's palette was expanded by a few contemporary pigments. The binding agent is classic egg tempera. Originally, the layers of paint had an oil varnish (olifa). The main aim of the project VirtEx, introduced in this paper, is to expand existing methods with numerical material and structural models to be able to predict quantitatively the behaviour of wooden artefacts under loads due to climate changes as well as mechanical loads. The detailed art technological investigation provides the required data for the computer models. The numerical data can then be validated with technologically exact copies and replicas. In the introduction to the article, the current state of research on icon painting techniques is also outlined. [ABSTRACT FROM AUTHOR]

This paper employed a nonlinear constitutive relation to describe the mechanical behavior of sintered neodymium iron boron (NdFeB) and studied the dynamic damage of NdFeB in the electromagnetic buffer. The systematic research on the constitutive model of NdFeB was yet studied. To end this, a suite of dynamic tests was implemented using a Split Hopkinson Pressure Bar (SHPB) system to obtain the compressive behavior at different strain rates of NdFeB. Referred to as Zhu-Wang-Tang (ZWT), the damage-modified constitutive model used herein was fitted by the experimental data, so that a set of ZWT model parameters for the tested materials was achieved. Then the incremental expression of the constitutive model was formulated and further embedded into ABAQUS via the VUMAT subroutine interface to establish the dynamic model of the electromagnetic buffer, followed by calculated. Finally, the damage peak of NdFeB was optimized according to the interval uncertain optimization method. The detailed assessments showed that the damage peak appeared in the inner side of the right-most permanent magnet, and its value was greatly reduced after optimization. [ABSTRACT FROM AUTHOR]

Vehicle frontal crashworthiness analysis is an important topic in the field automotive community, as it relates to legislative requirements. Frontal crash models contain a large number of elements and therefore present a high computational cost, especially when performing crashworthiness structural performance optimisations. A new numerical methodology is proposed in this paper with the aim to increase computation speed by implementing a sub-modelling approach on the frontal structure-rear wheels (FSRW) method. In this new method, the vehicle body structure behind the rear seats is replaced by a point mass, with an equivalent mass to the rear structure removed, and attached to the rear frame of the front structure and its wheels. This new method was rigorously tested against validated full size vehicle computer models of different classes provided by NHTSA, and included MPV, SUV, van, and sedan, against fixed rigid barrier (FRB), small overlap and a mobile progressive deformable barrier (MPDB) tests. The research has demonstrated that this new sub-modelling approach correlated against all the full size NHTSA computer models in deformations, intrusions, velocities, and accelerations, as well as providing a runtime average reduction between 7% and 23%. This new simplified method, which can be easily implemented, is innovative and will have an important impact vehicle design, as it will allow an easier use of optimisation techniques, which will lead to safer vehicles. [ABSTRACT FROM AUTHOR]

This paper deals with the numerical simulation of a ship's manoeuvring performance in regular waves. This is made possible by employing the time-domain code ELIGMOS, which adopts a hybrid formulation to couple seakeeping and manoeuvring contributions. The first and steady second-order wave-induced forces are incorporated, implementing a multidimensional interpolation scheme to account for their dependency on the instantaneous heading and forward speed values. Two methods have been adopted for the calculation of the added resistance regarding the size of the wavelength (short or long wave seas), namely a far and a near-field one, using the hydrodynamic software NEWDRIFT+ and NEWDRIFT v.7. Low-frequency hydrodynamic manoeuvring forces are incorporated by adopting the expressions suggested by the Japanese MMG (Manoeuvring Modelling Group) method. Validation of the suggested methodology is attempted through the comparison of numerical simulations of turning circle tests in calm water and in regular waves with available experimental evidence for the S-175 container ship. [ABSTRACT FROM AUTHOR]

Vacuum carburizing and high-pressure gas quenching process is being widely used in the heat treatment industry. There is an urgent need for a mature technology to predict the influence of carbon content and quenching gas flow on the microstructure and mechanical performance of workpieces. In this paper, a coupling simulation system of the flow field, temperature field, phase field, and stress–strain field was established. And simulations and experiments were carried out for an 18CrNiMo cylindrical sample and a 20CrMnTi gear hub. The results prove that this system can realize the synchronous coupling simulation of the above physical fields, and the simulation results are accurate and applicable to complex shape parts, therefore can guide the design of the process control scheme of the vacuum carburizing and high-pressure gas quenching process. [ABSTRACT FROM AUTHOR]

Since the construction of a weir at Iffezheim (Rhine-km 334) in 1977, a continuous deposition of sediments in the weir channel has been observed. The aim of this paper's underlying investigations was to assess the long-term riverbed evolution of the Iffezheim reservoir in terms of deposition and erosion. The computational fluid dynamic model SSIIM-3D was applied to simulate the morphological changes in the weir channel. To reduce the computation time of long-term simulation (e.g. several decades), a reduced complexity approach called 'classification of the boundary conditions for discharges (Q) and suspended sediment concentrations (SSC)' was developed and applied to the Iffezheim reservoir. The basic idea of the approach was to replace instationary simulations by a precalculated series of simulations with stationary boundary conditions. For doing so, daily volume changes were precalculated by combining representative discharge and suspended sediment concentration regimes. To determine the results of the instationary simulation, the number of days in each bin of Q and SSC was counted, multiplied with the precalculated result and added up. The amount of the volume change in the reservoir for a certain period could then be obtained by adding up the calculated daily volume changes. The results of this method showed an acceptable agreement with measurements for long-term periods (years) and for short-term periods (months) with remarkably shortened computation times compared to the instationary simulations (of 97%). [ABSTRACT FROM AUTHOR]

This paper employs the observer-based output feedback control technique to deal with the problem of spatiotemporally asynchronous sampled-data control for a linear parabolic PDE on a hypercube. By the spatiotemporally asynchronous sampled-data observation outputs, an observer-based output feedback control law is constructed, where the sampling interval in time is bounded. By constructing an appropriate Lyapunov–Krasovskii functional candidate and applying a weighted Poincaré–Wirtinger inequality on a hypercube, it is shown under a sufficient condition presented in terms of standard linear matrix inequalities that the suggested spatiotemporally asynchronous sampled-data control law asymptotically stabilises the PDE in the spatial H 1 (Ω) norm but its convergence speed can be regulated by a known constant. Moreover, both open-loop and closed-loop well-posedness analysis are done within the framework of C 0 semi-group. Finally, numerical simulation results are presented to support the proposed design method. [ABSTRACT FROM AUTHOR]

In this paper, we use a mean-reverting Ornstein-Uhlenbeck process to simulate the stochastic perturbations in the environment, and then a modified Leslie–Gower Holling-type II predator-prey stochastic model in a polluted environment with interspecific competition and pulse toxicant input is proposed. Through constructing V-function and applying It o ^ ′ s formula, the sharp sufficient conditions including strongly persistent in the mean, persistent in the mean and extinction are established. In addition, the theoretical results are verified by numerical simulation. [ABSTRACT FROM AUTHOR]

This paper mainly explores the complex impacts of spatial heterogeneity, vector-bias effect, multiple strains, temperature-dependent extrinsic incubation period (EIP) and seasonality on malaria transmission. We propose a multi-strain malaria transmission model with diffusion and periodic delays and define the reproduction numbers R i and R ^ i (i = 1, 2). Quantitative analysis indicates that the disease-free ω-periodic solution is globally attractive when R i < 1 , while if R i > 1 > R j ( i ≠ j , i , j = 1 , 2), then strain i persists and strain j dies out. More interestingly, when R 1 and R 2 are greater than 1, the competitive exclusion of the two strains also occurs. Additionally, in a heterogeneous environment, the coexistence conditions of the two strains are R ^ 1 > 1 and R ^ 2 > 1. Numerical simulations verify the analytical results and reveal that ignoring vector-bias effect or seasonality when studying malaria transmission will underestimate the risk of disease transmission. [ABSTRACT FROM AUTHOR]

In this paper, we consider the dynamical behaviour of a stochastic coronavirus (COVID-19) susceptible-infected-removed epidemic model with the inclusion of the influence of information intervention and Lévy noise. The existence and uniqueness of the model positive solution are proved. Then, we establish a stochastic threshold as a sufficient condition for the extinction and persistence in mean of the disease. Based on the available COVID-19 data, the parameters of the model were estimated and we fit the model with real statistics. Finally, numerical simulations are presented to support our theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, we study a stage-structured wild and sterile mosquito interaction impulsive model. The aim is to study the feasibility of controlling the population of wild mosquitoes by releasing sterile mosquitoes periodically. The existence of trivial periodic solutions is obtained, and the corresponding local stability and global stability conditions are proved by Floquet theory and Lyapunov stability theorem, respectively. And we prove the existence conditions of non-trivial periodic solutions and their local stability. We can find that the system has the bistable phenomenon in which the trivial periodic solution and the non-trivial periodic solution can coexist under certain threshold conditions. All the results show that the appropriate release period and release amount of sterile mosquitoes can control the wild mosquito population within a certain range and even make them extinct. Finally, numerical simulation verifies our theoretical results. [ABSTRACT FROM AUTHOR]

This paper is concerned with a modified Leslie–Gower and Holling-type II two-predator one-prey model with Lévy jumps. First, we use an Ornstein–Uhlenbeck process to describe the environmental stochasticity and prove that there is a unique positive solution to the system. Moreover, sufficient conditions for persistence in the mean and extinction of each species are established. Finally, we give some numerical simulations to support the main results. [ABSTRACT FROM AUTHOR]

In this paper, a general predator–prey model with state-dependent impulse is considered. Based on the geometric analysis and Poincaré map or successor function, we construct three typical types of Bendixson domains to obtain some sufficient conditions for the existence of order- 1 periodic solutions. At the same time, the existing domains are discussed with respect to the system parameters. Moreover, the Analogue of Poincaré Criterion is used to obtain the asymptotic stability of the periodic solutions. Finally, to illustrate the results, an example is presented and some numerical simulations are carried out. [ABSTRACT FROM AUTHOR]

This paper aims to analyse stability and Hopf bifurcation of the HIV-1 model with immune delay under the functional response of the Holling II type. The global stability analysis has been considered by Lyapunov–LaSalle theorem. And stability and the sufficient condition for the existence of Hopf Bifurcation of the infected equilibrium of the HIV-1 model with immune response are also studied. Some numerical simulations verify the above results. Finally, we propose a novel three dimension system to the future study. [ABSTRACT FROM AUTHOR]

Pile safety has received increasing attention in marine engineering, especially in the field of local scour. In this paper, a finite element numerical model is established for local scour around a cylinder in steady currents. The flow is described by unsteady Reynolds–averaged Navier–Stokes equations with a traditional k − ε turbulent closure model. The proposed scour model takes bed load into account. The Exner equation is solved to determine the bed variation and the moving mesh approach is used to capture the evolution of the bed. When the resulting slope exceeds the angle of repose, a novel sand-slide model based on Rodrigues' rotation formula is used to prevent simulation distortion. All the equations are discretized by the two-step Taylor–Galerkin algorithm, and the resulting approach is fast to implement with second-order accuracy in space. The numerical results are found to be in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

In terms of reliability, the damper represents the critical element of the suspension in the rail vehicle. A damper failure brings about a reduction in the damping of the suspension it belongs to, thus leading to the asymmetry of the suspension damping in the vehicle. The paper presents an analysis of the effect that the asymmetry of the secondary suspension damping has on the vertical vibration behaviour in the vehicle carbody and on the ride comfort, while using to that purpose the results derived from numerical simulations. The characteristics of the vibration behaviour for the resonance frequencies of the carbody dominant vertical modes are pointed out via the power spectral density of the carbody acceleration, which is weighted by the function of the sensitivity of the human body to the vertical vibrations. The ride comfort is assessed based on the ride index comfort calculated in three carbody reference points – at the centre and above the two bogies. [ABSTRACT FROM AUTHOR]

This paper presents an investigation on the compressible flow past spanwise wavy wings with an incoming flow of M ∞ = 0.5 and R e = 10 7 . The scale adaptive simulation is employed here to solve the Favre-averaged equations. Three wings, with the ratio of wavelengths (λ) to chord length (c) respectively equaling to 1/2 (W4), 1/3 (W6), 1/4 (W8), are aerodynamically investigated. The aerodynamic force and separation were compared. The results obtained show that the lift-to-drag ratio of W-8 is 12.7% and 14.4% higher than W-4 and W-6 because of the larger low-pressure regions, while the lift and drag coefficient curves of W-8 oscillate more strongly. Leading edge separated bubbles and dilation-type recirculation regions are observed in the flow field structures. Spanwise momentum transportation and local airflow downwash effect are generated by the flow around the separation regions. Spanwise momentum transportation and downwash effect play important roles in the flow control mechanism of spanwise wavy wings. Three components of three-dimensional velocity vectors are modally decomposed by dynamic mode decomposition method to reveal the flow control mechanisms and vortex structures. The main modes characterizing the motions of arched vortices and shear layer vortices have been obtained. Strouhal number (St) is adopted to define the periodic oscillations of vortex shedding. The St of the modes are related to the scale of the vortex structures in the flow field. Small-scale eddy motions have been decomposed in high-frequency modes, and thus the modes of the flow field are more meticulous for higher St. [ABSTRACT FROM AUTHOR]

In this paper, cyclone separator is proposed for the first time to separate particles according to density, and it is applied to the recovery of lithium iron phosphate (LFP) from spent lithium battery materials for the first time. The effect of the flow field on the motion of injected particles in a cyclone separator is studied by means of computational fluid dynamics (CFD). It is found that there is a classification phenomenon caused by the difference in the particle densities and the separation process is simulated accordingly. The results show that 60% LiFePO4 in the original feed can be separated after 7 separations, and the mass purity is 91%, with 7% Al and 2% Fe under instantaneous surface injection conditions. Compared with the original feed, LFP is effectively recycled. After 15 separations, the efficiency increases to 76%. Under simulated continuous injection conditions, the separation efficiency of LFP is 61.22% after 20 simulated separations, and the mass purities of the separated products are 92.53% LFP, 6.92% Al, 0.44% Fe and 0.11% Cu. Compared with the traditional method, the new method has advantages of low energy consumption, low cost, theoretically no pollution, and great development potential. [ABSTRACT FROM AUTHOR]

This paper proposes a bias-corrected expression for maximum likelihood estimators using the sequential number-theoretic method for optimization (SNTO) to improve the efficiency and accuracy of the estimators in three extreme value distributions (EVDs). It is well known that the widely used maximum likelihood estimation (MLE) could be often biased for small-size samples in EVDs. Meanwhile, numerical simulation results reveal that maximum likelihood estimators are suffered from high variance when the sample size is small and the impact is non-negligible. A comprehensive comparison study which includes classical bias-corrected methods and more recent ones is presented. Based on the simulation studies, the bias-correction estimator via SNTO is highly recommended to reduce the bias and variance of estimators. In addition, a real data set is illustrated to employ different techniques. [ABSTRACT FROM AUTHOR]

The critical size of clusters is a well-known key quantity for precipitation modelling, especially for nucleation. Classically, its value is obtained from a mean-field model which approximates the free energy of clusters. AKMC simulations rely on a set of physical parameters defined at the microscopic scale, thus the nature of hypotheses is very different from its equivalent in phenomenological models. It has been shown recently than the free energy of clusters as well as other important quantities can be directly extracted from AKMC simulations. Thanks to these advances, the critical size for nucleation can now be derived from such measurements. In practice, one faces various problems depending on the quality of the available information. Thus, one has to adapt the measuring method to the different ranges of cluster size and/or the different stages of precipitation. This paper focuses on three methods, considering the precipitation in concentrated AlLi alloys as a model case to explore the evolution of the critical size versus the physical time, from nucleation to coarsening. [ABSTRACT FROM AUTHOR]

This paper developed six cable logging incident scenarios that were modeled in a simulated environment, and conducted a pilot study in the Pacific Northwest to assess the potential for collecting worker risk assessment data. All the subjects in the pilot study reported that they understood the simulated incidents, and they were able to move around in the simulation to see what they needed. When reporting management requiring conditions (MRC) before performing the simulated task, the subjects consistently identified the first main MRC; however, there was variation in reporting the second main MRC. The results from the pilot study indicate that the simulations effectively modeled the spatial aspects of the incidents; however, the simulations lacked avatars to represent people in the simulations and this may have limited the ability to include cognitive aspects such as communication. Variation in the severity assigned by the subjects to the MRC, and to the unexpected events, revealed important differences in risk sensitivity between the subjects, and the importance of experiential learning in a safe environment when considering energized systems. [ABSTRACT FROM AUTHOR]

This paper is concerned with prescribed-time functional unknown input observer (PTFUIO) design for linear descriptor systems. First, by constructing two identical asymptotic convergence functional observers, a new PTFUIO is developed which can achieve an exact estimation within an arbitrarily prescribed time, where both the estimation accuracy and the convergence time pre-definition are independent of the initial conditions of the original system. Also, the necessary and sufficient conditions for the existence of such the PTFUIO are given in terms of the original system matrices which are easy to examine. Finally, numerical simulations are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

An attempt has been made to identify promising sites for tidal stream energy assessment along the Goa coast on central west coast of India. A two-dimensional tidal-driven validated numerical model is used to assess the tidal stream velocities. The numerical model results are further used to estimate the tidal stream energy over the simulation period which would form a resourceful input for future to optimize locations of tidal energy farms. The locations of current maxima in each of the tidal driven regions have been identified and the energy is estimated thereof. This paper describes the tidal driven currents using a numerical model and their validation with measurements; and estimation of tidal stream energy among the different selected locations to choose the most feasible location for tidal energy extraction along Goa coast. [ABSTRACT FROM AUTHOR]

The Nile River is considered one of the most important rivers in the world. The scouring of such a river must be comprehensively studied. Therefore, studying the general scour of the Nile River and adjusting the relevant scour equations are very important. Field data were collected (bathymetric, hydrological, and hydraulic) for several years in the selected study area (a river reach with a total length of 54 km). A geographic information system (GIS) database application was established to determine the scour hole characteristics. The scour equilibrium state (active, stable or passive) was classified according to the field observations. A numerical model was developed to calculate the hydraulic characteristics of the Nile River. Seven equations were selected to evaluate the general scour depth. The predictive performances of these equations were assessed using field data and computed scour depths. Four statistical tests were performed to evaluate the performances of the scour equations. The results showed that the equations are inadequate and can potentially lead to underestimation of the scour depth. The Lacey Natural Resources Conservation Service (NRCS) equation performs better than the other equations considered. The selected equations were modified to improve the prediction of the general scour depth of the Nile River. A new general scour equation was derived to simulate the Nile River general scour. Compared to the previously discussed equations, this new equation provided the most accurate prediction of general scour in the Nile River. Abbreviations: The following abbreviations are used in this paper. AHD = Aswan High Dam; ASCII = American Standard Code for Information Interchange; CAD = Computer-aided design; FESWMS = Finite Element Surface Water Modelling System; GIS = Geographic information systems; MAD = Mean absolute deviation; MAE = Mean absolute error; MKS = Metre-kilogram-second; NRCS = National Resources Conservation Service; NRI = Nile Research Institute; R2 = Coefficient of determination; RMSE = Root mean square error; SMS = Surface Water Modelling System; SPSS = Statistical Package for the Social Sciences; USBR = United States Bureau of Reclamation; UTM = Universal Transverse Mercator; WGS84 = World Geodetic System; 2D = Two-dimensional [ABSTRACT FROM AUTHOR]

This paper considers the bivariate copula-based first-order Markov models to describe nonlinear dependence in autocorrelated data. Then the cumulative sum (CUSUM) charts based on log-likelihood ratio are developed to monitor the mean shifts. The performance of the proposed CUSUM charts is studied in both linear and nonlinear time series under weak, moderate and strong dependence by numerical simulations. Comparisons with the AR(1) model-based CUSUM and EWMA charts are present under the same range of scenarios. Simulation results show that the Clayton copula-based CUSUM charts are more effective to almost all the mean shifts and further have an obvious advantage in strong dependence. An example from chemical production is given to illustrate the implementation of the proposed control scheme. [ABSTRACT FROM AUTHOR]

In this paper, we examine the application of the well-known hysteresis switching algorithm of adaptive control in the case of a continuously parameterised set of candidate controllers. Subject to existence of a feasible controller in the set, we prove that if the performance functions used at each time by the hysteresis algorithm are selected to be uniformly positive definite in the controller parameters, then one may safely set the hysteresis constant to zero without inducing chattering instability, and ensuring convergence to a performance-optimising controller. Expanding preliminary version of our work that we presented at the 2011 American Control Conference, the present paper adds new numerical simulation examples to demonstrate the application and benefit of the theory. [ABSTRACT FROM AUTHOR]

This paper presents a conversation strategy for interactive recommendations using a chatbot. Chatbots have recently been attracting attention for their use as a flexible user interface. To develop an effective chatbot, it is important to determine what kind of questions to ask, what information should be provided, and how to process a user's responses for a given task. In this paper, we target a chatbot that uses a graphical user interface (GUI) and focus on the task of recommending an item that suits a user's preference. We propose a conversation strategy where a chatbot combines questions about a user's preferences and recommendations while soliciting user's feedback to them. The balance between the questions and recommendations is controlled by changing the parameter values. In addition, we propose a simulation model to evaluate the performance of interactive recommendation under different parameter values. The simulation results with a prototype dataset are presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, the leader-following consensus problem of the fractional-order nonlinear multi-agent systems via event-triggered control is considered. An effective event-triggered controller is designed and then generalised exponential consensus of the controlled multi-agent systems is studied in the sense of Mittag-Leffler stability of fractional-order systems. The event-triggering function design is dependent on the parameter of the system structure and the minimum inter-event interval can be flexibly adjusted with different fractional-order α. With the event-triggered control scheme, the consensus condition is obtained and the convergence rate of the system is estimated. Numerical simulation indicates the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, a class of neutral-type fuzzy cellular neural networks with operator and time-varying delays is considered. By using the theory of fixed point and differential inequality techniques, some sufficient conditions are established to ensure the existence and global exponential stability of pseudo almost periodic solutions for the addressed system, which extend previously known researches. Finally, an example and its numerical simulations are presented to illustrate the correctness of our results. [ABSTRACT FROM AUTHOR]

In this study, the tensile shear and bending tests of adhesively bonded single lap joints with the acrylic adhesive was evaluated experimentally and numerically. In the previous paper, the traction-separation laws in mode 1 and mode 2 for an acrylic adhesive were directly obtained from the observation of failure process using Arcan type adhesively bonded specimens: simultaneous measurements of the J-integral and the opening displacements in the directions normal, δn and tangential to the adhesive layer, δs respectively. The experimental results were compared with numerical simulations conducted in ABAQUS including cohesive damage model. The cohesive laws obtained in the previous paper were simplified to trapezoidal shape from the experimentally obtained ones which were indicated in the previous paper. A good agreement was found between the experimental and numerical results. Then, to investigate the damage evolution in the adhesive layer for some lap joints, microscopic video observation was conducted near the end of the adhesive layer, and the video image have been compared with the contours of damage variable obtained by FEM corresponding to the video images. The observed damage evolution also agrees with the trend of damage variable. [ABSTRACT FROM AUTHOR]