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The critical role that numerical simulation plays in additive manufacturing has stimulated research on the effectiveness and potential applications of mesh-free, particle-based discretisation techniques. These methods excel at handling fluid flows and are viable alternatives to the mesh-based techniques typically used in commercial simulation software. In this paper, we review recent advances in developing computational models for metal additive manufacturing (MAM) processes using particle methods, in the theoretical understanding of the fundamental mechanisms that control such processes at the powder (or melt pool) scale, and in the predictability of physics-based modelling approaches. The paper explores the applicability and performance of particle-based methods in simulating powder bed fusion, directed energy deposition, and binder jetting processes. Since the progress of MAM relies on systematic material-process-structure realisations which are often impossible to sense or observe experimentally, developing efficient particle-based and multiscale simulation tools can be essential to achieving this objective through in-situ process control and optimisation. [ABSTRACT FROM AUTHOR]

Digital human models (DHM) allow for a proactive ergonomic assessment of products by applying different models describing the user-product interaction. In engineering design, DHM tools are currently not established as computer-aided ergonomics tools, since (among other reasons) the interaction models are either cumbersome to use, unstandardised, time-demanding or not trustworthy. To understand the challenges in interaction modelling, we conducted a systematic literature review with the aim of identification, classification and examination of existing interaction models. A schematic user–product interaction model for DHM is proposed, abstracting existing models and unifying the corresponding terminology. Additionally, nine general approaches to proactive interaction modelling were identified by classifying the reviewed interaction models. The approaches are discussed regarding their scope, limitations, strength and weaknesses. Ultimately, the literature review revealed that prevalent interaction models cannot be considered unconditionally suitable for engineering design since none of them offer a satisfactory combination of genuine proactivity and universal validity. Practitioner summary: This contribution presents a systematic literature review conducted to identify, classify and examine existing proactive interaction modelling approaches for digital human models in engineering design. Ultimately, the literature review revealed that prevalent interaction models cannot be considered unconditionally suitable for engineering design since none of them offer a satisfactory combination of genuine proactivity and universal validity. Abbreviations: DHM: digital human model; CAE: computer-aided engineering; RQ: research question [ABSTRACT FROM AUTHOR]

In view of the problem that time delay always existing in wide area power system can cause severe effects on the operation performance of the whole system, this paper studies the stability of the wide area power system with interval time-varying delays. Firstly, the model of wide area power system with interval time-varying delay is established, based on that, a new augmented vector and new Lyapunov-Krasoskii functional (LKF) are constructed. Then, the delay-partitioning approach, Wirtinger integral inequality, free-matrix-based inequality and convex combination approach are used to estimate the derivative of the functional, and as a result, a less conservative stability criterion for the delayed power system is obtained. Finally, numerical simulations of the typical second-order system, the single machine system and two-area four-generator power system are given to illustrate that the proposed method in this paper expands the stability margin of the system effectively. [ABSTRACT FROM AUTHOR]

This article reviews literature on the application of Discrete Event Simulation (DES) and optimisation methods for assembly systems. Data from papers is collated and classified based on application domain, optimisation objective functions, model formulations and optimisation methods. This classification enables the identification of key trends within the research. The most common objective functions applied within studies are time and throughput. In addition, what–if scenario analysis is identified as the most common optimisation method. An increase in the use of hybrid methods for simulation modelling and growing application of Artificial Intelligence methods for multi-objective optimisation of DES models has been noted. These growing trends provide a variety of interesting areas for progress in future research. [ABSTRACT FROM AUTHOR]

This paper proposes a prediction strategy for the hydrodynamic performance of bionic fish. The major challenges are meshing and building prediction model. The NACA0012 airfoil is used to replace the fish driven by the body and/or caudal fin (BCF), and a two-dimensional swimming geometric model is constructed. The geometric model is divided into hybrid meshes using the overset mesh method. The classical traveling wave model is studied using Matlab, and an improved self-propelled motion model is established. The hydrodynamic performance of the self-propelled model is numerically simulated based on computational fluid dynamics (CFD). In this strategy, the geometric model and the self-propelled motion model are integrated with user defined functions (UDF). The influences of the parameters such as inflow velocity, frequency, wavelength, and head fluctuation amplitude on the motion performance are studied. The results show that when inflow velocity is uniform, the self-propelled motion will eventually reach a quasi-steady state. According to the numerical simulation results, a hydrodynamic performance prediction model is established based on multilayer perceptron (MLP). The model is used to predict the performance of the optimized traveling wave parameters, and the error is within 3 %. The accuracy and generalization ability of the MLP prediction model is verified. [ABSTRACT FROM AUTHOR]

Owing to the complexity of flow patterns, modelling of flow in coastal areas remains a challenge, even with the numerical techniques of today. In this paper, we have tried to address the problem of modelling the currents off the coast of Bay of Bengal. It is found that ocean modelling using coastal community models like Delft3D and MIKE21 could produce inherent errors if used to study depths of continental shelf greater than the 50 m isobaths (called Far-Shelf). This error can be partly overcome by adding a data processing tool like Artificial Neural Network (ANN) to improve velocity predictions. Predictions from such a proposed ANN model are seen to improve the correlation from as low as 0.28 for stand-alone model to more than 0.9 for ANN augmented results for Far-Shelf. This is because the ocean parameters in the Far-shelf are dependent not only on coastal processes but also on the interactions with the deep ocean. The advantage of better numerical accuracy strongly offsets the disadvantages of using such data-driven methods and will aid in getting a more accurate flow field. [ABSTRACT FROM AUTHOR]

In this paper, the problem of circle formation of multi-agent system in a plane is investigated. Inspired by the idea of decouple design, we decompose the overall control objective into two sub-goals, the first one is circle forming that agents need to move to a circle with a desired radius and centred on a predefined target, and the second one is space adjustment that each agent form and maintain a desired relative position with its neighbours. Since the completion of the second objective requires information from neighbouring agents, a distributed event-triggered controller is proposed to save communication resources and reduce the number of controller updates, which consists of two parts corresponding to two sub-goals. Furthermore, it is proved that there exists no Zeno behaviour under the proposed control laws. Finally, a numerical simulation verifies the effectiveness of the distributed event-triggered circle formation controller proposed in this paper. [ABSTRACT FROM AUTHOR]

Vulnerability analysis of engineering structures is an important aspect of risk assessment. It involves the probability that the structure meets or exceeds various set damage conditions under the influence of different risk levels. In order to quantitatively analyze the vulnerability of the typical bridge substructure under debris flow, four vulnerability curves with different damage levels under debris flow impact are obtained by numerical simulation of 150 damage conditions with the aid of three-dimensional finite element analysis software. The results show that the vulnerability curves of debris flow established in this paper are well fitted with data of numerical simulation. The acceleration is fastest in the middle of the curve, and high-intensity debris flow is more likely to cause high-level damage of bridge structure. By using the vulnerability curves established in this paper, the damage probability distribution under a certain debris flow intensity and damage control points of bridge substructure can be further obtained, which provides a basis for disaster prediction, risk management and reliability analysis of transportation system. The method and model presented can provide a reference for the vulnerability analysis of other types of structures under debris flow. [ABSTRACT FROM AUTHOR]

In most research on the hot strip mill production scheduling problem (HSMPSP) arising in the steel industry, it is accepted that a schedule with lower penalty caused by jumps of width, hardness, and gauge will result in lower roller wear, so it is regarded as a better schedule. However, based on the analysis of production processes, it is realised that rolling each coil also cause roller wear. In order to assessing the roller wear associated with production scheduling more precisely, it is necessary to consider it as another factor besides those jumps, especially when complicated constraints are involved. In this paper, an improved method is proposed to quantify the expected wear of the rollers done by those jumps and rolling processes. Then the HSMPSP whose objective is to maximise the total length of all scheduled coils is formulated as a team orienteering problem with time windows and additional production constraints. A heuristic method combining an improved Ant Colony Extended algorithm with local search procedures dedicated to HSMPSP is developed. Finally, computational results on instances generated based on production data from an integrated steel mill in China indicate that the proposed algorithm is a promising solution specific to HSMPSP. [ABSTRACT FROM AUTHOR]

This paper presents a belt-conveyor based parallel storage system (PSS). Compared with the conventional AS/RS, it has advantages including more efficient utilisation of storage space, and faster storage and retrieval of products. The PSS consists of three components: the automated retrieval system (ARS), the automated storage system (ASS) and the compact storage rack (CSR). In the ARS, a vertical screw conveyor is used to facilitate the vertical movement of the unit loads, while a powered belt-conveyor is used for the horizontal dimension. Additionally, a powered conveyor system enables motion along the depth dimension, meaning each lane in the CSR is connected to several storage cells. Horizontal belt-conveyor and powered conveyor in the lane constitute cross-belt which causes the parallel process. On the other side of the rack, a unit load lift, a RGV lift, several rail-guided vehicles and a buffer rack constitute the ASS. Based on the system, we formulate separate travel-time models for ARS and ASS, under the assumption of randomised, uniformly distributed storage rack positions. Computer simulation with Matlab is used to validate the models, and optimise the automated storage system. [ABSTRACT FROM AUTHOR]

Autonomous vehicle storage and retrieval systems use vehicles that move horizontally along rails within the storage racks, while vertical movements are provided by lifts. The solution proposed in this paper addresses a particular system configuration that works with multiple deep storage lanes that are widely used in the food and beverage industry, characterised by large volumes of products of limited variety. The generic deep lane is single item, i.e. one stock keeping unit, and single batch, i.e. one production lot, thereby affecting the performance of the system in terms of storage capacity utilisation and throughput. Determining the number and depth of the lanes is crucial to aid the design and control of such a storage system. The aim of this paper was to support the design of AVS/RSs though a set of original analytic models for the determination of the travelled distance and time for single-command and dual-command cycles given alternative layout configurations. The models are validated by simulation and exemplified with a real-warehousing case study. The paper presents useful guidelines for the configuration of the system layout including the determination of the optimal shape ratio and the length of the lanes. [ABSTRACT FROM AUTHOR]

This paper analyzes a class of stochastic coupled systems with time-varying delays in infinite dimensions. The existence and uniqueness as a prerequisite to ensure synchronization of the solution is analyzed, based on the idea of the contraction mapping principle, graph theory, and mild Itô's formula. Next, the p-th moment exponential synchronization (PMES) of infinite-dimensional systems is realised using the discrete control strategy, namely, aperiodically intermittent control (AIC). By combining graph theory with the Lyapunov method, several criteria for synchronizing infinite-dimensional systems are obtained using the mild Itô's formula. These criteria show the effects of control parameters, topology, and time delays on PMES. Finally, the theoretical results are applied to a class of neural networks with reaction-diffusion, and some numerical simulations are also given. [ABSTRACT FROM AUTHOR]

This paper examines the dynamic performance of the pantograph passing through an overlap section of the catenary system, using a China's high speed railway with the 4-span overlap as an example. The pantograph and catenary system are simulated as a lumped mass model and finite element model, respectively. The model is verified according to EN50318:2018. The model is also assessed against an experimental study of the contact force and uplift of contact wire at 300 km/h. Then the contact force and uplift of contact wire at the speed of 150–350 km/h are calculated. The research shows that when the pantograph passes through the overlap, the maximum contact force increases beyond 14%, the standard deviation of the contact force increases by more than 26%, and the increase of the vertical displacement exceeds 38%, which becomes more apparent with the increase of speed. Under the influence of aerodynamic force, when the running speed increases from 150 to 350 km/h, the mean contact force in the knuckle-downstream and knuckle-upstream orientation increase by 59.49% and 97.85%, respectively. As a result, the contact force and vertical displacement increase greatly when passing through the overlap section, which could affect the current collection quality. [ABSTRACT FROM AUTHOR]

This paper designs event-triggered delay compensation and disturbance attenuation control algorithms for multi-agent systems. First, through predictor-based model reduction method, an unknown large input delay can be compensated and delay-free dynamics is obtained. Based on the transformed systems, predictive descriptor observers are proposed to obtain estimated system states and sensor faults. Then, an event-triggered fault-tolerant algorithm is designed to save energy resources for communication among the agents while attenuating the disturbances. Moreover, it is validated that the systems do not exhibit Zeno behaviour using the designed event-triggering sequence. Numerical simulations are conducted to demonstrate the effectiveness of designed algorithms. [ABSTRACT FROM AUTHOR]

Stochastic distribution methods were used to construct patient flow simulation sub-models such as patient inflow, length of stay (LoS), cost of treatment (CoT) and clinical pathways (CPs). However, the patient inflow rate demonstrates seasonality, trend, and variation due to natural and human-made factors. LoS, CoT and CPs are determined by social-demographics factors, clinical and laboratory test results, resource availability and healthcare structure. For this reason, patient flow simulation models developed using stochastic methods have limitations including uncertainty, not recognising patient heterogeneity, and not representing personalised and value-based healthcare. This, in turn, results in a low acceptance level and implementation of solutions suggested by patient flow simulation models. On the other hand, machine learning becomes effective in predicting patient inflow, LoS, CoT, and CPs. This paper, therefore, describes why coupling machine learning with patient flow simulation is important, proposes a conceptual architecture for machine learning integrated patient flow simulation and demonstrates its implementation with examples. [ABSTRACT FROM AUTHOR]

The paper analyzes the spatial distribution of the average air density in a supersonic jet based on the results of laser transillumination. The algorithm to retrieve the average air density from transverse (to the jet axis) deviations of the transilluminating wavefront was tested in experiments on the Vertical jet setup of ITAM SB RAS. The results of retrieval are compared with the known literature data of contact measurements and with results of numerical simulation. The good sensitivity of local wavefront tilts to oscillations in the air density at frequencies of discrete acoustic tones has been demonstrated. This opens up the possibility of experimental study of the spatial structure of air density inhomogeneities in the jet channel. [ABSTRACT FROM AUTHOR]

In this paper, the mathematical modeling of the novel corona virus (COVID-19) is considered. A brief relationship between the unknown hosts and bats is described. Then the interaction among the seafood market and peoples is studied. After that, the proposed model is reduced by assuming that the seafood market has an adequate source of infection that is capable of spreading infection among the people. The reproductive number is calculated and it is proved that the proposed model is locally asymptotically stable when the reproductive number is less than unity. Then, the stability results of the endemic equilibria are also discussed. To understand the complex dynamical behavior, fractal-fractional derivative is used. Therefore, the proposed model is then converted to fractal-fractional order model in Atangana-Baleanu (AB) derivative and solved numerically by using two different techniques. For numerical simulation Adam-Bash Forth method based on piece-wise Lagrangian interpolation is used. The infection cases for Jan-21, 2020, till Jan-28, 2020 are considered. Then graphical consequences are compared with real reported data of Wuhan city to demonstrate the efficiency of the method proposed by us. [ABSTRACT FROM AUTHOR]

This paper investigates synchronisation for Markovian master-slave neural networks (NNs), where the transition probabilities of Markov chain are partially unknown and uncertain. To cope with the communication channel bandwidth constraint, an event-triggered impulsive transmission strategy is adopted, a corresponding impulsive controller is then designed. In this method, information transmission occurs only at some discontinous instants, which are determined by a state-dependent event-triggered condition as well as a predesigned forced impulse interval. Synchronization for Markovian master-slave NNs is guaranteed by a sufficient condition, and the controller gains are designed by using the obtained results. A numerical simulation is given to show the effectiveness of the presented method. [ABSTRACT FROM AUTHOR]

This paper is concerned with the stochastic model predictive control problem (SMPC) for a class of networked control systems with exogenous disturbances and restrictions on communication frequency. A self-triggered SMPC algorithm with an improved triggering condition is designed which integrates the co-design of both the current control inputs and the maximum sampling interval, with the aim of reducing the amounts of communication transmission while guaranteeing the specific performance. To give consideration to both probabilistic guarantee and computability, chance constraints on both states and inputs are transformed into deterministic ones by leveraging Cantelli's inequality and linearisation techniques, so as to be solvable for the optimisation problem. Meanwhile, the nonconvex terms in dynamics of covariance propagation are averted through introducing the covariance upper bound control approach. The formulated online optimisation problem is convex to all decision variables. The theoretical analysis on recursive feasibility and closed-loop stability is addressed for the proposed self-triggered SMPC scheme. Finally, the efficacy and achievable performance of the proposed algorithm are showcased through numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impulsive synchronisation of linear complex dynamical networks (CDNs) with time delay on time scales by a method of pinning impulsive control. We use the time scales theory and the Lyapunov method to derive a synchronisation criterion. We find that we can achieve the synchronisation of CDNs through only controlling a small number of nodes and the modelling framework here can enrich the models of continuous/discrete-time CDNs. In the end, we give some numerical simulations to demonstrate the feasibility of the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, we focus on a patch-structured Nicholson's blowflies system incorporating mature delay and feedback delay. First, by exploiting the differential inequality technique, fluctuation lemma and Brouwer fixed point theorem, we obtain the persistence and existence of the positive equilibrium point with different components. Second, we develop an approach to establish some new criteria to guarantee the local stability and global attractivity of the positive equilibrium point vector, which complement and improve some existing results. Last, the effectiveness and feasibility of the theoretical results are illustrated by some computer simulations. [ABSTRACT FROM AUTHOR]

In this paper, an encryption scheme, based on a double deterministic phase mask and the Yang-Gu algorithm, is proposed. It consists of double random phase encoding and the Yang-Gu algorithm in Fresnel and Fourier transform, respectively. The random phase masks are replaced with deterministic phase masks that are constructed using chaotic logistic and cubic maps. The encrypted image obtained by the scheme in one-way binary modulation is real and more convenient for storage and transmission. The validation of the proposed cryptosystem is carried out using numerical simulations on greyscale images of Man, DICOM and CUH binary images. The proposed scheme is investigated for its robustness through statistical analysis using histograms and correlation plots. The scheme is also tested for its resistance against occlusion, noise and cryptographic attacks. The proposed cryptosystem is found to be highly sensitive to its private key and Fresnel parameters and therefore secure. [ABSTRACT FROM AUTHOR]

In the standard secretary problem (SP), a decision-maker (DM) tries to choose the best applicant of a sequentially ordered set, and the goal is to maximize the probability of choosing the best applicant. In this paper, we extend the standard SP and present a satisficing policy. There are several satisfactory applicants for the DM to choose under the satisficing policy. The DM cannot rank all the applicants from best to worst due to the limits of the DM's incomplete preferences, and the goal is to maximize the probability of choosing one of satisfactory applicants. For the secretary problem with 2 and 3 satisfactory applicants respectively, on the one hand, the asymptotic results of the maximum probability of choosing a satisfactory applicant and the corresponding optimal cutoff value are computed respectively. On the other hand, a series of computer simulations are conducted to estimate the optimal cutoff value and the maximum probability of choosing a satisfactory applicant. The effects of incorporating endogenous search cost in the case of 50 and 100 applicants are investigated respectively under the satisficing policy. The satisficing policy of this paper can be regarded as an extension of the optimal policy of the standard SP. [ABSTRACT FROM AUTHOR]

In this paper, the active disturbance rejection control approach is addressed for a class of lower triangular uncertain stochastic nonlinear systems driven by coloured noises. An extended state observer is first constructed to estimate the stochastic total disturbance including the total effects of internal uncertainties and external disturbances affecting system performance, and then an active disturbance rejection controller based on estimation and compensation is designed to obtain desired closed-loop performance. It is shown with a rigorous analysis that the closed-loop state tracks a reference trajectory generated from the target system in practically mean square and almost sure sense. Some numerical simulations are performed to validate the practicality of the proposed control strategy. [ABSTRACT FROM AUTHOR]

In robust parameter design, it is common to use computer models to simulate the relationships between input variables and output responses. However, for the contaminated experimental data, the model uncertainty between computer models and actual physical systems will seriously impair the robustness of the optimal input settings. In this paper, we propose a new weighted robust design approach concerning the model uncertainty from outliers based on the robust Gaussian process model with a Student-t likelihood (StGP). Firstly, to reduce the impact of outliers on the output means and variances, the StGP modelling technique is adopted to estimate the relationship models for contaminated data. Secondly, the Gibbs sampling technique is employed to estimate model parameters for better mixing and convergence. Finally, an optimisation scheme integrating the quality loss function and confidence interval analysis approach is built to find the feasible optimisation solution. Meanwhile, the hypersphere decomposition method and data-driven method are applied to determine the relative weights of objective functions. Two examples are used to demonstrate the effectiveness of the proposed approach. The comparison results show that the proposed approach can achieve better performance than other approaches by considering the model uncertainty from outliers. [ABSTRACT FROM AUTHOR]

This study aims to provide energy-efficient strategies for collections care in the face of financial and environmental challenges. Focusing on paper-based enclosures in storage rooms, the research proposes strategies to enhance energy efficiency by relaxing tight environmental controls. The five-stage process began with a standard test of hygrothermal properties and buffering capacity of the enclosures. In the second stage, a computer model was developed using the first stage results. This model was used in a series of specially designed tests simulating the transient heat, air, and moisture transfer between the room and enclosure to determine an acceptable room environment in which the enclosure conditions could meet collections care standards. The modelling results were used, in the third stage, to develop an AI model that predicted the enclosure conditions using room temperature and relative humidity (RH) inputs. In the final stage, a model for energy consumption of air-conditioning system operations was developed to predict across various control accuracies. Results indicate that the tight maintenance of room RH levels can be relaxed from 47–53% to 33–65%, with a corresponding reduction in energy consumption of approximately 16–18%. This relaxation, while maintaining enclosure conditions in line with conservation standards, was demonstrated through a simulation case at the National Library of Scotland. This study underscores the broader applicability of the developed procedure, asserting its relevance for cultural institutions seeking energy-saving potential through customized enclosure models. [ABSTRACT FROM AUTHOR]

A super-compact ultra-wideband (UWB) microstrip band-pass filter (BPF) with triple-notched bands and wide stopband is proposed in this paper. The super-compactness of the proposed filter is achieved by integrating the modified SCRLH-TL UWB-BPF and backbone-shaped defected ground structure (DGS). The equivalent LC circuit models of the DGS and the modified SCRLH-TL UWB-BPF with the DGS are analyzed to validate their numerical simulation results. To introduce the triple notched-bands to mitigate the interference the two triple-mode SIRs are designed and loaded on the modified UWB-BPF without increasing the circuit size. The proposed filter was fabricated by using a conventional PCB process with the substrate of FR4. The measured 3-dB passband ranges from 2.8 through 10.2 GHz with the fractional bandwidth (FBW) of about 114%. The triple-notched bands with attenuation of more than 15 dB are measured at 4.4, 5.3 and 8.2 GHz, respectively. The filter exhibits a high selectivity with steep skirt property and has a wide upper stopband with an out-of-band rejection of −10 dB at 11.8−20 GHz. Its total dimension, including the rectangular substrate with feed lines, occupies only 16mm × 8 mm. [ABSTRACT FROM AUTHOR]

Fast and accurate evaluation of flow and heat transfer phenomena in rod bundles is a problem of long-standing interest in nuclear engineering. Computational fluid dynamics (CFD) can provide accurate but relatively time-intensive estimates, such that simulations of very long transients with high spatial detail are infeasible. On the other hand, subchannel codes require relatively low computational time and can provide pin-level estimates, but have substantial empiricism in evaluating aspects such as crossflows and turbulent mixing coefficients. A multiscale method (SC+) for bridging this accuracy/speed gap, based on the Subchannel CFD (SubChCFD) method of Liu et al. [Nucl. Eng. Design, Vol. 355, paper 110318 (2019)], is demonstrated and developed here with a focus on a 5 × 5 square rod bundle geometry. The method has been newly implemented into the commercial code STAR-CCM+ and benchmarked against Liu et al.'s data. The 5 × 5 geometry was chosen in part due to the availability of direct numerical simulation (DNS) data at a relevant Reynolds number of a similar configuration for comparison. The SC+ results are variously compared against results from DNS, large eddy simulation, wall-resolved Reynolds-averaged Navier-Stokes, and coarse-mesh CFD methods. As an expansion to the original SubChCFD approach, a simple Hi2Lo approach is demonstrated using the DNS data as a correction to the original friction factor correlations employed. This is verified to improve the predictions. Additional test cases with geometric perturbations are pursued, illustrating the flexibility of SC+. The potential of this method for modeling the narrow gap vortex instability, which would represent an advancement over standard subchannel approaches, is also assessed. The method is expanded to include transverse flow losses, which was found to improve the results for modeling the gap instability. Initial extensions of SC+ for hexagonal rod bundles are also presented; some inaccuracies for the coarsest meshes prompted a detailed investigation of the mesh convergence behavior of the method. Geometric correction factors were devised that provided substantial improvement on these very coarse meshes, improving the prospects of SC+ for wider usage. Future work plans are to expand the methodology to wire-wrapped rod bundles and to implement the method into Pronghorn, with a unified pipeline via the Cardinal wrapper between the codes NekRS, Pronghorn, and BISON, to solve fuel performance problems of direct interest to industry. [ABSTRACT FROM AUTHOR]

This paper tackles high computational complexity in using Euclidean distance for residential load profiles (RLPs) similarity by proposing a three-stage incremental segmented slope clustering framework. The first two stages involve static clustering, where we obtain typical residential load profiles through piecewise slope clustering. In the third stage, dynamic clustering is performed based on the slope similarity of RLPs. This method enhances clustering performance and reduces computation cost, outperforming various benchmarks, with simulation results confirming the framework's effectiveness. [ABSTRACT FROM AUTHOR]

In this paper, stochastic Gilpin-Ayala model driven by α-stable process under regime switching is presented. Firstly, we prove the existence and uniqueness of the solution for the stochastic model. Then, under certain conditions, the almost sure exponential stability and pth moment exponential stability of the trivial solution are obtained. The results indicated that the α-stable noises can make the trivial solution stable under some conditions. Computer simulations are presented to illustrate our theory. [ABSTRACT FROM AUTHOR]

Indirect thermal desorption process of petroleum hydrocarbon contaminated soil is very complex and difficult to be analyzed by engineering full-scale numerical simulation considering multi-phase flow and interphase heat as well as mass transfer. Therefore, it is urgent to develop a simple and rapid calculation method to guide technology development and engineering applications. In this paper, the method of equivalent specific heat approximation was proposed to simplify the mass transfer process on the material side to the heat transfer process under variable specific heat conditions, and the numerical simulation of engineering scale indirect thermal desorption equipment was studied by coupling the diffusion flame combustion model, weighted-sum-of-gray-gases model, and discrete ordinates model. The heating process of soil in thermal desorption chamber was simulated, and the influence of soil residence time and designed feed rate on process parameters was obtained. The research results showed that soil residence time should be extended appropriately under the condition of less than 1.75 hours and designed feed rate be limited within 4 t/h to ensure reasonable soil discharge temperature that was directly related to the removal efficiency of petroleum hydrocarbons in contaminated soil. Meanwhile, the modification scheme of power distribution of combustion system was further studied to improve the heating uniformity of tubes. [ABSTRACT FROM AUTHOR]

Non-parametric control charts have been good alternatives to parametric control charts when little information is known about the type of process distribution or the value of parameters. Most approaches proposed by the current literature monitor either location or scale change in batch mode and their performance is discounted when monitoring distribution change in both location and scale simultaneously in a sequential pattern. This paper proposed a log-likelihood-ratio-based non-parametric cumulative sum (CUSUM) control chart to monitor arbitrary distribution change and diagnose the detailed change type simultaneously. By integrating the superiority of log-likelihood ratio test to detect any change of distribution and CUSUM chart to detect a small change, the proposed approach can detect small potential changes in location, scale and shape; and provide detailed information about change type when control chart gives a signal. Comparison results with many other non-parametric approaches were provided by numerical simulation and the results of an application case demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper investigates the security issue of the data replay attacks on control systems with the LQG controller. The attacker tries to store measurements and replay them in further times. The main novelty in this paper is stated as proposing a different attack detection criterion under the existence of a packet-dropout feature in the network by using the Kullback-Leibler divergence method to cover more general problems and with higher-order dynamics. Formulations and numerical simulations prove the effectiveness of the newly proposed attack detection procedure. Unlike previous approaches that the trade-off between attack detection delay or LQG the performance was significant, in this approach it is proved that the difference in this trade-off is not considered in early moments when the attack happens since the attack detection rate is rapid and thus, the attacks can be stopped with defense strategies in the first moments with the proposed attack detection criterion. [ABSTRACT FROM AUTHOR]

This paper proposes a fault-tolerant controller for active suspension to improve the bounce and pitch performance of a half-car system. In order to guarantee both the transient and steady-state control objectives, the prescribed performance control (PPC) method is applied to regulate the convergence rate, overshoot and tracking error of the closed-loop (CL) system. The system parametric uncertainties including sprung mass, sprung pitch inertia, suspension stiffness and damping coefficient, and axle distances are considered. The dynamics of three types of frequently encountered actuator faults are elaborated. Unlike most of the existing studies that use the adaptive method or neural network (NN) to estimate the uncertain parameters, this paper proposes a novel approximation-free method to deal with the uncertainties. The stability of the CL system is rigorously proved, and the suspension performance is examined with respect to physical constraints. In the numerical simulation, two kinds of imperfect actuators with hybrid nonlinear characteristic are employed to verify the effectiveness of the proposed controller. Simulation results show that the proposed controller can effectively suppress the bounce and pitch motions for the sprung mass and is robust to system uncertainties and actuator faults. [ABSTRACT FROM AUTHOR]

Miura-ori core sandwich structures are promising substitutes to conventional honeycomb core sandwich structures for both load bearing and multifunctional applications. While quasi-static or impact behaviors have been widely studied, no theoretical work has been done yet for free vibration analysis of carbon-fiber-reinforced Miura-ori core sandwich beams (MSBs). This paper presents a simple and effective methodology to investigate the free vibration behavior of MSBs under simply supported boundary conditions. The governing equation of motion is built by Hamilton's principle. Carbon-fiber-reinforced Miura-ori core is transformed to a continuous homogeneous material and the analytical expression of its equivalent transverse shear modulus is derived based on an energy approach. According to the deformation contributions of different components and shear modulus analysis of Miura-ori core, the differences of natural frequencies between the theoretical prediction and numerical simulation are analyzed. It indicates that the analytical model presented in this paper is effective to estimate the natural frequencies of carbon-fiber-reinforced MSBs, which may provide some references for further practical engineering applications of such kinds of composite sandwich structures. [ABSTRACT FROM AUTHOR]

This paper deals with Kriging models applied to optimise braking performances for freight trains. More precisely, it is focused on mass distribution optimisation aimed at reducing the effects of in-train forces among vehicles, e.g. compression and tensile forces, in-train emergency braking. To this end, Kriging models are applied with covariance structure based on the Matérn function, introducing specific input parameters to better outline the payload distribution on the train, also evaluating the shape of the payload distribution. The different shapes, related to the payload distributions, have been implemented into a model through a Python routine, which has been used to ‘assemble’ the simulated trains. The analysed train carries 80% of its maximum payload capacity during an emergency braking from the speed of 30 km/h. Satisfactory results have been obtained considering compression forces, tensile forces and their sum, also considering residuals and diagnositc measures. [ABSTRACT FROM PUBLISHER]

The problem of impulse analysis is considered for the T-S fuzzy singular system by using the Kronecker index and the generalised Kronecker index in this paper. The T-S singular system is divided into two cases: the uniformly regular T-S fuzzy singular system and the non-uniformly regular T-S fuzzy singular system. The contribution of this paper is twofold. First, a new definition of the generalised Kronecker form is introduced, and the algorithm of finding the generalised Kronecker form is given. Second, two theorems are proved, one is that the uniformly regular T-S fuzzy singular system is impulsive if and only if the Kronecker index is greater than one, the other one is the non-uniformly regular T-S fuzzy singular system is impulsive if and only if the generalised Kronecker index is greater than one. Finally, two numerical simulations and the population model with stage structure are carried out to show the consistency with theoretical analysis and illustrate the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

Generating a robust gait is one of the most important factors to improve the adaptability of quadruped robots on rough terrains. This paper presents a new continuous free gait generation method for quadruped robots capable of walking on the rough terrain characterized by the uneven ground and forbidden areas. When walking with the proposed gait, the robot can effectively maintain its stability by using the Center of Gravity (COG) trajectory planning method. After analyzing the point cloud of rough terrain, the forbidden areas of the terrain can be obtained. Based on this analysis, an optimal foothold search strategy is presented to help quadruped robot to determine the optimum foothold for the swing foot automatically. In addition, the foot sequence determining method is proposed to improve the performance of robot. With the free gait proposed in this paper, quadruped robot can walk through the rough terrains automatically and successfully. The correctness and effectiveness of the proposed method is verified via simulations. [ABSTRACT FROM AUTHOR]

In this paper, the line of sight (LOS) guidance law is improved to implement tracking toward a moving target. In the presence of sensor noise, an optimal information fusion Kalman filter weighted by scalars is utilized for two-sensor information fusing, improving the trajectory tracking precision. Under the communication delay, n-step ahead Kalman predictor compensates for communication delay and provides LOS guidance law with more accurate target estimates. The results of the simulation demonstrate the feasibility and effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

In this paper, an online convex optimisation problem with stochastic constraints in the bandit setup is investigated. We are particularly interested in the scenario where the gradient information of both loss and constraint functions is unavailable. Under this scenario, only the values of loss and constraint functions at a few random points near the decision are provided to the decision maker after the decision is submitted. We first propose an online bandit algorithm based on the virtual queue in which two-point feedback is used to approximate the gradient feedback. Then we adopt the static benchmark to analyse the optimisation performance and establish the sub-linear expected static regret and sub-linear expected constraint violations of the proposed algorithm in the two-point bandit feedback setup. Moreover, the expected static regret and constraint violations are further improved to O (ln ⁡ T) when loss functions satisfy the condition of strong convexity. Finally, an online job scheduling numerical simulation is shown to demonstrate the performance of the proposed method and to corroborate the theoretical guarantees. [ABSTRACT FROM AUTHOR]

This paper addresses the output tracking control problem for networked systems with plant-model mismatch, where two-channel random network delays are considered. According to the different ways of obtaining future control commands, two networked predictive control (NPC) methods are designed. One is the NPC method using one-way time delays, called ONPC, and the other is the NPC method using round-trip time delays, called RNPC. Furthermore, they are compared in terms of the way of compensation for two-channel delays, prediction process, and communication load, respectively. Then, the closed-loop stability conditions of the RNPC system and the ONPC system for the plant-model mismatch and match cases are derived, and their output tracking performance is also theoretically analysed. Finally, the results of the theoretical analysis are verified through numerical simulation that illustrates the effectiveness of the proposed two NPC methods as well as their separate advantages. [ABSTRACT FROM AUTHOR]

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

Nowadays, with the increasing demand for travel, the number of people using motorbikes is increasing, especially in Vietnam. People tend to face more injury risks when they are in traffic, such as vulnerable road users (VRU) – pedestrians, cyclists, and motorcyclists. Therefore, the objective of this study is to assess how car crashes influence Vietnamese motorcyclists' bodies, in particular their heads, because they are the most vulnerable parts of their bodies. The result of this study is to let people know what they're facing in case they are hit by a car. In addition, this research analyzes the injury to the motorcyclist's head when being hit by different configurations of the car. Due to the lack of facilities, car-to-motorcyclist frontal impact simulation has become the best way to resolve this problem. The impact conditions, which were obtained from real motorcyclist accidents in Vietnam, including the speed of vehicle and motorcycle, and impact angle, were defined as initial loading conditions in a simulation of the head striking the windscreen by using a finite element Vietnamese dummy model. Logistic regression models were developed to study brain injury risk with respect to injury-related variables: the head linear acceleration and head injury criterion (HIC) value. In this paper, the deformation of the motorbike structure model was neglected, so the material has been selected as a rigid form. The knowledge from this research could be a prerequisite for developing guidelines to improve motorcyclist safety in Vietnam. [ABSTRACT FROM AUTHOR]

External impact is one of the potential hazards for in-service subsea pipelines. The stress concentration by external impact can create a dent that affects the pipeline's ultimate bearing capacity. In this paper, a theoretical model based on the string-on-plastic foundation is established to model the local indentation of pressurised pipelines by a wedge indenter. The effects of internal pressure and boundary conditions on the denting process are investigated. With this model, the relationship between the indenting force and the dented depth is obtained under a set of two boundary conditions. The accuracy of the new analytical models is validated by comparing them with the specification and numerical simulation model. It is believed that the new analytical models will provide theoretical guidance for maintaining the reliability and integrity of in-service pressurised pipelines. [ABSTRACT FROM AUTHOR]

In this paper, the stability of a linear Timoshenko beam system involved with infinite memory is considered. Different from the previous results on where the monotony of kernel is always fulfilled, the memory kernel under consideration is assumed to be non-monotonic. The well-posedness of the system is obtained by means of resolvent family theory and the exponential stability is proved under certain conditions. Numerical simulations are also presented to verify the main results. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach to numerical simulations of stochastic biochemical oxygen demand equations. The analysis of biochemical oxygen demand is necessary in evaluating the effects of water pollution. Here, we consider radial basis functions. This approximation process can also be interpreted as a simple kind of neural network. An illustrative example is included to demonstrate the validity and applicability of the approach. The numerical experiments show that the method performs well. [ABSTRACT FROM AUTHOR]

In this paper, some complicate dynamical behaviors are formulated for a discrete predator–prey model with group defense and nonlinear harvesting in prey. After considering the existence and stability for all of its nonnegative fixed points, our main work is to present those conditions for the occurrences of transcritical bifurcation, saddle-node bifurcation and Neimark–Sacker bifurcation, respectively. Numerical simulations not only verify the theoretical results for saddle-node bifurcation and Neimark–Sacker bifurcation but also display more interesting dynamical properties of the model. [ABSTRACT FROM AUTHOR]

Last year, 2022, marked the 50th anniversary of the Rescorla-Wagner learning equations – a landmark in the development of learning theory. Originally based on animal learning, the equations and error-driven learning models as a whole were rapidly adopted and applied in several areas of human psychology. While language acquisition research initially took a different path, interest in the role of error-driven learning in language is growing. With the aim of strengthening this emerging research field, sparking discussion and cross-fertilisation of ideas across linguistics, psychology and cognate fields, this Special Issue presents nine papers that address the role of error-driven learning in language. The papers investigate a wide range of subfields of linguistics, and include two review articles, in addition to computational modelling and experimental research. The collection thus serves both as an introduction for those new to the subject and as an overview for those already working in the field. [ABSTRACT FROM AUTHOR]

Magnetic fluid sealing (MFS) is one of the most advanced applications of magnetic fluids (MF). To improve the pressure resistance of the traditional MFS with a large gap, this paper proposes a large-gap divergent embedded magnetic fluid seal (DEMFS) structure with radial and axial sealing capabilities. Through the simulation analysis of the radial and axial seal gaps (0.5–0.8 mm) and the number of radial and axial pole teeth (PT), the theoretical pressure resistance was obtained. A large-gap DEMFS test bench was built to experimentally verify the simulation results, and the effects of the MF volume and shaft speed on the pressure resistance of the sealing device were also experimentally investigated and compared with the theoretical pressure resistance of the traditional MFS structure. The numerical simulation and experimental results that the experimental values of the DEMFS are in good agreement with the theoretical values. When the MF injection volume was 2.5 ml, the pressure resistance reached the maximum and tended to be stable. With the change in the size of the seal gap and the number of PT, the variation trend of the pressure resistance of the DEMFS was different from that of the traditional MFS. When the shaft speed was low, the low speed had almost no effect on the pressure resistance of the DEMFS. The axial seal gap and axial PT were beneficial to the sealing effect. [ABSTRACT FROM AUTHOR]