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PurposeThis paper aims to propose a novel epigenetic learning (EpiLearn) algorithm, which is designed specifically for a decentralised multi-agent system such as swarm robotics.Design/methodology/approachFirst, this paper begins with overview of swarm robotics and the challenges in designing swarm behaviour automatically. This should indicate the direction of improvements required to enhance an automatic swarm design. Second, the evolutionary learning (EpiLearn) algorithm for a swarm system using an epigenetic layer is formulated and discussed. The algorithm is then tested through various test functions to investigate its performance. Finally, the results are discussed along with possible future research directions.FindingsThrough various test functions, the algorithm can solve non-local and many local minima problems. This article also shows that by using a reward system, the algorithm can handle the deceptive problem which often occurs in dynamic problems. Moreover, utilization of rewards from the environment in the form of a methylation process on the epigenetic layer improves the performance of traditional evolutionary algorithms applied to automatic swarm design. Finally, this article shows that a regeneration process that embeds an epigenetic layer in the inheritance process performs better than a traditional crossover operator in a swarm system.Originality/valueThis paper proposes a novel method for automatic swarm design by taking into account the importance of multi-agent settings and environmental characteristics surrounding the swarm. The novel evolutionary learning (EpiLearn) algorithm using an epigenetic layer gives the swarm the ability to perform co-evolution and co-learning.

With the increase of the span and height of modern engineering structures, the design complexity of the cable structure is constantly increasing, whose dynamic problem has become the key to structural design, performance monitoring and maintenance, and vibration control. Therefore, it is necessary to study and develop a new dynamic analysis theory for complex cable system with higher calculation accuracy and efficiency to meet the requirements of exact analysis of engineering structures. In view of this, a novel dynamic analysis method for shallow sagged cable system is proposed in this paper based on the dynamic stiffness method. Since the derivation process is given in analytical form, the calculation accuracy and efficiency are promoted greatly. The numerical cases are used to verify the accuracy of the proposed dynamic analysis method, meanwhile, the simulation results show that the proposed method can overcome the "root missing" phenomenon when solving the frequency equation by the existing analytical method.

In this paper, the dynamic Koiter's model is discussed for the hyperbolic parabolic shell, i.e., the saddle surface as its middle surface. The numerical computation for this kind of shell is the most difficult as its complex differential geometry. We provide a numerical algorithm for solving the dynamic problems with finite elements and finite difference methods. At the same time, we do the numerical experiments for the hyperbolic parabolic shell. Concretly, we consider the roof of the Valencia Aquarium as a hyperbolic parabolic shell with a geometric model of the roof deduced. Then, we simulate the deformation of the roof by the dynamic applied force coupled with the dynamic Koiter's model. Finally, a comparison of the displacement distribution on the middle surface is made, which verifies that the dynamic Koiter's model is efficient and that numerical algorithm is stable for the hyperbolic parabolic shell. This result provides a strong theoretical and applicable support for the design and protection of such large-span buildings whose roofs and walls are of one whole object.

Purpose The purpose of this paper is to improve the computational speed of solving nonlinear dynamics by using parallel methods and mixed-precision algorithm on graphic processing units (GPUs). The computational efficiency of traditional central processing units (CPUs)-based computer aided engineering software has been difficult to satisfy the needs of scientific research and practical engineering, especially for nonlinear dynamic problems. Besides, when calculations are performed on GPUs, double-precision operations are slower than single-precision operations. So this paper implemented mixed precision for nonlinear dynamic problem simulation using Belytschko-Tsay (BT) shell element on GPU. Design/methodology/approach To minimize data transfer between heterogeneous architectures, the parallel computation of the fully explicit finite element (FE) calculation is realized using a vectorized thread-level parallelism algorithm. An asynchronous data transmission strategy and a novel dependency relationship link-based method, for efficiently solving parallel explicit shell element equations, are used to improve the GPU utilization ratio. Finally, this paper implements mixed precision for nonlinear dynamic problems simulation using the BT shell element on a GPU and compare it to the CPU-based serially executed program and a GPU-based double-precision parallel computing program. Findings For a car body model containing approximately 5.3 million degrees of freedom, the computational speed is improved 25 times over CPU sequential computation, and approximately 10% over double-precision parallel computing method. The accuracy error of the mixed-precision computation is small and can satisfy the requirements of practical engineering problems. Originality/value This paper realized a novel FE parallel computing procedure for nonlinear dynamic problems using mixed-precision algorithm on CPU-GPU platform. Compared with the CPU serial program, the program implemented in this article obtains a 25 times acceleration ratio when calculating the model of 883,168 elements, which greatly improves the calculation speed for solving nonlinear dynamic problems.

An orbit-attitude coupling dynamic model for the spatial rigid rod that is abstracted from the large-stiffness slender components widely used in spatial structures is established, and the symplectic method is used to estimate the validity of the dynamic model by analyzing the coupling dynamic behaviors of the rod in this work. Based on the Hamiltonian variational principle, the orbit-attitude dynamic model of the spatial rigid rod is proposed, and the canonical form of the model is presented first. Then, the symplectic Runge–Kutta method is developed, and the structure-preserving properties of the canonical form, including the conservation law of energy and conservative property in the phase space, are investigated to illustrate the validity of the numerical results obtained by the symplectic Runge–Kutta method subsequently. Finally, the effects of the nonspherical perturbations of the Earth on the coupling dynamic behaviors are investigated numerically. From the simulation results, it can be concluded that the main orbit-attitude coupling dynamic behaviors of the spatial large-stiffness slender component excited by the nonspherical perturbation can be described by the proposed dynamic model ignoring the deformation as well as the transverse vibration of the slender component, which provides an approach for simplifying rapid dynamic analysis on the spatial large-stiffness slender component. In addition, the validity and the structure-preserving properties of the symplectic Runge–Kutta method for the orbit-attitude coupling dynamic problem of the spatial rigid rod are also illustrated.

As an important excitation source of gear dynamic problems, the time-varying friction of tooth surface is closely related to its topography. Considering the friction characteristics of tooth surface is of great significance to improve the calculation accuracy of gear dynamic characteristics. In order to solve the problem that the variation of tooth friction coefficient was simplified too much in the previous gear dynamics research, the time-varying tooth friction coefficient is obtained by fitting the results of twin-disc test in this research. To investigate the influence of tooth surface topography on the friction and dynamic characteristics of spur gears, the relationship between surface topography and friction coefficient under line contact condition is studied using twin-disc tester and analyzed by 3D topography parameters in ISO 25178. The time-varying friction coefficients of spur gears with different tooth surface topographies during meshing are fitted with the experimental results. The influence of time-varying friction coefficient caused by the tooth surface topography on the dynamic characteristics of spur gears under different operating conditions is examined by substituting the fitting curves of time-varying friction coefficient into the multi-degree-of-freedom dynamic model of spur gears. The results show that this influence is mainly embodied in the off-line-of-action direction, which is the direction of friction force acting on the tooth surface. The dynamic characteristics of gears with different surface topography are obviously different under various working conditions. The method presents in this paper simplifies the application of tooth contact analysis in the study of time-varying tooth friction characteristics, which will provide a new way for the gear dynamics research considering the tooth surface topography.

A new collocation integrator on Lobatto spacings is proposed for numerically solving mixed systems of first and second order differential equations of dynamic problems. The general theory of collocation integrators is described, from which the basic formulas of the new integrator are derived.

Modelling the thermodynamic and hydrodynamic interactions of suspended particles is a significant and ongoing numerical challenge. Addressing this is necessary in order to be able to fully model numerous industrial and scientific processes of practical interest. This paper describes extensions to a local and a non-local technique for the calculation of transient conjugate heat transfer within a lattice Boltzmann framework. The interface transition between phases in both methods has been incorporated via a partially saturated boundary condition that weights material properties and allows straight and curved boundaries to be captured. Transient and steady-state performance of the two methods has been compared using a number of static and dynamic problems to evaluate their suitability for modelling particle suspensions. In a number of the static tests the non-local method produced better results however for the dynamic cases the local method demonstrated more accurate behaviour.

In many real-world decision problems, there are specific objective, decision variables, conditions, data and/or parameters that may vary over time. When these problems are solved through an optimization process, they are generally known as dynamic optimization. Dynamic optimization is a challenging research topic as the optimal solution usually moves with any change in the problem environment. In locating the optimal point in any optimization problems, the effectiveness of the search process is influenced by the nature of the problem landscape. In order to improve the effectiveness of the search process, in this article, a new approach is developed by integrating a landscape-based strategy with appropriately designed evolutionary algorithms for solving dynamic problems. The proposed approach is named as Landscape Influenced Dynamic Optimization Algorithm (LIDOA). LIDOA checks the similarity before and after the changed environment which is then used as an input to guide the evolutionary search process. The dynamic benchmark functions from IEEE-CEC2009 are solved using LIDOA. LIDOA was able to enhance the performance of the evolutionary algorithms in their adaptation to dynamic changes, which in turn enhanced their ability to attain better results.

A technique for solving dynamic problems of the behavior of compound shell structures (solving the equations of motion subject to appropriate boundary and initial conditions) is developed. The structurally orthotropic model of a three-layer shell structure with a cellular core is used, for which the integral values of the elastic modulus and Poisson’s ratios are determined experimentally. Numerical algorithms are developed, and the corresponding problems of mathematical theory of elasticity are solved. The numerical results are analyzed.

Many real-world problems are modeled as multi-objective optimization problems whose optimal solutions change with time. These problems are commonly termed dynamic multi-objective optimization problems (DMOPs). One challenge associated with solving such problems is the fact that the Pareto front or Pareto set often changes too quickly. This means that the optimal solution set at period $t$ may likely vary from that at $(t+1)$ , and this makes the process of optimizing such problems computationally expensive to implement. This article proposes the use of adaptive mutation and crossover operators for the non-dominated sorting genetic algorithm III (NSGA-III). The aim is to find solutions that can adapt to fitness changes in the objective function space over time. The proposed approach improves the capability of NSGA-III to solve multi-objective optimization problems with solutions that change quickly in both space and time. Results obtained show that this method of population reinitialization can effectively optimize selected benchmark dynamic problems. In addition, we test the capability of the proposed algorithm to select robust solutions over time. We recognize that DMOPs are characterized by rapidly changing optimal solutions. Therefore, we also test the ability of our proposed algorithm to handle these changes. This is achieved by evaluating its performance on selected robust optimization over time (ROOT) and robust Pareto-optimality over time (RPOOT) benchmark problems.

The dynamic nonlinear complementarity problem (DNCP) consisting of a nonlinear differential system and a complementarity system has been used to formulate and study many dynamic problems. In a Gaus...

The aim of this study was to develop a new efficient strategy that uses the Vector form Intrinsic Finite-element (VFIFE) method to conduct the static and dynamic analyses of marine pipes. Nonlinear problems, such as large displacement, small strain, and contact and collision, can be analyzed using a unified calculation process in the VFIFE method according to the fundamental theories of point value description, path element, and reverse motion. This method enables analysis without the need to integrate the stiffness matrix of the structure, because only motion equations of particles established according to Newton's second law are required. These characteristics of the VFIFE facilitate the modeling and computation efficiencies in analyzing the nonlinear dynamic problem of flexible pipe with large deflections. In this study, a three-dimensional (3-D) dynamical model based on 3-D beam element was established according to the VFIFE method. The deep-sea flexible pipe was described by a set of spatial mass particles linked by 3-D beam element. The motion and configuration of the pipe are determined by these spatial particles. Based on this model, a simulation procedure to predict the 3-D dynamical behavior of flexible pipe was developed and verified. It was found that the spatial configuration and static internal force of the mining pipe can be obtained by calculating the stationary state of pipe motion. Using this simulation procedure, an analysis was conducted on the static and dynamic behaviors of the flexible mining pipe based on a 1000-m sea trial system. The results of the analysis proved that the VFIFE method can be efficiently applied to the static and dynamic analyses of marine pipes. (C) 2020 Society of Naval Architects of Korea. Production and hosting by Elsevier B.V.

In dynamic constrained optimization, changes may occur in either the objective function or constraint functions, or both. However, although research on dynamic optimization has been growing significantly, it is centered mainly around unconstrained problems. On the other hand, research on dynamic constrained problems has considered simple extensions of those conducted on unconstrained ones. These approaches are usually computationally expensive and exhibit slow convergence in changed environments. To develop an effective algorithm for dynamic constrained problems with changes occurring in only the constraint's space, in this research, we propose a sensitive constraint detection mechanism that provides valuable information for determining the movements of solutions in changing environments. As, by incorporating it with a search process, the convergence of an algorithm can be accelerated, it is adopted with a multi-operator evolutionary type of algorithm which is then tested on a set of constrained dynamic problems. The experimental results clearly demonstrate the benefits of this proposed approach.

This paper develops and evaluates a novel 3D fully-Lagrangian (particle-based) numerical model, based on the hybrid discrete element method (DEM) and moving particle semi-implicit (MPS) mesh-free techniques, for modeling the highly-dynamic ice-wave interactions. Both MPS and DEM belong to mesh-free Lagrangian (particle) techniques. The model considers ice-wave dynamics as a multiphase continuum-discrete system. While the MPS solves the continuum equations of free-surface flow in a Lagrangian particle-based domain, the DEM uses a multi-sphere Hertzian contact dynamic model to simulate the ice floes motion and interaction. The hybrid model predicts the motion and collision of ice floes as well as their interaction with water, boundaries, and any obstacle in their way. Considering the mesh-free Lagrangian nature of both DEM and MPS, the developed model has an inherent ability to predict the free-drift (absence of internal stress) movements of the ice floes, e.g., sliding, rolling, colliding, and piling-up, in violent free-surface flow. A small-scale and challenging experiment based on dam-break flow over dry and wet beds with floating block floes, which mimics the characteristics of an idealized jam release, has been conducted to provide useful and comprehensive quality data for the validation of the proposed model, as well as other numerical models. Experimental and numerical results of the free-surface profile and the position of the blocks are compared. The results show the ability of the model to numerically reproduce and predict the complex three-dimensional dynamic behavior of wave-ice floes interaction. Overall, this study is a first effort toward developing an ice-wave dynamics within a fully Lagrangian framework, and its results can be extended to bring an in-depth understanding of the physics of the real-scale ice-wave or river ice dynamic problems in the future., Comment: 53 pages, 29 figures

In this paper, we investigate a two-echelon, two-product Supply Chain (SC) inspired by a real-world production/distribution firm, in which the product change-over time, necessary to switch from a p...

Нарыжный А. Г., Тараненко М. Е. Механические процессы в системе с погружной электроразрядной камерой. Эксперимент и моделирование // Обработка материалов давлением. – 2019. – № 2 (49). - С. 136-142. Статья посвящена развитию методики исследования техпроцесса изготовления тонкостенных деталей методом электрогидравлической штамповки, а также анализу его закономерностей и особенностей. Рассмотрена технологическая система, использующая одну погружную камеру. Обсуждаются динамические механические процессы в импульсной технологической гетерогенной системе, включающей канал электрического разряда, превращающийся в паро-газовую полость, вязкую-упругую технологическую жидкость, упруго-пластическую оболочку, жесткую технологическую оснастку. Для анализа процессов совместно использованы методы экспериментального исследования и математического моделирования на основе численного решения контактных динамических задач механики сплошных сред. Описаны особенности кинетики процессов. Сравнены результаты двух методов. На основе данных математического моделирования системного взаимодействия элементов дано объяснение экспериментальных результатов. Сделаны выводы об адекватности математической модели и точности метода математического моделирования. Результаты могут быть полезны при разработке и оптимизации нового, а также модификации существующего технологического оборудования и параметров с целью повышения эффективности технологического процесса и качества изготовления деталей.

In multibody systems, there are not only holonomic bilateral constraints, but also unilateral constraints. The existence of unilateral constraints brings nonsmooth contact dynamic problems into multibody dynamic systems. In this paper, we present an approach based on the symplectic method and the linear complementary method to solve multibody dynamic problems with impact contact. As the symplectic method has good energy conservation and no numerical damping, the proposed approach is expected to inherit these properties for solving nonsmooth problems of multibody dynamic systems. We present multiple numerical examples to demonstrate a high accuracy and good energy conservation behavior of the proposed approach even for large time step sizes.

A new closed solution is constructed for the axisymmetric dynamic problem of the classical (CTE) theory of thermoelasticity for a rigidly fixed circular isotropic plate in the case of a temperature change on its face surfaces (boundary conditions of the first kind). The mathematical formulation of the problem under consideration includes linear equations of thermal conductivity and equilibrium in a spatial setting, assuming that their inertial elastic characteristics can be neglected in the structures under study. In constructing a general solution of related non-self-conjugate equations, we use the mathematical apparatus of separation of variables in the form of finite integral transformations i.e. Hankel along the radial coordinate and biorthogonal transformation (FIT) with respect to the axial variable. At each stage of the investigation, a procedure is performed to reduce the boundary conditions to a form that allows the corresponding transformation to be applied. A particular feature of this solution is the application of a FIT based on a multicomponent relation of the eigenvector functions of two homogeneous boundary value problems. An important point in the procedure of the structural algorithm is the separation of the adjoint operator, without which it is impossible to solve non-self-adjoint linear problems of mathematical physics. This transformation is the most effective method for studying similar boundary value problems. The calculated design relationships make it possible to determine the stress-strain state and the character of the distribution of the temperature field in a rigidly fixed circular isotropic plate for an arbitrary external temperature effect with respect to time. Numerical analysis of the strength characteristics of the concrete structure shows that during the period of the unsteady load the maximum values of mechanical stresses are observed. Later, at a constant temperature regime, as a result of heating the entire plate, the displacements increase and the stresses fall.

The purpose of the paper is to deduce, sufficient conditions for termination of the games, for which Pontryagin’s condition does not hold, by the use of the effect of information delay, to specify these conditions for the case of integro-differential dynamics, and to illustrate the obtained result with the model example. Мета статті — на основі ефекту запізнювання інформації вивести достатні умови завершення гри, для якої є не виконаною умова Понтрягіна, конкретизувати їх на випадок інтегро-диференційної динаміки з подальшою ілюстрацією отриманого результату на модельному прикладі. Цель статьи — на основе эффекта запаздывания информации вывести достаточные условия завершения игры, для которой не выполнено условие Понтрягина, конкретизировать их на случай интегро-дифференциальной динамики с последующей иллюстрацией полученного результата на модельном примере.

The paper describes the results of the comparative analysis of the applicability of several methods for solving dynamic DEA-models to the problem of monitoring of the ecological and economic efficiency of economic activities of regional economic systems (on the example of the regions of the Central Federal District). The method of forming time series based on point estimates of environmental and economic efficiency the Malmquist method and the window method is considered. The results obtained for different window widths are analyzed for stability and adequacy. A comparison of the obtained results allows us to conclude that the window method is uniquely preferable for solving problems of monitoring the ecological and economic efficiency of regions not only from a computational but also from a substantive point of view.

The aim of the work is to consider the problems of numerical modeling of seismic safety of the console with the base in the form of an elastic half-plane under unsteady wave influences. Stress waves of different nature, propagating in the deformed body interact with each other. After three or four times the passage and reflection of stress waves in the body, the process of propagation of disturbances becomes steady, the body is in oscillatory motion. The problem of modeling problems of the transition period is an actual fundamental and applied scientific problem. Methods. The finite element method in displacements is used to solve the two-dimensional plane dynamic problem of elasticity theory with initial and boundary conditions. On the basis of the finite element method in displacements, an algorithm and a set of programs for solving linear plane two-dimensional problems have been developed, which allow solving problems with non-stationary wave effects on complex systems. The algorithmic language “Fortran-90” was used in the development of the complex of programs. The study area is divided by spatial variables into finite elements of the first order. According to the time variable, the study area is also divided into finite elements of the first order. Results. The problem of the influence of a plane longitudinal elastic wave in the form of a Heaviside function on a console with a base (the ratio of width to height is one to ten) is considered. The initial conditions are taken as zero. The system of equations from 16 016 084 unknowns is solved. Contour stresses and stress tensor components are obtained in characteristic areas of the problem. On the basis of the conducted researches it is possible to draw the following conclusions: the console (the ratio of width to height one to ten) is modeled with the elastic basis in the form of an elastic half-plane; the elastic contour stresses on the faces of the console are almost a mirror image of one another, that is, antisymmetric; the console under seismic action works as a rod of variable cross-section, that is, if there are tensile stresses on one face, then compressive stresses on the other; on the contours of the console under seismic action, bending waves mainly prevail.

Recent advances in the development of methods and tools for enhanced accuracy reactor simulations have allowed moving towards time-dependent neutron transport solution without spatial cross-sections homogenization approximation. Although the full core reactor dynamic problems are still too much challenging for the modern codes, reduced order problems can be solved already today. Examples of the codes allowing such advanced transient calculations are, among several others, the SUHAM-TD and nTracer codes, which are discussed in this work. In order to perform an intermediate verification of the SUHAM-TD code, which is under development at the Kurchatov Institute, and to perform an independent verification of the nTracer code of the Seoul National University by its user team at the Paul Scherrer Institute, performances of these two codes have been assessed using the ongoing OECD/NEA C5G7-TD Phase-I benchmark exercises. In particular, two cases of positive reactivity insertion were selected for detailed comparison, being the most relevant from the point of view of future practical applications.

The solution of dynamic problems of the longitudinal impact of a homogeneous rod in a nonlinear formulation presents, notoriously, significant mathematical difficulties. Existing approaches have a rather limited application mainly due to the significant approximation of the solution of the problem. In addition, such approaches affect an extensive mathematical apparatus, which complicates their use in engineering calculations. The task of solving the problem of the longitudinal impact of a geometrically heterogeneous (stepped) rod remains far from the final solution to this day. The solution of this problem is complicated by the randomness of the interference pattern of longitudinal waves during their transition through the boundaries of homogeneous sections of a stepped rod, and therefore the deformations and longitudinal forces along the length of the rod quickly change in time. In this work, using the initial parameter method and the wave model of longitudinal impact, an attempt is made to develop a methodology for calculating the dynamic deflection of a stepped rod that performs transverse vibrations during a longitudinal impact on a rigid barrier. The value of the maximum deflection of a stepped rod with the initial curvature of one of its sections is modeled. The results of modeling the maximum deflection for various values of the initial curvature and the pre-impact speed of the rod are obtained. During the processing of simulation results, the so-called “Zone of maximum deflections” is the interval of variation of the pre-shock velocity, at which the maximum amplitude of the transverse vibrations of the curved section of the stepped rod is observed. The possibility of calculating the amplitudes of the transverse vibrations of the rods and rod elements under the most various fixing schemes and the various nature of the pre-shock state is noted. The relevance of applying this technique in dynamic calculations of various impact mechanisms, as well as in engineering calculations of rod systems for various purposes, is emphasized.

This thesis explored physicians’ in-the-moment experiences of uncertainty at work, seeking to better understand how they used dynamic appraisals of comfort and discomfort to safely manage complex problems in practice despite their ongoing sense of uncertainty. These efforts included making predictions about how a problem might evolve, thinking about the human and material resources they could draw upon to ensure patient safety, and engaging colleagues to ‘borrow comfort’ when they encountered problems that were at the borders of their abilities.

We introduce an innovative solution approach to the challenging dynamic load-shedding problem which directly affects the stability of large power grid. Our proposed deep Q-network for load-shedding (DQN-LS) determines optimal load-shedding strategy to maintain power system stability by taking into account both spatial and temporal information of a dynamically operating power system, using a convolutional long-short-term memory (ConvLSTM) network to automatically capture dynamic features that are translation-invariant in short-term voltage instability, and by introducing a new design of the reward function. The overall goal for the proposed DQN-LS is to provide real-time, fast, and accurate load-shedding decisions to increase the quality and probability of voltage recovery. To demonstrate the efficacy of our proposed approach and its scalability to large-scale, complex dynamic problems, we utilize the China Southern Grid (CSG) to obtain our test results, which clearly show superior voltage recovery performance by employing the proposed DQN-LS under different and uncertain power system fault conditions. What we have developed and demonstrated in this study, in terms of the scale of the problem, the load-shedding performance obtained, and the DQN-LS approach, have not been demonstrated previously.

Context: In this study, we report on a Systematic Mapping Study (SMS) for attraction basins in the domain of metaheuristics. Objective: To identify research trends, potential issues, and proposed solutions on attraction basins in the field of metaheuristics. Research goals were inspired by the previous paper, published in 2021, where attraction basins were used to measure exploration and exploitation. Method: We conducted the SMS in the following steps: Defining research questions, conducting the search in the ISI Web of Science and Scopus databases, full-text screening, iterative forward and backward snowballing (with ongoing full-text screening), classifying, and data extraction. Results: Attraction basins within discrete domains are understood far better than those within continuous domains. Attraction basins on dynamic problems have hardly been investigated. Multi-objective problems are investigated poorly in both domains, although slightly more often within a continuous domain. There is a lack of parallel and scalable algorithms to compute attraction basins and a general framework that would unite all different definitions/implementations used for attraction basins. Conclusions: Findings regarding attraction basins in the field of metaheuristics reveal that the concept alone is poorly exploited, as well as identify open issues where researchers may improve their research.

We contribute to the theoretical understanding of randomized search heuristics for dynamic problems. We consider the classical vertex coloring problem on graphs and investigate the dynamic setting where edges are added to the current graph. We then analyze the expected time for randomized search heuristics to recompute high quality solutions. The (1+1) Evolutionary Algorithm and RLS operate in a setting where the number of colors is bounded and we are minimizing the number of conflicts. Iterated local search algorithms use an unbounded color palette and aim to use the smallest colors and, consequently, the smallest number of colors. We identify classes of bipartite graphs where reoptimization is as hard as or even harder than optimization from scratch, i.e., starting with a random initialization. Even adding a single edge can lead to hard symmetry problems. However, graph classes that are hard for one algorithm turn out to be easy for others. In most cases our bounds show that reoptimization is faster than optimizing from scratch. We further show that tailoring mutation operators to parts of the graph where changes have occurred can significantly reduce the expected reoptimization time. In most settings the expected reoptimization time for such tailored algorithms is linear in the number of added edges. However, tailored algorithms cannot prevent exponential times in settings where the original algorithm is inefficient.

Deep mining is faced with severe rock dynamic problems. Coal bears high-strength static load in the deep and is prone to impact under the influence of dynamic load disturbance such as roof breaking. The true triaxial Hopkinson pressure bar system is used to conduct dynamic load impact tests on coal specimens under different triaxial prestressing forces to simulate the bearing characteristics of coal under different engineering conditions. The results show that the dynamic mechanical characteristics of coal are confinement-dependent under the same dynamic load, and the energy transmission of each component are significantly different, which is obviously different from that under static load; Furthermore, the influence range of intermediate principal stress on dynamic characteristics of coal specimen is 6~8 MPa. Based on the failure characteristics, the enhancement of the intermediate principal stress will increase the integrity and the internal damage of a coal specimen after failure; It should be noted that the strain signals obtained in the Y/Z axis direction are mainly the response to the triaxial prestress, and the stress wave of coal specimen is mainly influenced in the impact direction. In underground coal mining, by changing the triaxial prestressed state of coal, the buffering effect of stress wave is improved, and the damage of coal caused by the impact is reduced.

Temporal and dynamic extensions of Answer Set Programming (ASP) have played an important role in addressing dynamic problems, as they allow the use of temporal operators to reason with dynamic scenarios in a very effective way. In my Ph.D. research, I intend to exploit the relationship between automata theory and dynamic logic to add automata-based techniques to the ASP solver CLINGO helping us to deal with theses type of problems., In Proceedings ICLP 2021, arXiv:2109.07914

A new closed solution of the coupled dynamic problem of thermoelasticity for a long cylinder in the case of a change in temperature on its front surfaces is constructed. The mathematical formulation of the problem under consideration includes the linear equations of motion and heat conduction relative to the radial component of the displacement vector, as well as the function of changing the temperature field. The problem is solved using the method of separation of variables in the form of a generalized finite integral transformation (CIF). The constructed design ratios make it possible to determine the stress-strain state and the temperature field of an elastic element under an arbitrary temperature external effect.

The paper presents analytical estimates of the proximity of solutions to boundary value problems for elastic-creeping layered composite materials, which are widely used in construction, and must withstand loads for a long time, and the corresponding averaged model for such a material. The estimates show the possibility of using the averaged model over a long time interval for the problem of loading by a constantly acting force action. Previously, this statement was substantiated by numerical experiments comparing the solutions of boundary value problems for the effective (averaged) model and direct numerical calculation using the original model for a highly inhomogeneous layered material. Analytical estimates are based on previously obtained estimates of the proximity of solutions to stationary problems of elasticity theory. The problem under consideration is reduced to such problems using the Laplace transform in time. Next, we analyze analytically the dependence of the estimates for stationary problems with a complex parameter of the Laplace transform on this complex parameter, and the reverse transition to the original variables (time and spatial coordinate) is performed. The method used in this work for estimating the proximity of solutions for the averaged and original boundary value problems can also be used in the study of dynamic problems of viscoelasticity. It should also be noted that for the one-dimensional model considered in this work, an interesting property has been established: if the constitutive relations for various phases are written as dependences of deformations on stresses, then the coefficients for the same form of writing the constitutive relation of the averaged model are obtained as simple weighted averages of similar coefficients for individual phases.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Many multi-objective optimization problems in the real world are dynamic, with objectives that conflict and change over time. These problems put higher demands on the algorithm’s convergence performance and the ability to respond to environmental changes. Confronting these two points, this paper proposes a dynamic multi-objective particle swarm optimization algorithm based on adversarial decomposition and neighborhood evolution (ADNEPSO). To overcome the instability of the traditional decomposition method for the changing Pareto optimal front (POF) shape, the proposed algorithm utilizes the complementary characteristics in the search area of the adversarial vector, and the two populations are alternately updated and co-evolved by adversarial search directions. Additionally, a novel particle update strategy is proposed to select promising neighborhood information to guide evolution and enhance diversity. To improve the ability to cope with environmental changes, an effective dynamic response mechanism is proposed, including three parts: archive set prediction, exploration of global optimal information, and retention of excellent particles to accelerate convergence to the Pareto optimal set (POS) in the new environment. The proposed algorithm is tested on a series of benchmark problems and compared to several state-of-the-art algorithms. The results show that ADNEPSO performed excellently in both convergence and diversity, and is highly competitive in dealing with dynamic problems.

The solution of the dynamic problem of the acoustic-emission field displacements in an elastic half-space generated by steady-state displacements of the surfaces of a circular cracks system is obtained. The solutions are obtained by the boundary integral equations (BIEs) method. For the case of mode III cracks, the dependences of elastic displacements on the surface of the half-space on the wave number, the number of defects and the depths of their location are analyzed.

The elasticity problem of an anisotropic body with cracks under the action of time-varying loads and harmonic waves is studied at the antiplane dynamic consideration. To solve the problem, the basic equations are reduced to the consideration of dynamic problems for some isotropic material. The obtained equations were solved using the Laplace integral transformation. Laplace transforms are found on the basis of the method of integral equations and are reduced to solving hypersingular integral equations. A numerical method for solving the obtained equations using the quadrature method is proposed. The Laplace inversion is performed numerically on the basis of pre-regularized formulas that allow the calculation of stresses with controlled accuracy. A study of the stress concentration near cracks under dynamic loads and falling waves was performed.

Solutions of a three-dimensional dynamic problem for the displacement wave field initiated by a given time-harmonic displacement of opposite surfaces of a plane circular crack are constructed. The solutions are given in the form of integral representations using the classical Helmholtz potentials. For the case of the axial shear crack, the influence of the frequency of the defect surfaces displacements and the angular coordinate of the observation point on the redistribution of the parameters of the displacement wave field in the solid is investigated.

The control schemes of a wheelchair having two wheels with movable payload utilizing the concept of a double-link inverted pendulum have been investigated in this article. The proposed wheelchair has been simulated using SimWise 4D software considering the most efficient parameters. These parameters are extracted using the spiral dynamic algorithm while being controlled with interval type-2 fuzzy logic controller (IT2FLC). The robustness and stability of the implemented controller are assessed under different situations including standing upright, forward motion and application of varying directions and magnitudes of outer disturbances to movable (up and down) system payload. It is shown that the two-wheeled wheelchair adopted by the newly introduced controller has achieved a 94% drop in torque for both Link1 and Link2 and more than 98% fall in distance travelled in comparison with fuzzy logic control type-1 (FLCT1) controller employed in an earlier design. The present study has further considered the increased nonlinearity and complexity of the additional moving payload. From the outcome of this study, it is obvious that the proposed IT2FLC-spiral dynamic algorithm demonstrates better performance than FLCT1 to manage the uncertainties and nonlinearities in case of a movable payload two-wheel wheelchair system.