Interactive Simulation Model Research Articles

Using microworlds for policymaking in the context of resilient farming systems

ABSTRACT Resilience management of farming systems requires building an understanding of the underlying drivers of the adaptive capacity of the system. In this paper, we use the concept of resilience as a framework to understand how bovine livestock farming systems may adjust to challenging environmental, social, and political conditions. Using an interactive simulation model (microworld), we explored potential developments for livestock farmers in Bourbonnais, France, to the effect of simultaneous changes in the socioeconomic landscape and unpredictable weather conditions resulting from climate change. The results offer insights into the potential trade-offs between systems scale and long-term sustainability by suggesting that sacrificing socioeconomic performance in the short and medium term may increase long-term sustainability and resilience.

Utilization of nonlinear vibrations of soft pipe conveying fluid for driving underwater bio-inspired robot

Creatures with longer bodies in nature like snakes and eels moving in water commonly generate a large swaying of their bodies or tails, with the purpose of producing significant frictions and collisions between body and fluid to provide the power of consecutive forward force. This swaying can be idealized by considering oscillations of a soft beam immersed in water when waves of vibration travel down at a constant speed. The present study employs a kind of large deformations induced by nonlinear vibrations of a soft pipe conveying fluid to design an underwater bio-inspired snake robot that consists of a rigid head and a soft tail. When the head is fixed, experiments show that a second mode vibration of the tail in water occurs as the internal flow velocity is beyond a critical value. Then the corresponding theoretical model based on the absolute nodal coordinate formulation (ANCF) is established to describe nonlinear vibrations of the tail. As the head is free, the theoretical modeling is combined with the computational fluid dynamics (CFD) analysis to construct a fluid-structure interaction (FSI) simulation model. The swimming speed and swaying shape of the snake robot are obtained through the FSI simulation model. They are in good agreement with experimental results. Most importantly, it is demonstrated that the propulsion speed can be improved by 21% for the robot with vibrations of the tail compared with that without oscillations in the pure jet mode. This research provides a new thought to design driving devices by using nonlinear flow-induced vibrations.

Simulation of migration and demographic processes using FLAME GPU

This article presents an approach to modeling migration and demographic processes using a framework designed for large-scale agent-based modeling – FLAME GPU. This approach is based on the previously developed simulation model of interaction between two communities: migrants and natives that is implemented in the AnyLogic simulation software. The model has had a low dimensionality of the discrete space representing the operating environment of the agent populations and a deterministic decision-making system of each agent. At the same time, the presence of multiple interactions between agents and transitions between their states determines a high computational complexity of such a model. The use of FLAME GPU makes it possible to conduct extensive simulation experiments with the model, mainly due to the parallelization of computational processes at the level of each agent, as well as the implementation of the mechanism of multiple computations using Monte Carlo techniques. The developed framework is used to study the impact of the most important parameters of the model (e.g., rate of migration, governmental expenditures on integration, frequency of creation of new workplaces, etc.) on the key outputs of the modeled socio-economic system (in particular, population size, share of migrants, number of assimilated migrants, GDP growth rate, etc.). The proposed approach can be used to develop decision-making systems for planning the hiring of new employees based on the forecast dynamics of migration and demographic processes.

Thermodynamically Consistent Diffuse Interface Model for the Numerical Simulation of Interaction between Solid Explosive Detonation and Inert Materials

Thermodynamically Consistent Diffuse Interface Model for the Numerical Simulation of Interaction between Solid Explosive Detonation and Inert Materials

Thermodynamically Consistent Diffuse Interface Model for the Numerical Simulation of Interaction between Solid Explosive Detonation and Inert Materials

Thermodynamically Consistent Diffuse Interface Model for the Numerical Simulation of Interaction between Solid Explosive Detonation and Inert Materials

Динамическое взаимодействие блочной колесной пары и оценка его влияния на ресурс узлов тележки

A method of comparative assessment of the influence of the features of dynamic interaction in the «block wheel-set - rail track» system on the wear rate of the rolling surfaces of wheels, axle bearings, and the support of the freight car bogie due to new design solutions implemented in the block wheelset is presented. A block wheelset differs from a typical pair in that it has separated the functions of holding and directing movement (ridge) and ensuring the movement of the wheelset in a straight section of the track (straight and winding). In the process of simulation modeling of interaction of block and standard wheel pairs with the rail track, the parameters of this interaction (motion trajectories, wave-lengths and their amplitudes) are established. As an external disturbance in the mathematical model of the dynamic system «wheelset - track», geometric deviations of the rail track obtained under real operating conditions of main lines were used. The comparative calculated assessment of the levels of wear intensity of the rolling surfaces of the support wheel of the block and standard wheel pairs was carried out according to the developed methodology of a specific comparative indicator - the coefficient of the energy factor of wear. The resource of the bogie pivot bearing with block wheel pairs increases due to the growth in the wagging wavelength by six times compared to the typical wheel pairs, that is, the friction path in the «pivot bearing-axle bearing» component from a typical wheel pair increased proportionally.

Three-dimensional fluid-thermal-structure multiphysics interaction simulation model of aluminium extrusion process

Three dimensional fluid-thermal-structure multiphysics interaction simulation model of aluminium extrusion process has been simulated and presented in this paper. This multiphysics complex geometrical engineering process is simulated effectively using computational fluid dynamics (CFD) simulation with very high accuracy, where the aluminium material is treated as a fluid that has a very high viscosity which depends on temperature and velocity. When aluminium moving, the inner friction will work as a heat source, therefore the model of the heat transfer is completely coupled together with those governing model of the fluid dynamics. Material properties come into a viscosity function that can be related to the flow stress locally depending on forming velocity and temperature. In addition, the stresses distribution in the die that introduces due to the fluid pressure and the thermal loads has been modelled by fully coupled the simulation model with the structural mechanic's analysis. Fully three-dimensional results during the process of the temperature distribution, velocity profile, von Mises stress distribution, total displacement and deflection distribution, equivalent volumetric strain distribution, and pressure distribution are presented and analysed with a focus on the fundamental understanding. The model is shown to be able to provide a computer-aided design tool for optimize this complex engineering process by improving productivity and reducing scrap.

Fluid-Structure Interaction Modelling of a Soft Pneumatic Actuator

This paper presents a fully coupled fluid-structure interaction (FSI) simulation model of a soft pneumatic actuator (SPA). Previous research on modelling and simulation of SPAs mostly involves finite element modelling (FEM), in which the fluid pressure is considered as pressure load uniformly acting on the internal walls of the actuator. However, FEM modelling does not capture the physics of the fluid flow inside an SPA. An accurate modelling of the physical behaviour of an SPA requires a two-way FSI analysis that captures and transfers information from fluid to solid and vice versa. Furthermore, the investigation of the fluid flow inside the flow channels and chambers of the actuator are vital for an understanding of the fluid energy distribution and the prediction of the actuator performance. The FSI modelling is implemented on a typical SPA and the flow behaviour inside the actuator is presented. Moreover, the bending behaviour of the SPA from the FSI simulation results is compared with a corresponding FEM simulation.

PENGARUH COMPUTER BASED INSTRUCTION MODEL SIMULASI BERBASIS MULTIMEDIA INTERAKTIF TERHADAP RASA INGIN TAHU SISWA PADA PEMBELAJARAN IPA

The aim of this study is to explain the influences of computer based instruction, interactive multimedia-based simulation model on the curiosity of the fourth grade students. The design of this study uses a quasi experiment method with nonequivalent control-group design. The classes used were class IVA, IVB, and IVC with with each student numbers 24, 29, and 26. In this study, class IVA is used as a control class, while class IVB and class IVC as an experimental class. The results of the pretest showed that the curiosity of IVA students (control) was 65, while the post-test was 76.66. In class IVB (experiment 1) shows that, at pretest it was 63.44 and post-test 81. Meanwhile in the IVC (experiment 2) class the pretest was 61.53 and post-test 82.3. Thus the results of the Independent Sample T-test for students' curiosity showed significance (p) 0.041 <0.05 so Ho was rejected. This shows that, there are significant differences in curiosity of students who use computer based instruction products, interactive multimedia-based simulation models (experimental class) with those using conventional models (control class). With these results, it is expected to add to the repertoire of knowledge and alternative ways for teachers to influence students' curiosity, so that the development potential of students in the learning process becomes maximal.

Burgers viscoelastic model-based variable stiffness design of compliant clamping mechanism for leafy greens harvesting

To prevent mechanical damage during the feeding and conveying process for leafy greens when roots harvesting, it is necessary to redesign the clamping mechanism in consideration of the rheological properties of leafy greens under the mechanical compression. This study takes spinach, a typical representative of leafy greens, as the research object. Firstly, the rheological constitutive equation for leafy greens under clamping is derived using the Burgers viscoelastic model, and the equation coefficient is identified using a spinach creep test. The damage constraints for the feeding process for different feeding widths are constructed with deformation energy based on the rheological constitutive equation. Secondly, a compliant clamping mechanism with variable stiffness properties is proposed, comprising a clamping floating mechanism and a compact cam pendulum mechanism. This mechanism maintains a preconfigured nonlinear force-displacement curve by utilising off-the-shelf torsional spring and cam profile. Furthermore, the mathematical models of interaction between this mechanism and leafy greens are constructed, with which the low-damage and stable clamping as the optimisation objectives are analysed, and the optimal parameters are achieved with particle swarm optimisation algorithm. Finally, an interactive simulation model of the clamping belt with floating roller supported by the compliant clamping mechanism and the Burgers viscoelastic model is built to simulate the feeding process. The dynamic characteristics of the clamping force are analysed for three feeding widths represented by parallel width of spinach. The experimental results show that relative error of the maximum clamping forces between simulation analysis and theoretical computation is less than 10%, and the relative error between test and theoretical computation is less than 13%, indicating the validity of the simulation model and feasibility of the designed compliant clamping.

APPLICABILITY EVALUATION AND SHAPE OPTIMIZATION OF THE ELASTIC VALVE STATIONARILY INSTALLED IN PNEUMATIC IMPACT MACHINES

The possibility of using construction design with a stationarily installed conical ring-shaped elastic valve in pneumatic impact machines is considered. Using a simulation model of the contact interaction of the striker with the valve, the shape of the valve was optimized and its applicability was proved for sealing the return strike chamber.

Impacts of Water Resources Allocation on Water Environmental Capacity under Climate Change

Water environmental capacity (WEC) is an essential indicator for effective environmental management. The designed low water flow condition is a prerequisite to determine WEC and is often based on the stationarity assumption of low water flow series. As the low water flow series has been remarkably disturbed by climate change as well as reservoirs operation and water acquisition, the stationarity assumption might bring risk for WEC planning. As the reservoir operation and water acquisition under climate change can be simulated by a water resources allocation model, the low water flow series outputted from the model are the simulations of the disturbances and often show nonstationary conditions. After estimating the designed low water flow through nonstationary frequency analysis from these low water flow series, the WEC under the nonstationary conditions can be determined. Thus, the impacts of water resources allocation on WEC under climate change can be quantitatively assessed. The mid-lower reaches of the Hanjiang River basin in China were taken as a case study due to the intensive reservoir operation and water acquisition under the climate change. A representative concentration pathway scenario (RCP4.5) was employed to project future climate, and a Soil and Water Assessment Tool (SWAT) model was employed to simulate water availability for driving the Interactive River-Aquifer Simulation (IRAS) model for allocating water. Water demand in 2016 and 2030 were selected as baseline and future planning years, respectively. The results show that water resources allocation can increase the amount of WEC due to amplifying the designed low water flow through reservoir operation. Larger regulating capacities of water projects can result in fewer differences of WEC under varied water availability and water demand conditions. The increasing local water demand will decrease WEC, with less regulating capacity of the water projects. Even the total available water resources will increase over the study area under RCP4.5. More water deficit will be found due to the uneven temporal-spatial distribution as well as the increasing water demand in the future, and low water flow will decrease, which further leads to cut down WEC. Therefore, the proposed method for determining the WEC can quantify the risk of the impacts of water supply and climate change on WEC to help water environmental management.

Landscape-Scale Forest Reorganization Following Insect Invasion and Harvest Under Future Climate Change Scenarios

Emerald ash borer (EAB; Agrilus planipennis Farimaire) has been found in 35 US states and five Canadian provinces. This invasive beetle is causing widespread mortality to ash trees (Fraxinus spp.), which are an important timber product and ornamental tree, as well as a cultural resource for some Tribes. The damage will likely continue despite efforts to impede its spread. Further, widespread and rapid ash mortality as a result of EAB is expected to alter forest composition and structure, especially when coupled with the regional effects of climate change in post-ash forests. Thus, we forecasted the long-term effects of EAB-induced ash mortality and preemptive ash harvest (a forest management mitigation strategy) on forested land across a 2-million-hectare region in northern Wisconsin. We used a spatially explicit and spatially interactive forest simulation model, LANDIS-II, to estimate future species dominance and biodiversity assuming continued widespread ash mortality. We ran forest disturbance and succession simulations under historic climate conditions and three downscaled CMIP5 climate change projections representing the upper bound of expected changes in precipitation and temperature. Our results suggest that although ash loss from EAB or harvest resulted in altered biodiversity patterns in some stands, climate change will be the major driver of changes in biodiversity by the end of century, causing increases in the dominance of southern species and homogenization of species composition across the landscape.

Interactive Visual Simulation Modeling for Structural Response Prediction and Damage Detection

Cameras capture the dynamic behaviors of vibrating structures or systems in videos, and the object in videos can respond to new forces to explore more dynamics by visual simulation methods. However, existing visual simulation models usually suffer from strong noise interference and lack rigorous verification of the simulation accuracy in the field of structural dynamics analysis. In this article, we present an interactive visual simulation modeling (IVSM) method, aiming to build an effective and accurate visual simulation model for structure dynamic response analysis. The IVSM endows the object in videos with the ability to directly and visually respond to new forces, in a way of human–computer interaction. We demonstrate the excellent performance of the IVSM in two application scenarios, i.e., the response prediction and damage detection. In response prediction, experiments, and IVSM simulations are compared to verify the effectiveness and accuracy of the proposed IVSM. The synthesized animations of the IVSM also present high fidelity to the actual experiment. In damage detection, we propose a novel damage magnification technique to build the IVSM. The IVSM simulation results demonstrate the superior performance in detecting and visualizing abnormal behaviors caused by damage.

Case Study of Self-Organization Processes in Information System Caching Components

Most modern Information Systems (IS) are designed with Object-Relational Mapping components (ORM). Such components bring down the number of queries to the database server and therefore increase the system performance. Caching mechanisms in software components are complex dynamic systems of open type. A simulation model of cache-application interaction has been created to assess the critical modes of the system. The authors suggest accumulating the cache elements states during the application run at discrete moments of time and present them as multi-variable time series. This work also suggests a method for reconstruction of phase-plane portrait of the system with multidimensional dynamics of the cache elements states. The article shows self-organization processes in caching components of information systems and illustrates the variability of system states for various initial conditions followed by transition to steady-state conditions. In particular, the paper illustrates dissipative structures as well as deterministic chaos with the complete determinism of queries in simulated information systems.

Assessment of the Impact of the Motor Transport Complex on the Ecological and Demographic Situation in the Region

The aim of this work is to build a mathematical model of the dynamics and mutual influence of the population and environmental factors – pollution of the atmosphere and surface water bodies – on an urbanized territory. The paper proposes a simulation model of dynamics and interaction of external and internal directions in biosphere-compatible city activities. The external direction of city’s activities is removal of resources from the Biosphere and emission of waste polluting water, air and soil into it. The internal direction is the impact on the population: environmental state, health assessment, life expectancy, human potential. Motor transport and objects of the road infrastructure bring the main volume of all waste and emissions polluting the urban environment. The method of forecasting the ecological and demographic situation of an urbanized territory is constructed using a relatively simple, non-linear, with variable coefficients, mathematical model that reflects the interaction of several subsystems: population, pollution of the atmosphere and water bodies.

Modeling of an interactive distance learning platform by means of modern information technologies

According to the requirements of the Ministry of Science and Education, teachers of various qualifications are required to regularly improve their professional skills. Using the distance learning platform allows you to automate the learning process, starting with the paperwork, ending with the final testing and obtaining a diploma. The problem is that during the course of training, you have to wait a long time for a response from a consultant on the subject or on the course support. The study of this problem was carried out on the basis of the existing database of the company "InfoTeacher". To determine the most promising courses, we used cluster data analysis using the R software environment. At the beginning, we calculated the optimal number of clusters according to the criterion of rocky scree, and then continued the cluster analysis using the k-means method. Thus, the main input parameters for building an interactive simulation model were identified. This model is a queuing system and was implemented in the GPSS World programming language. The parameters of the model were selected so that it was effective: to minimize the queues for consultation with the curator, while the curators should be loaded by at least 50%.

Integrated force interaction simulation model for milling strategy optimization of thin-walled Blisk blade machining

Complex shaped thin-walled blades that are extensively used in jet engines or stream turbines are very difficult to machine due to low rigidity of the blades, typically limited space between the blades and strict requirements on the surface quality and accuracy. The paper focuses on multi-axis machining of thin-walled and complex shaped Blisk blades made of aluminium alloys. The resulting surface quality and accuracy is mainly affected by the risk of elevated vibration occurrence, both forced and self-excited, and static deflections between the compliant tool and workpiece. An innovative integration of the transformed FE model of the blade into virtual machining simulation has been proposed, allowing to effectively solve the complex optimization task considering both the criterion of stable machining condition and static deflections as well. When choosing a machining strategy and cutting conditions, there are many variables that fundamentally affect the process. These variables are not easy to choose correctly the first time, so it is advisable to choose to use a simulation model in production preparation. The proposed simulation model allowed to effectively optimize the process parameters to keep the machining process stable and the static deformation of tool and workpiece under a defined level. The proposed model and optimization strategy was validated on a thin-walled blade machining. At the top part of the blade, the surface roughness decreased from 1.6 Ra to 0.84 Ra, and the maximum deviations from the reference model were reduced from 0.18 mm to 0.08 mm.

A Cartesian cut-cell based multiphase flow model for large-eddy simulation of three-dimensional wave-structure interaction

A multiphase flow numerical approach for performing large-eddy simulations of three-dimensional (3D) wave-structure interaction is presented in this study. The approach combines a volume-of-fluid method to capture the air-water interface and a Cartesian cut-cell method to deal with complex geometries. The filtered Navier–Stokes equations are discretised by the finite volume method with the PISO algorithm for velocity-pressure coupling and the dynamic Smagorinsky subgrid-scale model is used to compute the unresolved (subgrid) scales of turbulence. The versatility and robustness of the presented numerical approach are illustrated by applying it to solve various three-dimensional wave-structure interaction problems featuring complex geometries, such as a 3D travelling wave in a closed channel, a 3D solitary wave interacting with a vertical circular cylinder, a 3D solitary wave interacting with a horizontal thin plate, and a 3D focusing wave impacting on an FPSO-like structure. For all cases, convincing agreement between the numerical predictions and the corresponding experimental data and/or analytical or numerical solutions is obtained. In addition, for all cases, water surface profiles and turbulent vortical structures are presented and discussed.

Optimization of Transfer Layout and Organization on Urban Rail Transit —— A Case Study on Split Scheme of Beijing Rail Transit Line 13

Based on the practical case “the Consultation on Split Scheme of Beijing Rail Transit Line 13”, this paper collects and forecasts the passenger flow information, to combine the situation of the line with the surrounding land use, to probe into those possible problems of the existing split scheme deeply. By adopting digital construction technology, three sets of transfer layout optimization schemes are studied and designed, in order to realize the seamless connection between 13A Line and 13B Line after split. Then, this paper is supposed to establish the index evaluation system, and the satisfactory optimization scheme is obtained by the comprehensive comparison and selection from the aspects of convenience for passengers, feasibility of scheme implementation and so on. AnyLogic software is used to build a simulation model of human-vehicle interaction, which realizes the effect display and dynamic index acquisition. And the optimization effect is analyzed from the perspective of transfer platform security.