Mesoscopic, agent-based simulations efficiently model and assess entire regions’ daily activities and travel patterns, exemplified by smaller countries like Switzerland. The queue-based simulation ...represents a compromise between computational speed on the one hand and the necessity of detailed modeling infrastructure on the other hand. Thus, mesoscopic simulations enable an efficient and reasonably detailed analysis of the complex interplay between supply and demand in mobility research. Conversely, microsimulations excel at reproducing individual speed profiles and behavior by modeling the interactions between traffic participants, including pedestrians, bicycles, and scooters. Although allowing for more detailed system analysis, the downside is the high computational burden, which often prevents large-scale microscopic simulations from running in optimization or calibration loops. hybridPY, an extension of SUMOPy, aims to close the gap and benefit from both environments. The simulation suite allows the running of mesoscopic as well as microscopic traffic simulations based on the core idea: running a microscopic simulation in a smaller dedicated area, using the routes or mobility plans generated from a larger mesoscopic model. The main features of this software are: (i) import, editing and visualization of MATSim and BEAM CORE networks; (ii) conversion of MATSim plans to SUMO routes or plans within the SUMO area; (iii) configuring and running of MATSim simulations. The capability of hybridPY is demonstrated by two applications: the simulation of Schwabing, Germany, based on the MITO MATSim model, and the San Francisco municipality, USA, based on the mesoscopic BEAM CORE model of the entire San Francisco Bay area. Both scenarios demonstrate that the hybrid approach results in significant computational gains with respect to a pure microscopic approach.
Most of the structures are fabricated by welded joints in various manufacturing units because of low cost and high strength. Welding process is largely used in almost all manufacturing units. Welded ...joints usually subject to welding deformation patterns. Welding deformation may lead to low dimensional accuracy, shape and aesthetics of the product, strength of the welded joint. Welding of two different materials having different mechanical properties is called dissimilar welding. Dissimilar welded joints are commonly used in power plants to connect martensitic steel components and austenitic stainless steel piping systems. Our approach involves conducting dissimilar welding on P91 and SS304H steels, and subsequently assessing the properties of the welded joints using simulation software. A 3-D thermal elastic plastic finite element computational process is designed to accurately forecast welding deformation by numerical method. Numerical and experimental outcomes were compared in terms of temperature distributions during welding and in terms of distortion. P91 is a chromium-molybdenum alloy known for its remarkable strength and exceptional resistance to high temperatures. Alloy SS304H represents an adaptation of the chromium-nickel austenitic stainless steel. This variant, Grade 304H stainless steel, offers enhanced heat-resistant properties, increased tensile yield strength, and improved short- and long-term creep strength.
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•By Increasing flow velocity, natural frequency decreases to zero and instability occurs.•SG and Nonlocal theories predict highest and lowest critical flow velocity, ...respectively.•Nonlocal theory is the best choice to study the vibration of proposed model.•The value of calibrated nonlocal parameter is in the range of 3.8–4.6.
In this article, a nonlocal strain gradient cylindrical shell model is developed to study vibration analysis and instability of a single-walled carbon nanotube conveying viscous fluid. The fluid flow is modeled by modified Navier-Stokes equation considering slip boundary condition and Knudsen number. The obtained governing equations of motion and corresponding boundary conditions are discretized using generalized differential quadrature method. Simplifying the nonlocal strain gradient theory, the results of this theory are compared to those of classical, strain gradient, and nonlocal theories. The effects of material length scale and nonlocal parameters on natural frequency and critical flow velocity are further investigated. Also, for the first time, the effect of fluid flow on vibration behavior of the carbon nanotube is studied by molecular dynamics simulation. In the simulations, TIP4P/2005 water model is used, which accurately considers thermo-physical properties of water such as viscosity. Moreover, in order to apply carbon–carbon interaction, modified Tersoff potential is used, with Lennard-Jones potential being employed for other interactions. In this study, size-dependent parameters of nonlocal strain gradient theory are calibrated and variation of calibrated values under the effect of flow velocity is explored.
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Simulations of cardiac electrophysiology and mechanics have been reported to be sensitive to the microstructural anisotropy of the myocardium. Consequently, a personalized representation of cardiac ...microstructure is a crucial component of accurate, personalized cardiac biomechanical models.
cardiac Diffusion Tensor Imaging (cDTI) is a non-invasive magnetic resonance imaging technique capable of probing the heart's microstructure. Being a rather novel technique, issues such as low resolution, signal-to noise ratio, and spatial coverage are currently limiting factors. We outline four interpolation techniques with varying degrees of data fidelity, different amounts of smoothing strength, and varying representation error to bridge the gap between the sparse
data and the model, requiring a 3D representation of microstructure across the myocardium. We provide a workflow to incorporate
myofiber orientation into a left ventricular model and demonstrate that personalized modelling based on fiber orientations from
cDTI data is feasible. The interpolation error is correlated with a trend in personalized parameters and simulated physiological parameters, strains, and ventricular twist. This trend in simulation results is consistent across material parameter settings and therefore corresponds to a bias introduced by the interpolation method. This study suggests that using a tensor interpolation approach to personalize microstructure with
cDTI data, reduces the fiber uncertainty and thereby the bias in the simulation results.
•The development of condition monitoring systems requires a large amount of currents.•A wide variety of motors with several types and degrees of fault must be used.•On-line condition monitoring ...systems require real time currents.•The use of test benches need a large number of destructive tests.•The use of accurate model will reduce the number of destructive tests.•The sparse identification method proposed will reduces the need of FEM simulations.•It obtains a model with a similar accuracy but able to run in a real time simulator.
The development of condition monitoring (CM) systems of induction machines (IMs) is essential for the industry because the early fault detection would help engineers to optimise maintenance plans. However, the use of several IMs to test and validate the fault diagnosis methods developed requires also costly test benches that, anyway, often face limitations in the range of faults and operating conditions to be tested. To avoid it, the use of accurate models such as those based on finite element method (FEM) would reduce the major drawbacks of test benches but their inability to execute FEM models in real time largely reduces their application in the development of on-line continuous monitoring systems. To alleviate this problem a hybrid FEM-analytical model has been proposed. It uses an analytical model that can be run in real-time in a hardware in the loop (HIL) system, after its parameters have been computed through FEM simulations. In this way, the proposed model provides high accuracy but at the cost of long simulation times and high computational costs (both computing power and memory resources) to compute the IM parameters. This work aims at reducing these drawbacks. In particular, a model based on sparse identification techniques is proposed. The method balances complexity and accuracy by selecting a sparse model that reduces the number of FEM simulations to accurately compute the coupling parameters of an IM model with different fault severity degrees. Particularly, the proposed methodology has been applied to develop models with abnormal eccentricity levels as this fault is related to development of mechanical faults that produce most of IM breakdowns.
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Underground mine fires are dangerous, consume resources, and emit pollutants. Therefore, acquiring in-mine data for fire research is hazardous and expensive due to unsteady temperature changes and ...toxic gas emissions. Computational fluid dynamics (CFD) models are often developed to mimic airflows and combustion-associated heat transfer. However, research on the performance evaluation of the CFD turbulence models to mimic fire events is limited. This paper summarises the modelling results for a diesel pool fire event in an experimental underground mine that uses an exhaust ventilation system. A fire dynamics simulator (FDS) model was developed to show the spatio-temporal temperature evolution. Reynolds-Averaged Navier-Stokes and large eddy simulation (LES) models were developed using ANSYS Fluent to model species transportation in the transient-state combustion event. LES models showed the closest agreement with the experiments but required the most computing resources. Similar exercises will assist the mine operators in emergency preparedness and in training their safety teams.
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Several applications of artificially modeled drivers, such as autonomous vehicles (AVs) or surrounding traffic in driving simulations, aim to provide not only functional but also human-like behavior. ...The development of human-like AVs is expected to improve the interaction between AVs and humans in traffic, whereas, in a driving simulation, the objective is to create realistic replicas of real driving scenarios to investigate various research questions under safe and reproducible conditions. In urban traffic, driving behavior strongly depends on the situational context, which introduces new challenges not only for modeling but also for the evaluation of such models. However, current objective assessment strategies rarely consider situational context and human similarity, whereas subjective approaches are not suitable for iterative development processes. In this paper, we present a first attempt to make the plausibility and human-likeness of vehicles’ trajectories objectively measurable. A multidimensional quality function is presented that incorporates various parameters characterizing human-like driving behavior and compares each of those parameters to human driving behavior under similar conditions. Among other things, our validation results show that the presented evaluation methodology is scalable to a wide range of situations has the ability to identify model weaknesses, and is able to reflect the way people distinguish between artificial and human behavior.
•The interfacial behavior of ethanol-water mixtures near graphyne surfaces were investigated.•The micro-phase demixing was observed with ethanol preferential adsorbing on graphyne.•Ethanol ...predominately occupy graphyne pores and display selective ethanol penetration.•This unique behavior could be attributed to the hydrophobic interaction from graphyne surfaces.
The interfacial behavior of ethanol-water mixtures with various concentrations near single-layer polyporous γ-graphyne (Graphyne-n, n=3,4,5) surfaces were investigated using molecular dynamics simulation. Comprehensive energetic analysis and structure properties, including density profiles, radial distribution functions, orientation distributions, and surface two-dimensional densities, have been simulated to quantify the surface-induced effect. Our simulation results illustrate micro-phase demixing phenomenon with ethanol molecules preferential adsorbing on the graphyne surfaces. This surface-induced demixing behavior is enhanced as the pore area decreases for the γ-graphynes, that is, G-3 surface induces the strongest demixing of ethanol-water mixture. Meanwhile, when in contacting with the graphyne-4 and graphyne-5 surfaces, ethanol molecules from the mixture are able to predominately occupy the nanopores of graphynes, and display selective ethanol penetration through single-layer graphynes. This unique interface behavior could be attributed to the enhanced hydrophobic interaction between amphiphilic ethanol molecules and graphyne carbon surfaces.
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The aim of this paper is to evaluate the accuracy, stability and efficiency of the overset grid approach coupled with the RANS (Reynolds Averaged Navier-Stokes) model via the benchmark computations ...of flows around a stationary smooth circular cylinder. Two dimensional numerical results are presented within a wide range of Reynolds numbers (6.31×104∼7.57×105) including the critical flow regime. All the simulations are carried out using the RANS solver pimpleFoam provided by OpenFOAM, an open source CFD (Computational Fluid Dynamics) toolkit. Firstly, a grid convergence study is performed. The results of the time-averaged drag and lift force coefficients, root-mean square value of lift force coefficient and Strouhal number (St number) are then compared with the experimental data. The velocity, vorticity fields and pressure distribution are also given. One main conclusion is that the numerical solutions in regard to a fixed cylinderare not deteriorated due to the implementation of the overset grid. Furthermore, it can be an appealing approach to facilitate simulations of Vortex Induced Vibrations (VIV), which involves grid deformation. The present study is a good start to implement the overset grid to solve VIV problems in the future.
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