Simulation Of Behavior Research Articles

Effect of the shape of microswimmers and slip boundary conditions on the dynamic characteristics of near-wall microswimmers

Although the interaction between microswimmers and walls during near-wall swimming has been extensively studied, the effect of microswimmer shapes and slip boundary conditions on the dynamic characteristics of near-wall microswimmers has received less attention. In this study, elliptical microswimmer models have been developed with various aspect ratios based on circular microswimmers. The lattice Boltzmann method has been used for the numerical simulation of the dynamic behaviour of microswimmers near walls. Under slip boundary conditions, the escape or capture of microswimmers by the walls is influenced by the swimming Reynolds number (Res), wall slip length (ls) and the aspect ratio (Cab) of a microswimmer. Changes in the Cab value of a microswimmer considerably affect its swimming state, especially for puller-type microswimmers. The tendency of pullers to be captured by the wall increases with increasing Cab. Moreover, changes in ls within the slip boundary condition of a puller can induce a transition in its movement state from a wall oscillation state to a stable sliding state and eventually to a wall lock-up state, a process influenced by the Cab value of the puller. Pusher-type microswimmers show a considerably increased tendency to escape from walls with increasing Cab and no wall lock-up state is observed, which is opposite to the case of pullers. Pushers and pullers show an increased tendency to be captured by the wall with increasing initial swimming angle of the microswimmer. The findings of this study enhance our understanding of the swimming patterns of natural microswimmers near walls and are of substantial importance for the design of artificial microswimmers and microfluidic devices.

Digital Garment Alteration

AbstractGarment alteration is a practical technique to adapt an existing garment to fit a target body shape. Typically executed by skilled tailors, this process involves a series of strategic fabric operations—removing or adding material—to achieve the desired fit on a target body. We propose an innovative approach to automate this process by computing a set of practically feasible modifications that adapt an existing garment to fit a different body shape. We first assess the garment's fit on a reference body; then, we replicate this fit on the target by deriving a set of pattern modifications via a linear program. We compute these alterations by employing an iterative process that alternates between global geometric optimization and physical simulation. Our method utilizes geometry‐based simulation of woven fabric's anisotropic behavior, accounts for tailoring details like seam matching, and incorporates elements such as darts or gussets. We validate our technique by producing digital and physical garments, demonstrating practical and achievable alterations.

Research on the Dynamic Response of a Bedding Rock Slope Reinforced by Pile–Anchor Structures Under Earthquakes: A Case Study of a Section of the Duyun-Shangri-La Expressway Project in Ludian County, Yunnan Province, China

Pile and anchor structures are extensively employed for slope stabilization. However, their dynamic response under seismic loading remains unclear and current seismic designs primarily use the pseudo-static method. Here, a three-dimensional numerical simulation of the dynamic behavior of a bedding rock slope supported by pile–anchor systems under earthquakes is conducted. The dynamic calculation for the slope subjected to seismic forces with varying excitation directions and acceleration amplitudes is performed. The dynamic behavior of both the slope and the pile–anchor system is investigated with respect to the slope’s failure mode, the dynamic soil pressure behind the pile, the anchor axial force, the bending moment, and the lateral displacement of the pile. The results indicate that the anti-slide piles cause a reflective and superposition effect on seismic waves within weak rock layers. As the input seismic intensity increases, the axial force in the anchor cables also increases, with the peak axial force occurring during the main energy phase of the seismic waves. The dynamic soil pressure acting behind the piles varies with the stratification of the slope rock layers, with lower peak dynamic earth pressure observed in weak layers. The weak layers on the slope surface experience through-shear failure. Under strong seismic loading, the structural element state undergoes significant changes.

Molecular dynamics simulation of shock-induced plastic deformation and spallation behavior of Cu/Cu64Zr36 crystalline/amorphous composites

Molecular dynamics (MD) simulations were performed to study the shock-induced plastic deformation and spallation failure of Cu/Cu64Zr36 crystalline/amorphous composites with a pre-existing void. The results show that the pre-existing void collapses always perpendicular to the direction of the shock loading, regardless of whether the shock direction starts from the crystalline phase or the amorphous phase. The Cu/Cu64Zr36 composites are more prone to spallation failure when the shock starts from the Cu crystalline phase. The changes of dislocation density and shear transformation zone (STZ) activation are closely related to the magnitude and direction of shock velocity. When the shock velocity reaches 2.0 km/s, dislocations in the crystalline phase disappear, dislocation density is close to zero and STZs activate throughout the entire amorphous phase. In addition, regardless of the shock velocity and direction, no shear bands are generated in the Cu/Cu64Zr36 composites under shock loading, which is significantly different from the case of tensile loading.

ETHOS.ActivityAssure—an open-source validation framework for synthetic European activity profiles

The simulation of human behavior is an essential component in the domain of energy demand modeling. However, due to its diverse nature, it is often unclear whether a simulated behavior pattern is fitting to certain contexts. Combined with the poor availability of appropriate activity data, this makes proper validation of behavior models difficult. Existing validation approaches are limited and specialized to the respective use case, and are therefore not reusable or comparable. To address this issue, the new open-source framework ETHOS.ActivityAssure is presented for evaluation of generated activity profiles, supporting the validation of behavior models. For this purpose, an aggregated activity dataset is created from restricted European time use data and published to ensure reusability. Validation is conducted through a set of indicators and comparative plots, taking into account activity duration, frequency, and time. A categorization of person types and activities enables mapping to result categories commonly used in behavior models. The framework's capabilities are demonstrated on the residential demand model LoadProfileGenerator. The developed framework allows for consistent and reproducible validation of synthetic activity profiles targeting Europe, without requiring access to confidential data. This offers the opportunity to enhance both new and existing behavior models by identifying flaws, compare multiple modeling approaches, and thoroughly evaluate model quality for diverse target purposes.

Experimental and numerical simulation of seismic behavior of reinforced concrete frames infilled with refractory straw blocks

Recent earthquakes have highlighted the vulnerability of infilled reinforced concrete structures due to the insufficient consideration of infill masonry walls' contribution to strength and stiffness. This study presents a novel refractory straw block (RSB) designed to address these challenges and improve the seismic performance of reinforced concrete (RC) frames. Unlike traditional infills, RSB is characterized by low-elastic-modulus, low-density, and high-ductility. Quasi-static tests were performed on three types of frames: unfilled, infilled hollow grouted bricks (HGB), and infilled RSBs. Failure model, stiffness, and load-displacement response of three specimens were investigated and analyzed. The results indicate that RSBs as infill material does not alter the failure mode and constitutive relationship of bare frame, while HGBs leads to shear failure. The peak load for the specimen IF-HGB was 69.3 kN at 1.1 % drift, compared to 38.8 kN at 2.4 % drift for the specimen IF-RSB, and 36.4 kN at 2.0 % drift for the specimen BF. The strengths of specimens IF-HGB and IF-RSB were 1.90 and 1.07 times that of specimen BF, respectively. The stiffness of specimen IF-HGB was 3.7 times that of the other specimens, but its allowable displacement was only 61 % of theirs. Dynamic time-history analyses were also performed on structures with no longitudinal infill (BF), with RSBs (SBF), and with fired bricks (FBF). At the design level of rare events (magnitude 8, PGA 400 gal), severe damage occurred, but collapse was limited. When the PGA increased further, the collapse probability of model FBF rose rapidly, whereas the collapse probabilities of models SBF and BF remained low and similar. Accounting for the confining effect of walls, model FBF showed a higher probability of severe damage than models SBF and BF, particularly under minor earthquakes. The maximum inter-storey drift ratio of the model SBF and FBF were respectively 1.2 times and 1.7 times that of the model BF, which shows that straw blocks as infill can greatly avoid the effect of infill on the seismic behavior of the structure. The study also emphasized the often-overlooked confining effect of masonry on columns, which can lead to unrealistic damage assessments and seismic shear force distributions.

Numerical simulation of hydrate particle behavior in vertical pipeline gas-liquid flow

During the extraction of deep terrestrial and deep-sea natural gas reservoirs, changes in temperature and pressure in the production well can lead to the formation of natural gas hydrates in the wellbore, blocking the flow channel and posing significant challenges to gas well production and management. To address this, we have established a mathematical model to describe the flow characteristics of hydrate multiphase flow systems in vertical pipelines. We employ Computational Fluid Dynamics simulations coupled with a Population Balance Model to predict the formation and breakage of hydrate particles, taking into account mechanisms such as particle collision, aggregation, and breakage. We have analyzed the impact of gas flow rate, slurry flow rate, and hydrate volume fraction on hydrate particle size in the pipeline. The results indicate that hydrate particles tend to aggregate at the bottom of the pipeline. The larger the hydrate slurry flow rate, the faster the hydrate particle size increases. As the gas phase flow rate increases, the increase in particle size slows down. High gas phase flow rates help form turbulence to suppress particle aggregation, velocity fluctuations contribute to particle aggregation growth, and stable velocities facilitate particle decomposition. The increase in hydrate volume fraction significantly increases the diameter of hydrates in the center of the pipeline. The research results can provide suggestions for wellbore blockage caused by hydrate particle aggregation on the wall and a decline in gas well production during actual natural gas well production.

Simulation of a Bio-Inspired Flocking-Based Aggregation Behaviour in Swarm Robotics

Simulation of a Bio-Inspired Flocking-Based Aggregation Behaviour in Swarm Robotics

Molecular dynamics simulation of solvation behavior and thickening properties of modified siloxanes in supercritical carbon dioxide under different pressure and temperature

Supercritical carbon dioxide (ScCO2) fracturing fluids have been limited in their application in unconventional reservoirs due to their weak proppant-carrying capacity resulting from their low viscosity. Consequently, numerous scholars have focused on modifying siloxanes to enhance their solubility and thickening performance in ScCO2. In this paper, the cohesive energy density, interaction energy, radial distribution function, shear viscosity and electrostatic potential distribution of modified siloxane with ScCO2 were calculated using molecular dynamics simulation. The effects of different temperatures and pressures on the dissolution and thickening ability of modified siloxanes in ScCO2 were investigated.The simulation results indicate that high temperature and low pressure have limited effects on promoting the solubility of modified siloxanes in ScCO2, with temperature exerting a more significant influence on solubility behavior than pressure. Additionally, PD4H+TMPTMA is less soluble in ScCO2 compared to PD4H+TAIC. The binding energy of ScCO2 and modified siloxanes decreases with increasing temperature but increases with increasing pressure. Van der Waals interactions and electrostatic interactions play decisive roles in the solubility of modified siloxanes in ScCO2. Finally, the thickening mechanism of modified siloxanes in ScCO2 was elucidated based on molecular structure and binding energy interactions.In summary, this paper aims to provide options and assistance in synthesis of better ScCO2 thickeners for unconventional reservoir fracturing applications through the study of modified siloxanes.

Tangeretin exerts and modulates the anxiolytic effects of the GABAkine drugs diazepam and flumazenil in mice: molecular interventions through animal behaviour and molecular dynamic simulations

Tangeretin exerts and modulates the anxiolytic effects of the GABAkine drugs diazepam and flumazenil in mice: molecular interventions through animal behaviour and molecular dynamic simulations

Dynamic recrystallization behavior and numerical simulation of 2209 duplex stainless steel

Dynamic recrystallization behavior and numerical simulation of 2209 duplex stainless steel

A novel modelling approach for realistically-wrapped state recycled aggregates and its application in meso-scale tensile behaviour simulation of recycled concrete

A novel modelling approach for realistically-wrapped state recycled aggregates and its application in meso-scale tensile behaviour simulation of recycled concrete

Design a Gating System for an Aluminum Cast Three-Way Pipe in Sand Casting

The study of aluminum casting work with market demand in the metal casting industry, designing a gating system in aluminum casting using a three-way pipe-shaped sand mold workpiece as a basic shape template in metal casting, namely a flat-face core box with a core. The gating system has a metal inlet with design variables including the pouring height, pouring basin cross-sectional area, rest basin cross-sectional area, running system cross-sectional area and inlet cross-sectional area. From the studying and designing, actual casting experiments were conducted and simulation behavior was analyzed using Cast-Designer software to make decisions and find appropriate design approaches from analyzing simulation results including liquid metal filling time, molten metal flow behavior, metal solidification time and shrinkage porosity formation of the workpiece. The results of the casting experiment and behavior simulation were able to cast the pipe workpiece which is a flat-face core box mold. The analysis results from the software can be used for actual pouring, where the fully cast mold successfully produced a complete workpiece. This can be a guideline for future improvements to reduce the shrinkage of actual cast workpieces.

Design Optimal Riser Size for Reducing Shrinkage Defect in 1100 Aluminum Alloy Sand Casting Process

This research aims to design a sprue system for aluminum castings in sand pores for a basic form prototype in metal casting, which is a one-piece pattern with a parting line. There are several types of liquid metal gating systems available. In the design, variables were specified regarding the height of the sprue, the cross-sectional area of the sprue, the cross-sectional area of the reservoir, the cross-sectional area of the runner, and the cross-sectional area of the gating. The riser size was used as a comparison variable. Following study and design, an experiment was conducted to cast the actual casting and to analyze the behavior simulation using Cast-Designer to determine a solution. In the simulation, the following results were found: the time taken to add liquid metal; the flow behavior of liquid metal; the metal hardening time; and the formation of shrinkage cavities in the casting. Based on the results of casting experiments and behavioral simulations, it was demonstrated that the large riser significantly reduced the shrinkage of the actual casting.

Atomistic Simulations of Hydration and Antibiofouling Behavior of Amphiphilic Polymer Brush Surfaces Functionalized with TMAO and Short Fluorocarbon.

Developing fouling-resistant materials is of paramount interest in marine industries and biomedical applications. In this work, we studied the interfacial hydration and surface-protein interactions of the amphiphilic brush surface functionalized with hybrid hydrophilic trimethylamine N-oxide (TMAO) and hydrophobic pentafluoroethyl groups using a combination of atomistic molecular dynamics simulations and free-energy computations. Our results show that while the interfacial hydration density of the amphiphilic surface slightly decreases with the introduction of small fluorocarbons compared to that of the pure TMAO-functionalized surface, the amphiphilic surface remains relatively strong in resisting protein adsorption. The nanosized clustering of hydrophobic fluorine atoms on the top of the amphiphilic brush surface introduces weak protein adsorption; however, due to the strong interfacial hydration and weak hydrophobic interaction, the amphiphilic surface exhibits sufficient antibiofouling activities. Our fundamental studies will be critical for the discovery of marine fouling-resistant coating surfaces.

Investigation on Dynamic Behaviors of Ship Propulsion Shafting with Misalignment Based on Stochastic Uncertainty Models

To investigate the effect of stochastic uncertainty on the dynamic behaviors of ship propulsion shafting with misalignment, a stochastic uncertainty model of ship shafting is established based on nonparametric theory and stochastic excitation. Numerical simulation and experimental verification of the dynamic behaviors are carried out using a ship shafting test bench. The results indicate that stochastic uncertainty has a significant effect on the dynamic behaviors of shafting with misalignment. With an increase in stochastic uncertainty, the fractional frequency appears in the spectrum, and the axis trajectory becomes more complex and gradually deviates from the center orbit. Therefore, to ensure the safe navigation of ships, it is necessary to consider the stochastic uncertainty in dynamic research on the misalignment of shafting.

Simulation of Adsorption and Separation Behavior of Elemental Gases on Lanthanide-Based Nd-MOF

Simulation of Adsorption and Separation Behavior of Elemental Gases on Lanthanide-Based Nd-MOF

An elasto-visco-plastic constitutive model for snow: Theory and finite element implementation

Snow exhibits unique mechanical behaviour due to its evolving properties influenced by temperature, stress conditions, and viscous effects. This paper introduces a nonlinear constitutive model for snow, featuring new formulations for the yield function and strain rate potential, and incorporating viscosity, sintering, and degradation effects. The model is numerically integrated into the Abaqus/Standard FEM software using a fully implicit backward Euler method for time integration and Powell’s hybrid method for linearizing the nonlinear system of equations. The robustness and stability of the numerical scheme ensure accurate simulation of snow behaviour under various loading conditions. The model is finally validated against experimental data available in the literature, demonstrating its effectiveness and reliability in capturing the complex mechanical response of snow.

Quantum Chemical Simulation for the Adsorption Behavior of Silicon in Water and Surface Property Study

Quantum Chemical Simulation for the Adsorption Behavior of Silicon in Water and Surface Property Study

Dielectric elastomer sensor integrated in a jaw coupling: Modeling and simulation of mechanical and electrical behavior

In recent years, the demand for compact and inexpensive sensor systems for the digitalization of production processes has risen. One solution to meet this demand are sensor-integrating machine elements. These are machine elements with integrated sensors, whose geometry is not altered and thus allows an uncomplicated exchange of the conventional machine elements with the sensor-integrating machine elements. In the current work, a numerical model for a sensor-integrating jaw coupling is presented. The aim of the sensor-integration is to determine the deformation of the teeth of the gear rim with dielectric elastomer sensors (DES) and thus draw conclusions about the applied torque. In the following, a model for the DES is presented which is validated with experimental results. It was shown that the experimental and simulation results for the capacitance agree well, if only 50% of the change in area of the electrodes is taken into account. After that, a finite element model for the sensor-integrating jaw coupling itself is presented, which is created with the commercial software ABAQUS. Finally, the advantages and disadvantages for different positions of the sensor inside the gear rim of the jaw coupling are evaluated.