Model Simulations Research Articles

Mean‐State and Seasonal Variability in Temperature Structure and Heat Transport in the East Australian Current System From a Multi‐Decadal Regional Ocean Model

AbstractWestern Boundary Currents (WBCs) such as the East Australian Current (EAC) are vital for moving heat from low to high latitudes, controlling regional weather and global climate. Previous EAC System studies have provided a general overview of temperature variability and heat transport, but they lacked spatial and seasonal detail. Using a high‐resolution, 26‐year‐long ocean model simulation, we systematically characterize the seasonal variability and structure in key temperature metrics and heat transport in the EAC System. Our findings reveal a clear seasonal cycle with a poleward expansion of key variables in summer (mean and eddy kinetic energy, upper ocean heat content, heat transport) and contraction equatorward with reductions in winter. We show that the dynamical regime transition, from jet to eddy‐dominated at the EAC separation zone (S), modifies the net meridional heat transport. Upstream of separation, transport is poleward, with some zonal input of heat. Downstream of EAC separation, there is an increase in heat recirculation by mesoscale eddies combined with a smaller zonal export of heat. This study highlights the significance of resolving spatio‐temporal variability in WBC systems driven by mesoscale dynamics, which will have implications for the representation of critical dynamics in future climate models.

Interacting Influences of Diurnal Tides, Winds, and River Discharge on a Large Coastal Plume

AbstractThe dispersal of large river plumes in the coastal ocean depends on multiple factors, and in some cases, can be categorized into distinct dynamical regimes: a tidally dominated near‐field, a rotational mid‐field, and a coastal current far‐field. In this study, observations and modeling are used to evaluate the factors controlling the variability in the buoyant plume from Mobile Bay. Rather than distinct dynamical regimes, the Mobile Bay plume depends on forcings that act at overlapping temporal and spatial scales: diurnal tides, river discharge events, and winds. Satellite synthetic aperture radar images along with shipboard in‐situ sampling and marine radar are used to observe plume fronts in spring 2021. Hydrodynamic model simulations are compared with observations and used to characterize a large coastal plume at consistent tidal phase across a range of forcing conditions. The along‐shore position of the plume depends primarily on advection by wind‐driven surface currents. The cross‐shore extent and plume area depend primarily on the tidal amplitude and river discharge, and secondarily on northerly (seaward) winds. Along‐shore winds influence the buoyancy anomaly by altering salinity in the estuary and offshore. Upwelling winds increase the buoyancy anomaly and advect previous plumes away from the mouth. Downwelling winds reduce the buoyancy anomaly by trapping previous plumes near the coast and directing freshwater discharge toward a secondary outlet. Thus, the combined, overlapping influences of the tide, wind, and discharge dominate the variability in freshwater delivery to the shelf at time scales of days and distances of tens of km.

Numerical model of changes in current patterns due to reclamation around the Mireng River estuary, Gresik

Abstract The Mireng River is in Gresik Regency and empties into the Madura Strait. Around the mouth of the Mireng River, two industrial areas require construction facilities through reclamation. The consequences of reclamation will cause phenomena due to the interaction of marine and environmental dynamics, which can change current patterns, wave heights, and sedimentation processes, affecting the surrounding environment. This study explicitly discusses the changes in flow patterns that occur due to reclamation. The investigation was performed using numerical model simulations with Delft 3D software. The model results show the movement pattern and current speed during the highest and lowest low tides. There was a change in the average flow speed to 0.18 m/s around the reclamation area due to flow obstruction due to reclamation. This condition has the potential for sedimentation to occur in the area. Therefore, mitigation efforts are needed to reduce this impact.

Tropical Cyclone Boundary Layer Asymmetries in a Tilt-Following Perspective

Abstract Previous observations and modeling studies showed that tropical cyclones (TCs) in a sheared environment develop an asymmetric boundary layer (BL). While the relationship between the BL asymmetries and environmental shear has been demonstrated, the exact cause of these BL asymmetries and the phase relationship between them are less well understood. In this study, we examine the dynamical processes leading to the asymmetric structure of the TC BL in a sheared environment using idealized, convection-permitting model simulations. Our results show that the emergence of the BL asymmetries is closely linked to the TC vortex tilt and rainband processes. Specifically, stratiform diabatic processes in the downtilt-left region result in midlevel descending inflow, which brings midtropospheric, low-θE air toward the BL and forms a surface cold pool in the downtilt-left quadrant. This descending inflow also advects high absolute angular momentum inward, redistributing the vertical vorticity and causing a storm-scale tangential wind acceleration within the downtilt-left quadrant. As the BL low-θE air advances inward, it becomes supergradient and decelerates radially, forming BL outflow in the uptilt-left quadrant. The outflow advects positive relative vorticity uptilt, forming an elliptic BL vorticity and circulation structure. As the tilted TC vortex and the accompanying rainband precess cyclonically over time, the above sequence of events and the resultant BL asymmetries also precess cyclonically, maintaining a quasi-stationary configuration relative to the vortex tilt. These results suggest that the primary organizing factor of the boundary layer asymmetries is the tilted vortex structure and not strictly the environmental shear direction.

An interprocess communication-based two-way coupling approach for implicit-explicit multiphysics lattice discrete particle model simulations

An interprocess communication-based two-way coupling approach for implicit-explicit multiphysics lattice discrete particle model simulations

Performance Implications of Digital Disruption in Strategic Competition

Pervasive digitalization is changing how firms engage in strategic competition. Some firms are pursuing digital disruption strategies, using digital resources to rewire their value chain and change the landscape of their industry by redefining performance expectations. Other firms are adapting to digitalization by adding digital resources into their existing value chain. Through NK model simulations, we advance our understanding of digital disruption vis-à-vis adaptation in strategic competition in two main ways. First, we unearth important nuances in performance trade-offs: A digital disruption strategy may be effective for relative performance at the expense of absolute performance gains. Second, we explore relevant market- and competitor-related conditions under which firms should opt (or not) for a digital disruption strategy.

Scenario Storyline Discovery for Planning in Multi‐Actor Human‐Natural Systems Confronting Change

AbstractScenarios have emerged as valuable tools in managing complex human‐natural systems, but the traditional approach of limiting focus on a small number of predetermined scenarios can inadvertently miss consequential dynamics, extremes, and diverse stakeholder impacts. Exploratory modeling approaches have been developed to address these issues by exploring a wide range of possible futures and identifying those that yield consequential vulnerabilities. However, vulnerabilities are typically identified based on aggregate robustness measures that do not take full advantage of the richness of the underlying dynamics in the large ensembles of model simulations and can make it hard to identify key dynamics and/or storylines that can guide planning or further analyses. This study introduces the FRamework for Narrative Storylines and Impact Classification (FRNSIC; pronounced “forensic”): a scenario discovery framework that addresses these challenges by organizing and investigating consequential scenarios using hierarchical classification of diverse outcomes across actors, sectors, and scales, while also aiding in the selection of scenario storylines, based on system dynamics that drive consequential outcomes. We present an application of this framework to the Upper Colorado River Basin, focusing on decadal droughts and their water scarcity implications for the basin's diverse users and its obligations to downstream states through Lake Powell. We show how FRNSIC can explore alternative sets of impact metrics and drought dynamics and use them to identify drought scenario storylines, that can be used to inform future adaptation planning.

Future projections of storm surge in Hurricane Katrina and sensitivity to meteorological forcing resolution

In this study, we investigated whether and how the storm surge induced by Hurricane Katrina could change if it occurs in a future warmer climate, and the sensitivity of the changes to atmospheric forcing resolution. Climate model simulations of Hurricane Katrina at 27 km, 4.5 km, and 3 km resolutions were used to drive storm surge simulations in historical and future climates using the ADvanced CIRCulation (ADCIRC) model. We found that peak surge height increased significantly in the future with all forcing resolutions. However, the future projection is 22% greater in the 3 km forcing, typical of regional climate models, compared to the 27 km forcing, typical of state-of-the-art global climate models. Additionally, the spatial extent of the future change is highly sensitive to forcing resolution, extending most broadly under the 27 km forcing. Furthermore, we found that storm surge duration decreases in the future with all forcing resolutions due to increasing TC translation speed and decreasing ocean lifetime. However, the future change in the surge duration is sensitive to the forcing resolution, decreasing by 31% in the 27 km forcing and 6% in the 3 km forcing.

Finite Element Analysis of Shear Performance for Reinforced Concrete T-Beams by Polymer Bars Strengthened with Carbon Fiber Using Embedded Through Section Technique

The purpose of this research presents the research results obtained from a numerical simulation using the ABAQUS/CAE version 2019 finite element software. This study tested the shear behavior of T-beams made of reinforced concrete (RC). The structure is reinforced with a carbon fiber reinforced polymer (CFRP) bar embedded through a section (ETS). The numerical validation approach implicated using numerical analysis on the experimental data collected from twelve reinforced concrete (RC) T-beams divide into two groups each group include reference beam, the field of numerical analysis was expanded to encompass the examination of many aspects, such as the impact of the diameter of CFRP bars. The main objective of this project is to create a computational model that accurately transcribes the complex nonlinear properties inherent in beams. This work conducts a comparative investigation of computational and experimental models, with a specific focus on their load-deflection features and cracking patterns. The study found that the average ratio of ultimate load to deflections in numerical model simulations for beams was 1.011, whereas in experimental testing it was 0.928. The research findings establish a clear correlation between the diameter of CFRP bars and the stiffness of a beam, assuming a constant angle of inclination and spacing.

Long-Term Climate Impacts of Large Stratospheric Water Vapor Perturbations

Abstract The amount of water vapor injected into the stratosphere after the eruption of Hunga Tonga–Hunga Ha’apai (HTHH) was unprecedented, and it is therefore unclear what it might mean for surface climate. We use chemistry–climate model simulations to assess the long-term surface impacts of stratospheric water vapor (SWV) anomalies similar to those caused by HTHH but neglect the relatively minor aerosol loading from the eruption. The simulations show that the SWV anomalies lead to strong and persistent warming of Northern Hemisphere landmasses in boreal winter, and austral winter cooling over Australia, years after eruption, demonstrating that large SWV forcing can have surface impacts on a decadal time scale. We also emphasize that the surface response to SWV anomalies is more complex than simple warming due to greenhouse forcing and is influenced by factors such as regional circulation patterns and cloud feedbacks. Further research is needed to fully understand the multiyear effects of SWV anomalies and their relationship with climate phenomena like El Niño–Southern Oscillation. Significance Statement Volcanic eruptions typically cool Earth’s surface by releasing sulfur dioxide, which then converts into aerosols, which reflect sunlight. However, a recent eruption released a significant amount of water vapor—a strong greenhouse gas—into the stratosphere with unknown consequences. This study neglects the aerosol effect and examines the consequences of large stratospheric water vapor anomalies and reveals that surface temperatures across large regions of the world increase by over 1.5°C for several years, although some areas experience cooling close to 1°C. Additionally, the research suggests a potential connection between the eruption and sea surface temperatures in the tropical Pacific, which warrants further investigation.

Temporal fine structure sensitivity measured with pulse-spreading harmonic complexes.

Two experiments investigated sensitivity to temporal fine structure (TFS) in a group of normal hearing participants. The stimuli were bandpass filtered pulse-spreading harmonic complexes (PSHCs) with a regular envelope repetition rate and a phase adjusted so that the TFS peaks were progressively shifted across envelope periods. For up-PSHCs, the TFS peaks were advanced, yielding a rising pitch percept, while for down-PSHCs, the peaks were delayed, yielding a falling pitch percept. Experiment 1 showed that in a fixed frequency region, there was a range of rates for which the direction of the pitch change could be identified. Cochlear model simulations suggested that participants may use either place-of-excitation and/or temporal cues to perform this task. Experiment 2 showed that there was an envelope rate below which down-PSHCs and up-PSHCs could not be discriminated. This lower envelope rate limit of TFS sensitivity significantly increased with increases in frequency region and was similar to the lower rate limit of melodic pitch. The results in high frequency regions suggest that TFS cues are available up to 10 kHz when the rank of the lowest component present in the passband is 18, and all harmonics are presumably unresolved.

A New Climatology of Depth of Nitracline in the Bay of Bengal for Improving Model Simulations

A New Climatology of Depth of Nitracline in the Bay of Bengal for Improving Model Simulations

상자모형을 이용한 서울 겨울철 질산염 생성 메커니즘 분석

상자모형을 이용한 서울 겨울철 질산염 생성 메커니즘 분석

The role of Nature-Based Solutions for the water flow management in a Mediterranean urban area

Due to climate change and rapid urban sprawl, central Mediterranean regions are subjected to short but intensive storm events resulting in a significant increase of flow rates and runoff volumes in low-lying coastal urban areas. Within the framework of green urban infrastructures (GUIs), a suitable combination of Nature-Based Solutions (NBS) with traditional grey infrastructures should be adopted to mitigate flood risk effects in urban and sub-urban areas contributing at the same time to achieve multiple benefits for both the environment and the community. The aim of this study is (i) to evaluate flood hazard maps for identifying the areas within a Sicilian hydrological river basin (Toscano catchment) with a high risk of flooding by implementing the HEC-RAS model at catchment scale; (ii) to quantify the peak flow and floodplain area reduction; (iii) to assess the effectiveness of small-scale NBS (green roofs, porous pavements, rain gardens and rain barrel), in terms of peak flow and runoff volume reductions, at urban block scale by using the EPA SWMM model Model simulations are performed integrating the hydraulic (HEC-RAS) and hydrological (EPA SWMM) models for return periods of 10, 50 and 200 years. The results showed that the estimated peak flow (m3 s−1) obtained from the simulations performed at catchment scale for each T in the current scenario (without NBS) using HEC-RAS and EPA SWMM models are very close to each other (R2 = 0.99). In addition, the utopian scenario simulation showed the HEC-RAS model sensitivity to CN calibration achieving a peak flow reduction up to about 60% with the floodplain area decreasing up to about 17%. Finally, the model EPA SWMM shows its sensitivity to NBS implementation at urban block scale with a peak flow reduction up to about 16% and a runoff volume (mm) reduction up to about 24%. These reductions decrease as T increases with a higher NBS mitigation effects for the lowest T. The results highlighted that the integration of NBS in urban areas could have hydrological and hydraulic positive effects, particularly in terms of peak flow and runoff volume reduction. Furthermore, the results suggest that small-scale NBS have a potential to be effective to smaller rainfall events, but a combination with large-scale NBS is necessary to cope with extreme events.

Theoretical study of a putative adsorption mechanism of arginine and glutamate on goldfish 5.24 and zebrafish Z06: Statistical physics modeling, thermodynamic study, and docking simulation

An adsorption phenomenon putatively involved in the sense of smell of arginine and glutamate amino acids in the goldfish olfactory receptor 5.24 and the zebrafish olfactory receptor Z06 was applied in this study to deeply interpret and characterize the olfaction process at a molecular level. As a result, the experimental concentration-olfactory response curves were adjusted using the mono-layer model with one energy (MLM1E). On the one hand, the physicochemical parameters involved in the chosen model were utilized to microscopically investigate the four olfactory systems. Indeed, the two amino acids were adsorbed via a non-parallel configuration, and the process of adsorption was multi-molecular. The molar adsorption energies, which ranged from 22.09 to 35.97 kJ/mol, could be utilized to define the energetic interaction types between the investigated amino acids and the two tested fish olfactory receptors. The size and adsorption energy heterogeneity of 5.24 and Z06 binding pockets were measured by estimating the pocket site size distributions or PSDs (stereographic characterization) and the adsorption energy distributions or AEDs (energetic characterization). On the other hand, these physicochemical parameters could also be applied to macroscopically investigate the four olfactory systems. Hence, three thermodynamic functions including the adsorption entropy Sa, the internal energy Eint, and the Gibbs free energy G were computed in order to investigate the disorder, the exothermicity, and the spontaneity of the studied systems, respectively. The docking modeling analysis of arginine and glutamate amino acids with goldfish 5.24 and zebrafish Z06 revealed simulated binding energies that closely matched the average adsorption energies (peaks of AEDs). These affinities corresponded to the adsorption energy bands known as olfactory bands or spectrums of vibration modes.

Intrinsically Disordered Proteins by Homology Modeling and Replica Exchange Molecular Dynamics Simulations: A Case Study of Amyloid-β42

Homology modeling emerges as a potent tool unveiling the structural enigma of intrinsically disordered proteins (IDPs), with recent advancements such as AlphaFold2 enhancing the precision of these analyses. The process usually involves identifying homologous proteins with known structures and utilizing their templates to predict the three-dimensional architecture of the target IDP. However, IDPs lack a well-defined three-dimensional structure, and their flexibility makes it difficult to accurately predict their conformations. On the other hand, special sampling molecular dynamics simulations have been shown to be useful in defining the distinct structural properties of IDPs. Here, the structural properties of the disordered amyloid-β42 peptide were predicted using various homology modeling tools including C-I-TASSER, I-TASSER, Phyre2, SwissModel and AlphaFold2. In parallel, extensive replica exchange molecular dynamics simulations of Aβ42 were conducted. Results from homology modeling were compared to our replica exchange molecular dynamics simulations and experiments for gaining insights into the accuracy of homology modeling tools for IDPs used in this work. Based on our findings, none of the homology modeling tools used in this work can capture fully the structural properties of Aβ42. However, C-I-TASSER yields a radius of gyration and tertiary structure properties that are more in accord with the simulations and experimental data rather than I-TASSER, Phyre2, SwissModel and AlphaFold2.

Cl--dependent amplification of excitatory synaptic potentials at distal dendrites revealed by voltage imaging.

The processing of synaptic signals in somatodendritic compartments determines neuronal computation. Although the amplification of excitatory signals by local voltage-dependent cation channels has been extensively studied, their spatiotemporal dynamics in elaborate dendritic branches remain obscure owing to technical limitations. Using fluorescent voltage imaging throughout dendritic arborizations in hippocampal pyramidal neurons, we demonstrate a unique chloride ion (Cl-)-dependent remote computation mechanism in the distal branches. Excitatory postsynaptic potentials triggered by local laser photolysis of caged glutamate spread along dendrites, with gradual amplification toward the distal end while attenuation toward the soma. Tour de force subcellular patch-clamp recordings from thin branches complemented by biophysical model simulations revealed that the asymmetric augmentation of excitation relies on tetrodotoxin-resistant sodium ion (Na+) channels and Cl- conductance accompanied by a more hyperpolarized dendritic resting potential. Together, this study reveals the cooperative voltage-dependent actions of cation and anion conductance for dendritic supralinear computation, which can locally decode the spatiotemporal context of synaptic inputs.

Enhancing middle ear implants: Study of biocompatible materials with hydroxyapatite coating

In this manuscript, the application of hydroxyapatite coatings to total ossicular reconstruction prostheses (TORPs) using finite element modeling simulations was investigated to enhance the biocompatibility and mechanical performance of these prosthetic devices for middle ear implants. We focused on evaluating biocompatible materials, particularly polyetheretherketone (PEEK) and titanium, by analyzing their mechanical behavior under simulated conditions. The results revealed that PEEK demonstrates mechanical performance almost on par with titanium, exhibiting excellent stability and resilience within the middle ear environment. PEEK offers several key advantages over titanium, including easier fabrication, greater availability, and a simplified application process for hydroxyapatite coatings. These benefits suggest that PEEK could be a highly effective alternative to titanium for use in middle ear prostheses. The findings of this study highlight the potential of PEEK to improve the design and functionality of middle ear implants, providing a promising direction for future research and development in this field. By leveraging the advantages of PEEK, we can advance the effectiveness and accessibility of middle ear prosthetic devices, ultimately benefiting patients requiring such interventions.

Transfer-AE: A novel autoencoder-based impact detection model for structural digital twin

Accurately detecting the location and intensity of impacts is crucial for ensuring structural safety. Currently, AI-based structural impact detection methods are widely used for their excellent detection accuracy. However, their generalization capability is limited by the scenarios present in the training data. Many complex and dangerous impact scenarios are difficult to conduct real-world experiments on to collect sufficient samples. To capture all impact scenarios and fully leverage the advantages of AI-based detection technologies, advanced methods involve combining real-world structural monitoring data with corresponding numerical models to construct digital twins. These methods continuously refine the created numerical models with limited real-world data and provide diverse impact scenarios through numerical model simulations. However, there are inevitable differences between digital models and physical models that are challenging to correct through mechanical means. This discrepancy in data distribution between the two models significantly hinders the application of digital twin technology in impact/event identification tasks. To address this challenge, this study proposes a novel model based on autoencoders, named Transfer-AE. Transfer-AE encodes the common features of digital twins in the latent space to bridge the uncertainty gap at a macro scale between numerical models and physical models and synchronously fits the magnitude and location of the impact load in the decoder. This enables consistent detection results for the same impact event, whether the sample comes from the numerical model or the physical model. Transfer-AE includes two operating modes: Mode 1 has a fixed computational complexity with stable inference speed, but the training cost and difficulty increase with data distribution. Mode 2's computational complexity increases with data distribution, but it has a fixed training cost and speed. In both cases involving the geodesic dome structure simulating a deep space habitat and the IASC-ASCE benchmark structure, Transfer-AE demonstrated the best performance in impact localization and quantification tasks compared to mainstream domain-adaptive transfer models.

Research on Application of Composite Facades for Civilian Reconstruction of Industrial Heritage in Cold Regions Based on Thermal Buffering Effect

Previous studies on the civil transformation of industrial heritage have been conducted mainly from the perspective of architectural history, culture and aesthetics, but rarely focus on energy-saving and the comfort of the new users. Most industrial heritage facades are of high conservation value, but efforts to preserve the authenticity of the facade can lead to the application of limited energy-saving technologies, ultimately resulting in poor indoor thermal environments. Therefore, it is valuable to research how to solve the contradiction between protecting the authenticity of the preserved facades of industrial heritage and improving the indoor environmental performance. This paper proposes two composite facade application strategies based on thermal buffer effects, takes two composite facades renovation methods of Shenyang Dongmao No. 2 Warehouse as an example, utilizes the natural environmental resources to enhance the spatial quality of industrial heritage. With the help of DesignBuilder software modelling simulation analysis, in-depth comparative analysis of the two types of composite facades on the indoor thermal environment of the industrial heritage of the impact and scope. Key findings show that the application of two different composite facade retrofitting techniques not only protects the skin texture of the wall, but also effectively increases the indoor temperature and reduces the indoor energy consumption of the industrial heritage. The composite facade of the external solid wall and the internal glass is more stable in raising the indoor temperature, more effective in reducing the building energy consumption, and more suitable for the civilian transformation of industrial heritage in cold areas. The research findings provide reference for studies on the civil transformation of industrial heritage, and serve as technical references for architects.