One-dimensional Analysis Research Articles

One-dimensional analysis of underground water using geoelectric methods

The regional development issues in Tambang Kampar District that are most important to solve are environmental issues related to surface water potential and limited clean water. Environmental potential through good environmental management can become potential natural resources that can be utilized to support the regional economic sector. Groundwater potential needs to be studied and interpreted in the matrix of groundwater resource management through geophysical studies, namely by using the geoelectric method. This matrix will be able to provide solutions to environmental problems with the potential for fresh water in Tambang District, Kampar, thereby supporting economic growth in terms of meeting water needs. The material that is the object of research is underground water, and the aspects of research that will be studied include clean water exploration and environmentally friendly management patterns of potential underground water resources. The research location is Tambang District, Kampar, Riau Province. The targeted finding is an environmental management model of potential underground water resources in Tambang Kampar District using the Schlumberger rule geoelectrical method. Fundamental contributions to a field of science are geophysics and environmental science disciplines related to groundwater availability.

Edge Behavior of the Model in Boundary Layers: Analysis and Improvement

We examine the outer-edge behavior in a turbulent boundary layer (TBL) predicted by the model with reference to a mathematical analysis of Cazalbou–Spalart–Bradshaw (CSB) (Physics of Fluids, Vol. 6, No. 5, 1994, pp. 1797–1804). Particular attention is given to one-dimensional analyses at the edge of the turbulent region. An inverted parabola analysis demonstrates that the correct edge behaviors of , and are reproduced for both high- and models. For a ramp analysis following CSB (involving the velocity field), a set of diffusion coefficients for that violates the CSB constraint, however, yields an unrealistic velocity profile at the interface between the turbulent and nonturbulent regions due to the excessively small turbulent diffusion. We therefore propose improved diffusion coefficients by considering both the CSB constraint and requirements in wall turbulence, and calculate a range of two-dimensional aeronautical flows with to clarify if the one-dimensional analyses support the predictions in realistic flows, fully coupled with the velocity field. Indeed, the corrected diffusion coefficients provide reasonable predictions for both the channel and TBL but also TBLs involving turbulent separation when becomes large. Over an airfoil, the correction improves the prediction for by a few counts.

A One-Dimensional Nonlinear Consolidation Analysis of Double-Layered Soil with Continuous Drainage Boundary

Based on the soil nonlinearity assumptions proposed by Mesri, the one-dimensional nonlinear consolidation of double-layered soil is investigated. To better align with engineering reality, a continuous drainage boundary is introduced, bolstering the reliability of the derived solution through comparison against existing findings. Subsequently, the consolidation behavior of double-layered soil is analyzed for the soil permeability, compressibility, nonlinear parameters, and interface parameters. The outcomes elicit a positive correlation between the consolidation rate of the double-layered soil and both the ratio of permeability coefficient from the lower to upper soil layers and the value of the interface parameter. Furthermore, it is observed that a lower compressibility coefficient ratio between the lower and upper soil layers, along with a reduced ratio of compression index to penetration index, both contribute to an increased consolidation rate within the context of double-layered soil. The one-dimensional nonlinear consolidation of double-layered soil is intricate, intertwined with the relative permeability and compressibility of soil layers, and the influence of nonlinear parameters and drainage boundary configuration. Integrating these factors is crucial for analyzing the consolidation traits of double-layered soil, leading to a more precise portrayal of the consolidation behavior of coastal soft soils.

Three-Dimensional Numerical Analysis on the Influence of Buttress Wall Removal Timing on the Lateral Deformation of Diaphragm Walls during Deep Excavation

Urban areas in Taiwan are densely populated with limited land. Excavation often takes place near existing buildings, necessitating protective measures for adjacent properties. Among these measures, cross walls or buttress walls are commonly employed, especially in weak foundation soils, which have seen many successful applications. These mechanisms mainly contribute to reducing lateral deformation of the diaphragm walls, ground subsidence, and excavation face uplift. However, the behavior of these walls is essentially three-dimensional, and common engineering analyses employing one-dimensional elastoplastic beam analysis cannot adequately simulate their mechanical behavior. This study utilized the PLAXIS 3D 2018 software to analyze real-life cases of buttress walls and cross walls. Then, the results of the numerical models were validated against actual field measurements, and the outcomes were satisfactory, and within the regulatory allowable values. The primary objective of this study was to find the influence of different buttress wall removal timings on the lateral deformation of the diaphragm wall. The findings suggest that the gradual removal of buttress walls will effectively control the lateral deformation of diaphragm walls during the excavation of deeper floors like mezzanines.

Numerical Modeling and Experimental Validation of Heat Transfer Characteristics in Small PTCs with Nonevacuated Receivers

The development of small-sized parabolic trough collectors (PTCs) for processing heat production at medium temperatures (100–250 °C) represents an interesting approach to increase the utilization of solar thermal technologies in industrial applications. Thus, the development of simplified models to analyze and predict their performance under different operative and climatic conditions is crucial for evaluating the application potential of this low-cost technology. In this paper, we present a numerical method that by combining three-dimensional finite element simulations (implemented with COMSOL Multiphysics software version 6.1) with a one-dimensional analysis (based on a MATLAB script) allows for the theoretical determination of the power output of a small-PTC with a nonevacuated tubular receiver operating at a medium temperature. The finite element model considers both the nonuniformity of the concentrated solar flux on the receiver tube (evaluated using Monte Carlo ray-tracing analysis) and the establishment of natural convection in the air gap between the glass envelope and absorber tube. The model calculates, for several values of direct normal irradiance (DNI) and inlet temperatures, the thermal power transferred to the heat transfer fluid (HTF) per unit length. The data are fitted using the multiple linear regression method, obtaining a function that is then used in a one-dimensional multi-nodal model to estimate the temperatures and the heat gains along the receiver tube. The outputs of the model are the outlet temperature and the total thermal power transferred to the HTF. In order to validate the developed methodology for the assessment of the heat transfer characteristics in the small-PTC with a nonevacuated receiver, an experiment at the ENEA Trisaia—Solar Thermal Collector Testing Laboratory was carried out. This work compares the theoretical data with those acquired through experimentation, obtaining a good agreement, with maximum differences of 0.2% and 3.6% for the outlet temperatures and the power outputs, respectively.

Unveiling Metastable Ensembles of GRB2 and the Relevance of Interdomain Communication during Folding.

The folding process of multidomain proteins is a highly intricate phenomenon involving the assembly of distinct domains into a functional three-dimensional structure. During this process, each domain may fold independently while interacting with others. The folding of multidomain proteins can be influenced by various factors, including their composition, the structure of each domain, or the presence of disordered regions, as well as the surrounding environment. Misfolding of multidomain proteins can lead to the formation of nonfunctional structures associated with a range of diseases, including cancers or neurodegenerative disorders. Understanding this process is an important step for many biophysical analyses such as stability, interaction, malfunctioning, and rational drug design. One such multidomain protein is growth factor receptor-bound protein 2 (GRB2), an adaptor protein that is essential in regulating cell survival. GRB2 consists of one central Src homology 2 (SH2) domain flanked by two Src homology 3 (SH3) domains. The SH2 domain interacts with phosphotyrosine regions in other proteins, while the SH3 domains recognize proline-rich regions on protein partners during cell signaling. Here, we combined computational and experimental techniques to investigate the folding process of GRB2. Through computational simulations, we sampled the conformational space and mapped the mechanisms involved by the free energy profiles, which may indicate possible intermediate states. From the molecular dynamics trajectories, we used the energy landscape visualization method (ELViM), which allowed us to visualize a three-dimensional (3D) representation of the overall energy surface. We identified two possible parallel folding routes that cannot be seen in a one-dimensional analysis, with one occurring more frequently during folding. Supporting these results, we used differential scanning calorimetry (DSC) and fluorescence spectroscopy techniques to confirm these intermediate states in vitro. Finally, we analyzed the deletion of domains to compare our model outputs to previously published results, supporting the presence of interdomain modulation. Overall, our study highlights the significance of interdomain communication within the GRB2 protein and its impact on the formation, stability, and structural plasticity of the protein, which are crucial for its interaction with other proteins in key signaling pathways.

One-dimensional thermomechanical bio-heating analysis of viscoelastic tissue to laser radiation shapes

This article studies the coupled thermo-vibrational response of skin tissues to different laser irradiation inputs. The presented model uses four different phase lags to capture various mechanical responses, like viscoelastic properties of the skin, the finite thermal propagation speed, thermal inertia, or temperature gradient phase lag. Here the dynamic motion differential equation of the skin tissues is jerk dependent and expressed through a third-order time derivative due to the stress dependence of the constitutive behavior. The transient response of the model for various laser inputs is obtained through numerical integration over time. Experimental studies with various applicable laser input samples are tested in the laboratory. The obtained temperature results of these studies are compared with the numerical results to validate the model. In this comparison, good agreement was obtained despite the one-dimensionality of the modeling due to the large radiating area. Furthermore, the steady-state response due to a harmonic laser irradiation input is obtained to evaluate the temperature and displacement in the tissue and validate the simulation results. The results illustrate that tissue response depends on the steady amount of different energies in different periods. By controlling the energy and the radiation of the tissue, the expected tissue response can be received with the least entered energy.

Integrated composite electrothermal de-icing system based on ultra-thin flexible heating film

Icing is a serious threat to the flight safety of aircraft. Lightweight and efficient electrothermal de-icing systems for carbon fiber reinforced polymer components are expected to contribute to the lightweighting and electrification of aircraft. This study presents the development and test of a novel, integrated, multifunctional composite electrothermal ice protection system. The system achieves this by incorporating a carbon-based ultra-thin flexible heating film into a carbon fiber-reinforced polymer composite laminate. T700 and M40 carbon fiber prepregs were used. The system composition and configuration were designed based on the anisotropic mechanical and thermal properties of the carbon fiber-reinforced polymer composite. The effects of ply stacking sequence, presence of insulation layer, ply angle, heating area, and prepreg type on thermal response and de-icing performance were investigated. Thermal response experiments were carried out in both room temperature and low temperature environments. A one-dimensional thermal response analysis model was developed for a representative heating structure. Comparative de-icing experiments were conducted on different samples in a low-temperature test chamber. A numerical model, based on the modified enthalpy-porosity method, was developed to simulate the de-icing process, and showed good agreement with the experimental results. Experiments and numerical calculations show that the arrangement of the heater close to the deicing surface improves the performance of the electrothermal deicing system while maintaining the overall mechanical properties of the multi-layer structure. While the insulation layer helps marginally with heat loss during de-icing, it significantly increases the system’s thermal inertia, which delays the de-icing’s start. It is recommended to minimize or eliminate insulation layer thickness. Rapid de-icing effects, combined with energy conservation, can be achieved through a short-term, high-power heating strategy.

Heterogeneous Beam Element for Multiscale Modeling of Non-prismatic Composite Beam-like Structures

Anisotropy, heterogeneity, and geometry make full system-level three-dimensional (3D) finite element analysis (FEA) simulation of real composite beam-like structures, such as wind blades, impossible due to limitations on computing resources. A popular approach is to cut the structure into multiple cross-sections, from which the beam properties based on the Euler-Bernoulli or Timoshenko beam models are extracted using two-dimensional (2D) cross-sectional analyses. These properties are then utilized in beam elements for system-level analyses. However, the mechanics behind 2D cross-sectional analyses are based on prismatic beams, limiting the accuracy of this approach on non-prismatic structures, especially in predicting stresses. In this work, we present a new multiscale method based on Mechanics of Structure Genome to analyze beam-like non-prismatic composite structures. A beam-like structure is homogenized into a series of 3-node Heterogeneous Beam Elements (HBE) with effective beam element stiffness matrices, which are then used as input for one-dimensional (1D) beam analysis using Abaqus User Element subroutine (UEL). Using the macroscopic beam analysis results as input, we can also perform dehomogenization to predict the stresses and strains in the original structure. We use three examples, a prismatic composite beam, an isotropic homogeneous tapered beam, and a composite tapered beam, to demonstrate the capability of HBE and show its advantages over the traditional cross-sectional analysis approach. HBE can capture macroscopic behavior and detailed stresses due to non-prismatic geometry. HBE provides a new concept to model non-prismatic composite beams by modeling heterogeneous beam-like structures as equivalent beam elements rather than beam properties of material points of the reference line.

Risk Terrain and Multilevel Modeling of Street Robbery Distribution in Baltimore City

The structure and functions of neighborhoods determine the impact of measures used to estimate the distribution of street robbery across space and time. The risk of street robbery could vary between different sections of the area. Prior research has typically relied on one-dimensional analysis, which sparsely accounts for the hierarchical configuration of a neighborhood’s influence on spatial crime distribution. Much less is known about how the predictor variables moderate each other at different neighborhood levels. Data was collected from 13,789 US Census blocks ( N = 13,788) aggregated to administrative neighborhoods ( N = 278) to examine how neighborhood structure affects street robbery distribution at two spatial levels. A Risk Terrain Model was adopted to develop a physical environment risk measure—Aggregate Neighborhood Risk of Crime (ANROC), which, alongside sociodemographic risk factors, predicted the outcomes of the Negative Binomial General Linear Regression models. Study findings suggest that individual-level (block) and group (neighborhood) level predictors influenced street robbery. Both group-level physical environment and total population moderated the impact of the individual-level physical environment on street robbery incidents.

Analysis of flow characteristics and cooling performance of a novel impingement/effusion structure with bypass hollow holes

As a promising cooling technique, the double-wall cooling structure has been integrated into the design of advanced aeroengine high-temperature components. However, its widespread application in configurations with low pressure ratios between secondary flow and the main flow is hindered due to significant internal flow resistance. To address this issue, a novel low-resistance hollow pillar double-wall structure (NHDW) is developed. This study conducts conjugated heat transfer numerical simulations of NHDW and the traditional solid pillar double-wall structure (TSDW) for comparative analysis. Flow characteristics are examined to understand the sources of internal flow resistance and the coupling mechanism between internal and external heat transfer. The results demonstrate that the NHDW exhibits substantially lower flow resistance than the TSDW, with the total pressure loss dropping to approximately 1/3 of the corresponding TSDW under hole inclination angles of 30°, 60°, and 90°. The reduced internal flow resistance of the NHDW is attributed to the parallel bypass flow within the hollow pillar. Moreover, the overall cooling effectiveness (ϕ) of NHDW is enhanced by 9.2%–16.9% for different inclination angles at a blowing ratio of M = 1.0. Additionally, the interaction vortex structure on the mainstream side surface of the NHDW significantly improves the external cooling effectiveness, contributing to the overall enhancement of the cooling performance. Furthermore, a one-dimensional thermal resistance analysis method is introduced to distinguish the contributions of internal cooling and external film cooling. This analysis highlights the importance of external cooling enhancements in the novel structure.

Origin of rate dispersion in translational diffusion: Distinguishing heterogeneous from homogeneous using 2D correlation analysis

Rate dispersion is commonly observed when measuring relaxation in complex media such as solution of a protein. Its origin is often associated to molecular heterogeneity in the system. However, interpretation of rate dispersion is not straightforward, and it can be exhibited by both heterogeneous (all molecules are different) and homogeneous (all molecules are identical) systems. Here, we report two-dimensional (2D) correlation analysis of intensity fluctuations originating from translational diffusion-lead fluctuations in number of particles simulated in an observation volume resembling fluorescence correlation spectroscopy experiment. Translational diffusion of particles representing a protein having two different conformations are simulated. Homogeneous and heterogeneous systems are simulated to have similar one-dimensional (1D) autocorrelation curves with comparable extent of rate dispersion, α ∼ 0.8. Time slices of 2D autocorrelation curves and rate-rate spectra obtained from them clearly demonstrate that similar extent of rate dispersion observed in 1D autocorrelation can originate from both heterogeneous and homogeneous systems. We establish that one-dimensional analysis only reports on the extent of rate dispersion. Two-dimensional analysis reports on the origin of rate dispersion and distinguishes heterogeneous from homogeneous.

A cross-scale modeling framework for simulating typhoon-induced compound floods and assessing the emergency response in urban regions

The cities within the Pearl River Delta (PRD), known as the Greater Bay Area (GBA), are flood-prone areas that faced frequent threats from typhoon-induced storm surges and rainfall in recent decades. To assess the potential consequences of a typical typhoon event, fine-scale simulations of inundation induced by both pluvial and fluvial flooding (known as compound flooding) are crucial for policymakers and concerned stakeholders to develop proper measures. In this study, we develop a cross-scale framework for modeling city inundation arising from typhoon-induced surges and torrential rainfall–runoff by coupling a three-dimensional ocean model (FVCOM) and a one-dimensional and two-dimensional coupling river analysis system (HEC-RAS). The ocean model is applied to capture the mesoscale behavior of surge and tide propagation from the deep sea to shallow offshore areas near the PRD. The river analysis system can simulate storm wave propagation along rivers, overtopping banks on floodplains and rainfall–runoff-induced flooding in urban regions at gradually refined scales. Second, the framework integrates GIS components (network analysis) with these hydraulic models. Through this framework, the urban emergency service coverage can be assessed under various potential flood scenarios during typhoon landfalls. Super Typhoon Mangkhut in 2018, the most devastating typhoon in the last decade in the PRD, is used as a case study in simulating and studying the flooding process. The simulated results show that in this typhoon event, pluvial and fluvial flooding play different roles in hindering the accessibility of emergency resources. Moreover, the interaction between pluvial and fluvial flooding significantly affects some urban regions.

One-dimensional thermal consolidation analysis of saturated clay with variable compressibility and permeability considering partial drainage boundaries

The nonlinear consolidation characteristics of saturated clay will be markedly impacted by temperature. However, despite the ample progress of calculation methods for the one-dimensional consolidation of soft ground, theoretical investigations into thermal consolidation have not been thoroughly explored. Moreover, partially drained boundary is more consistent with the engineering practice, which is imperative to be involved to mitigate computational error when determining the consolidation behavior. In this context, a mathematical model is established to incorporate the temperature-dependent nonlinear characteristics of compressibility and permeability. Subsequently, the resulting governing equations and numerical solutions for the one-dimensional nonlinear thermal consolidation of saturated clay are obtained under partial drainage boundaries. Then the accuracy and reliability of the proposed model are validated by degradation analysis and simulation analysis with good agreements. Furthermore, the computed results of current study are adopted to conduct an in-depth assessment of the influence of several crucial parameters on the nonlinear consolidation behavior. The results demonstrate that increasing the temperature can remarkably accelerate the dissipation rate of excess pore water pressure, thereby promoting the consolidation process of saturated clay. The inclusion of partial drainage boundaries also has a significant influence on the consolidation performance, with a maximum difference in the dissipation rate of excess pore water pressure reaching up to 40 % when transforming a completely drained boundary into a completely undrained boundary. Additionally, the increment of pre-consolidation pressure will induce a gradual acceleration of consolidation rate.

Transient non-Fourier behavior of large surface bodies

The variety and complexity of heterogeneous materials in the engineering practice are continuously increasing, open-cell metal foams filled with phase change materials are typical examples. These are also having an impact on the recent developments in the energy industry. Earlier room temperature heat pulse experiments on macroscale foam samples showed non-Fourier over-diffusive behavior on a particular time scale. Since there is a need to investigate such complex structures on larger spatial scales and extend the one-dimensional analysis on two-, and three-dimensional settings, here we develop a two-dimensional analytical solution for the Guyer-Krumhansl and Jeffreys-type heat equations in cylindrical coordinates to investigate the transient thermal behavior of large bodies. We provide the steady-state and transient temperature and heat flux distributions for a space-dependent heat source. The solutions presented here will be helpful for the thermal characterization of complex materials and for the validation of numerical methods.

Designing an Environmental Wind Tunnel Cooling System for High-Speed Trains with Air Compression Cooling and a Sensitivity Analysis of Design Parameters.

Environmental wind tunnels for high-speed trains play a significant role in their development. The cooling system of the wind tunnel poses a challenge as it requires lower temperatures and a higher cooling capacity during operation. The conventional approach to wind tunnel refrigeration uses evaporative cooling, which is less efficient at low temperatures and comes with environmental and safety risks. In this study, we propose an innovative air compression refrigeration method based on the Brayton cycle. This method converts high-pressure air into low-temperature air at atmospheric pressure for wind tunnel refrigeration. The new cooling system has reduced energy usage by 3.72 MW, leading to a 13.15% improvement. The return cooler of the system is modeled using the effective number of heat transfer units and the mean temperature difference design method. Additionally, the turbine within the system is analyzed using one-dimensional flow characteristic analysis and the principle of similarity. This method has been validated by comparing it to other published papers. Subsequently, we perform a thorough sensitivity analysis on the key design parameters of the system. We observe that with a sufficient heat transfer area of the recooler, the cooling efficiency of the system exhibits a gradual decline from 64% to 60% as the mass flow rate of the system rises. For a fixed turbine, the cooling efficiency of the system rises from 20% to 62% and subsequently declines to 37%, with an increase in the mass flow rate. As a result, we conclude that the design parameters of the turbine have a more significant influence on the cooling efficiency of the system than the recooler. Our study will establish a foundation for selecting parameters to optimize the refrigeration system in the future.

Multidimensional analysis for fabric drapability

This study analyzed fabric drapability in one, two, and three dimensions to provide an assessment method reflecting real conditions. One-dimensional analysis of drapability involved observing the fabric movement by reciprocating motion. The movement appeared differently depending on the fabric characteristics, and the shape and location of the node showed differently, which were considered to be influenced by the weight of the sample along with the drape coefficient. Two-dimensional analysis identified the significant factors for the drape information. This examination confirmed that, even if drape factors were similar, differences in draped shape were observed based on the factors related to node shapes. Three-dimensional analysis, using a 3D scanner, involved the use of the mean distances between draped samples and the standard truncated cone, their standard deviation, and the coefficient of variation. The coefficient of variation was high in the groups wherein the shape of the drape was irregular. In the 3D analysis, the distances between samples and the standard truncated cone were expressed in colors to intuitively deliver the drape information. To determine a factor that could indicate drapability among the factors derived from each dimension, the existing drape coefficient was employed for correlation analysis. Three pairs of samples with similar drape coefficients but different drape shapes were selected to verify the above results. In conclusion, one-dimensional node location, two-dimensional standard deviation of node severity, and three-dimensional coefficient of variation were shown to effectively demonstrate the drape characteristic that the drape coefficient could not indicate.

Rigid-flex stamped indium tin oxide film for convertible self-alignment

The alignment layer process, which is a key element for liquid crystal (LC) displays, was investigated for efficiency improvement and for suggesting a new mode. To produce alignment films that can be used in both twisted-nematic (TN) and vertical alignment (VA) configurations, InO solution is doped with SnO. Then, the pattern was transferred by attaching a one-dimensional soft-imprint mold, and pattern and orientation analyses were performed in accordance with the SnO ratio. The horizontal orientation performance improved as the SnO ratio increased, and the best orientation performance was observed for a film doped with 70% SnO. Further, the thermal stability improved and anchoring energy increased, which was measured to be very close to that of the rubbed polyimide film. The low transmittance of InO was overcome by doping with SnO, which has high transmittance. In the film doped with 80% SnO, the LC molecules were aligned in a vertical direction and were suitable for VA mode operation. By simple adjustment of the doping ratio, differences are observed with respect to the existing films in that the performance of the alignment layer is improved and the pretilt angles of the LC molecules can be changed. These convertible characteristics are expected to play a revolutionary role in the development of new LC driving modes.

Improvement of crossflow model of MULTID component in MARS-KS with inter-channel mixing model for enhancing analysis performance in rod bundle

MARS-KS, a domestic regulatory confirmatory code of Republic of Korea, had been developed by integrating RELAP5/MOD2 and COBRA-TF. The integration of COBRA-TF allowed to extend the capability of MARS-KS, limited to one-dimensional analysis, to multi-dimensional analysis. The use of COBRA-TF was mainly focused on subchannel analyses for simulating multi-dimensional behavior within the reactor core. However, this feature has been remained as a legacy without ongoing maintenance. Meanwhile, MARS-KS also includes its own multi-dimensional component, namely MULTID, which is also feasible to simulate three-dimensional convection and diffusion. The MULTID is capable of modeling the turbulent diffusion using simple mixing length model. The implementation of the turbulent mixing is of importance for analyzing the reactor core where a disturbing cross-sectional structure of rod bundle makes the flow perturbation and corresponding mixing stronger. In addition, the presence of this turbulent behavior allows the secondary transports with net mass exchange between subchannels. However, a series of assessments performed in previous studies revealed that the turbulence model of the MULTID could not simulate the aforementioned effective mixing occurred in the subchannel-scale problems. This is obvious consequence since the physical models of the MULTID neglect the effect of mass transport and thereby, it cannot model the void drift effect and resulting phasic distribution within a bundle. Thus, in this study, the turbulence mixing model of the MULTID has been improved by means of the inter-channel mixing model, widely utilized in subchannel analysis, in order to extend the application of the MULTID to small-scale problems. A series of assessments has been performed against rod bundle experiments, namely GE 3X3 and PSBT, to evaluate the performance of the introduced mixing model. The assessment results revealed that the application of the inter-channel mixing model allowed to enhance the prediction of the MULTID in subchannel scale problems. In addition, it was indicated that the code could not predict appropriate phasic distribution in the rod bundle without the model. Considering that the proper prediction of the phasic distribution is important when considering pin-based and/or assembly-based expressions of the reactor core, the results of this study clearly indicate that the inter-channel mixing model is required for analyzing the rod bundle, appropriately.

Seismic vulnerability of shield tunnels in interbedded soil deposits: Case study of submarine tunnel in Shantou Bay

This paper presents a numerical approach for deriving seismic fragility curves for a submarine shield tunnel subjected to transverse ground shaking in interbedded soil deposits. To simulate the nonlinear behavior of soils, PM4Sand and HS-small constitutive models were adopted. In contrast, the closed-form elastic design method or elastic–plastic design method was used for modeling the shield tunnel lining considering the effect of joints on the seismic performance of structures. Fully coupled numerical analyses provided a satisfactory interpretation of the seismic responses of soil–structure systems considering the effects of groundwater level and soil–tunnel interaction. Subsequently, free-field peak ground acceleration was selected as the intensity measure. The ratio of maximum bending moment to capacity bending moment or permanent joint rotation of the tunnel lining was selected as the damage measure, combined with incremental dynamic analysis, a series of fragility curves were generated. In this study, one-dimensional equivalent-linear earthquake site response analysis was implemented to validate the nonlinear dynamic analysis under weak earthquakes. However, the analysis overestimates the amplitude periodic vibrations in interbedded soil deposits under strong earthquakes. Additionally, numerical results show that the examined tunnel is prone to slight or moderate damage under ground shaking, and its joints are more vulnerable to damage than its segments. The fragility curves constructed were compared with existing fragility curves, highlighting the significant effects of local soil profiles, groundwater conditions, soil–tunnel interaction, and segmental joints on the seismic vulnerability of shield tunnels in a submarine environment. The developed fragility functions contribute to the prediction of seismic damage to submarine shield tunnels of similar characteristics, enabling the rapid and efficient response of structures to disasters in ocean engineering.