Full 3D Model Research Articles

A Simplified Approach to Simulate Quench Development in a Superconducting Magnet

Cross-sectional 2D models often represent a computationally efficient alternative to full 3D models, when simulating complex multi-physical magnet systems. However, especially for the case of self-protected, superconducting magnets, where the stored energy has to be dissipated within the magnet coils, the thermal diffusion and the quench development in all three dimensions become key aspects. In order to further improve the simulation of transients in 2D models, a new modelling method for simplified quench development along the direction of the transport current is introduced. The original 2D model is hereby utilized for modelling the thermal domain, and the electrical resistance of each turn is scaled by the estimated time-dependent fraction of quenched conductor. Furthermore, the turn to turn quench propagation following the electrical connections is implemented. The proposed approach allows a very computationally efficient and easy-to-implement calculation since the model is effectively two-dimensional while providing a good approximation of the coil resistance development with sufficient accuracy. In order to illustrate the proposed quench-propagation modelling approach, simulations are compared to experimental results for the case of a self-protected, superconducting Nb-Ti dipole magnet. In general, a very good agreement between measurements and simulations was achieved.

Research on a Design and Manufacturing Integration Mode Based on a Full 3D Model

In view of issues such as low reuse rate of three-dimensional design model in process and production during product research and design, insufficient ability of 3D process design and optimization application, and urgent needs for a closed-loop design-manufacture-inspection integrated control system based on 3D model, this paper is centered around the digital definition and application technologies based on 3D models and facing full process information of product design-process design-production-inspection, combining the product development process, and studies the design and manufacturing integration framework based on a full 3D model, software architecture and data integration management architecture. This paper too selects products with multi-subject features as verification objects and verifies the feasibility and superiority of the integrated design-production-inspection development mode based on a full 3D model.

Fighting the storm: could novel anti-TNFα and anti-IL-6 C. sativa cultivars tame cytokine storm in COVID-19?

The main aspects of severe COVID-19 disease pathogenesis include hyper-induction of proinflammatory cytokines, also known as ‘cytokine storm’, that precedes acute respiratory distress syndrome (ARDS) and often leads to death. COVID-19 patients often suffer from lung fibrosis, a serious and untreatable condition. There remains no effective treatment for these complications. Out of all cytokines, TNFα and IL-6 play crucial roles in cytokine storm pathogenesis and are likely responsible for the escalation in disease severity. These cytokines also partake in the molecular pathogenesis of fibrosis. Therefore, new approaches are urgently needed, that can efficiently and swiftly downregulate TNFα, IL-6, and the inflammatory cytokine cascade, in order to curb inflammation and prevent fibrosis, and lead to disease remission.Cannabis sativa has been proposed to modulate gene expression and inflammation and is under investigation for several potential therapeutic applications against autoinflammatory diseases and cancer. Here, we hypothesized that the extracts of novel C. sativa cultivars may be used to downregulate the expression of pro-inflammatory cytokines and pathways involved in inflammation and fibrosis.Initially, to analyze the anti-inflammatory effects of novel C. sativa cultivars, we used a well-established full thickness human 3D skin artificial EpiDermFTTM tissue model, whereby tissues were exposed to UV to induce inflammation and then treated with extracts of seven new cannabis cultivars. We noted that out of seven studied extracts of novel C. sativa cultivars, three (#4, #8 and #14) were the most effective, causing profound and concerted down-regulation of COX2, TNFα, IL-6, CCL2, and other cytokines and pathways related to inflammation and fibrosis. These data were further confirmed in the WI-38 lung fibroblast cell line model. Most importantly, one of the tested extracts had no effect at all, and one exerted effect that may be deleterious, signifying that careful cannabis cultivar selection must be based on thorough pre-clinical studies.The observed pronounced inhibition of TNFα and IL-6 is the most important finding, because these molecules are currently considered to be the main targets in COVID-19 cytokine storm and ARDS pathogenesis.Novel anti-TNFα and anti-IL-6 cannabis extracts can be useful additions to the current anti-inflammatory regimens to treat COVID-19, as well as various rheumatological diseases and conditions, and ‘inflammaging’ - the inflammatory underpinning of aging and frailty.

A computationally efficient hybrid 2D\u20133D subwoofer model

A subwoofer generates the lowest frequency range in loudspeaker systems. Subwoofers are used in audio systems for live concerts, movie theatres, home theatres, gaming consoles, cars, etc. During the last decades, numerical simulations have emerged as a cost- and time-efficient complement to traditional experiments in the design process of different products. The aim of this study is to reduce the computational time of simulating the average response for a given subwoofer design. To this end, we propose a hybrid 2D–3D model that reduces the computational time significantly compared to a full 3D model. The hybrid model describes the interaction between different subwoofer components as interacting modules whose acoustic properties can partly be pre-computed. This allows us to efficiently compute the performance of different subwoofer design layouts. The results of the hybrid model are validated against both a lumped element model and a full 3D model over a frequency band of interest. The hybrid model is found to be both accurate and computationally efficient.

2DSlicesNet: A 2D Slice-Based Convolutional Neural Network for 3D Object Retrieval and Classification

3D data can be instrumental to the computer vision field as it provides insightful information about the full 3D models' geometry. Recently, with easy access to both computational power and huge 3D databases, it is feasible to apply convolutional neural networks to automatically extract the 3D models' features. This paper presents a novel approach, called 2DSlicesNet, which deals with the issue of 3D model retrieval and classification using a 2D slice-based representation with a 3D convolutional neural network. The assumption in this context is that similar 3D models will be composed of almost identical 2D slices. Therefore, we first transform each normalized 3D model into a set of 2D slices corresponding to its first main axis, and then use them as input data to our 3D convolutional neural network. Experimental results and comparison with state-of-the-art approaches, using ModelNet10 and ModelNet40 datasets, prove that our proposed 2DSlicesNet approach can reach notable rates of accuracy in classification and retrieval.

Modelling the non-local thermodynamic equilibrium spectra of silylene (SiH2).

This paper sets out a robust methodology for modelling spectra of polyatomic molecules produced in reactive or dissociative environments, with vibrational populations outside local thermal equilibrium (LTE). The methodology is based on accurate, extensive ro-vibrational line lists containing transitions with high vibrational excitations and relies on the detailed ro-vibrational assignments. The developed methodology is applied to model non-LTE IR and visible spectra of silylene (SiH2) produced in a decomposition of disilane (Si2H6), a reaction of technological importance. Two approaches for non-LTE vibrational populations of the product SiH2 are introduced: a simplistic 1D approach based on the Harmonic approximation and a full 3D model incorporating accurate vibrational wavefunctions of SiH2 computed variationally with the TROVE (Theoretical ROVibrational Energy) program. We show how their non-LTE spectral signatures can be used to trace different reaction channels of molecular dissociations.

Improving precision of material extrusion 3D printing by in-situ monitoring & predicting 3D geometric deviation using conditional adversarial networks

Material extrusion 3D printing has long been established for rapid prototyping and functional testing in many research and industry fields. However, its inconsistency and intrinsic defects (surface roughness and geometric inaccuracies) hinder its application in several areas, most notably “certify-as-you-build” small-batch prototyping and large-batch production. In this study, we present an approach to reduce both inconsistency and the 3D geometric inaccuracies of products fabricated by material extrusion. To achieve these improvements in print quality, we developed an in situ metrology system, which scans each layer at the time of printing, providing a 3D model of the as-printed part. We then trained machine learning algorithms with data from this scanning system and predicted 3D geometric inaccuracies in new designs. Eight conditional adversarial network (CAN) machine learning models were trained on a limited number of scanned profile images of different layers, consisting of less than 50 actual images and 50 generated images, to predict the 3D geometric deviations of freeform shapes. The generated images were produced by randomly combining and cropping the actual images without any distortion. These CAN models produced predictions where at least 44.4%, 87.6%, 99.2% of data were within ± 0.05 mm, ± 0.10 mm, ± 0.15 mm of the actual measured value, respectively. A laser sensor was integrated into a material extrusion 3D printer to achieve in situ monitoring of dimensional inaccuracies during printing, which leaves the door open to implement a closed-loop feedback system to compensate geometric errors during printing in the future and fabricate “certify-as-you-build” products. • Developed a metrology system to provide a full 3D model of the as-printed part. • Monitored dimensional inaccuracies in situ during printing. • Trained Conditional Adversarial Networks (CAN) with data from this scanning system. • Predicted 3D geometric deviations of freeform shapes from CAD models. • Reduced inconsistency & inaccuracies of products fabricated by material extrusion.

AP1000 IRWST numerical analysis with GOTHIC

The AP1000 Passive Residual Heat Removal (PRHR) system plays a significant role as it helps to remove the core decay heat, using the In-containment Refueling Water Storage Tank (IRWST) as a heat sink. The IRWST is located above the core, promoting natural circulation and allowing to be the mid-term heat-sink for the reactor core. The thermo-hydraulic pool behavior during an accident has an influence in the containment pressure and temperature, as happens in the pressure suppression pool in BWR reactors.Due to the importance of the IRWST performance on the AP1000 containment, a numerical analysis of a scaled experiment has been done using the GOTHIC code. Firstly, an IRWST scaled-down model is created, a mesh sensitivity analysis is performed, and the results obtained are compared against experimental results available in the literature. It is found the importance of the mesh discretization for the proper thermal-stratification modeling. Then, the reference model setup and mesh are applied in a full-scale prototypic model. The mesh influence on the thermal stratification is analyzed, as well as its impact on the AP1000 containment pressure. The mesh and setup for the full-scale model are selected to be implemented in a full containment 3D model in future works.

Wave and structure interaction using multi-domain couplings for Navier-Stokes solvers in OpenFOAM®. Part I: Implementation and validation

This paper and its companion (Di Paolo et al., 2020b) present near-far field coupling schemes of Navier-Stokes (NS) equations for high-fidelity numerical modelling of wave generation, transformation and interaction with structures. The computational domain is subdivided into near and far field zones (2D and 3D subdomains, respectively) in which the NS equations are solved adopting the Finite Volume Method. The couplings can be made through the one-way or two-way exchange of flow information, thus providing a complete tool for studying one or bi-directional processes in which the three-dimensional flow is expected to be confined in the near field. The global coupled system, which is built on the OpenFOAM® platform, is based on a multi-domain approach in which the sub-domains (i.e., 2D and 3D meshes) are built independently.In Part I, the coupling methodologies have been validated against full 3D models taking into account wave propagation under different conditions with excellent results and high efficiency.Part 2 (Di Paolo et al., 2020b) involves the validation and application of the proposed methodologies to complex wave-structure interaction studies.

Experimental and numerical investigation on penetration of clay masonry by small high-speed projectile

This study investigates a kind of masonry consisting of clay-fired brick (fc = 10 MPa; ρ=1.38g/cm3) and mortar (fc = 10 MPa; ρ=1.8g/cm3). Clay-fired brick masonry connotes a traditional construction material of old architecture and public buildings. We carried out penetration experiments in which four clay-fired brick walls employing two different patterns were subjected to impact from small high-speed projectile, i.e. 12.7 mm armor-piercing explosive incendiary projectile and material tests in which the static and dynamic compressive strengths of clay-fired brick and mortar were determined by quasi-static and SHPB (Split Hopkinson Pressure Bar) tests. The experimental data include hit and exit velocities, damage configuration of clay brick masonry and mechanical properties of material at low and high strain rates, though which influence of thickness and bonding patterns of wall on kinetic loss of bullet, the damage patterns of masonry observed experimentally and dynamic increase of material strengths are analyzed. To keep minimum boundary inconsistency with reality, full 3D detailed finite element model consisting of two different material is established. Sharing common nodes and employing automatic tiebreak contact are combined to reduce computational time usage of large-scale model. For description of clay-fired brick and mortar Riedel–Hiermaier–Thoma (RHT) material model is employed. Material parameter set is derived based on experimental data, available literature and engineering assumptions. The numerical simulations study the mesh resolution dependency of material model, reproduce the crucial phenomena of masonry in experiment acceptably and offer more time-resolved insight into motion of bullet in the process of penetration. The feasibility of means of constructing finite element model and applying RHT model to the masonry herein and analogous constructions is explored through numerical investigation.

Numerical modelling of thin anisotropic membrane under dynamic load

ABSTRACTThis work aims to describe a mathematical model and a numerical method to simulate a thin anisotropic membrane moving and deforming in 3D space under a dynamic load of an arbitrary time and space profile. The anisotropic continuum medium model described in the article can be used to model a membrane made of composite material using its effective elastic parameters. The model and the method allow the consideration of problems when the quasi-static approximation is not valid and elastic waves caused by the impact should be calculated. The model and the method can be used for numerical study of different processes in thin composite layers, such as shock load, ultrasound propagation, non-destructive testing procedures and vibrations. The thin membrane is considered as a 2D object in 3D space, an approach that allows a reduction in the computational time compared with full 3D models, while still having an arbitrary material rheology and load profile.

An Analytical-Numerical Approach to Model and Analyse Squirrel Cage Induction Motors

Nowadays, finite element analysis represents the most accurate tool to analyse electrical machines. However, the time domain resolution of electromagnetic problem, in some cases, requires long simulation time due to the induced nature of the currents. The computational burden increases when the machine features a skewed layout on the stator or rotor structures, since this requires 2D multi-slices approximated analysis or even a full 3D model. In this paper, a general analytical method to model electromagnetic devices is applied to a squirrel cage induction motor featuring a skewed rotor structure. The modelling approach is wisely implemented and adapted to pursue a fair balance between accuracy of the analysis and computational burden, taking advantage of all the symmetries existing in the rotor cage of the machine, aiming to minimize the model complexity. A comparative analysis in term of the inductances between analytical and finite element is proposed. The results provided by the model developed are compared with respect to the corresponding values provided by both finite element and experimental test performed on the reference machine. Such comparisons show that the proposed model is actually able to achieve a pretty good balance between accuracy and computational efficiency.

Study of the Radio Frequency (RF) performance of a Wafer-Level Package (WLP) with Through Silicon Vias (TSVs) for the integration of RF-MEMS and micromachined waveguides in the context of 5G and Internet of Things (IoT) applications. Part 2: parameterised 3D model and optimisation

This study discusses the exploitation of a full-3D methodology for the electromagnetic simulation of a Wafer-Level Packaging solution featuring Through Silicon Vias (TSVs) for the redistribution of electrical signal from the in-package (RF-MEMS) passive devices to the external world. In particular, the Finite Element Method full-3D model is parameterised and allows analysing the influence of the most relevant Degrees of Freedom (DoFs) available in the package design, on the RF characteristics of encapsulated RF-MEMS passive devices. A previous part of this work, already published, discussed the validation of the mentioned full-3D model, comparing the results of simulations against experimental S-parameters datasets for a certain variety of Coplanar Waveguide test structures, in a frequency range from 50 MHz up to 30 GHz. Such a comparison showed good accuracy in predicting the behaviour of physical devices. Therefore, the soundness of the optimisation approach can be regarded as proven and consolidated for the optimisation purposes of the current work.

Mechanical design of a nested 4-layer Canted Cosine Theta (CCT) dipole

Nested CCT dipoles could be used in particle accelerators and proton therapy machines to bend a beam of charged particles in any direction. In the present study, a mechanical design of a 4 layer nested CCT dipole is evaluated with Finite Element Method (FEM). A full parametric 3D model of a 2.5 Tm 4-layer CCT dipole has been developed using the APDL scripting in the ANSYS software. The, so called, bottom up approach with direct generation of nodes and elements has been utilized, optimizing for the speed of the model generation as the time consuming meshing was bypassed. The properties of the Nb-Ti strands with the surrounding CTD-101K epoxy were obtained with a dedicated homogenization model. Resulting orthotropic properties were fully accounted for in the simulation. The shear stresses in the bonding composite layer: Kapton+S2-glass+CTD-101K were computed. With the results above the limit of 10 MPa, the necessity to provide additional rigidity against the torque was confirmed – castellated design. The shear stresses were mostly caused by thermal effects, and only ~25 % was caused by the Lorentz forces. The influence of the boundary conditions was analysed, leading to their optimal choice limiting the deformation due to Lorentz forces to 91 μm.

Study of the Radio Frequency (RF) performance of a Wafer-Level Package (WLP) with Through Silicon Vias (TSVs) for the integration of RF-MEMS and micromachined waveguides in the context of 5G and Internet of Things (IoT) applications: Part 1—validation of the 3D modelling approach

Packaging of Radio Frequency MicroElectroMechanical-Systems (RF-MEMS) and other passive components is a delicate issue, especially in the riverbed of upcoming application contexts like 5G and the Internet of Things, in which frequencies of operation are getting closer to mm-Waves (millimetre waves). In fact, when dealing with RF signals, the package, beyond protecting encapsulated devices, has also to exert an influence as limited as possible on their electromagnetic characteristics and performance. Therefore, the package design phase has to be performed with particular care. Given such a frame of reference, this study discusses the validation against experimental data of a full-3D methodology for the electromagnetic simulation of a Wafer-Level Packaging solution featuring Through Silicon Vias for the redistribution of electrical signal from the in-package (RF-MEMS) passive devices to the external world. In particular, the results of the full-3D finite element method RF simulations will be compared against experimental S-parameters datasets for a certain variety of Coplanar Waveguide test structures, in a frequency range from 50 MHz up to 30 GHz, showing good accuracy in predicting the behaviour of physical devices. For the sake of brevity, this work will be followed by a standalone second part in which the full-3D model, here validated, will be parameterised and exploited to analyse the influence of the most relevant Degrees of Freedom available in the package design, on the RF characteristics of encapsulated RF-MEMS passive devices.

3D microstructure design of lithium-ion battery electrodes assisted by X-ray nano-computed tomography and modelling

Driving range and fast charge capability of electric vehicles are heavily dependent on the 3D microstructure of lithium-ion batteries (LiBs) and substantial fundamental research is required to optimise electrode design for specific operating conditions. Here we have developed a full microstructure-resolved 3D model using a novel X-ray nano-computed tomography (CT) dual-scan superimposition technique that captures features of the carbon-binder domain. This elucidates how LiB performance is markedly affected by microstructural heterogeneities, particularly under high rate conditions. The elongated shape and wide size distribution of the active particles not only affect the lithium-ion transport but also lead to a heterogeneous current distribution and non-uniform lithiation between particles and along the through-thickness direction. Building on these insights, we propose and compare potential graded-microstructure designs for next-generation battery electrodes. To guide manufacturing of electrode architectures, in-situ X-ray CT is shown to reliably reveal the porosity and tortuosity changes with incremental calendering steps.

Empirical flash flood vulnerability functions for residential buildings

The estimation of flood losses is crucial for the quantitative estimation of risk and the cost–benefit analysis of risk mitigation and prevention measures. Flood losses are usually estimated by means of vulnerability functions, which are often developed in a synthetic way by experts, since loss datasets collected after events are sparse or lacking and mostly refer to slow riverine inundations. Simple univariable empirical vulnerability functions are recognized as a more valuable tool with respect to synthetic curves developed for different contexts. The aim of this work is to derive empirical vulnerability functions for a flash flood event which occurred in Livorno (Italy) in September 2017, based on the hydrologic–hydraulic reconstruction of the flood and observed losses to residential properties. The hydrologic processes are reproduced with a distributed hydrologic model, and the flood propagation is simulated with a full 2D model. Many open GIS data are used and combined with virtual on-site inspection in the study area to analyze building exposure. Different regression curves are tested to fit the data and obtain damage curves. The results show (i) a poor correlation between relative or absolute losses and flow velocity, (ii) a low correlation between relative losses and water depth, thus confirming the existing literature. More significant correlation is found between absolute losses and water depths. The curves here derived provide a first attempt to develop damage functions for flash flood in Italy, which could be applied in similar urban and morphologic contexts.

Study of coupling between shaft bending and disc zero nodal diameter modes in a flexible shaft-disc assembly

In a shaft-disk flexible assembly supported by linear bearings, the disk 1ND modes couple with the shaft lateral modes, whilst the 0ND “umbrella” modes couple with the shaft axial modes. The objective of this work is to investigate and quantify the coupling between disk 0ND modes and shaft lateral modes and its correlation with some innovative, oriented bearing supports, which couple shaft axial and lateral displacements. This phenomenon is investigated via two different models. In the first one, the shaft in isolation is considered and modelled with 1D beam elements. It is found that, if the supporting structure of the shaft is asymmetric, some lateral modes couple with the axial mode, giving rise to the so called “mixed modes”. In the second part of this work, a full 3D model of the assembly is implemented and a parametric study is carried out, varying the parameters of the supporting structure (stiffness and orientation) and of the disk (position along the shaft). A physical explanation of this coupling is provided, taking into account the reaction forces/moments at the interface between shaft and disk and the dynamic response of the separate components. The limitations of the current approach to modes coupling are also highlighted throughout this work.

Integrated hydrodynamic model for simulation of river-lake-sluice interactions

In this paper, an integrated model for simulating the hydrodynamic process of river-lake-sluice (RLS) systems is presented. It includes a novel one-dimensional (1D) and two-dimensional (2D) coupling method called the coupling-zone iteration-correction (CZIC) method, and an improved numerical algorithm for the sluice problem. The 1D river-network model and the 2D lake model are coupled by establishing a coupling region, and iterative correction is carried out to ensure the accurate transfer of hydraulic parameters. The convergence conditions of the CZIC method are discussed theoretically, and the proper spatial step of the coupling zone is adopted according to different inflow conditions to ensure stable computation. In order to deal with the transition of flow regimes during the gate operation, a method for calculating the discharge capacity is presented. In addition, a general difference coefficient of the river reach is deduced for hydrodynamic calculation with sluices included. Simulations on open channels demonstrate that (1) simulated values of the CZIC method are consistent with the results of the full 2D model; (2) the sluice solving algorithm can stably handle the flow transition between the orifice flow and weir flow. Furthermore, the developed integrated model is applied to the middle and lower reaches of the Huaihe River, including the Hongze Lake and fifteen sluices. Numerical simulation results reproduced the hydrodynamic process during the flood season of 2007 accurately and efficiently. The errors of the present model are also compared with that of the MIKE model, and the results show that the proposed methods perform better than MIKE, especially in rising and flood periods. Therefore, it seems likely that the developed integrated model will work well in hydrodynamic modelling of large-scale complex RLS systems.

An Implicit Coupled 1D/2D Model for Unsteady Subcritical Flow in Channel Networks and Embayment

In this study, 1D and 2D shallow-water models were coupled to simulate unsteady flow in channel networks and embayment. The 1D model solved the 1D shallow-water equations (St. Venant) using the Preissmann box method and targeted long narrow reaches of the river networks, while the 2D model targeted broad channels and embayment and solved the 2D shallow-water equations using a semi-implicit scheme applied to an unstructured grid of triangular cells. The 1D and 2D models were solved simultaneously by building a matrix for the free surface elevation at every 1D junction and 2D cell center. Velocities were then computed explicitly based on the results at the previous time step and the updated water level. The originality of the scheme arose from a novel coupling method. The results showed that the coupled 1D/2D model produced identical results as the full 2D model in classical to benchmark problems with considerable savings in computational effort. Application of the model to the Pearl River Estuary in southern China showed that complex patterns of tidal wave propagation could be efficiently modeled.