Coupling Procedure Research Articles

Scaled boundary isogeometric analysis with C1 coupling for Kirchhoff‐Love theory

AbstractScaled boundary isogeometric analysis (SB‐IGA) describes the computational domain by proper boundary NURBS together with a well‐defined scaling center; see [5]. More precisely, we consider star convex domains whose domain boundaries correspond to a sequence of NURBS curves and the interior is determined by a scaling of the boundary segments with respect to a chosen scaling center. However, providing a decomposition into star shaped blocks one can utilize SB‐IGA also for more general shapes. Even though several geometries can be described by a single patch, in applications frequently there appear multipatch structures. Whereas a C0 continuous patch coupling can be achieved relatively easily, the situation becomes more complicated if higher regularity is required. Consequently, a suitable coupling method is inevitably needed for analyses that require global C1 continuity.In this contribution we apply the concept of analysis‐suitable G1 parametrizations [2] to the framework of SB‐IGA for the C1 coupling of planar domains with a special consideration of the scaling center. We obtain globally C1 regular basis functions and this enables us to handle problems such as the Kirchhoff‐Love plate and shell, where smooth coupling is an issue. Furthermore, the boundary representation within SB‐IGA makes the method suitable for the concept of trimming. In particular, we see the possibility to extend the coupling procedure to study trimmed plates and shells.The approach was implemented using the GeoPDEs package [1] and its performance was tested on several numerical examples. Finally, we discuss the advantages and disadvantages of the proposed method and outline future perspectives.

Development of 3D transient neutronics and thermal-hydraulics coupling procedure and its application to a fuel pin analysis

This paper develops a three-dimensional fine-mesh coupled neutronics and thermal-hydraulics platform based on the open-source software OpenFOAM. For the neutronics, a three-dimensional multi-group multi-region neutron diffusion solver is developed for steady and transient problems with macroscopic cross-sections generated by the Monte Carlo code OpenMC. By modeling and calculating three typic neutronic benchmark problems, the results are compared with that of other programs to verify the correctness of this solver to solve neutron diffusion equations. The thermal-hydraulics is solved by the built-in solid-fluid conjugated heat transfer solver for steady or transient fluid flow and solid heat conduction between different regions. The unified solution of a coupled neutronic and thermal-hydraulic problem is implemented in the solver with the same time step size and the same set of meshes. The feasibility and rationality of this coupling procedure is verified through the simulation the 5×5 PWR assembly. Furthermore, the operator-splitting semi-implicit (OSSI) method and the fixed-point implicit (FPI) method have been applied to the coupling procedure. The performance of the above two neutronic and thermal-hydraulic coupling algorithms is evaluated by simulating the coolant inlet temperature decrease accident in a single fuel pin model of the pressurized water reactor. The numerical results indicate that the FPI coupling method outperforms the OSSI coupling method due to its accuracy and stability.

Combining numerical tools to determine wave forces on moored ships

Accurate modelling of waves in harbours and the response of moored ships to that type of forcing is of prime importance to determine the safety and workability of ships moored at berths exposed to local wave conditions. This study investigates the combination of a non-hydrostatic wave-flow model (SWASH) and a 3D boundary-integral diffraction model (Harberth) to compute wave forces acting on moored ships. A series of systematic numerical tests has been performed to develop the proposed methodology and gain insight on its limits of application. The approach is validated using physical scale model test data of waves and forces acting on a restrained ship. Results indicate a good performance even for extremely energetic wave conditions, setting the investigated modelling approach as a potential alternative for future applications. • The SWASH and Harberth models are coupled to simulate the interactions between waves and moored ships. • The wave modelling is the main potential source of inaccuracies to the overall approach. • The coupling procedure does not introduce additional requirements to the wave simulations. • The approach is effective for extreme non-linear waves in intermediate/shallow waters and influenced by complex geometry.

Gas Permeability Evolution of Coal with Inclusions under Triaxial Compression-Lab Testing and Numerical Simulations

Coalbed methane (CBM) exploitation leads to permanent stress redistributions in the coal bodies connected with fracturing processes and permeability changes due to deformation induced internal pore-fracture networks. Gas permeability evolution of coal samples is investigated with a newly developed three-dimensional fluid-mechanical coupled experimental system. X-ray CT is used to investigate the internal structure of the coal samples and delivers the basis to set-up numerical twins. The work focuses on coal samples with inclusions. A novel coupling procedure between two different tools-discontinuum and continuum codes-is established to simulate the permeability evolution. The permeability is related to the crack pattern in general, and crack width in particular. A prediction of permeability is proposed based on fracture distribution and microcrack behavior. The experimental studies validated the coupling approach. Shear fractures cause substantial permeability enhancement. Piecewise relations between permeability and volumetric strain can be used to fit the whole process, where a nonlinear exponential relation is established after the expansion point. The inclusions as important structural characteristics influence this relation significantly.

Assessment of the Shadow Auction Mechanism as a Fallback Procedure for Single Day-Ahead Coupling

Assessment of the Shadow Auction Mechanism as a Fallback Procedure for Single Day-Ahead Coupling

A new SDDA-based numerical approach for simulating rock cracking induced by temperature stresses

Temperature-induced rock failure occurs in geothermal exploitation, nuclear disposal, and other underground engineering scenarios. In this paper, the conventional spherical discontinuous deformation analysis (SDDA) method is extended to simulate the temperature-induced rock failure problems. Firstly, an improved bonded sphere algorithm is proposed to precisely modeling rock failure behavior in the SDDA framework. Secondly, a heat conduction model based on the thermal conductivity pipe between spheres is proposed and further implemented in the SDDA program through an explicit thermal–mechanical coupling procedure. Thirdly, three typical examples are selected to verify the accuracy of the heat conduction model by comparing the temperature evolution between numerical and analytical results. Finally, the improved SDDA model was applied to analyze several experimental cases involving thermal cracking, including lab-scale experiments and field-scale examples. The simulation results show that the improved SDDA approach is effective for the simulation of the temperature-induced crack propagation process.

Preparation of nanofiber core-spun yarn based on cellulose nanowhiskers/quaternary ammonium salts nanocomposites for efficient and durable antibacterial textiles

Antibacterial fabrics are critical for the prevention of illness. Herein, we present a strategy for the preparation of a novel efficient and durable antibacterial nanofiber core-spun yarn (NCY) and antibacterial textile based on cellulose nanowhiskers (CNWs)/quaternary ammonium salts (QASs) composites for addressing the problems of easy shedding of antibacterial agents, unstable antibacterial effect, and triggering bacterial resistance in traditional antibacterial textiles. Through a facile coupling procedure, QAS and CNW are synthesized as CNW-QAS, which is a stable nanocomposite antibacterial agent. Based on a conjugated electrospinning device, CNW-QASs are firmly immobilized on the CNW-QAS/polyacrylonitrile (PAN) nanofiber shell layer by combining in situ doping with co-spinning to construct CNW-QAS/PAN NCY with efficient, fast and durable antibacterial properties. Its antibacterial rates against E. coli and S. aureus are both 99.99% even after multiple washes and long-term storage. In addition, the antibacterial yarn possesses a stress of 42.25 MPa and strain of 96.08%, providing excellent mechanical properties and flexibility. The exceptional performance makes CNW-QAS/PAN NCY a promising candidate for next generation antibacterial textiles.

Large-Eddy Simulation of a Water Jet Exhausting into Quiescent Air

This study focuses on a water injection system, typical of those used to inject water in the motor jet plume of rocket engines to reduce noise, and particularly on the destabilization of the liquid jet that leads to a spray system. For that purpose, a large-eddy simulation is conducted for an experimental water jet of the literature. It is a sprinkler whose Reynolds number is and nozzle exit diameter is , similar to injectors used for jet noise reduction studies at a reduced scale. A diffuse interface method is used to calculate the dense liquid phase, and the dispersed phase containing droplets is calculated with an Eulerian solver. Transfers between the dense and the dispersed phases are modeled in the coupling procedure, including the atomization and impingement processes. The jet mean radius and initial instability frequency are consistent with the experimental data, while the position of the jet transition varies with the fluctuation levels at the nozzle exit. The droplets are created in the shear layer and accumulate on the jet center when only the atomization process is considered. When also implemented, the impingement phenomenon, however, is shown to absorb the droplets before they reach the center.

A multiscale method coupling peridynamic and boundary element models for dynamic problems

A novel multiscale method coupling peridynamics (PD) and boundary element method (BEM) is proposed for dynamic problems. In the coupling model, the discontinuous behaviors of materials such as crack development and branching processes are simulated by PD while the boundary and infinite domain are modeled by time-domain BEM, which can take full advantage of their salient features. A general stiffness matrix is introduced in the coupling model to combine the PD and BEM governing equations in such a way that the continuity of displacement and the equilibrium of tractions at the PD-BEM interface are satisfied. A variable horizon method is developed to further eliminate boundary effects and ghost forces at the coupling interface between PD and BEM. Then, a concurrent coupling procedure of PD and BEM is established and its implementation is also introduced based on the dynamic explicit algorithm, i.e. the central difference method. The proposed coupling method is verified by comparing its predictions with those from analytical and experimental results. Numerical examples demonstrate the applicability of the proposed model for wave propagation, infinite domain and fracture problems under dynamic loads.

Real Spinors and Real Dirac Equation

We reexamine the minimal coupling procedure in the Hestenes' geometric algebra formulation of the Dirac equation, where spinors are identified with the even elements of the real Clifford algebra of spacetime. This point of view, as we argue, leads naturally to a non-Abelian generalisation of the electromagnetic gauge potential.

Synthesis of Scyllatoxin-Based BH3 Domain Mimetics with Diverse Patterns of Native Disulfide Bonds.

This article outlines the design and development of scyllatoxin (ScTx)-based BH3 domain mimetics with diverse patterns of native disulfide bonds. More specifically, this method summarizes the total chemical synthesis of ScTx-based peptides that contain zero, one, two, or three disulfide linkages, including techniques to generate variants with any combination of native disulfides. Each peptide reported herein is generated on solid-phase support using microwave-assisted coupling procedures, and all reaction parameters related to the peptide synthesis are described in detail. The various disulfide patterns of the ScTx-based constructs are established during peptide synthesis and are ultimately verified by mass analysis of trypsin-digested fragments. The BH3 domain mimetics developed herein were generated by transposing residues from the helical BH3 domain of the pro-apoptotic BCL2 protein Bax to the α-helix of wild-type ScTx. Interestingly, we found that the relative binding affinities of ScTx-Bax peptides for the anti-apoptotic BCL2 protein Bcl-2 (proper) were heavily influenced by the number and position of disulfide linkages within the ScTx-Bax sequence. As a consequence, we were able to utilize ScTx-Bax BH3 domain mimetics with varied patterns of disulfide bonds to survey how structural rigidity within the helical Bax BH3 domain affects binding to promiscuous anti-apoptotic BCL2 proteins. More broadly, the ability to generate ScTx-based molecules that contain any combination of native disulfide bonds expands the utility of such constructs as tools to study the molecular nature of protein-protein interactions. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Synthesis and characterization of ScTx-based Bax BH3 domain mimetics Basic Protocol 2: Oxidation of ScTx-Bax BH3 domain mimetics containing one, two, or three disulfide linkages Support Protocol: Mapping of disulfide linkages in oxidized ScTx-Bax BH3 domain mimetics.

A coarse-grained concurrent multiscale method for simulating brittle fracture

This paper proposed a concurrent multiscale method for modeling crack propagation in brittle solids. The method couples the continuum finite element domain with a recently-developed coarse-grained atomistic potential, which has been developed to simulate crack nucleation and propagation within the molecular dynamics domain. The main advantage of this potential is to suppress dislocation nucleation from the crack tip which significantly eases the coupling procedure. In this multiscale framework, complexities like large deformation, crack nucleation and propagation are simulated in the atomistic domain while the rest such as elastic wave propagation and boundary conditions are modeled in the continuum domain. As a result, the atomistic area will be limited around the cracking zone which increases the computational efficiency. Two examples of edge crack propagation and sliding surfaces in contact are presented and compared with the fully atomistic models to verify and check the efficiency of the proposed multiscale method. The comparison shows that the proposed method can accurately capture the crack formation while the computation cost reduces significantly.

A simpler and greener alternative route for anchoring carbohydrates with structural integrity on silica and glass supports

A novel, straightforward, and environmentally friendly direct coupling procedure to immobilize carbohydrates on solid supports is presented. A characterization study showed that all amino groups on solid supports participated in the linkage with a carbohydrate unit, implicating that the surface load can be easily adjusted by tuning the amination coverage of the surface. Most importantly, the integrity of the cyclic conformation of the linked sugar unit was demonstrated, a feature that is critical for most of the possible applications of carbohydrate-functionalized surfaces. Furthermore, carbohydrate-immobilized submicron particles synthesized by the direct coupling method, on which lectin profiling experiments were conducted, validated the successfulness of our simplistic approach.

Simulation of runaway electron production with CQL3D coupled to NIMROD

A coupling between two distinctly different codes—one magnetohydrodynamic (MHD) and another kinetic—is achieved and applied for simulation of runaway electron (RE) production. The 3D initial value MHD code NIMROD simulates a DIII-D pure neon shattered pellet injection plasma quench including the propagation and ablation of the fragments, ionization and recombination of the impurities, and the radiated and transported energies. The field data from NIMROD is then used by the bounce-averaged Fokker–Planck Collisional QuasiLinear 3D (CQL3D) kinetic code to simulate the production of REs and their radial transport. The coupling procedure involves mapping of data between different grids and adjustment of the NIMROD toroidal electric field when REs appear. It is shown that without the radial transport, a large RE current is generated, up to 30% of the pre-pellet ohmic current. However, when the radial transport is included in CQL3D, the RE current is reduced to undetectable level, consistent with experiment. Various forms of the radial diffusion are surveyed to determine conditions when the fast electrons would not have time to be accelerated to relativistic energies before they are lost to chamber wall.

Dynamic Smart Numbering of Modular Cargo Containers

In this paper, the authors identify the existence of container imbalance that occurs in different types of ports, depending on the type of inbound and outbound cargo they serve. The authors further analyze international trade realities and maritime companies’ requirements and identified inefficiencies. A comprehensive review of the relevant container regulations and identification standards is performed. Based on their findings, a paradigm change is proposed in the form of a modular container solution that uses disruptive digital technologies to ensure dynamic container identification (numbering) that can be exploited to overcome such inefficiencies. The technical requirements for coupling and decoupling operations are identified, along with detailed analysis of the requirements for embedded electronic components. Considering the strict container data exchange rules, the required changes in global container tracking systems are identified and explained. Coupling, decoupling, and serial number assignment procedures are proposed along with analysis of the measured lead times. Modularization and dynamic smart numbering are identified as viable disruptive technologies to address the global container imbalance. The authors contribute to the existing research on maritime transport sustainability by proposing a modular container solution, exploiting disruptive digital technologies, and clearly defining the prerequisites for the global introduction of the solution as a part of the digital transformation portfolio of involved stakeholders managing global container movements.

A receptance coupling procedure considering frequency-dependent behavior of holder-tool contact dynamics

The current paper proposes a receptance coupling (RC) procedure considering all the frequency-dependent translational and rotational dynamics of the holder-tool contact. To this end, a novel implementation of the inverse receptance coupling (IRC) is conducted. In this implementation, the holder-tool contact, which includes tool portion inserted into the holder, is treated as a flexible component that is connected to the holder, and all its translational and rotational receptances are analytically identified without any assumption, unlike the existing studies in the literature. The holder-tool contact dynamics identification is completed by using two types holders such as shrink fit and collet chuck, and a carbide tool blank inserted into these holders. This procedure is carried out for four different tool blank contact/insertion lengths for each holder. To validate the proposed procedure, the identified holder-tool contact receptances are then employed in the spindle-holder-endmill assembly or tool point displacement-to-force receptance predictions with the RC method for all the corresponding holder type-contact length combinations. Those RC predictions are also completed with the holder-contact receptances achieved via an existing method. In addition, the above-mentioned tool point displacement-to-force receptances are experimentally acquired. Afterwards, for a reliable and an efficient assessment of the proposed procedure, all the predicted and measured tool point displacement-to-force receptances are both graphically and numerically compared to each other by using a frequency-dependent magnitude similarity metric. The assessment results show that, based on the high similarity metric values, the proposed holder-tool contact identification procedure ensures a well agreement between the predictions and the measurements. Besides, both the proposed procedure and the existing method enable highly similar tool point displacement-to-force predictions.

Antimicrobial Activity and In silico ADME Prediction of Synthesised 8-hydroxyquinoline Azo Compounds against Some ESKAPE Human Pathogens and Mycobacterium smegmatis

Introduction: Antimicrobial resistance has increasingly been a global health concern over the past decades and that has necessitated the quest to increase the pool of antibiotics.
 Methods: Five (5) azo compounds were synthesised by diazotization and coupling procedures with yields of 60 – 92%. They were characterized by melting point determination, Ultra-Violet Visible, and Infra-red spectroscopy. High-throughput spot culture growth inhibition (HT-SPOTi) antimicrobial assay was used to evaluate the compounds. Computational studies was also employed to predict some pharmacokinetic properties of the azo compounds
 Results: From the in silico studies, none of the compounds violated Lipinski’s rule and therefore, have the potential to be developed into an oral drug. They also showed Total Polar Surface Area (TPSA) values < 140 A2 (74.91 – 100.98 A2) and percentage absorption of 74 – 83 %. They were placed in category III of acute oral drugs. From the high-throughput spot culture growth inhibition antimicrobial assay, all the compounds possessed inhibitory activity against the ESKAPE human pathogens and Mycobacterium smegmatis, with MICs range of 3.9 \(\geq\) 500 \(\mu g/mL\). Except for 4e which showed liver toxicity, all the compounds demonstrated mutagenic and hepatotoxic tendencies. The modulatory assay of the azo compounds revealed that 4c and 4e modulated the antimicrobial activity of ciprofloxacin against Pseudomonas aeruginosa and Staphylococcus aureus. 4c and 4e also modulated the antimicrobial activity of rifampicin against Mycobacterium smegmatis. Exploiting the ability of 4c and 4e to act by a mode of action revealed that they have biofilm formation inhibitory potential.
 Conclusion: Compounds 4c and 4e exhibited the best antimicrobial activity in terms of resistant modulation and biofilm inhibition against Pseudomonas aeruginosa, Staphylococcus aureus and Mycobacterium smegmatis.

Optimization of Automated Synthesis of Amide-Linked RNA

The recent FDA approval of several antisense and siRNA drugs illustrates the utility of nucleic acid chemical modifications, but numerous challenges remain for generalized nucleic acid therapeutics, urging the exploration of new modification strategies. Replacing backbone phosphates with amides has shown promise for enhancing siRNA activity, specificity, and nuclease resistance; however, amide-linked RNA has not been fully explored due to lengthy and low yielding manual amide coupling procedures. We have addressed this by automating the assembly of amide-linked RNA using an Expedite 8909 nucleic acid synthesizer and optimizing solid-phase synthesis conditions to achieve 91–95% yields in just 5 min of coupling time. The optimized protocol allowed synthesis of a 21-nucleotide-long siRNA guide strand having six consecutive amide linkages at the 3′-end with an overall yield of ∼1%. Our results show that the steric hindrance caused by bulky 2′-O protecting groups and steric hindrance of the solid support are the key optimization variables for improving the amide couplings.

A novel method for bounding the phase fractions at both ends in Eulerian multi-fluid model

The study aims to present a convenient but practical method to guarantee the boundedness and conservation of phase fractions in the Eulerian multi-fluid model. The established Eulerian multi-fluid model is based on the finite volume method and implemented in the platform of OpenFOAM-v2012, which is an open-source software. It is completely unnecessary to employ any reconstruction techniques or rewrite the phase continuity equations to maintain the boundedness and conservation of phase fractions in the proposed method. The advection flux of the phase continuity equation is constructed within the coupling procedure of velocity and pressure and explicitly evaluated when solving the phase continuity equation. The upwind interpolation of the phase fraction is carried out before constructing the pressure equation; thus, the advection flux of the phase continuity equation could be corrected by the pressure equation for boundedness and conservation consideration. Those unique treatments only slightly differ from the standard solution procedure, but the boundedness and conservation could be naturally guaranteed. The proposed method is verified by two test cases, including the phase separation and the two-phase upward flow, to demonstrate the boundedness, conservation, and accuracy of the proposed method.

Hybrid boundary full-wave-equation depth migration based on dual-sensor acquisition system and its application

The dual-sensor acquisition system arranges two-layer geophones on the surface and their corresponding underground positions, and receives the wavefield simultaneously for accurately solving the full-wave equation. Theoretically, using the two-layer wavefield data obtained by the acquisition system, the two-way wavefield extrapolation can be realized in the depth domain without approximate processing of the wave equation, and the migration algorithm based on the dual-sensor framework has better amplitude preservation. However, limited to the acquisition expenses and difficulties, the spacing of the two-layer sensors is hard to match the actual migration step in real data acquisition. Meanwhile, poor geophone coupling and nonstandard data processing procedures would also lead to unsatisfied imaging results. Thus, some schemes suitable to dual-sensor data, including hybrid boundary wavefield extrapolation strategy, data processing, quality monitor, are proposed to handle these issues, using the delay time difference as a main analyzing object. The numerical simulation and actual data verify the feasibility and effectiveness of the proposed method.