Structural System Research Articles

Defect Monitoring System of the Internal Structures of a Sodium Fast Reactor using an Artificial Intelligence Model

This study developed a defect-monitoring system with an artificial intelligence model, YOLOv7, which is tailored for processing image data from an ultrasonic visualization system within sodium fast reactor (SFR) internal structures. For the safety of SFR internal structures, although it is a crucial inspection for defect monitoring, it is difficult to identify structural defects because of the invisible environment. Therefore, we applied the YOLOv7 model in this study; however, we encountered challenges including decreased accuracy with complex defect shapes and complications from data augmentation during pre-training. To solve these problems, we additionally applied the enhanced super-resolution generative adversarial network for higher resolution and a Sobel noise-filtering algorithm to enhance the defect detection accuracy. And we evaluated our system by comparing it with a confidence score. This underscores the effectiveness of the approach in enhancing the defect detection capabilities. Therefore, this defect-monitoring system should be designed to preemptively identify internal structure deformations and enhance SFR safety and maintenance practices.

Enhancing asphalt-based waterproof materials for building cement substrates: Modifications, construction, and weathering resistance

Three distinct systems of asphalt-based waterproof material structures were designed for building cement substrates. These asphalt-based waterproof materials were modified using either Styrene Butadiene Rubber (SBR) or Ethylene Acrylic Acid Copolymer (EAA) along with various inorganic fillers. To enhance the adhesion between the waterproof materials and the cement substrate, the surface of the cement substrate was chemically treated with either γ-methacryloyloxypropyltrimethoxy silane (KH-570) or vinyltrimethoxy silane (SG-Si 171) through atomization spraying and infrared irradiation. The adhesion properties and debonding failure modes of waterproof materials for cement substrates were analyzed, and six groups of samples with relatively good adhesion properties were screened for further environmental aging tests. The samples were subjected to temperature fluctuations, water immersion, freeze-thaw cycles, thermal aging, acid, alkali, and salt, to identify favorable asphalt-based waterproof structure systems for five climate zones, acid rain-affected regions, and saline-alkali-affected regions in China. These results provide valuable insights for designing effective waterproof materials for different environments.

Experimental and parametric study on friction-type high-strength bolted connections between steel frames and cross-laminated timber infill walls

Timber-steel hybrid structural systems provide a prospective solution for utilizing timber in multi-storey and high-rise buildings. The system of steel frame with infilled cross-laminated timber (CLT) shear walls is an effective hybrid timber-steel one. In the design of this kind of hybrid system, the connections between CLT walls and steel frame beams are key issues, because they have great impacts on the distribution of lateral forces in structures. In this paper, a friction-type high-strength bolted connection (FHBC) between CLT walls and steel frame beams is proposed. To investigate the performance of the proposed FHBC, experiments were conducted on the FHBCs fabricated with three- and five-ply CLT. The mechanical behaviors of the connections were evaluated. The pretension loss in the tested FHBCs with three-layer CLT is less than 15 % within a displacement of 10 mm. Besides, enhancement of axial force in the high-strength bolt was observed in the five-layer connections during the loading procedure. Theoretical analysis was performed to provide recommendations on the initial pretension force of FHBCs. Furthermore, a solid element-based numerical model was developed and validated by the experimental results. The parametric analysis was conducted to investigate the effect of friction coefficient and initial pretension force on the mechanical behaviors of FHBC. The numerical simulation results show that the greater the initial pretension force is, the bigger the slip activation force and ultimate load-carrying capacity of the FHBC are. When the friction coefficient between CLT wall and steel beam is greater than 0.4, the ultimate load-carrying capacity does not increase much. The experimental and numerical results demonstrate that such connections can provide sufficient stiffness, strength, and ductility to transfer the shear force between the CLT shear walls and the steel frame beams.

Conceptual shaking table tests for resilient segmental bridge columns with resettable sliding joints

The ever-increasing demand for accelerated construction of urban bridges or viaducts calls for more prefabrication with various joint schemes, while satisfying the need for seismic resilience. On the other hand, segmentation into components of various shapes and morphologies is common for multifunctional structures found in living organisms and ancient Chinese timber structures, which also inspires the development of resilient segmental bridge column design. To provide further insights into the cost-effective resilient design of precast bridge columns, this paper suggests the use of resettable sliding joints (RSJ) comprising lubricated gently-inclined joint interface with partially debonded tendon arrangement, essentially forming a hybrid sliding and rocking seismic isolation system of precast segmental structures. The deformability of the proposed design is high. Similitude analysis was conducted considering the rigid body behavior of individual segments under seismic input. It presents the conceptual shaking table testing of four 1:12 prestressed segmental column models fabricated with special three-dimensional (3D) printed plastic molds and interface treatment. A motion capture system was installed for accurate 3D displacement data acquisition and five typical major near-fault earthquake records were selected. Among all specimens, the RSJ segmental column could reach a high damping ratio of about 20 % during the tests, and it outperformed the others in many aspects: (i) a tolerable maximum top drift of about 1 %; (ii) a moderate percentage of transient rocking of about 20 %; (iii) an evenly distributed sliding displacement among all sliding joints; and (iv) negligible residual sliding drift at sliding joints. These superior attributes of RSJ segmental column are consistent under excitation of consecutive rounds of different major earthquake records, indicating high robustness as well as high seismic resilience in the design of RSJ segmental columns.

Impact of ageing on structure of random sequentialadsorption packings of discorectangles

Abstract The ageing processes in the systems of elongated particles (discorectangles) adsorbed on a plane was studied numerically. An off-lattice model with continuous positional and orientational degrees of freedom was tested. The initial jammed state was produced using the random sequential adsorption (RSA) model. The transition from the jammed to equilibrium states were 
performed via translational and rotational Brownian motions. An aspect ratio of the particles (length-to-width ratio) was varied within the range $\varepsilon=1-12$. At $\varepsilon < 10$ the relaxation into the isotropic state %with $S=0$ 
was always observed. In the intermediate range, $10 \le \varepsilon \le 11$, the relaxation transition into the states with ordered domains was observed. Particularly, for $ \varepsilon=10$ this transition was related with significant finite size scaling effects. For particles with $\varepsilon=12$ formation of the large scale quasi-nematic domains and unlimited domain growth was observed. The impact of the relaxation on the domain structure, porosity, percolation connectivity and tracer particle diffusion in such barrier systems was also discussed.

Computational engine for finite element digital twins of structural dynamics via motion data

Typical structural health monitoring systems employ limited numbers of sensors capable of measuring discrete local behaviours. However, practical challenges arise as these sensor arrays cannot cover all local areas of interest. To address this challenge, this article introduces a novel method for twinning structural dynamic behaviour by constructing a finite-element-model-based digital twin, enabling the observation of non-sensor positions crucial for downstream tasks. The approach utilises streaming monitoring data, e.g., displacement and acceleration, as external dynamic loads to reproduce the dynamic response of the entire physical structure. Subsequently, the dynamic behaviour of specific non-sensor locations can be extracted from the digital twin. The method is formulated as a local-global-local procedure. To validate the proposed approach, two virtual experiments were conducted on: 1) a simply supported Euler-Bernoulli beam subjected to static loads and 2) a high-fidelity finite element model of a composite bridge carrying dynamic traffic loads. The results demonstrate remarkable accuracy in reproducing both global and local behaviours, facilitating observations at non-sensor positions for downstream estimations.

Identification of combined sensor faults in structural health monitoring systems

Fault diagnosis (FD), comprising fault detection, isolation, identification and accommodation, enables structural health monitoring (SHM) systems to operate reliably by allowing timely rectification of sensor faults that may cause data corruption or loss. Although sensor fault identification is scarce in FD of SHM systems, recent FD methods have included fault identification assuming one sensor fault at a time. However, real-world SHM systems may include combined faults that simultaneously affect individual sensors. This paper presents a methodology for identifying combined sensor faults occurring simultaneously in individual sensors. To improve the quality of FD and comprehend the causes leading to sensor faults, the identification of combined sensor faults (ICSF) methodology is based on a formal classification of the types of combined sensor faults. Specifically, the ICSF methodology builds upon long short-term memory (LSTM) networks, i.e. a type of recurrent neural networks, used for classifying ‘sequences’, such as sets of acceleration measurements. The ICSF methodology is validated using real-world acceleration measurements from an SHM system installed on a bridge, demonstrating the capability of the LSTM networks in identifying combined sensor faults, thus improving the quality of FD in SHM systems. Future research aims to decentralize the ICSF methodology and to reformulate the classification models in a mathematical form with an explanation interface, using explainable artificial intelligence, for increased transparency.

A Multi-Criteria Decision-Making Approach for Assessing the Sustainability of an Innovative Pin-Connected Structural System

A Multi-Criteria Decision-Making Approach for Assessing the Sustainability of an Innovative Pin-Connected Structural System

Towards a unified ontology of cybernetics: bridging mechanology and CAS for cooperative societies through thematic synthesis

PurposeThis paper aims to conceptually unite an ontology of cybernetics, bridging living and technical systems, to facilitate future epistemological and theoretical advancements applicable to highly technical societies by crafting a set of definitions that elucidate the nature of the world in which these systems operate.Design/methodology/approachThe research uses a thematic synthesis of two systems/cybernetic traditions: complex adaptive systems and mechanology. The primary sources for this research were the main theses and correlated papers published in the Simondon case for mechanology, and the seminal literature preselected by the Santa Fe Institute for complex adaptive systems.FindingsThe study proposes the following concepts: Individuation: the emergence of new properties in an individual composed of synergistically related parts; Technical evolution: the notion that technical objects evolve into living beings; circular causality: the notion that feedback and feedforward processes shape the organisation and structure of systems and their relationship with the environment; The milieu refers to the part of the environment that has a relationship of co-production, co-dependency, and co-evolution with systems. Metastability is a state that transcends stability and instability and motivates changes in the system. Transduction is the cumulative process of individuation in which systems change structure and organization to maintain operational coherence with their surroundings.Originality/valueThe concepts the paper identifies can serve as a starting point for an extended study on the ontology of cybernetics or as the basis for an evolutionary epistemology both in humans and machines.

Evaluation of Point Group Symmetry in Lanthanide(III) Complexes: A New Implementation of a Continuous Symmetry Operation Measure with Autonomous Assignment of the Principal Axis.

The structure of molecular systems dictates the physical properties, and symmetry is the determining factor for all electronic properties. This makes group theory a powerful tool in quantum mechanics to compute molecular properties. For inorganic compounds, the coordination geometry has been estimated as idealized polyhedra with high symmetry, which, through ligand field theory, provides predictive capabilities. However, real samples rarely have ideal symmetry, and although continuous shape measures (CShM) can be used to evaluate deviation from an ideal reference structure σideal, this often fails for lanthanide(III) complexes with high coordination numbers, no obvious choice of principal axes, and no obvious reference structure. In lanthanide complexes, the unique electronic structures and associated properties are intricately tied to the symmetry around the lanthanide center. Therefore, robust methodologies to evaluate and estimate point group symmetry are instrumental for building structure-property relationships. Here, we have demonstrated an algorithmic approach that orients a molecular structure Q in the best possible way to the symmetry axis of any given point group G and computes a deviation from the ideal symmetry σsym(G,Q). This approach does not compute the deviation from an ideal reference system, but the intrinsic deviation in the structure induced by symmetry operations. If the structure contains the symmetry operation, there is no deviation and σsym(G,Q) = 0. The σsym deviation is generated from all of the symmetry operation ÔS in a point group G using the most correct orientation of the sample structure in each group G. The best orientation is found by an algorithm that minimizes the orientation of the structure with respect to G. To demonstrate the methodology, we have investigated the structure and symmetry of 8- and 9-coordinated lanthanide(III) aqua complexes and correlated the luminescence from 3 europium(III) crystals to their actual symmetry. To document the methodology, the approach has been tested on 26 molecules with different symmetries. It was concluded that the method is robust and fully autonomous.

The Study of TRPV1 Channels of the Central Nervous System and Their Effect on Anxiety in ICR Mice.

The TRPV1 channel is actively involved in various neuronal processes and is found in various structures of the nervous system, including peripheral and central neurons, sensory ganglia, spinal cord, and various parts of the brain. Due to its ability to respond to various stimuli, TRPV1 can have a significant impact on the body's responses to stress. Studies indicate the involvement of TRPV1 in the regulation of anxiety behavior. Suppression of TRPV1 activity leads to a decrease in the level of anxiety in animals, which indicates the importance of this channel in psychoemotional regulation. A promising compound for inhibiting this channel is the APHC3 peptide, which is a selective receptor antagonist. The results obtained this study show that this peptide has a pronounced anxiolytic effect, reducing the level of anxiety in the studied animals.

Multi-weighted symbolic sequence entropy: a novel approach to fault diagnosis and degradation monitoring of rotary machinery

Abstract Structural health monitoring relies heavily on measurements. Entropy theory is emerging as a critical quantitative analysis technique for interpreting measured data for both health monitoring and fault identification of structural systems. This paper introduces the algorithms of weighted symbolic sequence entropy (WSSE) and its multi-weighted derivation, termed multi-weighted symbolic sequence entropy (MWSSE). WSSE optimizes the existing algorithms, including symbolic sequence entropy (SSE) and improved symbolic sequence entropy (ISSE), by introducing a weighting factor in the computation process of the algorithm. WSSE significantly contributes to enlarging the difference between normal and fault sequences of signals in rotary machinery. The multi-weighted derivation of WSSE, namely MWSSE, more effectively depicts the dynamical characteristics of rotary machinery by utilizing entropy values of multiple weighting factors as health indicators. The MWSSE-based degradation monitoring and fault identification approaches developed by the authors are validated through application research and comparative analysis. These novel entropy algorithms offer innovative quantitative analysis techniques for fault diagnosis in rotary machinery and structural health monitoring and hold potential for application in broader research fields.

Improving Typhoon Muifa (2022) Forecasts with FY-3D and FY-3E MWHS-2 Satellite Data Assimilation under Clear Sky Conditions

This study investigates the impacts of assimilating the Microwave Humidity Sounder II (MWHS-2) radiance data carried on the FY-3D and FY-3E satellites on the analyses and forecasts of Typhoon Muifa in 2022 under clear-sky conditions. Data assimilation experiments are conducted using the Weather Research and Forecasting (WRF) model coupled with the Three-Dimensional Variational (3D-Var) Data Assimilation method to compare the different behaviors of FY-3D and FY-3E radiances. Additionally, the data assimilation strategies are assessed in terms of the sequence of applying the conventional and MWHS-2 radiance data. The results show that assimilating MWHS-2 data is able to enhance the dynamic and thermal structures of the typhoon system. The experiment with FY-3E MWHS-2 assimilated demonstrated superior performance in terms of simulating the typhoon’s structure and providing a prediction of the typhoon’s intensity and track than the experiment with FY-3D MWHS-2 did. The two-step assimilation strategy that assimilates conventional observations before the radiance data has improved the track and intensity forecasts at certain times, particularly with the FY-3E MWHS-2 radiance. It appears that large-scale atmospheric conditions are more refined by initially assimilating the Global Telecommunication System (GTS) data, with subsequent satellite data assimilation further adjusting the model state. This strategy has also confirmed improvements in precipitation prediction as it enhances the dynamic and thermal structures of the typhoon system.

Life’s building blocks: the modular path to multiscale complexity

Modularity, the structuring of systems into discrete, interconnected units, is a fundamental organizing principle in biology across multiple scales. Recent progress in understanding the role of modularity as an evolutionary mechanism and a key driver of biological complexity has highlighted its importance in shaping the structure and function of living systems. Here, we propose a unifying framework that identifies the potential evolutionary advantages of modularity in systems ranging from molecular networks to ecologies, such as facilitating evolvability, enhancing robustness, improving information flows, and enabling the emergence of higher-level functions. Our analysis reveals the pervasiveness of modularity in living systems and highlights its crucial role in the evolution of multiscale hierarchies of increasing complexity.

Study of the Dynamic Reaction Mechanism of the Cable-Stayed Tube Bridge under Earthquake Action

In order to explore the failure mode of the cable-stayed pipe bridge under earthquake action, taking the structural system of an oil and gas pipeline–cable-stayed pipe bridge as the research object, the full-scale finite element calculation model of the cable-stayed pipe bridge–oil and gas pipeline structural system as well as the finite element calculation model considering the additional mass of the oil and gas medium and the fluid–structure interaction effect were established by using ANSYS Workbench finite element software. The stress and displacement of the cable under the earthquake action were analyzed in the time history, as were the response characteristics of the cable when subjected to both methods. The calculation results show that the overall failure of the pipeline is basically the same under the two methods. Compared with the additional mass method, the solution for the fluid–structure coupling method can be derived through a comprehensive analysis of the flow field and structure, respectively, avoiding the sudden change caused by model simplification or calculation error so that the analysis results can better simulate the actual situation. In summary, the fluid–structure interaction method enables a more precise prediction of the dynamic response of the structure, and the findings of this research can provide a theoretical foundation and technical guidance for optimizing the seismic performance of cable-stayed pipe bridges.

Structural health monitoring of a swivel bridge for evaluating builder comfort under train-induced vibration

The swivel bridge being built overcrossing the railway service line, the builder’s comfort level under the train-induced vibration is one of the critical issues in the bridge construction process. This study compares the applicability and usage limits of existing vibration comfort evaluation indicators for reasonably selected vibration comfort evaluation criteria. A framework is therefore proposed to evaluate builder comfort under train-induced vibrations during the construction process. Taking a swivel bridge overcrossing the Shanghai-Kunming railway line as an example, the structural health monitoring system is performed in three construction stages of the swivel bridge. Then, the acceleration response is measured, the acceleration-based evaluation indicators are compared, and the builder comfort level is evaluated in the three construction stages. The results demonstrate that the on-site measured indicators are close to the standard limits, and the builder comfort on the swivel bridge under the excitation of passing trains should be given attention.

GCMe: Efficient Implementation of the Gaussian Core Model with Smeared Electrostatic Interactions for Molecular Dynamics Simulations of Soft Matter Systems.

In recent years, molecular dynamics (MD) simulations have emerged as an essential tool for understanding the structure, dynamics, and phase behavior of charged soft matter systems. To explore phenomena across greater length and time scales in MD simulations, molecules are often coarse-grained for better computational performance. However, commonly used force fields represent particles as hard-core interaction centers with point charges, which often overemphasizes the packing effect and short-range electrostatics, especially in systems with bulky deformable organic molecules and systems with strong coarse-graining. This underscores the need for an efficient soft-core model to physically capture the effective interactions between coarse-grained particles. To this end, we implement a soft-core model uniting the Gaussian core model with smeared electrostatic interactions that is phenomenologically equivalent to recent theoretical models. We first parametrize it generically using water as the model solvent. Then, we benchmark its performance in the OpenMM toolkit for different boundary conditions to highlight a computational speedup of up to 34 × compared to commonly used force fields and existing implementations. Finally, we demonstrate its utility by investigating how boundary polarizability affects the adsorption behavior of a polyelectrolyte solution on perfectly conducting and nonmetal boundaries.

Research on the technical principles and applications of massage robots

Massage robots, as innovative therapeutic devices, have garnered significant attention and application due to technological advancements and society's increasing focus on wellness. However, amidst this progress, gaps persist in fully understanding their capabilities and optimizing their functionalities, highlighting the need for further research in this domain. This paper focuses on exploring the intricate technical principles, mechanical structure, sensing technology, and intelligent control systems of massage robots, with the aim of providing both theoretical foundations and practical insights for researchers and practitioners in this field. Specific inquiries encompass the elucidation of working principles, emulation of human massage techniques, mechanical design considerations, applications of sensor technology, and implementations of intelligent control systems within massage robots. Employing a blend of literature review, comparative analysis, and experimental validation, this paper aims to not only deepen the understanding of massage robot functionality but also contribute to the advancement and refinement of this technology, fostering innovation and growth within the industry.

Improving stability in hybrid fire testing: Advancements in analysis method and software implementation

In large-scale structural fire resistance tests, the interaction between the individual elements and the surrounding structure causes discrepancies in behaviour compared to single-element fire tests. Large-scale tests of real structures are challenging due to financial and time limitations. To bridge this gap, the concept of “Hybrid Fire Testing (HFT)” emerges, where a portion of the structural system (i.e., physical substructure) is experimentally tested while the remaining structure (i.e., numerical substructure) is analyzed numerically. The primary challenges in HFT involve ensuring stability throughout the analysis by considering the varying stiffness of the fire-exposed element during the test and establishing a versatile communication platform between the physical substructure (PS) and numerical substructure (NS) components. This paper presents a comprehensive HFT framework, implemented within a user-friendly software interface, facilitating both virtual and experimental testing. The software incorporates a new method addressing stability concerns by predicting PS stiffness during the test, achieving convergence within a limited number of iterations. Additionally, the framework includes a communication platform utilizing internet protocols (IP) and COM ports for rapid and easy connection to diverse experimental control systems and finite element software packages. The functionality of the developed software is validated through its successful application in an HFT conducted on a 3-story steel structure within a simulated environment. Both force-controlled and displacement-controlled approaches confirm the method’s adaptivity to the employed test procedures.

Seismic performance and cost comparison of RC moment resisting and dual frames using UBC 97 and IBC 2021

The transition from the Uniform Building Code (UBC-97) to the International Building Code (IBC-21) marked a major shift in the definition of seismic hazard. The term “seismic hazard” in the form of peak ground acceleration (PGA) is replaced by spectral acceleration. This paper investigates the effect of using new seismic hazards on the structural performance of reinforced concrete (RC) buildings. It also looks into the financial impact on the capital costs of new buildings. Useful insights are made to understand the structural performance and financial impact of adopting IBC 21 for structural design in contrast to UBC 97. This study was carried out from the perspective of a developing country, Pakistan. Reinforced concrete moment resisting and dual frames are used as the main structural system of a typical 7-story residential building to investigate the aforementioned effect. The frames are assumed to be located in two locations with high and low seismic hazards. The effect on structural performance is investigated via nonlinear pushover analysis. Financial impact is judged mainly through cost estimation for steel and concrete. A detailed discussion is also presented on the seismic design guidelines in both codes.