Search

In highway reconstruction and expansion projects, the impact of the abandoned dreg body produced by the original highway on the new bridge project cannot be ignored. If the abandoned dregs are not handled properly, they will cause great threat to the operation of the new highway as well as to the safety of the surrounding environment and personnel. In this paper, based on a South China highway reconstruction and expansion project, a model of the abandoned dreg body, bridge pile and anti-slide pile is established with the help of finite difference software FLAC3D 5.0. The calculation results show that compared with burying the anti-slide pile, slope cutting is more effective for improving the stability of the abandoned dreg body. Under the action of vertical force intensity, the displacement of the top of the pile increases continuously, and the maximum bending moment of the pile body increases firstly and then decreases. The pile displacement and bending moment of the bridge pile increase significantly in the storm condition compared with the normal condition. In addition, the abandoned dreg body hazard prevention and control technical measures are studied. The impacts of different locations of anti-slide pile burial on bridge piles are analyzed and compared, and it is determined that the optimal location of anti-slide pile burial is the middle of the secondary slope. [ABSTRACT FROM AUTHOR]

Small‐radius curved bridges are mostly used for overpass ramps, that are spatially irregular and usually have very complex seismic behavior. It is not easy to reproduce such behavior because of the need for large‐scale shaking tables. The hybrid test is one of the most effective approaches for solving this problem by considering the structural elements of interest as physically tested substructure while the rest is numerically simulated. In this paper, a hybrid test system was first developed based on the OpenFresco framework, where one of the piers was considered as the tested substructure, and the rest was simulated by OpenSees. A novel spatial loading device (SLD), configured as the Stewart pattern, was then developed to achieve the boundary conditions between substructures. The control schemes to perform the force‐displacement mixed control, conduct the geometric transformation while considering the load point offset, and achieve an external displacement control were proposed and validated through several rounds of hybrid testing. The experimental results indicate that the experimental system including loading control subsystem and hybrid control subsystem can realize the loading command accurately. [ABSTRACT FROM AUTHOR]

The safety of bridges, which are key components of roads, has attracted the attention of experts, technical engineers, and maintenance managers. Various apparent problems such as cracks, voids and pits, white precipitate, and corrosion must be identified during the visual inspection of a bridge. In this study, using soft-nonmaximum suppression (NMS), we improved the original NMS algorithm of the faster regional convolutional neural network (Faster R-CNN) and built a fine identification network model to classify and identify the structural problems of bridges to effectively reduce the missed detection rate. In addition, through manual inspection by photography, the average accuracies of the identification of problems, namely, voids and pits, cracks, and white precipitate, can reach 80.86, 81.42, and 87.39%, respectively, which are about 20 percentage points higher than that of the original Faster R-CNN. [ABSTRACT FROM AUTHOR]

Aims. Recent low-frequency radio observations at 140 MHz discovered a bridge of diffuse emission with a length of 3 Mpc that connects the galaxy clusters Abell 0399 and Abell 0401. We present follow-up observations at 60 MHz to constrain the spectral index of the bridge, which has only been detected at 140 and 144 MHz so far. Methods. We analysed deep (∼18 h) LOw Frequency ARray (LOFAR) Low Band Antenna (LBA) data at 60 MHz to detect the bridge at very low frequencies. We then conducted a multi-frequency study with LOFAR HBA data at 144 MHz and uGMRT data at 400 MHz. Assuming second-order Fermi mechanisms for the re-acceleration of relativistic electrons driven by turbulence in the radio bridge regions, we compared the observed radio spectrum with theoretical synchrotron models. Results. The bridge is detected in the 75″ resolution LOFAR image at 60 MHz, and its emission fully connects the region between the two galaxy clusters. Between 60 MHz and 144 MHz, we found an integrated spectral index value of α60144 = −1.44 ± 0.16 for the bridge emission. For the first time, we produced spectral index and related uncertainties maps for a radio bridge. We produce a radio spectrum that shows a significant steepening between 144 and 400 MHz. Conclusions. This detection at low frequencies provides important information for models of particle acceleration and magnetic field structure on very extended scales. The spectral index gives important clues about the origin of inter-cluster diffuse emission. The steepening of the spectrum above 144 MHz can be explained in a turbulent re-acceleration framework, assuming that the acceleration timescales are longer than ∼200 Myr. [ABSTRACT FROM AUTHOR]

Crowdsourcing in science is one of the ways of conducting scientific research which responses to the postulates of the democratization, openness, and inclusiveness of science. Although much is known about crowdsourcing in science, less attention is paid to the barriers to the use of crowdsourcing in science and how to overcome them. The purpose of this research is to identify barriers to the use of crowdsourcing in science from the perspective of scholars across management who have little or no experience in organizing crowdsourcing in science initiatives. At the same time, we identify bridges that reduce those barriers. We collected the data using unstructured interviews with 40 junior and senior management scholars who represent different academic ranks. We identified sixteen barriers grouped into six categories: individual, data, knowledge, delegation, quality, and financial barriers. Barriers refer to lack of trust in the crowd, scholars’ reluctance to be open to new things, methodological preferences, concerns about data being shared, data theft, insufficient knowledge of scholars, insufficient crowd knowledge, difficulties in communications, the discomfort of delegating tasks to the crowd, the possibility of the crowd abandoning the tasks, additional work resulting from the need to control and verify the crowd's work, a potential violation of methodological rigor, the feeling of wasting time, concerns about fees for crowdsourcing in science and the employee evaluation system. We also identified the following two bridges that help eliminate barriers and fosters the use of crowdsourcing in science: autonomy of scholars and university support. [ABSTRACT FROM AUTHOR]

Bridge wear and deterioration occur over time under typical operations. Inspections can be resource intensive, infrequent, and sometimes require bridge closure. Instrumented passing vehicles may be used to record vibration responses and extract damage‐sensitive bridge frequency response characteristics. This paper presents a methodology for extracting bridge frequencies from crowdsourced dynamic response data recorded within passing vehicles. Detected bridge frequency changes and a novel point cloud methodology are used to identify critical damage scenarios and estimate remaining life. The use of a novel crowdsourced Welch methodology allows for spectra averaging that reduces the influence of noise and transient events. Numerical and experimental studies illustrate that bridge frequencies can be accurately estimated and that changes in bridge frequency caused by different damage scenarios can be characterized. Numerical examples for the damage scenario analysis, including estimation of remaining life, are provided for two bridge types and three specific damage scenarios. [ABSTRACT FROM AUTHOR]

The mechanical properties of cooperative system bridges are complex. This paper describes the construction monitoring and load tests of a cable-stayed and arch cooperative bridge. The cable force, girder stress and arch alignment were monitored during construction to ensure the safety of the bridge structure and attain the intended internal force state in the completed bridge. Static and dynamic load tests were performed after completing the bridge to test its bearing capacity. The construction monitoring observations indicated that the cable force and suspender force change of the bridge during construction were generally consistent with theoretical calculations. The measured cable force of cable C01 was between 2155 and 3085 kN, and the measured value of suspender LS15 was between 980 and 1250 kN; these values conform to the laws of mechanics. The load test results demonstrated that the maximum deflection of the mid-span section of the girder was 5.8 mm, which was less than the theoretical value (6.3 mm). The measured impact coefficients of the bridge under four sets of working conditions based on dynamic load testing were similar to the computed results. These results confirm that the girder has sufficient structural stiffness. [ABSTRACT FROM AUTHOR]

Cable-stayed bridges (CSBs) are flexible and complex structures. Impact-induced vibrations may play an important role in the behaviours of the structural elements. Much effort has been devoted to clarifying the experimental static and dynamic responses of CSBs. However, experimental dynamic responses of the structural elements of CSBs under impact-induced vibrations have not been widely addressed in the literature. The focus of this paper is on the real experimental dynamic behaviours of cables, decks and pylons in CSBs under impact-induced vibration due to fully loaded trucks passing over a bump positioned on the deck centre. Tests were carried out on the new Kömürhan CSB under the passage of two 40 t trucks travelling at 30 km/h and passing over a timber bump of 50 mm thickness. The dynamic responses of the structural elements were recorded using load cells and two- and three-dimensional accelerometers. Forces, accelerations and frequencies of the main- and back-span cables and the acceleration responses of the deck and pylon, recorded with and without impact effects, were evaluated and compared. Significant impact-induced amplification ratios on the responses of the main- and back-span cables, deck and pylon were observed for the studied bridge. [ABSTRACT FROM AUTHOR]

Deep learning-based scan-to-building information models (BIMs) approaches have gained popularity in generating as-built BIMs for highway bridges. However, several critical challenges emerge. First, the acquisition of large-scale training data is prohibitively expensive. Second, the complex geometry of bridges, such as variable curvature and cross sections, poses difficulties for modeling. Lastly, these generated models often lack a parametric definition. To address these challenges, this paper introduces an enhanced scan-to-BIM framework that uses low-cost synthetic point clouds and parametric modeling. This approach contains two main components: (1) semantic segmentation using augmented datasets, and (2) a projection-based parametric modeling method. Through rigorous experiments, it is evident that augmenting the training process with synthetic data significantly improves model performance, yielding up to a 12.2% segmentation improvement in this work. In terms of modeling, the reconstructed model showed a marginal mean difference of 0.06 m against the ground truth. Notably, when applied to real-world bridges, the framework demonstrated a comparable accuracy level, with deviations primarily stemming from occlusions in the bridge abutments. In conclusion, this study highlights the effectiveness of the proposed framework in creating as-built BIM models for highway bridges. Additionally, it emphasizes the significance of combining synthetic and real data for optimal accuracy and proves its potential in modern highway infrastructure applications. [ABSTRACT FROM AUTHOR]

The design of high-speed simply supported bridges in critical conditions, such as road or canal crossings, is a matter of concern, particularly under two-way crossings with sequential wheel loads. Contrarily to simple classical support, elastic bearings can serve towards vibration mitigation under high speed. In this paper, a non-dimensional framework is developed to understand the impact mechanism of an elastically supported (ES) beam under the action of single as well as opposite traversing loads. A good agreement with the available literature has been confirmed for the one-way crossing using the present methodology. Moreover, a parametric study is conducted for an ES beam, in which the effects of speed parameter (η), speed parameter ratio between two trains (R), interspatial distance between loads to the length of the bridge (ϵ), damping ζ, stiffness parameter (κ), and traversing time difference between two trains (t os ) are investigated. The theoretical results suggest the effective use of the ES beam under higher values of η for one-way and R for two-way traffic. Additionally, various resonances and cancellation speed ratios under particular values of ϵ have been identified under varying values of κ. [ABSTRACT FROM AUTHOR]

Stretchable inorganic electronics have been of growing interest over the past decades due to their various attractive potential applications. The island-bridge structure is the most widely used structural design, where rigid inorganic devices (islands) and interconnects (bridges) are attached to an elastomer substrate, and large deformations in the structure are accommodated by the large stretchability of the interconnects and the elastomer underneath them. Due to the large modulus mismatch of more than five orders of magnitude between the rigid island and elastomer substrate, there is a severe stress and strain concentration at the interface between the island and the substrate during large deformations, which may cause the interface fracture and delamination. In this work, the analytical solution of the interfacial shear and peel stress between the island and the substrate is derived to reveal the mechanism of interface fracture and agrees well with finite element analysis (FEA) results. A simple porous partition substrate design strategy is proposed to alleviate this stress and strain concentration at the boundary of the interface, where the porous region can undergo larger deformation due to the reduced stiffness of the material. FEA obtains the key parameters affecting the pore layout. The digital image correlation (DIC) experiment verifies the design strategy. The results show that, compared to the solid substrate, the porous partition substrate strategy can significantly reduce the maximum normal strain of the substrate around the island, thus effectively reducing the risk of structural interface failure. [ABSTRACT FROM AUTHOR]

Modeling realistic human skin with pores and wrinkles down to the milli‐ and micrometer resolution is a challenging task. Prior work showed that such micro geometry can be efficiently generated through simulation methods, or in specialized cases via 3D scanning of real skin. Simulation methods allow to highly customize the wrinkles on the face, but can lead to a synthetic look. Scanning methods can lead to a more organic look for the micro details, however these methods are only applicable to small skin patches due to the required image resolution. In this work we aim to overcome the gap between synthetic simulation and real skin scanning, by proposing a method that can be applied to large skin regions (e.g. an entire face) with the controllability of simulation and the organic look of real micro details. Our method is based on style transfer at its core, where we use scanned displacement maps of real skin patches as style images and displacement maps from an artist‐friendly simulation method as content images. We build a library of displacement maps as style images by employing a simplified scanning setup that can capture high‐resolution patches of real skin. To create the content component for the style transfer and to facilitate parameter‐tuning for the simulation, we design a library of preset parameter values depicting different skin types, and present a new method to fit the simulation parameters to scanned skin patches. This allows fully‐automatic parameter generation, interpolation and stylization across entire faces. We evaluate our method by generating realistic skin micro details for various subjects of different ages and genders, and demonstrate that our approach achieves a more organic and natural look than simulation alone. [ABSTRACT FROM AUTHOR]

Seamless expansion joints for small- and medium-span bridges attract engineers due to their acknowledged integrity (durability), driving comfort and noise attenuation. Traditional asphalt plugin joints are easy and cheap to install, but they are hindered by premature failures frequently observed in situ. Comparatively, polyurethane (PU) possesses good durability and toughness and excellent chemical resistance, etc. The purpose of this study is to identify the proper PU material and devise a new seamless expansion joint. As such, the mechanical properties of three PU materials were tested, including initial setting time, tensile strength, rupture strain, hardness, wheel rutting, adhesion to pavement, water absorption, and aging. The appropriate mass ratio was identified to be polyol/isocyanate = 100/105. Subsequently, monotonic tensile/compressive, vertical loading and low-cycle fatigue tests were performed on the four full-scale expansion joints. It revealed that the rate-dependent behavior rendered the PU material suitable for seamless joints, as it was softer to accommodate the low-rate longitudinal deformation and was stiffer to sustain the high-rate vehicle loadings. Furthermore, the inclined angle between the PU and pavement would ameliorate the strain status and is recommended for practical use. Experimental and numerical results were synthesized into a proposed alternative polyurethane-based design that reduces the vertical displacement and circumvents the possible early failures under the effect of dynamic traffic loading. [ABSTRACT FROM AUTHOR]

Macrocyclic arenes show conformational adaptability, which allows host–guest complexations with the size‐matched guest molecules. However, their emission properties are often poor in the solid states due to the self‐absorption. Herein, we newly synthesized pillar[6]arene derivatives having alternate methylene and nitrogen bridging structures. Solvatochromic study reveals that the nitrogen‐embedding into the cyclic structures can strengthen the intramolecular charge transfer (CT) nature compared to that of the linear nitrogen‐bridged precursor. Owing to the large Stokes shift in the solid state, one of the nitrogen‐embedded pillar[6]arenes shows high absolute photoluminescence quantum yield (ΦPL=0.36). Furthermore, it displays a turn‐off sensing ability toward nitrobenzene (NB) vapor; a fluorescence quenching is observed when exposed to the NB vapor. From the structural analysis before and after the exposure of NB vapor, the amorphous nitrogen‐embedded pillar[6]arene efficiently co‐crystallize with NB and formed non‐emissive intermolecular CT complexes with NB. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (Quasi2D) perovskite materials gained widespread attention due to whose unique and highly desirable luminescence properties. However, the behavior of perovskite lightemitting diodes (PeLEDs) is prejudiced by inefficient cascading energy transfer of perovskite film and unbalanced charges injection. Here, ferrocene carboxylic acid (FcAd) is employed between hole transport layer (HTL) and perovskite layer as a molecular bridge to solve the current problems of PeLEDs. Ferrocene units can bond with [PbBr6]4−, forming one‐dimensional (1D) intermediate phases of FcPbBr3 at the interface, which can manipulate the growth kinetics of perovskite and reconstruct the phase distribution. Therefore, due to the suppression of low dimensional phase content, not only is the cascaded energy transfer of PEA2(CsPbBr3)2PbBr4 films effectively achieved, but also the quasi‐2D perovskite's work function is reduced. Additionally, Pb2+ coordinated with the carboxyl group of FcAd, inducing an electric dipole effect that leads to an further upward shift of the perovskite energy level. Eventually, the synergy achieves a significant tailoring between the perovskite and HTL energy exhibits the most excellent external quantum efficiency (EQE) exceeds 27% and optimal brightness exceeds 240000 cd m−2. Therefore, the preparation method will provide an effective strategy to widen the color gamut of next‐generation displays. [ABSTRACT FROM AUTHOR]

This study takes the indoor substation adjacent to the elevated bridge subway line as the engineering background, investigates the structural vibration response law of the substation induced by the operation of the subway line through on-site vibration measurement, and proposes a novel nonlinear gas-spring quasi-zero stiffness isolator (NGS-QZSI) is proposed to reduce the structural vertical vibration and further reduce the safety distance. The software ABAQUS is used to establish a structure-equipment coupling numerical analysis model considering soil-structure interaction, and its effectiveness and accuracy are validated based on the measured results. The structural vibration response analysis is carried out under different vibration source distances, and a nonlinear gas-spring quasi-zero stiffness isolator is proposed to be employed for substation structural vibration isolation. The research results show that the substation structure under subway load excitation is dominated by vertical vibration, and its vibration response increases gradually with the increase of floor level. When the substation structure is less than 45 m from the subway line, the structural response exceeds the safety limit (12.5 µm/s) of the VC-C standard. With the vibration isolator attached, the structural vibration response is significantly reduced, with the peak and root mean square response controlled by more than 70 %. Particularly, the safe distance of the substation from the subway line is reduced from 45 m to 20 m. Moreover, the frequency domain result analysis indicates that the proposed nonlinear vibration isolator can effectively control the low-frequency vibration of the structure. [ABSTRACT FROM AUTHOR]

An improved theoretical calculation method was proposed to determine the transverse load distribution of airport and highway bridges under heavy loads using the rigid-joint girder (RJG) method. The effects of torsion, distortion, and vertical inclination of the adjacent box girder joints under an eccentric heavy load were considered. The coefficients and influence lines of a taxiway bridge and a highway bridge were calculated using the proposed method, the RJG method, and the modified RJG methods. The accuracies of the three methods were evaluated by the refined finite element model, and the cosine similarity and peak deviation rate were used as quantitative indices. The results showed that the cosine similarity obtained from the proposed method for the taxiway bridge was 0.996 compared with the finite element method (FEM). The maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 14.88 % and obviously lower than 34.74 % for the RJG method. For the highway bridge, the cosine similarity of the influence line derived from the proposed method was 0.995, and the maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 6.66 % and lower than 16.14 % for the RJG method. The results indicate that the proposed method can be used to calculate the transverse load distribution of wide box girder bridges accurately and efficiently. [ABSTRACT FROM AUTHOR]

The field of evolutionary biology must bridge the gap between its diversity, equity, and inclusion (DEI) commitments and data-driven educational actions in the nation's undergraduate classrooms and degree programs. In this article, we discuss the urgent need for the adoption of equity frameworks and why they are centrally important to data-driven DEI efforts in evolutionary biology. We describe why equity indicators (e.g. measures) must be anchored in and aligned with equity frameworks. We introduce a specific equity framework for learning (the enhanced educational debt framework) and illustrate how it may be leveraged to document, interpret, and improve outcomes in evolutionary biology. We apply the equity framework and associated indicators to >3,500 students' first college-level experience with evolutionary biology at a public, 4-year institution in the Northeastern United States to demonstrate how these conceptual tools and empirical perspectives may be used by faculty, departments, and degree programs to better understand their roles in mitigating or perpetuating inequities. We end by discussing how this framework may be applied to a range of evolution concepts and courses in the educational hierarchy and used to help evolutionary biologists better understand the extent to which a core aspect of SSE's diversity statement is being realized. [ABSTRACT FROM AUTHOR]

The paper investigates the seismic performance of a novel passive vibration isolation and damping device termed Extended KDamper (EKD). The concept is applied to a representative two-span highway bridge, initially designed on conventional seismic isolation (CSI) bearings. An optimization process is developed and executed to design the EKDs, underscoring the importance of accounting for seismic motion variability. Compared to CSI, the incorporation of EKDs leads to a 40% to 70% reduction in deck drifts. In contrast to the CSI bridge, which may sustain excessive bearing shear strains when subjected to the most adverse seismic motions within the examined set, the bearings of the EKD bridge never exceed the 200% threshold. Through the use of nonlinear 3D time-history analyses, it is demonstrated that the nonlinearity of the EKD elements may result in residual deck drifts. The nonlinear EKDs exhibit a variation in maximum drifts and accelerations on the order of ±20% compared to the preliminary (linear elastic) design for the examined set of spectrum-compatible motions. The increased accelerations result from the stiffening of the negative stiffness elements (NSEs), being more pronounced for seismic motions that entail large displacement demands. With the aid of a fully nonlinear 3D model of the entire soil – foundation – structure system, the effects of soil-structure interaction (SSI) are explored and shown to significantly influence the seismic response of the system. Deck collision with the abutments restricts the movement of the deck and pier; however, it compromises the performance of the EKDs and leads to a substantial increase in deck accelerations. Overall, EKDs may facilitate a more economical design and enhanced seismic performance, particularly for displacement-sensitive structures like rail bridges. [ABSTRACT FROM AUTHOR]

To facilitate seismic analysis of bridges, especially on a regional scale, this study established a parametric finite element model of bridges incorporating simplified component elements. It employs a knowledge-enhanced neural network (KENN) to calibrate the parameters of the lumped plasticity model of pier columns. Along with a database of historical experimental results, the influence of the key characteristics of reinforced concrete columns on model parameters are investigated and formulated as physical laws to supervise KENN training. The developed KENN model was then developed, yielding root mean square errors within the range of [0.027, 0.209]. These errors are slightly larger than those of the purely data-driven neural network, yet the KENN model aligns more consistently with the physical principles. Further, to demonstrate its accuracy and efficiency, the proposed methodology was applied for the rapid seismic response analysis of typical bridges. [ABSTRACT FROM AUTHOR]

A comparative study of the dynamic behavior of twin single-span bridges was carried out based on operational modal analysis and a linear finite element model updating with the aim of finding a potential damage indicator. The bridges are skewed, 30 m long and with prestressed concrete girders as the main support structure, but one of them were collided and suffered damage in two of its I-shape girders. Ambient vibration tests were conducted by deploying 14 uniaxial accelerometers along the sidewalks, experimental modal parameters were identified using the COVariance-driven Stochastic Subspace Identification method (SSI-COV). Six vertical modes were clearly identified for each structure. Additionally, some extra modes with non-proportional damping were identified. It was found that the modal frequencies are sensitive to the support conditions and the overall stiffness of the bridge but not to the localized girder damage, which, on the contrary, is reflected in the discrepancy in the fundamental bending mode shape amplitude between the lateral sides of the bridge, and a so-called Continuous Symmetry Measure adopted as a symmetry index seems to be a good damage indicator for this type of straight-alignment simply supported bridges, given the symmetric nature of the bending mode shapes and the asymmetric nature of the damage. [ABSTRACT FROM AUTHOR]

This paper addresses the need for accurate and objective safety assessments of bridges in Brazil taking into account the increase in traffic load and limited funding for infrastructure. In Brazil, the usual method of ensuring bridge safety involves strengthening based on design codes using deterministic analysis and partial safety factors. This method leads to an increase in the maintenance cost of the bridges. Structural reliability assessment, a higher-tier assessment method, is recommended globally for assessing the safety of existing bridges beyond current deterministic methods. This paper presents a study that evaluates the structural safety of existing road bridges in Brazil using the semi-probabilistic method defined in Brazilian standards and the full probabilistic method. The study selected six case studies of existing reinforced and prestressed concrete bridges to evaluate their structural safety concerning current normative loads. The results suggest that the partial safety factors defined in the Brazilian standards are consistent with international standards. The reliability analysis can guarantee the bridges' safety, even with increased traffic loads, without additional costs for structural strengthening. Therefore, the paper highlights the importance of promoting reliability analysis in Brazil to ensure the safety of existing bridges and promote cost-effective and objective safety assessments. [ABSTRACT FROM AUTHOR]

The disengagement of bridge bearings is a pervasive issue encountered in the realm of bridges, which can potentially lead to changes in operational circumstances, diminished longevity, and compromised traffic safety. The current methods employed for detecting such disconnections primarily rely on force sensors, cameras, and acceleration sensors. However, their practical implementation on-site and effectiveness in accurately identifying disengagement require enhancement. To address the challenges associated with the installation and layout of conventional contact sensors, as well as the potential introduction of additional mass, a sophisticated "bridge-bearing disconnection detection system" has been devised. This innovative system is based on laser Doppler vibrometer technology, which eliminates the need for physical contact. The feasibility of employing non-contact laser Doppler vibration measurement technology in the detection of bridge-bearing disconnection has been successfully verified within the framework of this study. Furthermore, a comprehensive analysis of the sensitivity of key dynamic parameters, specifically natural frequencies and vibration modes, to bridge-bearing disengagement has been conducted. The verification process included evaluating the identification effectiveness of regularized combined absolute changes in vibration modes and flexibility matrix diagonal matrix change rate (FDMCR) under diverse working conditions simulating complete disconnection. This assessment involved using both finite element analysis and empirical measurements. The findings unequivocally demonstrate that the disconnection of bridge bearings results in a reduction in the natural frequencies for each mode order, with an observed cumulative effect. In addition, it is noteworthy that the vibration mode indices typically exhibit greater sensitivity toward the disconnection of outer bearings. By contrast, FDMCR demonstrates commendable positioning capabilities and exceptional noise resistance in identifying bridge-bearing disengagement. The empirical insights gleaned from these research findings hold significant value in terms of on-site identification of bridge-bearing disengagement, ultimately contributing to the preservation of bridges' long-term operational integrity. [ABSTRACT FROM AUTHOR]

The structural temperature gradient (STG) is one of the most key factors causing cracking and even damage to bridge structures. However, its real effects on bridge structures are often over- or underestimated in practice. For most operating bridges, the structural health monitoring systems have just been put into use recently, and the monitoring structural temperature data are limited, which always leads to unreasonable STG representative value for a long return period based on such short-term structural temperature data. To solve the problems, this article proposes an STG determination method based on the long-term historical meteorological parameters at bridge sites. First, the main meteorological parameters affecting the STG were determined by correlation analysis. Second, considering the different influence mechanisms of various meteorological conditions on STG, a training sample set construction method is proposed by clustering the meteorological parameters and STG monitoring data. Based on such training data, a correlation model between STG and meteorological parameters can be established to extend the STG dataset based on the historical meteorological data. Finally, the peak over threshold method is applied to analyze the obtained extended STG data and to estimate its representative value. The proposed method was verified through a long-span cable-stayed bridge. The results show that the monitoring dataset of the STG can be effectively extended through the established correlation model. Compared with the short-term monitoring data, more reasonable representative values of the STG can be obtained through the extended dataset of monitoring STG. [ABSTRACT FROM AUTHOR]

By exploiting the opening of the Öresund Bridge between Denmark and Sweden, we examine the impact of access to larger labor markets on wages and employment. We show that the bridge generated a substantial increase in the cross-country commuting behavior of Swedes and a 13.5% increase in the average wage of workers in the region. We further show that the wage gains are unevenly distributed: the effect is largest for high-educated men and smallest for low-educated women. Thus, the wage gains come at the cost of increased income inequality and a widening of the gender wage gap, both within and across households. [ABSTRACT FROM AUTHOR]

Various hazards can have immediate or long-term impacts on the safety of bridges, and the interactions between them are complicated. This study examined the multihazard concerns in bridge engineering. Through a comprehensive literature review, 16 hazards that pose threats to bridges were identified and analyzed by considering their temporal-spatial characteristics. The interactions between hazards were described using a hazard correlation matrix, and specific chained hazards were identified based on the site-specific conditions. The methods of probability analysis were discussed in terms of the hazard correlation, and a generalized formula is proposed to illustrate the chained effect process by considering the uncertainty in both primary and secondary hazards. Additionally, a lifetime model was introduced to address the long-term effects. A case study was conducted using field investigation data to demonstrate the proposed method, with emphasis on the joint probability of the earthquake–landslide chained effect. Moreover, the lifetime model was also incorporated to account for the scour effects serving as a long-term hazard. This study is aiming to complement the types of critical hazards threatening bridges and to provide guidance for engineers to select design hazards in accordance with the site-specific conditions. [ABSTRACT FROM AUTHOR]

Based on the systematic study of digital construction of assembled bridges, an overall system of digital construction of the whole process of assembled bridges based on BIM + GIS + IoT is proposed. The digital construction process is divided into four stages, including the three-dimensional design, digital production, intelligent transportation and intelligent assembly. The three-dimensional design of assembled bridges is carried out through fine BIM modeling. The digital production concept and component complete production process are applied to the factory production of prefabricated components of assembled bridges. The intelligent transportation body with GIS and IoT as the core is used to provide intelligent transportation control of the whole process of components. Based on IoT intelligent assembly, this research supports realizing the digital construction of prefabricated bridges in the field of bridge engineering. [ABSTRACT FROM AUTHOR]

The need for new railway bridges is driven by the growing volume of transportation demands for both passenger and freight traffic on railway networks. In the design of these bridges, the fatigue limit state is a criterion that usually limits the allowable applied load level and thus also the utilization of the high strength of the steel material. Therefore, improving the fatigue performance of welded details by high‐frequency mechanical impact (HFMI) treatment leads to a more efficient design. However, the fatigue performance of HFMI‐treated welds is known to be affected by the mean stress and this needs to be considered in the design of treated welded details in steel bridges. This is rather straightforward if the bridge is subjected to cycles from one type of train but becomes cumbersome when several different sets of trains (e. g. axle loads, axle distances) cross the bridge. In this article, a factor to take the mean stress effect (including self‐weight and traffic load variations) into account is derived from traffic data measured in Sweden. Moreover, the mean stress effect is also predicted using the different fatigue load models in the Eurocode. These models either consist of one‐load patterns such as LM71, SW/0, and SW/2 or are composed of different trains with different combinations. It was found that the mean stress effect is underestimated by the first group of models. On the other hand, the mean stress predicted by the light traffic mix is found to be close to that calculated using real traffic data, while other mixes (standard and heavy) underestimate the mean stress effect. Therefore, a correction factor to account for the mean stress effects in real traffic is derived (called here λHFMI). This factor can be used to correct the design stress range for fatigue verification of HFMI‐treated welded details in railway bridges. [ABSTRACT FROM AUTHOR]

When an inductive power transfer (IPT) system conducts wireless charging for electric cars, the coupling coefficient between the coils is easily affected by fluctuations in the external environment. With frequent changes in the battery load impedance, it is difficult for the IPT system to achieve constant-voltage and constant-current (CVCC) controls. A CVCC control method is proposed for the IPT system that has a double-sided LCC compensation structure based on full-bridge synchronous rectification. The proposed method achieved good dynamic stability and was able to effectively switch between the output current and voltage of the system by adjusting only the duty cycle of the switch on the secondary side of the rectification bridge. As a result, the system efficiency was improved. The output characteristics of the double-sided LCC compensation structure was derived and the conduction condition with zero voltage was analyzed by using four switches through two conduction time series of the rectifier circuit. Then, the output voltage of the synchronized rectifier was derived. The hardware implementation of the full-bridge controllable rectifier was described in detail. Finally, a MATLAB/Simulink 2018a simulation model was developed and applied to an 11 kW prototype to analyze and validate the design. The results showed that the designed system had good CVCC output characteristics and could maintain constant output under certain coupling offsets. Compared with semi synchronous rectification methods, the proposed method had a higher efficiency, which was 95.6% at the rated load. [ABSTRACT FROM AUTHOR]

The current study deals with simulation of 3D-flow around three different types of bridge pier shapes on a flatbed surface. The main objective of this article is to explore how water flows around various types of bridge piers. In this article, the CFD-Fluent (k-epsilon) turbulence model was used to simulate the flow turbulence around untraditional piers named upstream facing aero-foiled shaped pier (US- FASP) and downstream facing aero-foiled shaped pier (DS-FASP) and were compared with the circular pier, Results from the experiments were compared to the expected flow velocity (m/s), turbulent kinetic energy (TKE), and other variables. The results of the three-dimensional simulation of the water flow behavior and turbulent kinetic energy around the three various designs of bridge piers support that. The findings suggest that (DS-FASP) is the most effective sort of form to employ since it allows water to flow around it extremely smoothly, resulting in minimal obstruction of the water flow in addition to the lowest TKE. In this investigation, root mean errors were used. mean squared errors (MSE), mean absolute errors (MAE), and both the correlation coefficient (R) and the root mean square error (RMSE). The findings also demonstrated that the type of form (DS-FASP) outperformed pavements with other diverse shapes in terms of performance. From this, it was found that the turbulent kinetic energy (TKE) and longitudinal velocity (u) had mean least square errors (MSE) of 1.5E-0 and 7.6E-08, respectively, and coefficients (R2) of 0.92 and 0.98. The shape of a wake vortex in a wake region is captured by the (k-epsilon) model. The k-epsilon turbulence model showed good similarities with the experimental results. The study's findings suggest that local cleaning in the vicinity of bridge piers can be scaled back in the future. [ABSTRACT FROM AUTHOR]

To reduce risk incidents in large bridge construction, it is necessary to study the interaction mechanisms and dynamic changes among various risk factors during the construction of large bridges. First, the evolution mechanism of construction risks for large bridges is analyzed, and a risk factor structure system is established. Then, based on system dynamics theory, a causal loop diagram and flow–stock diagram are constructed, and system dynamics equations for each variable in the flow diagram are established to build a system dynamics model. Finally, taking a large bridge construction project as an example, the variable equations are assigned actual values, and the construction risk level is simulated and analyzed. The results show that, ➀ continuous investment in safety funds can effectively reduce the overall risk level of the system, ➁ changes in the management risk subsystem have a significant impact on the overall risk level of large bridge construction, and ➂ increasing the safety investment ratio in both the personnel risk subsystem and the management risk subsystem can effectively reduce the total risk level of the system. [ABSTRACT FROM AUTHOR]

To address the issue of insufficient deep contextual information mining in the semantic segmentation task of multiple defects in concrete bridges, due to the diversity in texture, shape, and scale of the defects as well as significant differences in the background, we propose the Concrete Bridge Apparent Multi-Defect Segmentation Network (PID-MHENet) based on a PID encoder and multi-feature fusion. PID-MHENet consists of a PID encoder, skip connection, and decoder. The PID encoder adopts a multi-branch structure, including an integral branch and a proportional branch with a "thick and long" design principle and a differential branch with a "thin and short" design principle. The PID Aggregation Enhancement (PAE) combines the detail information of the proportional branch and the semantic information of the differential branch to enhance the fusion of contextual information and, at the same time, introduces the self-learning parameters, which can effectively extract the information of the boundary details of the lesions, the texture, and the background differences. The Multi-Feature Fusion Enhancement Decoding Block (MFEDB) in the decoding stage enhances the information and globally fuses the different feature maps introduced by the three-channel skip connection, which improves the segmentation accuracy of the network for the background similarity and the micro-defects. The experimental results show that the mean Pixel accuracy (mPa) and mean Intersection over Union (mIoU) values of PID-MHENet on the concrete bridge multi-defect semantic segmentation dataset improved by 5.17% and 5.46%, respectively, compared to the UNet network. [ABSTRACT FROM AUTHOR]

Identifying bridge damage using a movable test vehicle is highly regarded for its mobility, cost-effectiveness, and broad monitoring coverage. Previous studies have shown that the residual contact-point (CP) response between connected vehicles is free of the impact of vehicle self-vibrations and road roughness, making it particularly suitable for the indirect extraction of bridge modal properties. However, most experimental campaigns regarding contact-point (CP) responses focus on a single-axle testing vehicle within a non-moving state. This study aims to theoretically and experimentally identify bridge damage using the instantaneous amplitude squared (IAS) extracted from the residual CP response of a two-axle passing vehicle. First, the closed-form solution of the residual CP acceleration was derived for a two-axle vehicle interacting with a simply supported beam. The IAS index was constructed from the driving frequency of the residual CP acceleration. Then, numerical investigations using finite element simulation were conducted to validate using the IAS index for indirect bridge damage identification. The application scope of the approach under various vehicle speeds and road roughness grades was examined. Finally, a laboratory vehicle–bridge interaction system was tested to validate the approach. Numerical studies demonstrated that bridge damage could be directly determined by observing the IAS abnormalities, which were baseline-free. The IAS from the residual CP response outperformed the IAS from CP responses in identifying bridge damage. However, it was better to use the IAS when the vehicle speed was no greater than 2 m/s and the grade of the road surface roughness was not high. Laboratory tests showed that it was possible to identify bridge damage using the IAS extracted from the residual CP acceleration under perfect road surfaces. However, it fell short under rough road surfaces. Hence, further experiments are required to fully examine the capacity of the IAS for bridge damage identification in practical applications. [ABSTRACT FROM AUTHOR]

Wind-sand flow generates erosion and deposition around obstacles such as bridges and roadbeds, resulting in sand damage and endangering railway systems in sandy regions. Previous studies have mainly focused on the flow field around roadbeds, overlooking detailed examinations of sand particle erosion and deposition patterns near bridges and roadbeds. This study employs numerical simulations to analyze the influence of varying heights and wind speeds on sand deposition and erosion characteristics at different locations: the bridge-road transition section (side piers), middle piers, and roadbeds. The results show that the side piers, experience greater accumulation than the middle piers. Similarly, the leeward side of the roadbed witnesses more deposition compared to the windward side. Another finding reveals a reduced sand deposition length as the vertical profile, in alignment with the wind direction, moves further from the bridge abutments at the same clearance height. As wind speeds rise, there's a decline in sand deposition and a marked increase in erosion around the side piers, middle piers and roadbeds. In conclusion, a bridge clearance that's too low can cause intense sand damage near the side piers, while an extremely high roadbed may lead to extensive surface sand deposition. Hence, railway bridges in areas prone to sandy winds should strike a balance in clearance height. This research provides valuable guidelines for determining the most suitable bridge and roadbed heights in regions affected by wind and sand. [ABSTRACT FROM AUTHOR]

The article explores the feasibility of establishing a German-Australian hydrogen bridge to meet Germany's increasing energy demands, focusing on the potential import of green hydrogen from Australia. Topics discussed include the technical, economic, and legal aspects of such a project, alongside the importance of flexible distribution options for hydrogen derivatives within Germany, as outlined in the HySupply feasibility study conducted by Acatech and BDI.

In the design of conventional steel and concrete highway girder bridges, the amount of live load carried by a single girder is quantified through distribution factors (DFs). However, moment DFs for the recently developed fiber-reinforced polymer (FRP) composite tub (CT) girders are not defined in current design codes, leaving questions as to these bridges' live load distribution. To address this, two diagnostic live load tests were performed on an in-service CT girder bridge under heavy truck loads. The measured strains from each test were analyzed and compared with predictions from a calibrated, high-fidelity finite-element (FE) model, which was shown to accurately predict the live load distribution. Then, a simplified FE model was developed that was also shown to accurately predict the live load distribution at a significant computational discount. The simplified model was subsequently used in a parametric study to assess current CT girder design practices, which were found to be consistently conservative. One conclusion was that unintended end restraint of the girder significantly impacted the maximum measured flexural strains, and the high-fidelity FE model required modification and calibration to capture this effect. However, simplified FE models that were not calibrated to the field data were shown to reasonably accurately predict the live load distribution to the most heavily loaded, interior girders. Ultimately, the results of this study show that live load moment DFs should be developed that are specific to the CT girder to ensure efficient future designs with this new technology. [ABSTRACT FROM AUTHOR]

States may allow vehicles to exceed US federal weight limits off the interstate system, but state-specific load rating vehicles are developed to ensure that bridges can carry such vehicles safely. However, if the load effects of state rating vehicles are not similar to those of the vehicles operating in the state, the load factors required for the safety of some bridges may be too large for others, resulting in unnecessary remediation that may include retrofitting, posting, or even closure. In this study, a quantifiable measure of load rating efficiency is used to analyze the load effects of rating and operating vehicles on a wide range of bridges. Using this measure of efficiency, a novel heuristic approach is used to identify nearly optimal rating loads that envelope the load effects of state operating vehicles, potentially reducing the need for remedial action. To illustrate, the approach is used to develop new rating loads proposed for the state of Indiana. This approach may be combined with further analyses to assess the potential economic impact of new rating vehicles. [ABSTRACT FROM AUTHOR]

A split-type two-axle vehicle for bridge indirect measurement is proposed to address the deficiencies of single-axle and conventional two-axle vehicles. At first, the conceptual design of the split-type two-axle vehicle is put forth, and the analytical solution for the vehicle-bridge interaction (VBI) system response is derived. After that, the regularity of the vehicle frequency response function is studied, and the numerical analysis method is utilized to validate the analytical solution. Based on the theoretical findings, the vehicle frequency and speed are studied to investigate their impacts on extracting bridge frequencies from vehicle responses. The results indicate that a peak will form in the frequency response function (FRF) curves when the input frequency is near to the vehicle frequency. The single peak phenomenon will occur when the zero-point condition of the FRF from the contact point to the vehicle body is remarkably close to the second vibration frequency of the vehicle. It is preferable for the first frequency of the vehicle to be higher than that of the bridge since this helps to extract the bridge frequency. On the other hand, at low speeds (≤ 43.2km/h), higher vehicle speeds will result in a greater distance between the peaks of the left- and right-shifted frequencies of the bridge, wider frequency bands, and lower spectral resolution, which is not conducive to bridge frequency identification. [ABSTRACT FROM AUTHOR]

As the frequency variation in a moving mass-plate system is seldom discussed in the previous work, this study first formulates the semi-analytical solutions of a system consisting of a moving mass on a square plate. Based on the moving mass-plate system, several finite element models with designed plate-type bridges are established to further investigate the effect of moving mass on a plate, the influence of bridge local modes, and the influence of moving loads on a bridge. The numerical results have shown that the frequency variation of a plate-type bridge can reach 30% for the first three modes. The unique phenomenon of wave propagation is exhibited in the acceleration responses of the plate-type bridge, while it is uncommon for a beam-type bridge. For design purpose, the following are remarked: (1) The use of Rayleigh damping on the stiffened bridge can effectively suppress the influence of local modes on the bridge deck. (2) The high stiffness in the moving load can be served as the damper to reduce the dynamic responses of a vehicle. (3) In the design stage of a plate-type bridge subjected to moving loads, the moving force is the most conservative one among the three moving loads. [ABSTRACT FROM AUTHOR]

As a critical characteristic curve of bridge structures, the influence line (IL) is effective in evaluating the bridge damage and bearing capacity. Contrary to conventional methods using static loading to obtain IL, this study proposes a methodology to determine the rotation influence line (RIL) based on the vehicle–bridge interaction (VBI) under random traffic loads. A key feature is the employment of the machine learning algorithm to determine the RIL from the upper and lower bridge response data induced by traffic flow, which is simulated using the cellular automata (CA) approach. Subsequently, by establishing a relationship between the RIL difference and the structural damage coefficient, this study identifies the bridge damage location and degree effectively. The numerical example results validate the accuracy in identifying both single- and multi-damage cases. The parameter analysis indicates that larger vehicle speed induces higher errors in identifying the RIL and the bridge damage. [ABSTRACT FROM AUTHOR]

Here, we demonstrate superconducting Dayem-bridge weak-links made of different stoichiometric compositions of NbRe. Our devices possess a relatively high critical temperature, normal-state resistance, and kinetic inductance. In particular, the high kinetic inductance makes this material a good alternative to more conventional niobium-based superconductors (e.g., NbN or NbTiN) for the realization of superinductors and high-quality factor resonators, whereas the high normal-state resistance yields a large output voltage in superconducting switches and logic elements realized upon this compound. Moreover, out-of-plane critical magnetic fields exceeding 2 T ensure that possible applications requiring high magnetic fields can also be envisaged. Altogether, these features make this material appealing for a number of applications in the framework of quantum technologies. [ABSTRACT FROM AUTHOR]

Segmenting esophageal tumor from computed tomography (CT) sequence images can assist doctors in diagnosing and treating patients with this malignancy. However, accurately extracting esophageal tumor features from CT images often present challenges due to their small area, variable position, and shape, as well as the low contrast with surrounding tissues. This results in not achieving the level of accuracy required for practical applications in current methods. To address this problem, we propose a 2.5D context-aware feature sequence fusion UNet (2.5D CFSF-UNet) model for esophageal tumor segmentation in CT sequence images. Specifically, we embed intra-slice multiscale attention feature fusion (Intra-slice MAFF) in each skip connection of UNet to improve feature learning capabilities, better expressing the differences between anatomical structures within CT sequence images. Additionally, the inter-slice context fusion block (Inter-slice CFB) is utilized in the center bridge of UNet to enhance the depiction of context features between CT slices, thereby preventing the loss of structural information between slices. Experiments are conducted on a dataset of 430 esophageal tumor patients. The results show an 87.13% dice similarity coefficient, a 79.71% intersection over union and a 2.4758 mm Hausdorff distance, which demonstrates that our approach can improve contouring consistency and can be applied to clinical applications. [ABSTRACT FROM AUTHOR]

The single-stage dual active bridge (DAB) AC-DC converter has the advantages of high power density, low cost, and simple control; it has a broad potential for application in the field of onboard chargers (OBC). However, the lack of fast and accurate quantitative parameter optimization design methods in single-stage DAB AC-DC converters limits the overall efficiency of the converter. Based on the above problem, in order to improve the overall operating efficiency of the converter by optimizing the parameter transformer ratio and power inductance, this paper proposes a parameter design method considering a multi-timescale strategy by combining the steady-state analysis model of the converter in the line cycle and switching cycle and step-by-step reducing its design space through the constraints on the parameters. The first step is to obtain a safe design space for the parameters under the converter's transmitted power and current stress constraints. The second step obtains the optimization design space of the parameters under the optimization of conduction loss and switching loss of the converter. Finally, the optimal parameters are determined by the loss analysis model. The proposed parameter optimization method entirely takes into account the steady-state characteristics of the DAB AC-DC converter during the line cycle, and the step-by-step constraints greatly accelerate the parameter design process. In addition, the proposed parameter optimization design method applies to all types of single-stage DAB AC-DC converters, which can be well applied to engineering practice. [ABSTRACT FROM AUTHOR]

This work explores the possibility of automating the aerial survey of bridges to generate high-resolution images necessary for digital damage inspection. High-quality unmanned aerial vehicle (UAV) based 3D reconstruction of bridges is an important step towards autonomous infrastructure inspection. However, the calculation of optimal camera poses remains challenging due to the complex structure of bridges and is therefore often conducted manually. This process is time-consuming and can lead to quality losses. Research in this field to automate this process is yet sparse and often requires high informative models of the bridge as the base for calculations, which are not given widely. Therefore, this paper proposes an automated camera pose calculation method solely based on an easily accessible polygon mesh of the bridge. For safe operation, point cloud data of the environment are used for automated ground detection and obstacle avoidance including vegetation. First, an initial set of camera poses is generated based on a voxelized mesh created in respect to the quality requirements for 3D reconstruction using defined camera specification. Thereafter, camera poses not fulfilling safety distances are removed and specific camera poses are added to increase local coverage quality. Evaluations of three bridges show that for diverse bridge types, near-complete coverage was achieved. Due to the low computational effort of the voxel approach, the runtime was kept to a minimum, even for large bridges. The subsequent algorithm is able to find alternative camera poses even in areas where the optimal pose could not be placed due to obstacles. [ABSTRACT FROM AUTHOR]

Prediabetes and colorectal cancer (CRC) represent compelling health burdens responsible for high mortality and morbidity rates, sharing several modifiable risk factors. It has been hypothesized that metabolic abnormalities linking prediabetes and CRC are hyperglycemia, hyperinsulinemia, and adipokines imbalance. The chronic stimulation related to these metabolic signatures can favor CRC onset and development, as well as negatively influence CRC prognosis. To date, the growing burden of prediabetes and CRC has generated a global interest in defining their epidemiological and molecular relationships. Therefore, a deeper knowledge of the metabolic impairment determinants is compelling to identify the pathological mechanisms promoting the onset of prediabetes and CRC. In this scenario, this review aims to provide a comprehensive overview on the metabolic alterations of prediabetes and CRC as well as an overview of recent preventive and therapeutic approaches for both diseases, focusing on the role of the metabolic state as a pivotal contributor to consider for the development of future preventive and therapeutic strategies. [ABSTRACT FROM AUTHOR]

Highway bridges are crucial civil constructions for the transport infrastructure, which require proper attention from the corresponding institutions of each country and constant financing for their adequate maintenance; this is important because different types of damage can be generated within these structures, caused by natural disasters, among other sources, and the heavy loads they transport every day. Therefore, the development of simple, efficient, and low-cost methods is of vital importance, allowing us to identify damage in a timely manner and avoid bridges collapsing. As reported in a previous work, the wavelet energy accumulation method (WEAM) and its corresponding application in the Rio Papaloapan Bridge (RPB) represented an important advance within the field. Despite identifying damage in bridges with precision and at a low cost, there are several aspects to improve in that method. Therefore, in this work, that method was improved, eliminating several steps, and meaningfully reducing the computational burden by implementing an algorithm based on the Shannon entropy, thus giving way to the new entropy wavelet-based method (EWM). This new method was applied directly with regard to the real-life RPB, in both its healthy and damaged conditions. Also, its corresponding numerical model based on the finite element method in its healthy condition and different damage scenarios were carried out. The results indicate that the new EWM retains the advantages of WEAM, and it allows for damage identification to be completed more efficiently, increasing the precision by approximately 0.11%, and significantly reducing the computing time required to obtain results by 5.67 times. [ABSTRACT FROM AUTHOR]

With the rapid development of national infrastructure projects, there has been a significant increase in intersecting lines in transportation construction. As a result, rotating bridges are increasingly used in engineering projects that span existing railway lines. In order to study the spatial response characteristics and vibration wave transmission mechanisms of the rotating bridge structure under the loading of existing railway trains, field experiments and numerical analyses were conducted. The response characteristics of these bridges were investigated under different types and speeds of adjacent existing lines. A comprehensive methodology has been proposed, integrating the time domain spectrum and the Hilbert–Huang Transform (HHT) energy spectrum for signal processing and vibration analysis. The analysis was carried out using MATLAB 2018a software. This methodology was applied to analyze the test data. The results show that significant resonance phenomenon occurs in the girders of the rotating bridge under the loading of trains on the existing line. The low-frequency component f1 (2–5 Hz) is the primary factor contributing to the amplification of the acceleration response in the rotating bridge, while f3 (10–13 Hz) plays a secondary role. The frequency distribution characteristics of vibration waves caused by train loads on the existing line have a significant influence on the acceleration response of the rotating bridge's girders. The predominant frequency of vibration waves at each measuring point along the transmission path shows a trend of decreasing → increasing → decreasing. The impact on the rotating bridge structure of vibration waves generated by low-speed freight trains on existing railways is greater. The research findings are of great importance for studying the dynamic response of rotating bridges adjacent to existing railway lines. [ABSTRACT FROM AUTHOR]

Bridges situated on small-radius reverse curves play a pivotal role within some railway networks, exerting influence over project-wide design progress. Typically, assessing the safety of bridge design parameters necessitates laborious vehicle-bridge dynamic coupling vibration numerical analysis or model experiments. To streamline the design process and enhance efficiency during the preliminary design phase, we propose an efficient method to assess the dynamic performance of bridges on small-radius reverse curves. This approach enables direct prediction of bridge dynamic performance based on design parameters, eliminating the need for numerical simulations and model experiments. We first develop a vehicle-bridge coupling vibration program grounded in train-curve bridge coupling vibration theory, validated using on-site measured data. Subsequently, through numerical simulation experiments, we evaluate 80 simply supported beam bridges on small-radius reverse curves under various operating conditions, generating ample dynamic response data for bridge pier tops and girders. These data are then compared with regulatory thresholds to assign dynamic performance labels. After identifying essential design parameters as data features using Fisher scores, we proceed to input these features into a support vector machine (SVM). Through supervised training with dynamic performance labels, this process empowers the SVM model to predict the dynamic performance of the bridge. Our results demonstrate that this method circumvents the need for detailed vehicle-bridge interaction analysis, yielding an impressive 86.9% accuracy in predicting dynamic performance and significantly boosting computational efficiency. Besides, the top five design parameters that significantly influence the prediction of bridge dynamic performance are obtained. This novel approach has the potential to expedite design assessments and enhance safety in railway bridge construction. [ABSTRACT FROM AUTHOR]

The racemization of chiral organic compounds is a common chemical phenomenon. However, it often poses configurational‐stability issues to the application of this class of compounds. Achieving chiral organic compounds without the risk of racemization is fascinating, but it is challenging due to a lack of strategies. Here, we reveal the cove‐regions bridging strategy for achieving persistently chiral multi‐helicenes (incapable of racemization), based on the synthesized proof‐of‐concept double hetero[4]helicenes featuring macrocycle structures with a small 3D cavity. Additionally, we demonstrate that the strategy is also effective in tuning the electronic structures of multi‐helicenes, resulting in a conversion from luminescence silence into thermally activated delayed fluorescence (TADF) for the present system. Furthermore, red circularly polarized TADF based on small double [4]helicene systems is achieved for the first time using this strategy. The disclosed cove‐regions bridging strategy provides an opportunity to modulate the electronic structures and luminescent properties of multi‐helicenes without concern for racemization, thus significantly enhancing the structural and property diversity of multi‐helicenes for various applications. [ABSTRACT FROM AUTHOR]

Indenyl-(Ind) and fluorenyl-(Fl) substituted NHC-stabilized alanes and gallanes (NHC)·EH2R 1–12 (NHC = IiPrMe, IiPr, IMeMe; E = Al, Ga; R = Ind, Fl) were prepared via reaction of the corresponding NHC-iodoalanes and -gallanes with LiInd and LiFl, respectively. Analogously, the alane adducts with two Ind/Fl substituents (NHC)·AlHR213–18 (NHC = IiPrMe, IiPr, IMeMe; R = Ind, Fl) were obtained by using two equivalents of LiInd/LiFl. Elimination of indene and fluorene was induced thermally affording unusual dimeric and trimeric NHC-alane adducts {(NHC)·AlH2}2-μ-Fl 19–20 and {(NHC)·AlH-μ-R}n21–23 (R = Ind, Fl; n = 2, 3) with bridging indenyl and fluorenyl ligands. [ABSTRACT FROM AUTHOR]