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Although no known asteroid poses a threat to Earth for at least the next century, the catalogue of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation 1 , 2 . Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid 1 – 3 . A test of kinetic impact technology was identified as the highest-priority space mission related to asteroid mitigation 1 . NASA’s Double Asteroid Redirection Test (DART) mission is a full-scale test of kinetic impact technology. The mission’s target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by the impact of the DART spacecraft 4 . Although past missions have utilized impactors to investigate the properties of small bodies 5 , 6 , those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft’s autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in the orbit of Dimorphos 7 demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary. The impact of the DART spacecraft on the asteroid Dimorphos is reported and reconstructed, demonstrating that kinetic impactor technology is a viable technique to potentially defend Earth from asteroids.

As the worlds first floating wind farm, one of the main technical challenges in the design phase of Hywind Scotland was the uncertainty related to wake interaction effects between the floating wind turbines. In this paper, we address this challenge by presenting an analysis of full‐scale measurements from the Hywind Scotland wind farm. Measurements of the floaters' roll, pitch and yaw motions are presented, both in the form of statistical data and response spectra. The floater responses of a turbine in free wind and a turbine in wake are compared, and the influence of different atmospheric stabilities on the floater motions is investigated. Despite the large distance between the turbines of 9 rotor diameters, wake effects in the measured floater motions are observed at the downstream turbine. Furthermore, both the wake responses and the free wind responses show a clear dependency on atmospheric stability. However, overall motions are small for all wind speeds, showing that the design performs satisfactorily in both free wind and wake conditions.

To explore the load-bearing performance and the failure patterns of the lining structures, a full-scale loading test on the three-ring staggered assembled shield tunnel segments is carried out through a hydraulic loading system. In the experimental study, the segments’ internal force, convergence deformation, and displacement, and the bolts’ internal force, are analyzed. According to the experimental results, the relationship between internal force and deformation is obtained to determine the residual bearing capacity of the shield tunnel at each stage. Three stages are specified for the evolution of the segment’s maximum bending moment during the loading process, in which, the elastic stage is the main and longest stage, in which the bending moment of the segment increases the most. There are two stages for convergence deformation development and segment misalignment development. At the end of loading, the segment’s maximum positive and negative convergence values reach 61.22 and −57.69 mm, respectively. Besides, the maximum segment misalignment is 3.67 mm, which occurs in the direction of 90°. The segment cracks when its maximum convergence value reaches 25.03 mm. Moreover, there are signs of fracturing on the waist joint of the segment when its maximum convergence value reaches 32.73 mm. The concrete at the waist joint starts fracturing in pieces when the segment’s maximum convergence value reaches 38.93 mm, which is defined as the type of shear failure. Finally, the bearing capacity of shield tunnels during segment failure period can be evaluated by using the corresponding relationship between deformation and internal force.

This study employed a combined experimental and theoretical approach to investigate the influence of foreign object damage (FOD) on the fatigue limit of surface-strengthened EA4T axles. FOD was introduced on surface-strengthened axle specimens to generate surface defects, and finite element analysis was subsequently performed to evaluate the stress fields in the damaged regions. Fatigue tests were conducted on prefabricated defective specimens to characterize their fatigue behavior. Based on test results, an improved backward statistical inference method was used to fit the fatigue P-S-N curves for each specimen group and derive corresponding fatigue limits. The fatigue limit of full-size damaged axles was estimated by extrapolating from small-scale test results, with due consideration of geometric scale effects on mechanical performance. Considering the stochastic distribution of impact defect depths, an exponential fitting was performed to establish the quantitative relationship between defect depth and full-size axle fatigue limit. Finally, a multivariate fatigue limit prediction model was developed for surface-strengthened full-size EA4T axles based on the El-Haddad formula framework. This model enables comprehensive assessment of fatigue performance under multi-parameter coupling conditions, providing a robust theoretical basis for safety evaluation and maintenance strategies of high-speed train axles subjected to foreign object impacts.

The hippocampus is a key brain region for memory and cognitive functions, which consists of distinct subregions with different developmental trajectories throughout adolescence. However, trajectories of hippocampal subfield change in young adulthood remain uncharacterized, as is their potential relationship with cortical brain aging and cognitive ability during this time. We conducted two magnetic resonance imaging (MRI) follow‐ups of a prenatal birth cohort in young adulthood and studied the effects of chronological age and cortical brain age on the volume of hippocampal subfields in the early 20s (n = 109; 51% men) and late 20s (n = 251; 53% men) and how these age‐related volumetric changes might relate to full‐scale IQ (FSIQ). We showed that CA1 and CA4DG subfields continue to grow in the third decade of life and that this growth can be observed both at the level of chronological age as well as estimated cortical brain age at both MRI timepoints. Moreover, in men, a larger size of these age‐related subfields was associated with higher FSIQ, and the deviations between cortical brain age and chronological age mediated the relationships between right CA1 and FSIQ, as well as right CA4DG and FSIQ. These findings reveal that coordinated patterns of advanced cortical brain aging and hippocampal maturation may confer a cognitive advantage in young adulthood. Hippocampal subfields continue to develop in young adulthood, and in young adult men, the deviations between one's global cortical brain age and chronological age mediate the relationship between the size of CA1 and CA4DG and full‐scale IQ. These findings suggest that faster brain maturation early on is beneficial.

Digital image correlation (DIC) is an optical technique used to measure surface displacements and strains in materials and structures. This technique has demonstrated significant utility in structural examination and monitoring. This manuscript offers a comprehensive review of the contemporary research and applications that have leveraged the DIC technique in laboratory-based structural tests. The reviewed works encompass a broad spectrum of structural components, such as concrete beams, columns, pillars, masonry walls, infills, composite materials, structural joints, steel beams, slabs, and other structural elements. These investigations have underscored the efficacy of DIC as a metrological instrument for the precise quantification of surface deformation and strain in these structural components. Moreover, the constraints of the DIC technique have been highlighted, especially in scenarios involving extensive or complex test configurations. Notwithstanding these constraints, the effectiveness of the DIC methodology has been validated as a strain measurement instrument, offering numerous benefits such as non-invasive operation, full-field measurement capability, high precision, real-time surveillance, and compatibility with integration into other measurement instruments and methodologies.

Strong excitation effect on the outer windshield structure induced by unsteady airflow around the connection between carriages has been normally detected in full-scale tests, which leads to violent vibration of the outer windshields due to strong nonlinear fluid–structure interaction (FSI) between the flow field and the structure. Previous studies normally treat the outer windshield structure as rigid bodies, and the coupling effect between unsteady flow and elastic structure has not been considered. The purpose of this study is to establish a two-way iterative FSI model based on a full-scale test, obtain the flow field characteristics around the outer windshields through FSI simulation, and analyze their vibration mechanism and characteristics. The results show that the iterative computing of two-way coupling has good applicability for the analysis of the vibration of the outer windshields of a high-speed train (HST). The relative deviation of the surface pressure of the outer windshield between the test and simulation is 4.3%, and the relative deviation of the main frequency of pressure change is 1.9%. Under the action of aerodynamic loading, two opposite U-section rubber capsules produce dislocation deformation movement, which produces bending deformation, and the deformation vibration frequency is close to the first-order natural frequency of the structure. Then, under the coupling action of aerodynamic, elastic, and inertial forces, the vibration mode close to the high-order natural frequency of the outer windshield structure is excited, and the displacement phase of the outer windshield presents prominent periodicity. This study can provide a reference for the study of aeroelastic problems of the external structure of HSTs.

Accelerated epigenetic aging has been associated with changes in cognition. However, due to the lack of neuroimaging epigenetics studies, it is still unclear whether accelerated epigenetic. Aging in young adulthood might underlie the relationship between altered brain dynamics and cognitive functioning. We conducted neuroimaging epigenetics follow‐up of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) prenatal birth cohort in young adulthood and tested the possible mediatory role of accelerated epigenetic aging in the relationship between dynamic functional connectivity (DFC) and worse cognition. A total of 240 young adults (51% men; 28–30 years, all of European ancestry) participated in the neuroimaging epigenetics follow‐up. Buccal swabs were collected to assess DNA methylation and calculate epigenetic aging using Horvath's epigenetic clock. Full‐scale IQ was assessed using the Wechsler adult intelligence scale (WAIS). Resting‐state functional magnetic resonance imaging (rs‐fMRI) was acquired using a 3T Siemens Prisma MRI scanner, and DFC was assessed using mixture factor analysis, revealing information about the coverage of different DFC states. In women (but not men), lower coverage of DFC state 4 and thus lower frequency of epochs with high connectivity within the default mode network and between default mode, fronto‐parietal, and visual networks was associated with lower full‐scale IQ (AdjR2 = 0.05, std. beta = 0.245, p = 0.008). This relationship was mediated by accelerated epigenetic aging (ab = 7.660, SE = 4.829, 95% CI [0.473, 19.264]). In women, accelerated epigenetic aging in young adulthood mediates the relationship between altered brain dynamics and cognitive functioning. Prevention of cognitive decline should target women already in young adulthood. Neuroimaging epigenetics follow‐up of a prenatal birth cohort reveals that in women, accelerated epigenetic aging in young adulthood might alter brain dynamics leading to worse cognition.

Advancement trends in DTH air hammer engineering are described, and the modern design requirements are presented. The schematic of DTH air hammer to comply with the current standards is given. Reliability of the machine with three-stage hammering unit is discussed. The process of bottomhole cleaning in this DTH air hammer operation is described. The capacities of an elastic valve arrangement at the largest stage of the hammering unit are determined. The theoretical and full-scale test data of the proposed DTH air hammer design are presented.

Automated sensing instruments on satellites and aircraft have enabled the collection of massive amounts of high-resolution observations of spatial fields over large spatial regions. If these datasets can be efficiently exploited, they can provide new insights on a wide variety of issues. However, traditional spatial-statistical techniques such as kriging are not computationally feasible for big datasets. We propose a multi-resolution approximation (M-RA) of Gaussian processes observed at irregular locations in space. The M-RA process is specified as a linear combination of basis functions at multiple levels of spatial resolution, which can capture spatial structure from very fine to very large scales. The basis functions are automatically chosen to approximate a given covariance function, which can be nonstationary. All computations involving the M-RA, including parameter inference and prediction, are highly scalable for massive datasets. Crucially, the inference algorithms can also be parallelized to take full advantage of large distributed-memory computing environments. In comparisons using simulated data and a large satellite dataset, the M-RA outperforms a related state-of-the-art method. Supplementary materials for this article are available online.