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An inertial micro-switch with multi-threshold acceleration detection capability has been proposed, taking advantage of electromechanical coupling behavior. A mathematical model of electromechanical coupling behavior was established to display the dependence of highly sensitivity on pull-in characteristic and show the ability to detect threshold acceleration by controlling the voltage applied to the inertial micro-switch. The capability of sensitivity and detection that was described in mathematical model was implemented to occur at the inertial switch and showed agreement with that of a simulation. Inertia switches that were comprised of various microstructures with dimensions ranging 3.5 µm from 180 µm were manufactured by means of the micro-electro-mechanical system (MEMS) manufacturing process, and their functions were evaluated by a dropping system. The control method related to the manufacturing of inertial switches was obtained by analyzing the effect of the structural parameters of the inertial switch on threshold voltage and threshold acceleration, resulting in a relatively small error between simulation and experiment. The inertial micro-switch showed high sensitivity to achieving the pull-in effect at 30 V, sense multi-threshold acceleration ranging from 500 g to 2000 g in 2.46 ms and provided enough time for outputting the acceleration signal. Furthermore, the multi-threshold acceleration can be adjusted by controlling the voltage applied to inertial micro-switches. In addition, other functions of inertial micro-switches, such as lower residual stress, high recoverability, and repeatability, have been displayed.

This paper presents a tunable multi-threshold micro-electromechanical inertial switch with adjustable threshold capability. The demonstrated device combines the advantages of accelerometers in providing quantitative acceleration measurements and g-threshold switches in saving power when in the inactive state upon experiencing acceleration below the thresholds. The designed proof-of-concept device with two thresholds consists of a cantilever microbeam and two stationary electrodes placed at different positions in the sensing direction. The adjustable threshold capability and the effect of the shock duration on the threshold acceleration are analytically investigated using a nonlinear beam model. Results are shown for the relationships among the applied bias voltage, the duration of shock impact, and the tunable threshold. The fabricated prototypes are tested using a shock-table system. The analytical results agree with the experimental results. The designed device concept is very promising for the classification of the shock and impact loads in transportation and healthcare applications. [ABSTRACT FROM AUTHOR]

As a typical type of MEMS acceleration sensor, the inertial switch can alter its on-off state while the environmental accelerations satisfy threshold value. An exhaustive summary of the design concept, performance aspects, and fabrication methods of the micro electromechanical system (MEMS) inertial switch is provided. Different MEMS inertial switch studies were reviewed that emphasized acceleration directional and threshold sensitivity, contact characteristics, and their superiorities and disadvantages. Furthermore, the specific fabrication methods offer an applicability reference for the preparation process for the designed inertial switch, including non-silicon surface micromachining technology, standard silicon micromachining technology, and the special fabrication method for the liquid inertial switch. At the end, the main conclusions of the current challenges and prospects about MEMS inertial switches are drawn to assist with the development of research in the field of future engineering applications.

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Shaking table tests were performed on reduced-scale models of integrated and two-tiered mechanically stabilized earth walls (TMSEWs) to evaluate the effect of a tiered configuration on the dynamic behavior of geogrid-reinforced soil walls. The results of particle image velocimetry and instrumentation indicate that preventing the development of a slip surface in the lower half of the wall, improving the seismic stability by increasing the failure threshold acceleration, mitigating acceleration amplification and decreasing the reinforcement load were the main advantages of a tiered configuration. It was found that the use of an insufficient offset distance in TMSEWs not only eliminated the advantage of the tiered configuration for reducing wall deformations, but also increased the lateral displacement at the wall crest. In this regard, 0.22H was identified as the minimum offset distance required when constructing MSE walls in a tiered configuration. Moreover, comparison of integrated and tiered MSE walls showed that the effect of a tiered configuration on reducing the force of the reinforcements in the lower tier was approximately 2.2 times that for the upper tier reinforcements. It was also found that Mononobe-Okabe method can be used to find the upper bound for estimating the load of reinforcements in TMSEWs. [ABSTRACT FROM AUTHOR]

A pseudostatic coefficient is required for pseudostatic analysis of mechanically stabilized earth (MSE) walls, but there are no clear criteria for its selection. The current study assessed the horizontal pseudostatic coefficient (kh) for MSE walls by considering the effects of a tiered configuration and reinforcement type. A series of shaking table tests were performed on reduced-scale models of integrated and two-tiered MSE walls reinforced by metal strips and geogrids to determine the failure threshold acceleration, axial force distribution along the reinforcements at the failure stage, and geometry of the slip surfaces. Physical models were simulated using the limit equilibrium horizontal slice method to estimate the value of kh required to establish slip surfaces and reinforcement forces similar to those observed in shaking table tests. Based on the results, the horizontal pseudostatic coefficient was introduced as a function of the maximum horizontal acceleration, offset distance, and reinforcement type. [ABSTRACT FROM AUTHOR]

Recent experiments by Shao et al. ["Surface wave pattern formation in a cylindrical container," J. Fluid Mech. 915, A19 (2021)] have revealed complex wave dynamics on the surface of a liquid bath in a vertically vibrated cylindrical container that are related to the presence of a meniscus on the container sidewall. We develop a corresponding theoretical model for this system by detuning the driving acceleration of the container, which results in an inhomogeneous Mathieu equation that governs the wave dynamics whose spatial structure is defined by the mode number pair (n , m) , with n and m the radial and azimuthal mode numbers, respectively. Asymmetric m ≠ 0 modes are unaffected by the detuning parameter, which is related to the meniscus shape and satisfy a homogeneous Mathieu equation with the shape of the instability tongues computed by the Floquet theory. The Poincaré–Lindstedt method is used to compute the instability tongues for the axisymmetric m = 0 modes, which have a lower threshold acceleration and larger bandwidth that depend upon the detuning parameter. Our model results explicitly show how the shape of the meniscus and spatial structure of the wave determine the temporal response and are in good agreement with prior experimental observations for both pure modes and mixed modes. [ABSTRACT FROM AUTHOR]

Shake table tests on two-tiered metal-strip MSE walls showed that the prevention of slip surface development in the lower half of the wall, improving seismic stability by increasing failure threshold acceleration, and mitigating acceleration amplification were the main advantages of using a two-tiered configuration in constructing MSE walls. This was also found that the use of an insufficient offset distance not only eliminated the advantage of the tiered configuration for reducing wall deformations, but also increased the wall crest displacement. Hence, 0.22 H was found to be as the minimum offset distance required when constructing MSE walls in a two-tiered configuration. [ABSTRACT FROM AUTHOR]

S-net is a large-scale seafloor observation network for earthquakes and tsunamis around the Japan Trench, consisting of 150 observatories equipped with seismometers and pressure gauges. The sensors have been set up inside cylindrical pressure vessels, which have been buried in the shallow-water regions (water depth <1,500 m), while the vessels have been laid freely on the seafloor in the deeper-water regions. Previous studies showed that the cylindrical pressure vessels rotate during strong shakings due to poor coupling with the seabed sediments, thus making it difficult to retrieve the actual ground motions. We investigated the static changes in the orientations of S-net accelerometers due to shakings from 1,878 earthquakes of Mj greater than 4 that occurred around the network, and found that rotations as large values as 16° were observed during the 2022,Mj 7.4, off-Fukushima Prefecture earthquake. We estimated the threshold acceleration levels after which the sensors are likely to rotate at all S-net stations separately and found that the threshold values lie mostly between 5 and 50 cm/s². Finally, we discussed the observed peak accelerations and velocities at the S-net stations with those recorded on land, where high-quality records were obtained, during the 2022, Mj 7.4 earthquake, which was also the largest magnitude earthquake to occur in the region after the network commenced operation. The results presented herein complement several previous studies and form the basis for more comprehensive future investigations. [ABSTRACT FROM AUTHOR]

The nonlinearity of the soil may considerably affect the response of structures subjected to seismic events. This paper aims to show under which circumstances geometry, soil, and earthquake-type; the nonlinearity is important. A simple model based on a 1D shear column was developed to calculate the maximum shear strain (γ) in the soil subjected to earthquake excitation. It was found that Δ is a function of peak ground acceleration PGA and the maximum horizontal ground displacement (Δ). EC8 provides an expression for calculating Δ that is independent of the soil thickness. It was found that this expression is conservative for shallow layers and underestimates γ for thick ones, as a result, improvements have been suggested. By performing several time history analyses, simple formulas are developed which enable the designer to assess when nonlinearity must be taken into account. Four curves based on soil thickness and peak ground acceleration have been introduced for different soil types (A, B, C, and D) using a limit value of γ = 10-4. These curves show that depending on the soil depth, the threshold acceleration of nonlinear soil behavior is around 0.48, 0.36, 0.29, and 0.10 m/s2 for soil types A, B, C, and D, respectively. Obviously, nonlinear analysis must be performed for shallow soil layers under moderate seismicity. [ABSTRACT FROM AUTHOR]

Shaking table tests were performed on reduced-scale models of integrated and two-tiered mechanically stabilised earth (MSE) walls to evaluate the effect of a tiered configuration on the seismic behaviour of metal-strip and geogrid reinforced soil walls. The results showed that, although inextensible reinforcements could reduce the fundamental period, acceleration amplification and lateral deflection and improve wall stability, these benefits declined with the use of a tiered configuration and gradually faded with an increase in the offset distance. This made changing the degree of extensibility a low-impact factor in two-tiered MSE walls with a sufficiently large offset distance (D > (0.4–0.5)H). In order to benefit from the advantage of a tiered configuration, it was found that 0.22H should be considered as the minimum offset distance. The findings indicated that preventing the development of a slip surface in the lower half of the wall, improving the seismic stability by increasing the failure threshold acceleration, mitigating acceleration amplification and decreasing the reinforcement load were the main advantages of a tiered configuration. Moreover, it was concluded that the Mononobe–Okabe method could be used to find the upper bound for estimating the reinforcement forces in two-tiered MSE walls. [ABSTRACT FROM AUTHOR]

This paper describes a study on identifying vortex-induced vibration (VIV) of the Osman Gazi Bridge tower during construction and in-service conditions and its control strategy using an active mass damper. In the wind tunnel tests conducted before bridge construction, tower VIV was identified in the first out-of-plane tower bending mode despite the presence of aerodynamic corner cuts on the tower cross section. Bridge towers are made of steel boxes with inherently low damping, resulting in a VIV amplitude exceeding the limits for the workability and safety required in the design specification. An active mass damper (AMD) was proposed to mitigate tower VIV during construction and in-service conditions. The investigations of tower aerodynamic characteristics related to VIV in wind tunnel tests, design considerations, and implementation of AMD in construction and in-service conditions are presented. Unlike active control systems on other long-span bridge towers that were removed after construction completion, the AMD systems on the Osman Gazi Bridge tower continue to function even after bridge construction completion. This makes the AMD on the Osman Gazi Bridge the world's first application of a full active control system on a long-span bridge tower for in-service conditions. The AMD system was found effective in controlling the vibration under both conditions by providing additional damping higher than the requirement in the design specification. The robustness and effectiveness of the active control system are demonstrated in a 1-year full observation of AMD performance via a structural monitoring system. In general, the RMS of tower VIV accelerations under AMD control is lower than 15 cm/s2 or approximately 50% smaller than the corresponding accelerations without AMD control. [ABSTRACT FROM AUTHOR]

In off-road environments, the lateral rollover stability of articulated unmanned rollers (URs) is critical to ensure operational safety and efficiency. This paper introduces the concept of a rollover energy barrier (REB), a symmetry-based metric that quantifies the energy margin between the current state and the critical rollover threshold of articulated rollers. URs exhibit dynamic asymmetry due to their hydraulic steering systems, which differ significantly from traditional passenger vehicles. To address these challenges, we propose a hierarchical control framework inspired by the principles of dynamic symmetry. This framework integrates Nonlinear Model Predictive Control (NMPC) and Active Disturbance Rejection Control (ADRC): NMPC is used for trajectory planning by incorporating the REB into the cost function, ensuring rollover stability, while ADRC compensates for dynamic asymmetries, model uncertainties, and external disturbances during trajectory tracking. Simulation and experimental results validate the effectiveness of the proposed control strategy in enhancing the rollover stability and tracking performance of the URs under off-road conditions. [ABSTRACT FROM AUTHOR]

For the purpose of monitoring security for the elderly in daily life, a novel space-omnidirectional wearable inertial switch was designed, fabricated and tested for fall detection system in this paper. Omnidirectional dynamic response of the inertial switch was simulated and analyzed using ANSYS software. The simulation results indicated that the inertial switch can be closed in the omnidirectional space at an acceleration of 4.24 g, the response time of the switch is less than 2.6 ms, and the contact time of the switch is more than 200 μs. Besides, the inertial switch was fabricated using UV-LIGA multilayer photolithography and precision micro electroforming technologies, and the dynamic test of the switch was carried out by the drop hammer experiment. The test results showed that the inertial switch can be closed at an acceleration of more than 5 g. Meanwhile, all contact time is more than 110 μs and the longest is 366 μs, which can meet the application requirements. [ABSTRACT FROM AUTHOR]

Emissions of nitrogen oxides from road vehicles pose a public health hazard because of their role in smog and acid rain formation. Although a great body of research exists on driving techniques to reduce vehicular fuel use and carbon dioxide emissions, solutions for other pollutants such as nitrogen oxides are not nearly as well studied. Unfortunately, nitrogen oxides do not necessarily trend with fuel consumption as carbon dioxide emissions do and the fuel-minimal solution may produce excess nitrogen oxides. This article addresses the emissions eco-driving problem for compression-ignition engines with EGR and SCR using an optimal control approach based on Pontryagin’s minimum principle (PMP). In anticipation of eco-coaching applications, a simplified piecewise-affine model results in optimal acceleration as rational functions of speed. The effectiveness of this approach is compared to dynamic programming (DP) and heuristic rules from an available eco-driving mobile app. When applied to a real-world human driving dataset from an urban area, the proposed technique reduced modeled emissions of nitrogen oxides by 35%–36% while simultaneously reducing carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

Given the complexities of reinforced soil materials' constitutive relationships, this paper compares reinforced soil composite materials to a sliding structure between steel bars and soil and proposes a reinforced soil constitutive model that takes this sliding into account. A finite element dynamic time history calculation software for composite response analysis was created using the Fortran programming language, and time history analysis was performed on reinforced soil retaining walls and gravity retaining walls. The vibration time histories of reinforced soil retaining walls and gravity retaining walls were computed, and the dynamic reactions of the two types of retaining walls to vibration were compared and studied. The dynamic performance of reinforced earth retaining walls was evaluated. [ABSTRACT FROM AUTHOR]

A source of ground-motion recordings in urban Los Angeles that has seen limited prior application is the Community Seismic Network (CSN), which uses low-cost, micro–electro–mechanical system (MEMS) sensors that are deployed at much higher densities than stations for other networks. We processed CSN data for the 29 earthquakes with M > 4 between July 2012 and January 2023 that produced CSN recordings, including selection of high- and low-pass corner frequencies (fcHP and fcLP, respectively). Each record was classified as follows: (1) Broadband Record (BBR)—relatively broad usable frequency range from fcHP < 0.5 to fcLP > 10 Hz; (2) Narrowband Record (NBR)—limited usable frequency range relative to those for BBR; and (3) Rejected Record (REJ)—noise-dominated. We compare recordings from proximate (within 3 km) CSN and non-CSN stations (screened to only include cases of similar surface geology and favorable CSN instrument housing). We find similar high- to medium-frequency ground motions (i.e. peak ground acceleration (PGA) and Sa for T < 5 s) from CSN BBR and non-CSN stations, whereas NBRs have lower amplitudes. We examine PGA distributions for BBR and REJ records and find them to be distinguished, on average across the network, at 0.005 g, whereas 0.0015 g was found to be the threshold between usable records (BBR and NBR) and pre-event noise. Recordings with amplitudes near or below these thresholds are generally noise-dominated, reflecting environmental and anthropogenic ground vibrations and instrument noise. We find nominally higher noise levels in areas of high-population density and lower noise levels by a factor of about 1.5 in low-population density areas. By applying the 0.0015 g threshold, limiting distances for the network-average site condition, based on the expected fifth-percentile ground-motion levels, are 89, 210, 280, and 370 km for M 5, 6, 7, and 8 events, respectively. [ABSTRACT FROM AUTHOR]

Background: The landslide inventory of the western flank of Mount Oku, Cameroon, includes spreads or complex landslides, indicating sudden soil weakening, possibly due to seismic activity or heavy rainfall causing groundwater rise. These landslides were likely triggered between 2009 and 2018 based on the dates of the aerial imagery. Identifying triggers for past landslides remains a major unresolved issue in landslide science. However, understanding these triggers is crucial for accurately assessing future landslide hazards. Methodology: In this paper, we investigate the possibility of earthquakes to precondition landslide development or reactivation during climatic events. By assuming a magnitude 5.2 earthquake, an epicenter of 10 km from this area, and different wetness conditions, the factor of safety (FS) and Newmark displacement (ND) models were calculated for shallow and deep-seated landslides with sliding depths of 3 and 7.5 m. Afterward, the relationship between FS, assumed ND, and observed landslides was analyzed in a cluster analysis, to derive patterns of climatically and seismically triggered landslides. Results: The comparison of FS maps and FS values of the observed landslides revealed that especially for landslides at 7.5 m depth, most sites that are stable during dry conditions become instable under saturated conditions, indicating a climatic trigger. At 3 m depth, however, some landslide sites that are still marginally stable under saturated conditions, display relatively high ND values for the investigated hypothetical earthquake, indicating a possible seismic influence. In the cluster analysis, we clustered the observed landslides according to their distances to rivers and topographic ridges and obtained three clusters. Landslides from cluster 3 with 31% of the landslides display medium to high ND for the assumed earthquake, and were found near ridges and farther away from rivers, suggesting seismic triggering. Cluster 2, with 12% of landslides closer to rivers, suggested climatic origins. Thus, while climate is a critical landslide contributing factor, seismic events may also contribute, either by predisposing to landslides or by reactivating them alongside climatic factors. These results enable the establishment of more precise and effective landslide mitigating measures considering mostly rainfall but also earthquakes as possible triggers. [ABSTRACT FROM AUTHOR]

The increasing demand in structural engineering now extends beyond collapse prevention to encompass business continuity planning (BCP). In response, energy dissipation devices have garnered significant attention for building response control. Among these, buckling-restrained braces (BRBs) are particularly favored due to their stable hysteretic behavior and well-established design provisions. However, BCP also necessitates the prevention of furniture overturning—an area that remains quantitatively underexplored in the context of buckling-restrained braced frames (BRBFs). Addressing this gap, this research designs BRBFs using various design criteria and performs incremental dynamic analysis (IDA) with artificially generated seismic waves. The results are compared with previously developed fragility curves for furniture overturning under different BRB design conditions. The findings demonstrate that the fragility of furniture overturning can be mitigated by a natural frequency shift, which alters the threshold of critical peak floor acceleration. These results, combined with hazard curves obtained from various locations across Japan, quantify the mean annual frequency of furniture overturning. The study reveals that increased floor acceleration in stiffer BRBFs can lead to a 3.8-fold higher risk of furniture overturning compared to frames without BRBs. This heightened risk also arises from the greater hazards at shorter natural periods due to stricter response reduction demands. The probabilistic risk analysis, which integrates fragility and hazard assessments, provides deeper insights into the evaluation of BCP. [ABSTRACT FROM AUTHOR]

Large deformation of sand due to soil liquefaction is a major cause for seismic damage. In this study, the mechanisms and modeling of large post-liquefaction deformation of sand considering the significant influence of water absorption in shearing and seismic wave conditions. Assessment of case histories from past earthquakes and review of existing studies highlight the importance of the two factors. Based on the micro and macro scale mechanisms for post-liquefaction shear deformation, the mechanism for water absorption in shearing after initial liquefaction is revealed. This is aided by novel designed constant water-absorption-rate shear tests. Water absorption in shearing can be classified into three types, including partial water absorption, complete water absorption, and compulsory water absorption. Under the influence of water absorption in shearing, even a strongly dilative sand under naturally drained conditions could experience instability and large shear deformation. The mechanism for amplification of post-liquefaction deformation under surface wave load is also explained via element tests and theoretical analysis. This shows that surface wave-shear wave coupling can induce asymmetrical force and resistance in sand, resulting in asymmetrical accumulation of deformation, which is amplified by liquefaction. A constitutive model, referred to as CycLiq, is formulated to capture the large deformation of sand considering water absorption in shearing and seismic wave conditions, along with its numerical implementation algorithm. The model is comprehensively calibrated based on various types of element tests and validated against centrifuge shaking table tests in the liquefaction experiments and analysis projects (LEAP). The model, along with various numerical analysis methods, is adopted in the successful simulation of water absorption in shearing and Rayleigh wave-shear wave coupling induced large liquefaction deformation. Furthermore, the model is applied to high-performance simulation for large-scale soil-structure interaction in liquefiable ground, including underground structures, dams, quay walls, and offshore wind turbines. [ABSTRACT FROM AUTHOR]

As a typical type of MEMS acceleration sensor, the inertial switch can alter its on-off state while the environmental accelerations satisfy threshold value. An exhaustive summary of the design concept, performance aspects, and fabrication methods of the micro electromechanical system (MEMS) inertial switch is provided. Different MEMS inertial switch studies were reviewed that emphasized acceleration directional and threshold sensitivity, contact characteristics, and their superiorities and disadvantages. Furthermore, the specific fabrication methods offer an applicability reference for the preparation process for the designed inertial switch, including non-silicon surface micromachining technology, standard silicon micromachining technology, and the special fabrication method for the liquid inertial switch. At the end, the main conclusions of the current challenges and prospects about MEMS inertial switches are drawn to assist with the development of research in the field of future engineering applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel microelectromechanical system (MEMS) inertial switch with self-latching mechanism and adjustable acceleration threshold is proposed. The switch consisted of a proof mass suspended by flexible springs. Permanent magnets, ferromagnets and planer coils were integrated in the device to realize the latching and threshold tuning mechanism. The centrifugal experiment and laser based position measurement have been conducted to measure the acceleration threshold and the stiffness of the spring respectively. The inertial threshold value and the spring stiffness were measured as 5.27 g and 163.12 N/m. The discrepancy between measured acceleration threshold results (5.27 g) and the analytical acceleration threshold results (5 g) is mainly due to the dimension errors during device fabrication. By applying a reverse current of 0.1 A, the switch can be unlatched from its 'on-state'. Experiment also demonstrates that by applying a current varying from − 0.5 A to 0.5 A, the threshold value can be adjusted from 6 g to 3.75 g. [ABSTRACT FROM AUTHOR]

This paper presents a generalised Newmark method (GNM) incorporating a displacement hardening mechanism for the prediction of permanent displacements accumulated by diaphragm walls during earthquakes. A key feature of the proposed approach is the adoption of an evolution law for the critical acceleration, which links its current value to the accumulated wall permanent displacements. This displacement hardening mechanism is based on a simplified relation between the average plastic shear deformations experienced by the passive zone of soil below dredge level and the mobilised soil friction angle. This relation is determined indirectly by the evolution of the passive earth-pressure coefficient with wall displacement/rotation, as obtained in quasi-static model wall experiments. The proposed approach has been validated by comparing its predictions with the experimental data obtained in centrifuge model tests of cantilevered and propped walls. In spite of the simplifying assumptions on which it is based, the GNM has demonstrated that it is capable of capturing the essential features of the retaining structures' kinematics and provides realistic predictions of permanent wall displacements. [ABSTRACT FROM AUTHOR]

Wheelchair basketball (WB) is a sport modality adapted for people with disabilities who present functional classification (FC) according to their mobility, from 1.0 for players with lesser functional capacity up to 4.5 for great mobility and trunk control players. This study aimed to analyze and compare the external load (EL) and the internal load (IL) of the WB players according to their FC in 5 × 5 simulation game tasks. The main objective of this task was to develop a simulated game in which two teams of five players faced each other to resemble the physical demands of an official match. The development of these tasks allowed for the players to learn the different systems of play, and to improve tactical skills. To conduct the study, 12 (male) national professional WB players (years: 30.7 ± 4.82 and WB experience: 5 ± 1.43) participated in the study and were grouped according to FC. WIMU PROTM devices monitored the EL manufactured by RealTrack Systems in Almería, Spain, and to measure the player's IL, GarminTM Heart Rate (HR) bands were used (GarminTM in Olathe, KS, USA). The EL variables were divided as kinematic (distance, explosive distance, acc, dec, max. acc, max. dec, average speed, max. speed) and neuromuscular (player load, impact). The IL variables were average HR, max. HR and %max. HR. The main results show that players with greater functional capacity (FC = 4.0) developed higher values in the IL and neuromuscular variables analyzed (p < 0.05), as well as in some kinematic variables like distance, dec and average speed (p < 0.05). This information is relevant because it helps to personalize the training load based on competitive demands and create a gradual and adaptable training program. This information helps athletes to develop better performance during training and prevent injuries caused by overexertion. [ABSTRACT FROM AUTHOR]

ABSTRACT Fatigue vibration is a primary cause of fruit damage during transportation. Drawing on the Palmgren–Miner fatigue accumulation damage theory and the correlation between fruit vibration damage characteristics and external vibration excitation, this paper proposes a fruit vibration fatigue accumulation damage model and its method for parameter determination. Using pears as the research objects, we conducted fatigue damage vibration and critical fatigue damage vibration tests under various conditions to determine the vibration fatigue constant of the pears. By utilizing the critical value of the damage area specified in the pear grading standard for premium grade, we derived the threshold acceleration value for pear damage. These findings serve as a technical foundation for advancing our understanding of fruit vibration fatigue damage mechanisms and guiding the development of cushioning packaging to protect fruit from vibrations.

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]

The earthquake sequence that occurred on 6 February 2023 in Turkiye caused significant damage to various infrastructures including geostructures such as dams. A total of 17 earth dams within a 200-km radius of the earthquake epicenter experienced varying degrees of damage, ranging from minor (∼2 cm) to major (up to ∼150 cm) deformations. As study of these reveals that the damaged dams are located within the closest distance to the fault of less than 30 km, with an average value of ∼12 km. This study specifically focuses on the seismic displacement analysis of the 17 damaged dams, utilizing the sliding block methods. The recorded motion data was analyzed using the kriging technique to estimate the spectral response at the dam sites. Moreover, the recorded ground motions were scaled to the resonant period of the dam site to estimate acceleration time history. The findings reveal that the rigid block analysis can provide an average estimation of seismic displacement with a relative error of less than 44%. The results of the damage analysis indicate that seven dams reached the ultimate limit state and two dams experienced the serviceability limit state. Moreover, the univariate and multivariate fragility functions are developed to estimate seismic probabilistic analysis of earth dams based on the observed data and the limit states. The results show that the selection of a single intensity measure (IM) and a combination of IMs can affect the predicted probability of failure. The findings provide an insight into the resilience assessment of dams and other geosystems during this strong earthquake. [ABSTRACT FROM AUTHOR]

Of order one in 10 3 quasars and high-redshift galaxies appears in the sky as multiple images as a result of gravitational lensing by unrelated galaxies and clusters that happen to be in the foreground. While the basic phenomenon is a straightforward consequence of general relativity, there are many non-obvious consequences that make multiple-image lensing systems (aka strong gravitational lenses) remarkable astrophysical probes in several different ways. This article is an introduction to the essential concepts and terminology in this area, emphasizing physical insight. The key construct is the Fermat potential or arrival-time surface: from it the standard lens equation, and the notions of image parities, magnification, critical curves, caustics, and degeneracies all follow. The advantages and limitations of the usual simplifying assumptions (geometrical optics, small angles, weak fields, thin lenses) are noted, and to the extent possible briefly, it is explained how to go beyond these. Some less well-known ideas are discussed at length: arguments using wavefronts show that much of the theory carries over unchanged to the regime of strong gravitational fields; saddle-point contours explain how even the most complicated image configurations are made up of just two ingredients. Orders of magnitude, and the question of why strong lensing is most common for objects at cosmological distance, are also discussed. The challenges of lens modeling, and diverse strategies developed to overcome them, are discussed in general terms, without many technical details. [ABSTRACT FROM AUTHOR]

Loess is a typical structural soil with properties such as water sensitivity, collapsibility, and seismic vulnerability. The dynamic response of a water transmission pipe crossing a fault zone is highly complex in a loess site. The Hanjiang River to the Weihe River Diversion Project (Phase II) crossing the Weihe fault was selected as the prototype for a shaking table test, through which the responses of acceleration, dynamic stresses, strains, and pore-water pressure were systematically investigated. The acceleration response of a geologic body similar to the experimental model was greatly affected by factors such as fault location, degree of soil saturation, distribution of internal structure, and so on. The acceleration along elevation experienced its highest amplification factor of approximately 2.0, mainly due to seismic waves with frequencies above 2.0 Hz being amplified. To ensure the seismic fortification of the pipeline near the fault belt, it is recommended to utilize an acceleration of 1.2 times within the severe impact zone. This zone involved 36.0 m of the hanging wall and 30.0 m of the footwall, which are approximately 6.0 times and 5.0 times of the fault belt width. It is recommended to use an acceleration of 1.1 times for areas within 200 m from the fault of the hanging wall; refer to the fault-avoiding distance of the seismic design code. The deformation mode of the water pipeline was expansion/shrinkage in the transverse section and slight bending in the longitudinal section. The pore-water pressure response demonstrated coupling features of hysteresis, accumulation, and dissipation. The seismic collapsibility modes of the loess at the studied site were generalized into four stages: energy accumulation, state mutation, failure extension, and successive failure. Seismic subsidence could be expressed by adopting a piecewise function with a maximum value of approximately 18.0 cm. Based on the similarity calculation, the maximum seismic subsidence of the prototype can be recommended as 3.6 m. Liquefaction occurred when the input acceleration amplitude reached 0.5g. These shaking table test results provided reasonable parameters for the seismic design and construction of the Hanjiang to Weihe River Diversion Project across this fault. [ABSTRACT FROM AUTHOR]

Interfacial instability would be aroused on a spherical liquid droplet when it is subject to external vertical vibration. In this paper, a linear analysis was conducted on this instability problem. The polar-angle dependent acceleration in the spherical coordinate is strongly coupled with the temporal and spatial component of the surface deformation displacement, which gives a recursion equation that implicitly expresses the dispersion relation between the growth rate and the spherical mode numbers. The unstable regions (or unstable tongues) for the inviscid fluids considering the latitudinal mode (longitudinal mode number m = 0) were derived and presented in the parameter space. Compared to the solution of the spherical Faraday instability under radial vibration acceleration, the regions of harmonic unstable tongues for the mono-directional vibration cases become much narrower, and the subharmonic unstable tongues almost approach straight lines. The analysis shows that the latitudinal waves emerging on the spherical droplet surface ought to oscillate harmonically instead of subharmonically, which is opposite to the results for the case under radial vibration acceleration. A corresponding experiment of a liquid droplet lying on a vertically vibrating plate was conducted, and the observations substantiate our theoretical predictions. [ABSTRACT FROM AUTHOR]

This paper investigates the steady-state pattern evolution of symmetric Faraday waves excited in a brimful cylindrical container when driving parameters much exceed critical thresholds. In such liquid systems, parametric surface responses are typically considered as the resonant superposition of unstable standing waves. A modified free-surface synthetic Schlieren method is employed to obtain full three-dimensional spatial reconstructions of instantaneous surface patterns. Multi-azimuth structures and localized travelling waves during the small-elevation phases of the oscillation cycle give rise to modal decomposition in the form of $\nu$ -basis modes. Two-step surface-fitting results provide insight into the spatiotemporal characteristics of dominant wave components and corresponding harmonics in the experimental observations. Arithmetic combination of modal indices and uniform frequency distributions reveal the nonlinear mechanisms behind pattern formation and the primary pathways of energy transfer. Taking the hypothetical surface manifestation of multiple azimuths as the modal solutions, a linear stability analysis of the inviscid system is utilised to calculate fundamental resonance tongues (FRTs) with non-overlapping bottoms, which correspond to subharmonic or harmonic $\nu$ -basis modes induced by surface instability at the air–liquid interface. Close relationships between experimental observations and corresponding FRTs provide qualitative verification of dominant modes identified using surface-fitting results. This supports the validity and rationality of the applied $\nu$ -basis modes. [ABSTRACT FROM AUTHOR]

Radiator reliability is crucial in environments characterized by high temperatures and friction, where prompt interventions are often required to prevent system failures. This study introduces a proactive approach to radiator fault diagnosis, leveraging the integration of the Gaussian Mixture Model and Long-Short Term Memory autoencoders. Vibration signals from radiators were systematically collected through randomized durability vibration bench tests, resulting in four operating states—two normal, one unknown, and one faulty. Time-domain statistical features of these signals were extracted and subjected to Principal Component Analysis to facilitate efficient data interpretation. Subsequently, this study discusses the comparative effectiveness of the Gaussian Mixture Model and Long Short-Term Memory in fault detection. Gaussian Mixture Models are deployed for initial fault classification, leveraging their clustering capabilities, while Long-Short Term Memory autoencoders excel in capturing time-dependent sequences, facilitating advanced anomaly detection for previously unencountered faults. This alignment offers a potent and adaptable solution for radiator fault diagnosis, particularly in challenging high-temperature or high-friction environments. Consequently, the proposed methodology not only provides a robust framework for early-stage fault diagnosis but also effectively balances diagnostic capabilities during operation. Additionally, this study presents the foundation for advancing reliability life assessment in accelerated life testing, achieved through dynamic threshold adjustments using both the absolute log-likelihood distribution of the Gaussian Mixture Model and the reconstruction error distribution of the Long-Short Term Memory autoencoder model. [ABSTRACT FROM AUTHOR]

The frequent occurrence of seismic events in Italy poses a strategic problem that involves either the culture of preservation of historical heritage or the civil protection action aimed to reduce the risk to people and goods (buildings, bridges, dams, slopes, etc.). Most of the Italian architectural heritage is vulnerable to earthquakes, identifying the vulnerability as the inherent predisposition of the masonry building to suffer damage and collapse during an earthquake. In fact, the structural concept prevailing in these ancient masonry buildings is aimed at ensuring prevalent resistance to vertical gravity loads. Rarely do these ancient masonry structures offer relevant resistance to actions other than vertical ones and then they are intrinsically vulnerable to stresses induced by the earthquakes. One of the main technical activities carried out by the Civil Protection after an earthquake is to assess the damage in the buildings and to evaluate their own usability. Regarding historical buildings, ad-hoc synthetic forms, drafted in agreement between the Italian Civil Protection Department and the Ministry of Cultural Heritage and Activities and Tourism and based on visual inspection, are adopted by qualified technicians. In this paper, such activities are described and discussed along with the Italian Civil Protection System. However, given the complexity of the main technical activities to be performed after an earthquake there is a need for more accurate methods based on Structural Health Monitoring. [ABSTRACT FROM AUTHOR]

Several empirical models for the prediction of ground motion duration were developed across the world, but no model has been generated for the Himalayan region in the past. In this study, an attempt is made to study the duration models developed for different regions and compare them with a reference model developed for the Himalayan region for a wide range of magnitudes. The comparison is performed using the log-likelihood method and aims to identify the best duration prediction models based on the developed by Bajaj and Anbazhagan (2019) for the study region. The data support index values along with the weights of the corresponding models across the different distances and magnitude ranges have also been estimated. The study found that the predictive duration relation given by Lee and Green (2014) for Western North America is suitable for M ≤ 5, while the model developed by Ghanat (2011) is suitable for M > 5 for the Himalayan region. The model developed by Afshari and Stewart (2016) is also very close to the reference model. It is always preferable to have a single duration predictive model for a wide range of magnitude and distance range; hence, there is a need to develop a region-specific duration predictive model for the Himalayan region. [ABSTRACT FROM AUTHOR]

Wave-piercing catamarans have center-bow to diminish slamming pressure and acceleration in sea waves. Bow section modification of marine craft towards low slamming loads is an on-going research topic. This study suggests insertion of a flat-bar, called spray rail, to center-bow to reduce both slamming pressure and acceleration. A section which is called J1-section from previous research is adopted for further modification. Modification is made via appending the spray rail to its center-bow, and the new section is called J1-section with spray rail. Evaluation of the slamming pressure and acceleration of both sections are experimentally accomplished using the water entry test facilities of Amirkabir Laboratory of Hydrodynamics. J1-section with spray rail in comparison with J1-section has shown peak acceleration and pressure drop of about 60% and 70%, respectively. This study suggests that the insertion of appendages to the catamaran sections is a superior solution for the slamming impact load reduction. [ABSTRACT FROM AUTHOR]

Advancements in plant space biology are required for the realization of human space exploration missions, where the re-supply of resources from Earth is not feasible. Until a few decades ago, space life science was focused on the impact of the space environment on the human body. More recently, the interest in plant space biology has increased because plants are key organisms in Bioregenerative Life Support Systems (BLSS) for the regeneration of resources and fresh food production. Moreover, plants play an important role in psychological support for astronauts. The definition of cultivation requirements for the design, realization, and successful operation of BLSS must consider the effects of space factors on plants. Altered gravitational fields and radiation exposure are the main space factors inducing changes in gene expression, cell proliferation and differentiation, signalling and physiological processes with possible consequences on tissue organization and organogenesis, thus on the whole plant functioning. Interestingly, the changes at the cellular and molecular levels do not always result in organismic or developmental changes. This apparent paradox is a current research challenge. In this paper, the main findings of gravity- and radiation-related research on higher plants are summarized, highlighting the knowledge gaps that are still necessary to fill. Existing experimental facilities to simulate the effect of space factors, as well as requirements for future facilities for possible experiments to achieve fundamental biology goals are considered. Finally, the need for making synergies among disciplines and for establishing global standard operating procedures for analyses and data collection in space experiments is highlighted. [ABSTRACT FROM AUTHOR]

The Artificial Intelligence of Things (AIoT) connects everything with intelligence, while the increase in energy consumption generated by numerous electronic devices puts forward an impending demand on the power supply. Energy harvesting technology has emerged as a compelling innovation technology for the net zero emissions of the power supply for the AIoT. Although significant advances have been witnessed in energy harvesting, some issues such as poor electrical output, weak environmental adaptability, and low reliability are difficult to satisfactorily resolve. Mechanical intelligent energy harvesting can be defined as the system identifying the external excitation or its own state and reacting to it, rather than relying on electrical sensing elements or a central controller for certain adaptive or programmed functions. The adaptive and programmed functions exhibit great potential in solving the above‐mentioned issues that seriously restrict the development of the energy harvesting technology. Here, a generalized definition of mechanical intelligent energy harvesting is given critically and the design methodology is elaborated. The typical reported energy harvesting systems with the characteristics of mechanical intelligence are reviewed. The key research directions in mechanical intelligent energy harvesting are discussed. The mechanical intelligence is expected to revolutionize the development of the energy‐harvesting technology and pave the way for applications. [ABSTRACT FROM AUTHOR]

A novel multibody rocking model is developed to investigate the dynamic response of two stacked rigid blocks placed on a linear base isolation device. The model is used to investigate the dynamic response of a realistic statue‐pedestal system subject to pulse‐like ground motions. The analysis shows that, in general, base isolation increases the safety level of the rocking system. However, for large period pulses or small size blocks, the isolator can amplify the ground motion, resulting in a lower minimum overturning acceleration than for the nonisolated system. Further, the amplification or shock spectrum of a linear mass‐dashpot‐spring oscillator, was found to be the reciprocal of the minimum nondimensional overturning acceleration of the investigated rocking system. Novel rocking spectra are obtained by normalizing the frequency of the pulse by the frequency of the isolator. The analysis also demonstrates how the dynamic response of the two stacked blocks is equivalent to that of a single‐block configuration coincident with the whole system assumed monolithic or the upper block alone, whichever is more slender. [ABSTRACT FROM AUTHOR]