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Dental implants offer an effective solution for partial and total edentulism, but mechanical and biological complications exist. Furthermore, high occlusal loads challenge implants and lead to potential failures. This review focuses on impact testing in contrast to incremental and static tests, an underexplored aspect of assessing daily loads on implants, bringing to light potential complications. The review examines studies employing impact forces to assess implant-supported prostheses and natural teeth properties, highlighting their significance in dental research. A systematic search following PRISMA guidelines identified 21 relevant articles out of 224, emphasizing studies employing impact forces to evaluate various aspects of dental implant treatments. The diverse applications of impact forces in dental research were categorized into tooth structure, restorative materials, interface evaluation, implant properties, and finite element models. Some studies showed the significance of impact forces in assessing stress distribution, shock absorption, and biomechanical response. Impact testing is a critical tool for understanding the daily forces on implants. Despite diverse experimental approaches, a lack of standardized protocols complicates the systematization of the results and, therefore, the conclusions. This review highlights the need for consistent methodologies in impact testing studies for future research on implant-supported prostheses. [ABSTRACT FROM AUTHOR]

In this study, the author replaced the leaf-spring suspension system with an air suspension system to reduce the chassis' dynamic load, evaluating the chassis' durability when using two suspension systems to complete the structure of the multi-purpose forest fire-fighting vehicle. The author uses Ansys software to build a finite element model of a multi-purpose forest fire-fighting vehicle chassis, evaluates its fatigue strength under dynamic loads from previous research, and proposes a structural improvement plan to extend its life chassis. The dynamic load acting on the chassis as an input parameter for the calculation is used from the research results. Fatigue test results utilizing Ansys software with dynamic load computed in moving conditions on ISO roads class E and F with leaf-spring and air suspension systems demonstrate that the original chassis is not robust. After enhancing the chassis structure, the texturing region around the fatigue point has increased (raising the corner radius). As a result, the chassis weight increased by 35.15 kg and the minimum fatigue cycle was larger than 106 cycles while employing the air suspension system. The durability study suggested increasing the corner radius at the fatigue point to strengthen the chassis structure. The stress concentration radius is gradually increased from 5 to 10 mm to enhance material thickness and chassis fatigue cycles. These findings can be used to provide a scientific method for calculating and assessing the durability of car chassis and shell details, helping Vietnam's auto sector grow. [ABSTRACT FROM AUTHOR]

Purpose: During operation, dynamic load from the road surface acting on the vehicle affects the dynamic safety of the vehicle. Therefore, it is necessary to research solutions to reduce the dynamic load of the multi-purpose forest fire fighting vehicle. While the active and semi-active suspension system equipped on the vehicle has not been effective compared to the price, the optimal solution to reduce the current dynamic load is to replace the traditional suspension using springs with the air suspension system. This research aims to replace the leaf spring suspension of a multi-purpose forest fire fighting vehicle with an air suspension system in an effort to lessen the vehicle's dynamic load. Methods: By building a dynamic model of the vehicle according to the method of splitting the structure of the multi-body system (MBS) and the Newton–Euler equation, in which the binding force between the suspended and unsuspended masses is described by two submodules are "leaf-spring" and "air balloons". Use this model to investigate the influencing factors including vehicle speed and road type on the dynamic load of the vehicle. The results of the study were carried out on the road type in accordance with ISO 8608:2016 to estimate the DLC value for vehicles utilizing spring suspension and air suspension to evaluate the level of decrease in dynamic loads placed on the vehicle. Results: The survey results of the model with two types of suspension systems compared show that when using an air suspension instead of a metal suspension (leaf-spring) on a multi-purpose forest fighting vehicle, the dynamic load can be reduced up to 19.6%, contributing to reducing the impact load on the vehicle. Conclusions: The author has conducted research and analysis on the capability of reducing dynamic loads based on road type and speed, and evaluation according to DLC criteria. According to the findings, automobiles equipped with air suspension systems perform significantly better; according to ISO 8608:2016, when a vehicle is moving on a road of class A, B, or C, the vehicle is not limited in speed but nevertheless ensures road-friendly criteria. This ensures the detailed durability and dynamic safety of the vehicle. Class D roads are restricted to a maximum speed of 15 km/h, which helps to meet the aforementioned standards, Even with the air suspension system, the vehicle fails to achieve the road-friendly criteria necessary to guarantee its detailed durability and dynamic safety when driving on extremely poor roads (class F), but wheel separation appears narrower than leaf spring suspension. [ABSTRACT FROM AUTHOR]

Higher efficiency of rail transportation at the present stage of development of the transport industry necessitates the creation and introduction of rail vehicles with improved technical and economic characteristics among which is reduced tare weight. The issue of reducing the tare weight of wagons is quite urgent. It deals not only with the sprung mass of the wagon but also with the load on the rail track, which is under the influence of constant cyclic loads. Therefore, the present study deals with the development of a wagon covered with tarpaulin for carrying goods requiring protection against the environment. The loads inherent for operation on 1520 mm gauge lines are considered. The covered wagon mod. 11-217 is chosen as a prototype. The profiles of the covered wagon frame components are selected according to the moment of resistance of their cross-sections. It is found that the proposed design has a 16% lower tare weight than that of the prototype. The results of the strength calculation for the wagon under the main design operating modes have proved the feasibility of its structural design. The motion of the covered wagon over a track irregularity has been assessed as 'excellent'. The results of the study will contribute to the creation of recommendations for the development of modern structures of covered wagons as well as improve the efficiency of railway transportation. [ABSTRACT FROM AUTHOR]

The frequency support capacity of power loads is essential for maintaining active power symmetry and balance between the generation and demand sides of power systems. As the proportion of renewable energy sources and power electronic equipment increases, the inertia on the power generation side decreases, highlighting the growing importance of frequency support on the load side. As it is generally believed that the active power balance of power systems determines the frequency stability, few studies have considered the effect of voltage variation on the frequency response dynamics. It is important to note that the node voltage keeps fluctuating throughout the frequency dynamic process, which affects the active power of loads and should not be neglected. Based on the aforementioned rationales, this paper endeavors to investigate the modeling of power load frequency response and analyze its support capability considering the voltage variation effect. This paper initially establishes the small-signal model of dynamic load under frequency dynamics, derives the transfer function relating active power to system frequency deviation, and subsequently develops its frequency response model. Subsequently, commencing with the ZIP model of static load, the power fluctuation of load nodes is derived from the influence of preceding nodes, and the frequency response model of the static load is formulated and its frequency support capacity is scrutinized. Based on this foundation, a comprehensive aggregation model of the complex load is constructed, and its frequency support capability is assessed using actual data. Finally, the proposed model and analysis results are validated through simulation, confirming their correctness and effectiveness. [ABSTRACT FROM AUTHOR]

The article formulates proposals for improving the calculation methodology for punching. The methods in the current regulatory documents for assessing the tensile strength are based mainly on empirical dependencies obtained on the basis of numerous experimental studies. It should be noted that they give reliable results if certain design requirements are met (typical column sections). Along the interface line of the plate with a rectangular (square) column, supporting bending moments act in two orthogonal directions. The magnitude of these moments for the most common spans is large and, in an elastic setting, exceeds the span by two times. Taking into account the redistribution of forces and the most likely formation of cracks in the stretched zone, it can be argued that in the operational stage, the support sections of the plates have compressed and stretched zones. With such a stress-strain state, in the calculation scheme, when evaluating the tensile strength, the stretched part of the side surface of the “reduced” pyramid, bounded by the neutral axis along all faces, should be excluded. As a result, expressions are presented to determine the parameters of the reduced punching pyramid and the value of forces in concrete and reinforcement at the maximum bearing capacity stage.

This study investigated influence of varying waviness characteristics of fiber, represented by path amplitude Δ and different numbers of half sine waves k , on the elastic-plastic dynamic behaviour of laminated composite plates with variable fiber spacing. The analysis was based on the equations for action of constant axial dynamic loading and two-dimensional layered approach with classical first order shear deformation theory with five degrees of freedom per node, and it was performed with FORTRAN 94 programming language. Von-Karman’s assumptions were used for the discretization of the laminated plates to include geometric nonlinearity for nine-node Lagrangian isoperimetric quadrilateral elements. Complete bond between the layers was assumed with no delamination, which was based on first-order shear deformation theory. The Newmark implicit time integration method and Newton-Raphson iteration were simultaneously used to solve the nonlinear governing equation in conjunction. It was proven in the research that the nonlinear performance of the laminated composite plate was affected by the studied waviness parameters Δ and k , and also by the variable distribution pattern selected for this study.

Introduction. In connection with the constantly existing threats of deliberate damage to the infrastructure of critical facilities using vehicles, the task of development and research of protective structures aimed at preventing this kind of damage becomes relevant and of practical interest. The application of steel ropes as the main load-bearing elements of such structures is substantiated.Materials and methods. The proposed numerical algorithm was used to determine the minimum permissible cross-sectional area of steel ropes based on the requirements for a protective structure in terms of resistance to impact caused by the collision of a car with a given mass and speed. The developed method is based on mathematical modelling of the conditional optimization problem. The objective function was the function of the longitudinal force arising in the steel ropes. At the same time, requirements were made to comply with the conditions of energy conservation and continuity of deformations, as well as strength limitations. A verification calculation of the designed protective structure was carried out in a commercial software package implemented on the generally recognized finite element method. The methodology of the full-scale experiment is presented. A full-scale experiment was carried out in order to determine the true distribution of deformations over the structural elements of the test object under impact.Results. The results of the experimental study are presented. A comparative analysis of the data obtained in the process of numerical and computer simulation, as well as in the course of a full-scale test, was carried out. A slight discrepancy in the values of the controlled parameters obtained by different methods was found.Conclusions. The proposed numerical algorithm for searching the minimum permissible cross-sectional area of steel ropes, based on the requirement of a given strength, confirmed its reliability, and the adopted design solutions of the developed protective structure proved their validity. The results of the research can be used in the design of such engineering structures designed for the physical protection of critical facilities.

This study investigates the impact of renewable energy penetration on system stability and validates the performance of the (Proportional-Integral-Derivative) PID-(reinforcement learning) RL control technique. Three scenarios were examined: no photovoltaic (PV), 25% PV, and 50% PV, to evaluate the impact of PV penetration on system stability. The results demonstrate that while the absence of renewable energy yields a more stable frequency response, a higher PV penetration (50%) enhances stability in tie-line active power flow between interconnected systems. This shows that an increased PV penetration improves frequency balance and active power flow stability. Additionally, the study evaluates three control scenarios: no control input, PID-(Particle Swarm Optimization) PSO, and PID-RL, to validate the performance of the PID-RL control technique. The findings show that the EV system with PID-RL outperforms the other scenarios in terms of frequency response, tie-line active power response, and frequency difference response. The PID-RL controller significantly enhances the damping of the dominant oscillation mode and restores the stability within the first 4 s—after the disturbance in first second. This leads to an improved stability compared to the EV system with PID-PSO (within 21 s) and without any control input (oscillating more than 30 s). Overall, this research provides the improvement in terms of frequency response, tie-line active power response, and frequency difference response with high renewable energy penetration levels and the research validates the effectiveness of the PID-RL control technique in stabilizing the EV system. These findings can contribute to the development of strategies for integrating renewable energy sources and optimizing control systems, ensuring a more stable and sustainable power grid. [ABSTRACT FROM AUTHOR]

Despite the significant interest of researchers, icing of aircraft, vehicles, ships, and equipment of offshore oil structures remains to be an urgent problem. This paper considers the factors that promote a decrease in the strength of the contact between ice and surfaces under an applied shear load. The main attention is focused on studying the influence of the rate of shear loading on the fracture of the interfacial contact between ice and superhydrophobic coatings. The strength of the adhesive contact under the conditions of controlled variations in the applied load is measured using a technique based on the detachment of ice from a surface under the influence of centrifugal force. The study is carried out for large ensembles of samples in the temperature range from −5 to −20°C, thereby making it possible to evaluate the influence of the quasi-liquid layer and the Rehbinder effect on a decrease in the shear adhesive strength. The results obtained indicate that the contact between ice and a superhydrophobic coating is fractured through a mixed viscous–brittle mechanism. In this case, a decrease in temperature or an increase in the loading rate causes a transition from the viscous to the brittle fracture. These results indicate a potential acceleration of ice shedding with an increase in the growth rate of the shear stress. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The accuracy of voltage transformer (VT) measurements is imperative for the security and reliability of power systems and the equitability of energy transactions. The integration of a substantial number of electric vehicles (EVs) and their charging infrastructures into the grid poses new challenges for VT measurement fidelity, including voltage instabilities and harmonic disruptions. This paper introduces an innovative transformer measurement error prediction model that synthesizes Multivariate Variational Mode Decomposition (MVMD) with a deep learning framework integrating Bidirectional Temporal Convolutional Network and Multi-Head Attention mechanism (BiTCN-MHA). The paper is aimed at enhancing VT measurement accuracy under fluctuating load conditions. Initially, the optimization of parameter selection within the MVMD algorithm enhances the accuracy and interpretability of bi-channel signal decomposition. Subsequently, the model applies the Spearman rank correlation coefficient to extract dominant modal components from both the decomposed load and original ratio error sequences to form the basis for input signal channels in the BiTCN-MHA model. By superimposing predictive components, an effective prediction of future VT measurement error trends can be achieved. This comprehensive approach, accounting for input load correlations and temporal dynamics, facilitates robust predictions of future VT measurement error trends. Computational example analysis of empirical operational VT data shows that, compared to before decomposition, the proposed method reduces the Root-Mean-Square Error (RMSE) by 17.9% and the Mean Absolute Error (MAE) by 23.2%, confirming the method's robustness and superiority in accurately forecasting VT measurement error trends. [ABSTRACT FROM AUTHOR]

Thin Spray-On Liner (TSL) has been widely used in underground engineering support such as mining due to its convenient operation and good support effect. The TSL applied to the rock is inevitably affected by dynamic loads from excavation. In order to study the support effect of TSL on a rock under dynamic load, a series of uniaxial compression experiments under static and dynamic loads are carried out on the TSL-coated specimen, and the costing thickness is 1 mm, 3 mm and 5 mm, respectively. The results showed that the TSL can improve the strength and peak strain of sandstone, and the degree of improvement is more obvious with the increase of costing thickness under static and dynamic load, and the loading rate of the dynamic load is about 70 ∼ 110 s−1. It was also found that the dynamic strength increases exponentially with strain rate, with the costing thickness increases, the strain rate index of sandstone increases. The good bonding ability and tensile properties of TSL ensure support to rock. Application of TSL can delay the time for cracks to appear in the specimen and increase the energy required for the failure of the specimen. The phenomenon was also simulated using ABAQUS, and the simulations show that TSL provides passive support that the pressure of TSL gradually increases with the deformation of the sandstone during the impact, and can delay the failure time of the specimen and reduce the number of cracks. That is consistent with the experiment. [ABSTRACT FROM AUTHOR]

The use of heavy machinery is increasing in agricultural industries, and in particular cotton farming systems in Australia, which induces an increased risk of soil compaction and yield reduction. Hence, there is a need for a technical solution to use available tools to measure projected soil compaction due to farm machinery traffic. The aim of this work was to compare the effects of static and dynamic loads on soil compaction. In this study, three Vertisols (soils commonly used for cotton production in Australia) were selected to examine soil compaction under a range of static and dynamic loads, respectively, using uniaxial compression equipment and a modified Proctor test. In general, soils behaved similarly under static and dynamic loads with no significant difference between bulk density values for all moisture contents with a high index of agreement (d = 0.96, RMSE = 0.056). The results further indicate better agreement between soil compaction produced under static and dynamic loads. Uniaxial compression test (static loads) produced greater compaction compared with the modified Proctor test (dynamic loads), in particular at moisture contents less than the plastic limit condition. The variation in soil compaction for static and dynamic loads was often evident for loads ≥600 kPa, with the greatest soil compaction induced under loads ≥1200 kPa. The findings of this study confirm the suitability of a modified Proctor method to assess soil compaction as an alternative tool under a range of moisture contents and machinery loads for Vertisols. [ABSTRACT FROM AUTHOR]

In rock engineering, the dynamic loads caused by mechanical action and rock blasting have an extremely significant influence on the stableness of surrounding rock masses. To examine the impact of dynamic load on the mechanical properties and fracturing characteristics of hard rocks as well as the failure responses of underground openings, a number of prismatic samples with holes of different numbers and configurations were prepared for dynamic tests employing an SHPB loading device. The experimental results demonstrate that the order of dynamic compressive strength of each group of samples under the impact nitrogen pressure of 0.45 MPa is: G3 > G2 > G5 > G4 > G7 > G6, and the dynamic deformation process of the samples is parted into three phases: linear elastic deformation, plastic deformation and post-peak deformation. A total of three categories of cracks, i.e., spalling cracks, shear cracks and tensile cracks, occur in the specimens. The failure mode of the samples having one or two holes arranged in a vertical direction is controlled by shear cracks, whilst that of the rest groups of pre-holed specimens belongs to tensile-shear failure. The existence of the fabricated holes in the samples significantly weakens the mechanical properties and affects the fracture evolution characteristics, which rely on the quantity and layout of the cavities in the specimens. The interesting results are also discussed and explained, and could supply some insight in the mechanisms of tunnel surrounding rock failure and rock dynamic hazards such as rock burst. [ABSTRACT FROM AUTHOR]

Numerous approaches and methodologies have been established for online (while the load is supplied) estimation of the State-of-Charge of Lithium-ion cells and batteries. However, as battery load consumption fluctuates in real time because of delivered device operations, obtaining a precise online state of charge estimation remains a challenging task. This work proposes a new technique for online open circuit voltage measurement to estimate state of charge of batteries. This novel technique proposes the addition of an auxiliary regulated load that may be utilized to temporarily force specifically defined forms of the battery's current curve under particular conditions, which results in improving and simplifying online open circuit voltage computations. The effectiveness of the proposed technique was successfully validated through several experimental tests. The acquired findings demonstrated its efficiency with an acceptable online state of charge estimation accuracy. Typically, an estimation error of less than 2% was recorded in most tests, while the error was less than 1% when the battery's state of charge was high. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study proposes two curves that depict the vehicle–bridge contact force in a novel transportation system named AERORail, which is a lightweight cable-supported structure in which the rails and the prestressed cable form the load bearing system. Based on the contact force identified from a full-scale AERORail system, single and double-valley curves were obtained as the idealized contact force model for large- and small-span AERORail systems, respectively. This was achieved by utilizing the Bezier curves and the least squares method. The proposed curves were verified through a moving load model from a previous study under various spans and speeds. Moreover, the structural response of the AERORail structure under high-speed vehicle passing was explored using the idealized contact force model. The simulation results show that the proposed contact force model can predict the displacement response of 5 m and 15 m spans with a relative error of less than 5%, proving that the model can be used for dynamic analysis of AERORail. [ABSTRACT FROM AUTHOR]

The results of research into the dynamic characteristics of technical objects under the influence of loads of natural and man-made origin are presented. The object of research is the phenomenon of propagation of vibrations in the load-bearing elements of construction structures. One of the problems in the inspection and monitoring of construction objects is the assessment of the dynamic action on the load-bearing elements of the structure. The external influence of dynamic phenomena of natural and man-made origin on the condition of the load-bearing structures of the Cathedral "Sophia of Kyiv" was studied. The revealed phenomena of the transmission of vibrations of the general system of the building made it possible to formulate the reasons for the appearance of defects. The obtained research results can be used in the development of numerical and experimental methods and algorithms for assessing the technical condition of load-bearing elements of buildings and structures under the action of dynamic loads of various sources. [ABSTRACT FROM AUTHOR]

The mining activation of hidden faults under dynamic and static loads is an important reason for the occurrence of floor water inrush disasters in deep coal seam mining. The formation and evolution mechanism of water inrush channel caused by mining on the floor of hidden faults were analyzed through numerical simulation, from the perspective of fracture mechanics, a model was constructed to explore the influence of combined dynamic and static loads on the propagation of water with cracks. A conclusion was drawn that the effects of mining stress and confined water have led to rapid expansion of hidden fault cracks and significant improvement in permeability, at the same time, the confined water in the hidden fault also has a scouring and expansion effect on the cracks, accelerating their development speed. There are spatial and temporal differences in the penetration patterns of hidden faults at different positions of floor, and the closer it is to the goaf, the more likely it is to experience activation of hidden faults and water inrush. When there are multiple hidden small faults in the floor, there is an alternating change between the water inrush growth area and the flow stable area with similar cyclic characteristics. The effect of dynamic load will increase the pore pressure in cracks, and increase the stress intensity factor at the crack tip, and more easily induce crack expansion and penetration failure. The critical water pressure calculation equation for crack propagation and failure under dynamic and static loads was derived, and the calculation method for the minimum safe thickness of the floor was further analyzed, the influence of water pressure, crack length, inclination angle, and mining depth on it was discussed. The effect of dynamic load will increase the pore pressure in cracks, and increase the stress intensity factor at the crack tip, and more easily induce crack expansion and penetration failure. Finally, the theoretical analysis results were verified by an engineering examples. The research results can provide theoretical basis for predicting and preventing water inrush from the mining floor, which is beneficial for the safe and sustainable mining of coal mines.

This research studies geogrid reinforcement of sandy soils under the influence of the three earthquakes (Halabjah, Bolunun, and Ali Al-Gharbi) due to the recent increase in seismic activity and the need to reduce damage to foundations due to settlement. Sand samples prepared with a relative density of 70%, with and without geogrid reinforcement, were tested on a shaking (vibrating table) table. Five geogrid layers were used, respectively. Settlement occurs due to dynamic force, and the plastic foundation was used with dimensions of 100 * 100 * 30 mm. Withstands a static load of 5.294 kN/m2. Increasing the acceleration of the earthquake leads to an increase in the settlement of the foundation in the sandy soil. The greater the number of geogrids reinforcing layers, the leads to a decrease in the base settlement, where the rate of settlement decrease is greater, the lower the earthquake acceleration and the greater the number of geogrid reinforcement layers. The time of onset of settlement and the general pattern of settlement are similar in all cases studied. The rate of settlement is approximately twice as high when the soil is saturated than when the soil is dry, and the effect of geogrids is less for the soil when it is saturated than when it is dry.

For expedited transportation, vehicular tunnels are often designed as two adjacent tunnels, which frequently experience dynamic stress waves from various orientations during blasting excavation. To analyze the impact of dynamic loading orientation on the stability of the twin-tunnel, a split Hopkinson pressure bar (SHPB) apparatus was used to conduct a dynamic test on the twin-tunnel specimens. The two tunnels were rotated around the specimen’s center to consider the effect of dynamic loading orientation. LS-DYNA software was used for numerical simulation to reveal the failure properties and stress wave propagation law of the twin-tunnel specimens. The findings indicate that, for a twin-tunnel exposed to a dynamic load from different orientations, the crack initiation position appears most often at the tunnel corner, tunnel spandrel, and tunnel floor. As the impact direction is created by a certain angle (30°, 45°, 60°, 120°, 135°, and 150°), the fractures are produced in the middle of the line between the left tunnel corner and the right tunnel spandrel. As the impact loading angle (α) is 90°, the tunnel sustains minimal damage, and only tensile fractures form in the surrounding rocks. The orientation of the impact load could change the stress distribution in the twin-tunnel, and major fractures are more likely to form in areas where the tensile stress is concentrated.

Malan loess possesses unfavourable engineering mechanical properties that may vary depending on the geological context in which it exists. In the context of roadbed loading, the structural characteristics of the loess roadbed often result in uneven settlement, which significantly impacts transportation safety. To investigate the dynamic behaviour of loess under the influence of vehicle loading, groups of dynamic rebound modulus tests were conducted using a dynamic triaxial apparatus. Three key aspects are highlighted: compaction degree, moisture content and stress state. The results reveal that the dynamic rebound modulus of loess tends to increase with higher compaction degrees, decrease with increased moisture content and rise under greater confining pressure. For Maran loess, the water content has the greatest influence on its physical and mechanical properties. Under conditions of a confining pressure of 60 kPa and a deviatoric stress of 30 kPa, as the moisture content increased from w = 9% to w = 18%, the minimum dynamic rebound modulus decreased by 63%. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of the presence and circulation of water on asphalt mixture performance. In this study, Indirect Tensile Tests were conducted on unconditioned and conditioned samples in the dry, immersion, and water circulation modes under dynamic loading at the frequency of 0.5 and 2 Hz at the temperatures of 10 and 40°C. The findings indicated that the moisture damage resistance of the samples was more affected by their conditioning than by the mode of testing. Moreover, the water circulation had a greater impact on the results compared to the other testing modes. According to the test results, it was noted that the performance of asphalt mixtures was negatively impacted to a greater extent by the high temperature of 40°C. Also, the impact of pumping and hydraulic scouring is more significant at low temperatures than the high temperatures. [ABSTRACT FROM AUTHOR]

Purpose: Dynamic load from road surface acting on a vehicle has a variable value, depending on road surface profile, movement speed, and stiffness of suspension system, etc. The purpose of this study is to determine the dynamic load from the road surface acting on the multi-purpose forest fire fighting vehicle when the vehicle moves on the forest road by theoretical and experimental methods. Experimental results are compared with the theoretical simulation results to verify the reliability of the simulation model. Methods: This article presents the study results to determine the dynamic load acting on multi-purpose forest fire fighting vehicle by the theoretical and experimental methods when the vehicle moves on the forest road. With the theoretical research method, the authors use the analysis method to separate the structure of the system of many objects and apply Newton–Euler equations to establish the car dynamics model, using the Matlab Simulink software to investigate for determining the dynamic load. By the experimental method, the authors have determined the forest ground roughness to serve as an input parameter for the theoretical survey results and determine the dynamic load acting on the vehicle to compare with the simulation results. Results: The study results of the dynamic load determination show that the error between theory and experiment is the largest of 6.22%. Coinstantaneously, to ensure kinetic safety and durability, when the vehicle moves on the forest road, the vehicle's speed must be less than or equal to 15 km/h. Conclusions: In order to be able to make a meaningful comparison between the findings of the simulation and the outcomes of the experiment, the experiment was performed under the exact identical parameters as the theoretical simulation calculation conditions. The final results of the experiments provided rules that were comparable to those derived from the model's calculations of the survey data. When the extremes of dynamic loads from the simulation and the experimental findings are compared, it can be shown that the largest deviation is 6.22%. This can be considered a demonstration of the correctness and dependability of the dynamic model that the author has constructed and used to identify the load that is acting on the vehicle. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high efficiency and environmental friendliness make hydrogen and fuel cell technology important players in today's energy market. However, the durability issue is a major setback for fuel cells' adoption in various applications, including automotive. As automotive fuel cells exhibit non-linearity and dynamic behavior, predicting their performance has become a complex task since their response changes rapidly to varying operating conditions. To enhance performance prediction reliability, this study proposes a novel recursive multi-step performance prediction method for automotive fuel cells based on conditional time series forecasting with convolutional neural network (CNN). The method incorporates a conditional CNN architecture to extract representative features from the input data and a recursive strategy to iteratively predict future values based on previous predictions. Moreover, the seasonality in the data is detected to correct the prediction results by considering the intermittent performance recoveries. Experimental results show that the proposed approach achieves high prediction accuracy, particularly for long-term performance prediction. The proposed method could have significant implications for improving the reliability and efficiency of automotive fuel cell systems. • Interval of recoverable degradation is identified by seasonality identification. • A conditional CNN is developed to mitigate error accumulation problem. • Dynamic durability test data are used for model training and validation. [ABSTRACT FROM AUTHOR]

The main issues associated with cement concrete pavements are cracks and broken plates that affect driving comfort and road service life. To ensure sustainable use of the cement concrete, a buffer layer (AC-10) can be introduced between the base and the cement concrete panel. In this study, the interlayer shear test was performed, and the interlayer bonding coefficient under different temperature conditions was determined. The creep test of the buffer layer was also conducted, and the four parameters (E1, E2, η1, and η2) of the Burgers model of the buffer layer were analyzed using regression. According to the parameters obtained from the test, the finite-element model was established, and the moving load was applied to analyze the structural model response under high-, medium-, and low-temperature conditions. The results show that the (1) temperature stress is mainly concentrated in the buffer layer and regions above the structural layer. At low temperatures, the maximum stress at the top of the surface layer is 2.16 MPa, and the vertical strain decreases as a function of depth. (2) Under the combined action of temperature and moving load, the variation ranges of tensile and compressive stresses at the top of the surface layer are the largest; the variation range of the buffer layer and the subsequent structure is small; the maximum warpage deformation of the surface layer is 0.453 mm under high-temperature conditions; and the maximum compression deformation is 0.219 mm under low-temperature conditions. (3) The comprehensive coefficient k c of the fatigue equation was modified, and the comprehensive coefficient k c of the fatigue equation under different vehicle speeds was proposed. This study provides a reference for the sustainable development of cement concrete pavements with buffer layers. [ABSTRACT FROM AUTHOR]

For wind turbine applications, there is a cyclic load-varying process between rolling elements and raceways in pitch bearings. This kind of motion can also lead to radial fretting. However, this is seldom addressed under grease-lubricated conditions in the literature. In this study, grease-lubricated point contact problems have been investigated experimentally under cyclic load-varying conditions. The findings revealed that as the load-varying range diminishes, the variation in grease film distribution becomes more subtle and the rate of discharge of thickener fiber clusters in the stick zone decelerates. This is due to the fact that the rate of change in the Hertz contact radius is reduced and the migration of grease is weakened during the unloading process. Due to the large apparent viscosity of grease with a high soap content, entrapped grease is not easily discharged during loading, and the thickness of the film in the stick zone progressively increases as the soap content of the grease is augmented. This also causes the variable load zone to wear out more easily. As the grease is subjected to repeated loading and unloading, there is a gradual reduction in film thickness, and larger thickener fiber clusters tear, resulting in a flattened form and shear thinning. Grease containing sulphur–phosphorus additives demonstrates a superior effect on reducing fretting wear within the large variable load range but generally proves effective for smaller load-varying ranges. This study may offer insights into the degradation of grease under variable load motion and methods to prevent radial fretting wear. [ABSTRACT FROM AUTHOR]

The loss of life and property in economically developed areas due to geological hazards caused by intense ground subsidence is incalculable. As one of the fastest growing areas in the Guangdong-Hong Kong-Macao Greater Bay Area, the study of ground subsidence in Nansha will help to provide a scientific basis for urban planning and improve the capacity of monitoring and prevention of ground subsidence. The combination of coastal soft soil foundation and urbanization conditions creates a certain risk of land subsidence. We chose Nansha District, the geographical center of the Greater Bay Area, as the study area to analyze its surface subsidence characteristics in recent years. The 20-view Sentinel-1A data and SBAS-InSAR technique were used to monitor the ground subsidence in Nansha from 2017 to 2023. The main rate of ground subsidence in Nansha ranges from −19.4 to 7.7 mm/yr and is distributed in the urban area, along the rivers, in the construction area, and in the reclamation area. As of 4 May 2023, the average ground settlement in Nansha is 10.05 mm and the maximum settlement can be up to 142.45 mm. The 6-year total settlement at all four settlement intensities is greater than 60 mm, with the highest value exceeding 110 mm. The cumulative settlement increases with time, but inverse settlement and no settlement also occur at points where settlement is severe. For settlement caused by soft soil consolidation, it is recommended that drainage pipes be installed to accelerate drainage as a means of stabilizing settlement. For settlement caused by groundwater extraction and additional loads on the road surface, it is recommended to rationally extract groundwater and reinforce the foundation of the road surface with severe settlement. [ABSTRACT FROM AUTHOR]

This research studies geogrid reinforcement of sandy soils under the influence of the three earthquakes (Halabjah, Bolunun, and Ali Al-Gharbi) due to the recent increase in seismic activity and the need to reduce damage to foundations due to settlement. Sand samples prepared with a relative density of 70%, with and without geogrid reinforcement, were tested on a shaking (vibrating table) table. Five geogrid layers were used, respectively. Settlement occurs due to dynamic force, and the plastic foundation was used with dimensions of 100 * 100 * 30 mm. Withstands a static load of 5.294 kN/m2. Increasing the acceleration of the earthquake leads to an increase in the settlement of the foundation in the sandy soil. The greater the number of geogrids reinforcing layers, the leads to a decrease in the base settlement, where the rate of settlement decrease is greater, the lower the earthquake acceleration and the greater the number of geogrid reinforcement layers. The time of onset of settlement and the general pattern of settlement are similar in all cases studied. The rate of settlement is approximately twice as high when the soil is saturated than when the soil is dry, and the effect of geogrids is less for the soil when it is saturated than when it is dry. [ABSTRACT FROM AUTHOR]

Foamed mixture lightweight soil using river sludge (FMLSS) is a novel method of dredged silt reuse in the engineering field. The variation law of dynamic stress strain backbone curve of FMLSS under different confining pressures, different water contents, different cement contents and different air foam contents is analyzed by the indoor dynamic triaxial test. The results show that the dynamic stress strain backbone curve of FMLSS presents a law of linear increase at first and then gradually stabilize, which accords with the hyperbolic model. Compared with confining pressure, water content and air foam content, the influence of cement content on dynamic stress strain relationship of FMLSS is more significant. Considering the complexity of the mechanical properties of FMLSS, the original Hardin-Drnevich model is improved, the correction coefficient A and its function expression are proposed, then the coefficient A value is derived from the fitting curve and the change rule of coefficient A value is analyzed, and it is founded that the coefficient A value decreases with the increase in confining pressure, cement content and air foam content, increases with the increase in water content. According to the fitting results, the undetermined oefficients in the A value function are further optimized, and finally a modified Hardin-Drnevich model conforming to the dynamic characteristics of FMLSS is established, which provides support for the stability analysis, disaster prediction and engineering application of FMLSS. [ABSTRACT FROM AUTHOR]

Modeling the propagation of waves in geomechanics is an essential part of dynamic analysis. In geotechnics, the study of the interaction between the soil and the foundation is particularly interesting. In order to mimic low-speed operating types (less than 1,500 rpm), this study details the creation of a dependable and efficient approach for designing and fabricating the steel box container. When employed as a boundary, an absorbing layer drastically reduces the amount of wave reflection that occurs inside the limited region. The present effort is split into two halves. The first step is to calculate the damping layer’s damping constants, subgrade response modulus, damping ratio, shear modulus, vibration amplitude, and resonant frequency. The second section focuses on the dynamic study of the circular foundation by measuring the vibration amplitude, acceleration, velocity, and displacement caused by harmonic vibration machines. The findings demonstrate that simple material borders prevent the wave from dissipating as a consequence of reflection. Attenuation of waves is possible when the absorbing layer of energy represents semi-infinite soil. When absorbing just one layer, the vertical displacements at positions located at the box side boundary and its base decreased by 65, 63, and 67%, respectively. However, it dropped by 97, 96, and 98%, respectively, when two absorbent layers were used. On the basis of these promising results, the model results were compared with and without the absorbing layer. It would appear that the modeling of the absorbing layer, which is designed as two layers, has been satisfied for low speeds of harmonic vibration.

This study aims to tackle the problem of frequent coal-rock dynamic events caused by local stress concentration in deep mining working face under high static stress environment. Specifically, by taking the deep working face of Hongqinghe Mine located in Xinjie Mining Area as an example for analysisthis paper investigates the geological conditions of No. 3-1coal seam that are affected by the mining method and the coal rock dynamic disaster events occurred during mining; utilizes numerical simulation to simulate the mining stress field and energy field of the stope; analyzes the potential coal burst instability area and mechanism of coal burst gestation and catastrophe in the stope during the mining of the No. 3-1103 working face; probes into the sources of catastrophic stress and influencing factors of coal-rock disasters in dangerous areas, puts forward targeted prevention and control measures. Results show that: ① the roof strata structure, goaf and coal pillar are the key factors influencing coal burst in the stope during the mining of the No. 3-1103 working face; ② the simulation results indicatethe location and characteristics of the coal burst instability area in the stope of the No. 3-1103 working faces, as well as the simulation outlines 5 strong coal burst areas and 11 medium coal burst areas presented in the stope; ③ Measures are proposed for coal burst during mining from the perspective of cutting off the dynamic load source, reducing static load stress concentration, and blocking the transmission of high concentration stress. Detailed measures include implementing multi-source prevention and control in areas with high static or high static+dynamic loads, implement pre-pressure off-load measures prior to mining, and local risk relief and coal burst prevention and reduction treatments during mining.

In this paper, the critical threshold associated to the activating of strain hardening capacity with respect to typical Hadfield steel Mn13Cr2 was explored quantitatively utilizing a Separated Hopkinson Press Bar (SHPB). The strain hardening behavior of the Mn13Cr2 under dynamic load was investigated, systematically, and the strain hardening mechanisms involved in different plastic deformation conditions were illuminated. Results indicated the overall plastic deformation process under different dynamic loads could be divided into three stages, including the (LHS), the (HHS) as well as the parabolic hardening stage (PHS). The critical transformation strength (CTS) from LHS to the HHS showed a trend of increasing first and then decreasing with the shock pressure increasing from 0.1 MPa to 0.8 MPa, and the maximum hardening effect with respect to the studied Mn13Cr2 steel could be activated at dynamic load threshold of 0.6 MPa with max CTS of ∼493.6 MPa. Dislocation-dominated strengthening mechanism and C–Mn atomic dipoles strengthening mechanism induced by dynamic strain aging were responsible for the excellent strain hardening capability when the impact load was increased above 0.6 MPa.

Dental implants offer an effective solution for partial and total edentulism, but mechanical and biological complications exist. Furthermore, high occlusal loads challenge implants and lead to potential failures. This review focuses on impact testing in contrast to incremental and static tests, an underexplored aspect of assessing daily loads on implants, bringing to light potential complications. The review examines studies employing impact forces to assess implant-supported prostheses and natural teeth properties, highlighting their significance in dental research. A systematic search following PRISMA guidelines identified 21 relevant articles out of 224, emphasizing studies employing impact forces to evaluate various aspects of dental implant treatments. The diverse applications of impact forces in dental research were categorized into tooth structure, restorative materials, interface evaluation, implant properties, and finite element models. Some studies showed the significance of impact forces in assessing stress distribution, shock absorption, and biomechanical response. Impact testing is a critical tool for understanding the daily forces on implants. Despite diverse experimental approaches, a lack of standardized protocols complicates the systematization of the results and, therefore, the conclusions. This review highlights the need for consistent methodologies in impact testing studies for future research on implant-supported prostheses.

Higher efficiency of rail transportation at the present stage of development of the transport industry necessitates the creation and introduction of rail vehicles with improved technical and economic characteristics among which is reduced tare weight. The issue of reducing the tare weight of wagons is quite urgent. It deals not only with the sprung mass of the wagon but also with the load on the rail track, which is under the influence of constant cyclic loads. Therefore, the present study deals with the development of a wagon covered with tarpaulin for carrying goods requiring protection against the environment. The loads inherent for operation on 1520 mm gauge lines are considered. The covered wagon mod. 11-217 is chosen as a prototype. The profiles of the covered wagon frame components are selected according to the moment of resistance of their cross-sections. It is found that the proposed design has a 16% lower tare weight than that of the prototype. The results of the strength calculation for the wagon under the main design operating modes have proved the feasibility of its structural design. The motion of the covered wagon over a track irregularity has been assessed as ‘excellent’. The results of the study will contribute to the creation of recommendations for the development of modern structures of covered wagons as well as improve the efficiency of railway transportation.

The frequency support capacity of power loads is essential for maintaining active power symmetry and balance between the generation and demand sides of power systems. As the proportion of renewable energy sources and power electronic equipment increases, the inertia on the power generation side decreases, highlighting the growing importance of frequency support on the load side. As it is generally believed that the active power balance of power systems determines the frequency stability, few studies have considered the effect of voltage variation on the frequency response dynamics. It is important to note that the node voltage keeps fluctuating throughout the frequency dynamic process, which affects the active power of loads and should not be neglected. Based on the aforementioned rationales, this paper endeavors to investigate the modeling of power load frequency response and analyze its support capability considering the voltage variation effect. This paper initially establishes the small-signal model of dynamic load under frequency dynamics, derives the transfer function relating active power to system frequency deviation, and subsequently develops its frequency response model. Subsequently, commencing with the ZIP model of static load, the power fluctuation of load nodes is derived from the influence of preceding nodes, and the frequency response model of the static load is formulated and its frequency support capacity is scrutinized. Based on this foundation, a comprehensive aggregation model of the complex load is constructed, and its frequency support capability is assessed using actual data. Finally, the proposed model and analysis results are validated through simulation, confirming their correctness and effectiveness.

During the braking manoeuvre of a vehicle on a pavement, the mechanics associated with load transfer is complex due to the presence of slip, load shift between the front and rear axles, and development of longitudinal forces. The road profiles, braking intensity, truck mass, and speed during braking play a critical role here. This investigation reports an attempt to collect such data. A unique Hardware-in-Loop set-up was integrated with vehicle dynamics software, TruckMaker, to perform a realistic braking manoeuvre. Three truck loadings were chosen from the axle load survey conducted in the field (unladen, laden, and overloaded). Three ISO road profiles (A, B, C) generated using the power spectral density approach, three initial speeds (30, 50, and 80 km/h), and three braking intensities (Partial (10%), Partial (45%), and Complete (100%)) were chosen for the simulation. In total 81 simulations were performed considering all the above-said factors. From the analysis of wheel slip values, it was identified that the wheels of unladen trucks lock during complete braking, irrespective of the speeds and road profiles. The complete braking manoeuvre for all vehicle types showed more load shift from the rear axle to the front axle compared to partial braking manoeuvres. Also, the unladen trucks were found to transfer more percentage (>50%) of their rear axle load to the front axle during braking. The maximum longitudinal force developed at the tyre-pavement interface was found to be independent of the loading conditions during complete braking. [ABSTRACT FROM AUTHOR]

The main dependences that make it possible to determine and evaluate the dynamic components of stresses and displacements in main gas pipelines under the action of a moving concentrated force are considered. The solution of the problem is given for single-span, two-span, and three-span beam transitions. According to the requirements of industry documents, decisions were made on the further operation of crossings or the need for their reconstruction. [ABSTRACT FROM AUTHOR]

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A brief review of known digital speckle pattern interferometry methods for retrieving the surface displacement and deformation fields under dynamic loads is presented. A new nondestructive test method of three-step phase-shifting correlation speckle pattern interferometry to study the dynamic loads of structural materials is proposed. In this method three speckle interferograms (SIs) of the specimen surface, differing only by arbitrary unknown phase shifts, are recorded before the loading and one SI is recorded under the dynamic load. The surface displacement field under dynamic loading is determined using the obtained SIs. Two algorithms for the implementation of the method are proposed. They use an integrating bucket technique to record SIs and make it possible to determine the phase maps of the surface displacement fields at any moment of applying the dynamic load. We can use this method to produce a temporal sequence of surface displacement fields during loading. [ABSTRACT FROM AUTHOR]