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Negative Poisson's ratio in auxetic structures plays a crucial role in energy absorption and impact mitigation. Origami-based lattices within the realm of auxetic structures offer the advantage of facile fabrication and design. Nevertheless, the utilization of periodic lattices in origami-based auxetic structures constrains the available design space for achieving diverse mechanical properties. Addressing this limitation, our study introduces origami-based auxetic structures with functionally graded thickness, utilizing origami-based lattices known as Tachi–Miura polyhedra. We investigated the impact of functionally graded thickness on buckling behavior and force responses through dynamic loading experiments employing 3D-printed test pieces. The experimental results indicate that functionally graded thickness induces partial auxetic deformation in lattices, and the resulting nonsymmetric deformation prevents global buckling, thereby averting bounded forces observed in structures with uniform thickness. These findings extend the applicability of auxetic structures, spanning from energy absorption to the design of cushioning structures. [ABSTRACT FROM AUTHOR]

The deterioration of the US transportation highway network and the onset of new technologies in the freight industry are expected to cause changes in the axle load magnitude and distribution, further exacerbating the reduction in the service life of flexible pavements. In this study, a reviewed framework to incorporate roughness-induced dynamic wheel loading into tire–pavement contact stress prediction is presented. The response to nonfree-rolling conditions, usually overlooked, was considered. State-of-the-art numerical models were used to account for pavement unevenness, vehicle dynamics, and 3D and nonuniform contact stresses. In this framework, for a given target international roughness index, an artificial multitrack roughness profile was converted into a dynamic loading profile based on the mechanical properties of a Class 9 vehicle. Upon discretization of the dynamic loading profile into a finite number of loads based on percentile distributions, a 3D finite element model of a dual-tire assembly was used to predict the contact stress distribution over a rigid surface. The performed numerical simulations allowed us to analytically quantify the variation of vertical and in-plane contact stress distribution. Hence, changes in the stress/strain field distribution and peak values under various axle loading scenarios were determined. The findings reveal that disregarding the effect of road roughness and vehicle maneuvering could result in considerable underestimation of the net forces and contact stress distribution developed at the tire–pavement interface. These considerations are particularly impactful on in-plane contact stresses, which, in turn, are associated with near-surface distresses. Practical Applications: The distribution of contact stresses at the tire–pavement interface influences the likelihood of failure near the surface and is greatly affected by driving behavior (braking, cornering, and acceleration). Truck electrification is likely to modify driving behavior due to the instant torque availability provided by electric powertrains, and the incorporation of battery packs is likely to alter the distribution of axle loading. The impact of these variables on the applied load to a pavement system could be further exacerbated by road conditions. In that regard, this paper aims to quantify the changes in the contact stress distribution when roughness, driving behavior, and axle loading are compounded. Because these considerations are not taken into account by current pavement analysis procedures, pavement engineers can use the results to assess the importance of each parameter on load characterization, a controlling variable on the prediction of pavement responses. [ABSTRACT FROM AUTHOR]

A proper and reliable fracture fixation is important for fracture healing. The proximal femoral intramedullary nail (IN), such as proximal femoral nail anti-rotation (PFNA) or Gamma nail, is widely used for intertrochanteric fracture fixation. However, it still suffers considerable stress concentrations, especially at the junction between the nail and the blade or lag screw. In this study, we propose a novel intramedullary nail design to enhance the intramedullary nail integrity by introducing a bolt screw to form a stable triangular structure composed of the nail, the lag screw, and the bolt screw (PFTN, Proximal femoral triangle nail). Systematic finite element numerical simulations were carried out to compare the biomechanical performances of PFTN and PFNA under both static and dynamic loads during the postures of ascending and descending stairs. The simulation results highlight the advantages of the proposed PFTN design with lower stresses, less stress concentration, and higher structure stability. [ABSTRACT FROM AUTHOR]

Aiming at resolving trajectory tracking control challenges during high‐speed lane changes in intelligent driving vehicles, an innovative fractional‐order sliding mode control approach is introduced in the present study. The control strategy comprises upper and lower‐level controls. First, the upper‐level control designs the vehicle trajectory tracking controller, integrating a non‐singular terminal sliding mode (NTSM) surface with a fractional‐order fast super‐twisted sliding mode control (FOF‐STSMC) algorithm. The NTSM surface properties ensure rapid convergence of the system tracking error to zero within a finite time, while the fractional‐order control extends the control system's regulation range and enhances algorithm flexibility. Additionally, the integration with the super‐twisting algorithm effectively mitigates oscillation issues in the control input, achieving a smooth input. Second, the lower‐level control aims to enhance vehicle driving stability. Utilizing the reference yaw rate, and sideslip angle and accounting for tire force saturation, a fractional‐order sliding mode control (FOSMC) algorithm is developed to compute the external yaw moment. Through dynamic load allocation, considering the vertical load for each tire, intelligent external yaw moment distribution significantly improves vehicle stability. Finally, the results of the Carsim–Simulink co‐simulation demonstrate that, compared to the STSMC strategy, the FOSMC strategy with front‐wheel‐only steering, and the linear quadratic regulator (LQR) control strategy, the proposed control strategy in this paper reduces the tracking error by 77%, 61%, and 58%, respectively, achieving more precise and stable trajectory tracking under high‐speed conditions. [ABSTRACT FROM AUTHOR]

Hanging sleepers, which result from the differential settlement of the ballast layer, are a prevalent issue that leads to the rapid degradation of track components that include the ballast, sleeper, fastener, and rail. A novel type of sleeper, the wedge-shaped self-leveling sleeper (WSS), was proposed as a solution to the hanging sleeper problem. The WSS leverages the train's dynamic loading and the gravity of the ballast to naturally allow the ballast particles to fill the gap between the ballast and the sleeper. This paper focuses on the dynamic performance of the WSS from different aspects, which include wedge angles (30°, 45°, and 60°), sleeper materials (concrete and plastic), and the number of WSS to replace regular sleepers in the transition zone. A series of numerical modeling [which coupled multibody simulation (MBS) and discrete-element methods (DEM)] were conducted to design, optimize, and test the WSS. The results reveal that a concrete WSS is well-suited to address the problem of hanging sleepers in transition zones. The WSS with a 45° angle demonstrated superior performance compared with other types of WSS. Importantly, the WSS could reduce vibrations in the vehicle and track, even when dealing with hanging sleepers. Due to the self-leveling function, the WSS shows significant promise for applications in transition zones, which could reduce the frequent need for track geometry maintenance. [ABSTRACT FROM AUTHOR]

Mechanically stabilized earth (MSE) retaining walls have been successfully implemented in numerous applications, particularly where dynamic loads such as earthquake and traffic loading are prevalent. However, using MSE walls as foundations for high-speed train track systems remains uncertain, and their performance under high-speed train loading is inconclusive. This paper extensively investigates the behavior of MSE walls under various high-speed train loading conditions, addressing key considerations, challenges, and findings. The study focuses on evaluating wall performance in terms of horizontal displacement, settlement behind the facing, tensile load and displacement of reinforcement elements, and wall amplification characteristics. The performance of the wall is also assessed by examining the influence of the cement asphalt mortar layer. The total axle load and loading duration are identified as critical design parameters for high-speed train loading, and an empirical equation is developed to estimate horizontal wall displacement based on these parameters. [ABSTRACT FROM AUTHOR]

In alternating current (AC) microgrids, the prevalent approach for controlling the power distribution between generators and loads is droop control. This decentralized technique ensures accurate power sharing; however, its utility is restricted by significant drawbacks. Notably, in scenarios involving dissimilar power sources, mismatched impedance lines, or meshed microgrids, conventional droop control fails to ensure effective reactive power sharing among inverters, often leading to notable circulating currents. Hence, the primary objective of this paper is twofold: firstly, to examine limitations inherent to conventional droop control; secondly, to introduce a robust power-sharing methodology for AC microgrids. This novel approach is specifically designed to achieve consistent sharing of active and reactive power across meshed topology microgrids. The technique considers the presence of distributed power loads and the dynamic nature of the topology. Despite the attainment of satisfactory active and reactive power sharing, deviations in voltage and frequency occasionally manifest. To address this issue, a supplementary control mechanism is proposed as a third phase. This secondary control method focuses on reinstating the microgrid's voltage and frequency to rated values, all while upholding the precision of power sharing. The efficacy of this multi-stage methodology is rigorously validated through simulations using MATLAB/Simulink and practical experimentations. [ABSTRACT FROM AUTHOR]

AbstractThis study systematically investigated the dynamic mechanical properties and penetration-damage behavior of high-density VNbTa medium-entropy alloys under dynamic loading. The split Hopkinson bar, impact energy release, and spaced-target plate tests were carried out. Results from the impact energy release test indicated that a significant chemical reaction and substantial energy release occurred when the alloy hit a rigid target plate at high speed. The spaced-target plate penetration test verified the combined destructive effect of the alloy’s kinetic and chemical energies during penetration, leading to large perforations and severe deformation of the rear target plate. Moreover, a shock-induced energy release model and a fragment cloud diffusion model were established, uncovering the energy release mechanism and fragment-cloud expansion law. These findings provide a theoretical and experimental basis for the design and application of high-density, high-energy structural materials. [ABSTRACT FROM AUTHOR]

AbstractThis study introduces a novel hybrid tetra-chiral honeycomb (NHTCH) structure achieved by combining a tetra-chiral honeycomb and its inverse configuration. The honeycomb prototype was created through 3D printing, and a quasi-static compression experiment was conducted in the opposite direction. Utilizing Abaqus/Explicit, we developed a finite element numerical model and verified its accuracy. The mechanical properties of the proposed structure, denoted as NHTCH, were compared with those of traditional tetra-chiral honeycombs (TCH). Results indicated that NHTCH exhibits superior mechanical properties compared to TCH, and its plastic deformation displays a noticeable negative Poisson’s ratio effect. Furthermore, we analyzed the in-plane mechanical response of NHTCH under varying impact velocities and conducted parametric studies on the angle between chiral elements and the radius of the node circle. Our findings reveal that, under high-speed impacts, NHTCH demonstrates higher energy-absorbing and load-carrying capacities compared to the other two configurations. Simultaneously, optimizing the clamping angle and nodal circle radius of NHTCH efficiently enhances the mechanical properties within a specific range, without causing significant changes to the plastic deformation of the structure. [ABSTRACT FROM AUTHOR]

This study examines the vibration characteristics of static drill-rooted nodular (SDRN) piles in elastic soils under time-harmonic torsional loads via an analytical approach. SDRN piles, which are characterized by uniformly distributed nodes and enhanced surrounding cemented soil, are able to increase the vertical bearing capacity of piles in soft soils. Piles are modelled using elastic rod theory, while surrounding soils are separated into two sublayers along radial direction: a core zone made up of cemented soil and an outer semi-infinite natural soil layer. An analytical method is proposed to solve the problem after formulating the wave equations for pile and radial soil layer. This methodology rigorously considers the continuity of twist angle and shear stress across the interface of the pile and radial soil layers. The simulation of nodes in the SDRN pile involves discretizing the pile-soil system and applying the principle of impedance function recursion to accurately compute the torsional stiffness at the top of the pile. Developed results are validated against the existing benchmarks for a cylindrical pile in elastic soil. Detailed numerical examples are carried out to assess the effect of major factors on the torsional impedance of the pile. For improved comprehension in engineering applications, the impedance function is applied to derive the twist angle of the rigid foundation, with the amplitude-frequency response expressed in a closed form. Results indicate that the vibration behavior of the piles is significantly influenced by the inner radius, outer radius, the dimension of the node, the radial width of the cemented soil and the damping ratio of the radial soil layer. The developed solution offers valuable insights for the optimization design of SDRN piles under dynamic torsional loads. [ABSTRACT FROM AUTHOR]

AbstractCoral reef limestone (CRL) is found only in ocean reef islands. Deepening the investigation of the dynamic performances of CRL helps expand its utilization in reef engineering. This study studied the dynamic response of shallow weakly-cemented CRL (WCRL) using experimental and numerical methods. First, the impact performance of the WCRL was tested using the Split Hopkinson Pressure Bar apparatus. The dynamic peak stress and peak strain of WCRL exhibited rate-sensitivity. Subsequently, the impact process of the WCRL was calculated in the numerical software LS_DYNA, with key dynamic parameters of WCRL calibrated based on the Holmquist-Johnson-Cook (HJC) model for the first time. The accuracy of the numerical results was verified with the experimental results. Thereafter, the dynamic failure process and energy dissipation mechanism of the WCRL were numerically investigated. As the strain rate increased, the failure of the WCRL specimens intensified. The energy analysis demonstrated that the destruction of WCRL specimens consumed more energy at high strain rates, though the distribution proportion of energy was rate-independent. Finally, the sensitivity analysis revealed that the certain parameters (A, B, C, N, pc, and μc) of the HJC model played a crucial role in describing the material’s dynamic response. [ABSTRACT FROM AUTHOR]

Structural fatigue can lead to catastrophic failures in various engineering applications and must be properly monitored and effectively managed. This paper provides a state-of-the-art review of recent developments in structural fatigue monitoring using piezoelectric-based sensors. Compared to alternative sensing technologies, piezoelectric sensors offer distinct advantages, including compact size, lightweight design, low cost, flexible formats, and high sensitivity to dynamic loads. The paper reviews the working principles and recent advancements in passive piezoelectric-based sensors, such as acoustic emission wave and strain measurements, and active piezoelectric-based sensors, including ultrasonic wave and dynamic characteristic measurements. These measurements, captured under in-service dynamic strain, can be correlated to the remaining structural fatigue life. Case studies are presented, highlighting applications of fatigue life monitoring in metals, polymeric composites, and reinforced concrete structures. The paper concludes by identifying challenges and opportunities for advancing piezoelectric-based sensors for fatigue life monitoring in engineering structures. [ABSTRACT FROM AUTHOR]

The ride comfort of vehicles traveling on the road has always been a concern. In addition, the braking force of vehicles will aggravate the damage to road structures and reduce the comfort of drivers and passengers. In the present study, the dynamic response of pavement, road friendliness, and human comfort are investigated by setting up the human-bus-road coupled vibration system considering the braking forces. Firstly, the three-dimensional finite element model of asphalt pavement with interlayer contact and the human-bus model with multiple degrees of freedom (2n + 7) were established to analyze the dynamic responses of asphalt pavement, human body, and bus under different braking conditions. Then, the dynamic load coefficients of wheels under different combined conditions were investigated to evaluate the road friendliness and the human annoyance rate was adopted to evaluate the human comfort. The results show that for the asphalt pavement, the shear stress of the pavement is larger than the normal stress due to the bus braking, and the combined effect of road surface roughness and braking force on the road friendliness is the largest. For the human comfort, the pitch acceleration of human body increases more than the roll acceleration due to bus braking, resulting in the decreased human comfort and increased annoyance rate. [ABSTRACT FROM AUTHOR]

Bone behaves as a complex composite material, and is highly heterogenous and anisotropic in nature due to its hierarchical structure. The effect of the location and orientation of bone specimens on the viscoelastic properties of bovine femoral cortical bone was examined in this study. The bone samples were extracted from different locations i.e., proximal, central and distal along the direction of longitudinal and transverse and underwent sinusoidal loading. The longitudinal orientation shows more values of loss tangent and loss modulus in comparison to transverse orientation bone samples. Across locations reveal no significant difference in the storage modulus, loss tangent, loss modulus and complex modulus. The trends in the complex and storage moduli remain consistent within both types of orientations. Significant differences were observed across the locations for both storage and recovered energy, with no variance in the hysteresis loss. The findings from the study shall help in a deep understanding of the bone biomechanics, offering insights for material design and orthopedic interventions in biomechanical engineering. [ABSTRACT FROM AUTHOR]

Understanding the characteristics of biogas demand in rural areas is essential for on-demand biogas production and fossil fuel offsetting. However, the spatiotemporal features of rural household energy consumption are unclear. This paper developed a rural biogas demand forecasting model (RBDM) based on the hourly loads of different energy types in rural China. The model requires only a small amount of publicly available input data. The model was verified using household energy survey data collected from five Chinese provinces and one year's data from a village-scale biogas plant. The results showed that the predicted and measured biogas consumption and dynamic load were consistent. The relative error of village biogas consumption was 11.45%, and the dynamic load showed seasonal fluctuations. Seasonal correction factors were incorporated to improve the model's accuracy and practicality. The accuracy of the RBDM was 19.27% higher than that of a static energy prediction model. Future research should verify the model using additional cases to guide the design of accurate biogas production and distribution systems. [ABSTRACT FROM AUTHOR]

To improve the adaptability of grid load collaborative scheduling, a multi-objective collaborative scheduling method based on a simulated annealing algorithm for the load storage of grid loads on the load side of a new power system is proposed. Local bus transmission technology is adopted to collect the dynamic parameters of energy network load energy storage on the load side of the new power system. The collected load dynamic parameters are fused with energy distribution state parameters to extract the state characteristics of energy network load storage. The simulated annealing algorithm is adopted to realize the load characteristics fusion and adaptive scheduling processing of energy network on the load side of the power system, and the spectral characteristics of the load dynamic parameters are extracted. The dynamic scheduling method of simulated annealing is used to realize the multi-objective optimization of dynamic load of energy network. Based on the co-optimization results of simulated annealing, the optimization application of the simulated annealing algorithm in the multi-objective co-scheduling of loads and energy storage in a new power system is realized. The experimental results show that after 400 iterations, the control convergence accuracy of the proposed method reaches 0.980, which is significantly better than that of the comparison method, and performs well in terms of scheduling efficiency improvement, load scheduling stability, scheduling time and energy waste ratio, proving that the method has good multi-objective integration and strong optimization ability in the scheduling process, and improves the load balanced scheduling and adaptive control ability of the power system. [ABSTRACT FROM AUTHOR]

Understanding the dynamic response of granular shear zones under cyclic loading is fundamental to elucidating the mechanisms triggering earthquake-induced landslides, with implications for broader fields such as seismology and granular physics. Existing prediction methods struggle to accurately predict many experimental and in situ landslide observations due to inadequate consideration of the underlying physical mechanisms. The mechanisms that influence landslide dynamic triggering, a transition from static (or extremely slow creeping) to rapid runout, remain elusive. Herein, we focus on the inherent physics of granular shear zones under dynamic loading using ring shear experiments. Except for coseismic slip caused by the dynamic load, varying magnitudes of postseismic creep with increasing cycles of dynamic loading are observed, highlighting the effects of coseismic weakening (shear zone fatigue) and subsequent postseismic healing. A metastable state, characterized by a significant increase in postseismic creep, typically precedes shear zone instability. The metastable state may arise as weakened shear resistance approaches the applied shear stress, demonstrating a phase transition from a solid-like state to a fluid state (plastic granular flow). The metastable state may potentially indicate the shear zone's stress state and serve as a precursor to impending instability. Furthermore, the proposed mechanisms offer a compelling explanation for the widespread postseismic landslide movement following earthquakes. Incorporating these mechanisms into the Newmark method has the potential to improve the prediction of earthquake-induced landslide displacement and enhance our understanding of dynamic triggering. [ABSTRACT FROM AUTHOR]

To address the challenges of handling the dynamic load variations caused by the unpredictable nature and energy asymmetry of renewable energy sources in isolated microgrids, this study introduces a novel approach known as Learning-Enhanced Load Frequency Control (LE-LFC). This method conceptualizes controllers as autonomous entities capable of making independent decisions. It employs a sophisticated High Scene Generalization Soft Actor-Critic algorithm, augmented with transfer learning, to enhance decision-making speed, generalization, robustness, and efficiency. This algorithm leverages environmental data for interaction, aiming for optimal frequency management and economic operation of isolated urban microgrids. By incorporating a maximum entropy approach, it enhances the robustness of conventional deep reinforcement learning and integrates dominance learning to refine Soft Actor-Critic's Q-value function update, mitigating overestimation issues and boosting algorithmic performance. In addition, transfer learning is utilized to bolster the agents' learning efficacy and adaptability to new conditions. Demonstrated effectively in China Southern Grid's island microgrid setup, LE-LFC emerges as an advanced solution for modern grid variability, offering superior robustness, adaptability, and learning speed, thus enabling flexible and efficient energy system management. [ABSTRACT FROM AUTHOR]

A novel robust control strategy is proposed in this work to address the dynamic control problem of permanent magnet synchronous motors (PMSM) position tracking and lessen the effect of system parameter and load fluctuations on the dynamic performance of PMSM. The tracking performance is improved by a robust control element built with the Lyapunov method to reduce the impact of uncertain factors such as parameter uncertainty, nonlinear friction, and external interference; the nominal control element is stabilized by the dynamics model. The uniformly bounded and uniformly final bounded systems are proven, and the associated conclusions are provided using the Lyapunov minimax approach. In this work, modeling and experimental investigation are conducted using the cSPACE fast controller, based on the permanent magnet synchronous motor test platform. The results of the testing and simulation show that the developed controller can effectively regulate the permanent magnet synchronous motor and achieve more accurate position tracking even in the face of ambiguity. [ABSTRACT FROM AUTHOR]

The complete dynamic stall process encompasses a series of complex developmental stages, such as flow separation, leading edge vortex shedding, and reattachment. Unlike static stall, dynamic stall exhibits hysteresis, rendering phenomenological models as complex nonlinear state-space systems, often accompanied by numerous empirical parameters, which complicates practical applications. To address this issue, the Goman–Khrabrov (G-K) dynamic stall model simplifies the state space and retains only two empirical parameters related to time delays. Our study finds that different developmental stages of dynamic stall exhibit various time delay scales. The G-K dynamic stall model, which utilizes a first-order time-invariant inertia system, forcibly unifies the time scales across different stages. Consequently, this leads to intractable nonphysical modeling errors. This paper introduces the latest revised G-K model that employs a time-varying state space system. This model not only maintains a concise form but also eliminates the nonphysical modeling errors previously mentioned. In response to the challenge of identifying empirical parameters, this paper presents a parameter identification method for both the original and revised G-K models utilizing a Physics-Informed Neural Network. The revised model was validated through dynamic stall load prediction cases for mild, moderate and deep dynamic stall on various airfoils, achieving a maximum accuracy improvement of up to 74.5%. The revised G-K model is capable of addressing a broader range and more complex practical applications. [ABSTRACT FROM AUTHOR]

Based on the reclamation project of the Dalian Airport, a dynamic compaction method was used to reinforce the foundation of the high back-filled crushed stone strata in coastal areas. Due to the thick backfill rock on the site, the ultra-high energy level dynamic compaction tests with compaction energies of 15 000 kJ, 18 000 kJ and 25 000 kJ, which are rare in China, were carried out. In order to verify the feasibility of the construction process and the effectiveness of foundation treatment, dynamic observations of foundation settlement, displacement, pore water pressure, and in-situ heavy dynamic penetration tests before and after reinforcement were carried out during the dynamic compaction construction process. By establishing a finite element numerical simulation model, the total settlement of the foundation was calculated through dynamic loading. The results show that the ultra-high energy level dynamic compaction treatment has a significant effect, with significant compression deformation of the foundation, improved foundation compactness, and effectively eliminated settlement. The strength of the foundation soil before and after dynamic compaction increased respectively by 130%, 152% and 170%. The total settlement value of the foundation is in good agreement with the range of measured values. [ABSTRACT FROM AUTHOR]

Ramie is a valuable natural fiber resource. The fabric made of ramie fiber has distinctive natural characteristics, and its products are widely favored in the international market. Because the cellulose fiber in ramie is closely adhered by a viscous material composed of pectin, hemicellulose, and lignin, mechanical stripping and processing is needed to obtain primary ramie fiber for downstream use. To address the production challenges posed by high labor intensity and the scarcity of small, direct-feeding ramie decorticators in hilly and mountainous regions, this study designed and optimized a spiral ramie decortication component that integrated functions of ramie stalk crushing, xylem removal, outer shell scraping, and phloem separating and throwing. The three-dimensional model of the ramie stripping component was crafted with SolidWorks software, and subsequent modal analysis and dynamic simulation studies were conducted using Abaqus software. The Box–Behnken experimental design method was used to construct a mathematical model describing the effects of the decorticating drum rotation speed and the decorticating gap on the fiber percentage of fresh stalk, and the optimal operating parameters were determined accordingly. The research findings indicated that the component's initial ten natural frequencies span from 234.41 to 431.70 Hz, which do not overlap with the external excitation frequencies, thus ensuring that no resonance phenomenon occurs during the operation process, meeting the design requirements for the ramie decortication operation. Under dynamic load conditions, the ramie decorticator can efficiently perform the task of ramie fiber decortication, and the stress and strain experienced by the device meet the established design specifications; by optimizing operating parameters, the optimal operating conditions were determined to be the speed of feeding and crushing parts (SFCP) of 100 r/min, the speed of separating and throwing parts (SSTP) of 400 r/min, the gap of feeding and crushing parts (GFCP) of 8 mm, and the gap of separating and throwing parts (GSTP) of 0 mm. Experimental results indicated that under this optimal parameter combination, the fiber percentage of fresh stalk of the spiral ramie decorticator can reach 5.03%, with a relative error of less than 3% compared to the theoretical model prediction value, thus confirming the accuracy of the model prediction. This study establishes a robust technical basis for the development of a convenient decortication technology for ramie fibers. However, this technique is more suitable for small growers, especially in hilly areas, to achieve large-scale applications, schemes must be reevaluated based on production efficiency. [ABSTRACT FROM AUTHOR]

This research aims to assess the massif vibration that results from hydraulic transitions of pumped storage power plant (PSPP) and probe into their consequences on mountain stability. Firstly, numerical simulations of the hydraulic transitions in a pumped storage power plant were carried out, and the pressure pulsations within different sections of the waterway system under pumping and generating conditions were obtained. The historical pressure during the hydraulic transients was used as the dynamic loading condition for transient structural analysis. The time-history curves of horizontal and vertical accelerations were obtained for four main working conditions, and four detection areas were demarcated on the massif surface for analysis. The results showed that the maximum amplitude of horizontal acceleration occurred within the height range of 760 m to 960 m of work condition T2. Statistical methods and one-third octave analysis were further applied to analyze the acceleration time-history curves, showing that the highest vibration levels in the horizontal direction were observed at a specific frequency of 50 Hz. This study indicates that the hydraulic transition process of pumped-storage power stations will have a significant impact on massif stability; therefore, it is crucial to consider corresponding seismic mitigation measures during the design and operating stages to ensure structural safety. [ABSTRACT FROM AUTHOR]

Hydraulic concrete is quite different from normal concrete in the terms of aggregate gradation and construction-induced interfaces. To explore their influences on the dynamic mechanical behaviors of hydraulic concrete, several mesoscale numerical models with different aggregate gradations and interfaces were established and subjected to dynamic compressive or tensile loadings. The results show that aggregate gradation significantly affected hydraulic concrete failure patterns under dynamic loads, but interface effects were less obvious, and stressing uniformity improved with an increasing loading rate. The dynamic compressive and tensile strengths of hydraulic concrete showed a strain rate effect independent of gradation, but decreased with larger coarse aggregates, especially at higher rates. Weak-bonding interfaces significantly reduced strength at low loading rates, with a more pronounced effect on tensile strength than compressive strength. The results of this study provide a theoretical basis for the application of hydraulic concrete containing large-size aggregates in practical engineering. [ABSTRACT FROM AUTHOR]

Coastal defense has traditionally relied on hard infrastructures like breakwaters, dykes, and groins to protect harbors, settlements, and beaches from the impacts of longshore drift and storm waves. The prolonged exposure to wave erosion and dynamic loads of different nature can result in damage, deformation, and eventual failure of these infrastructures, entailing severe economic and environmental losses. Periodic post-construction monitoring is crucial to identify shape changes, ensure the structure's stability, and implement maintenance works as required. This paper evaluates the performance and quality of the restitution products obtained from the application of UAV photogrammetry to the longest breakwater in the province of Cádiz, southern Spain. The photogrammetric outputs, an orthomosaic and a Digital Surface Model (DSM), were validated with in situ RTK-GPS measurements, displaying excellent planimetric accuracy (RMSE 0.043 m and 0.023 m in X and Y, respectively) and adequate altimetric accuracy (0.100 m in Z). In addition, the average enveloping surface inferred from the DSM allowed quantification of the deformation of the breakwater and defining of the deformation mechanisms. UAV photogrammetry has proved to be a suitable and efficient technique to complement traditional monitoring surveys and to provide insights into the deformation mechanisms of coastal structures. [ABSTRACT FROM AUTHOR]

This study proposes a main inner loop control technique to address the dynamic response of the electromagnetic suspension during vehicle driving. The genetic algorithm is employed to optimize the control parameters of the linear quadratic adjustment controller in the control main loop, with the aim of achieving the desired control force. In the control inner loop, a closed-loop sliding mode controller is designed based on the exponential approximation law to regulate the current. The Lyapunov function was utilized to assess the stability of the controller in terms of its theoretical feasibility. The simulation results of Matlab/Simulink show that under the given working conditions, compared with the passive suspension, sliding mode control and fuzzy sliding mode control for references, the root mean square value and peak value of the vertical acceleration of the body and the dynamic load of the tire with the improved sliding mode control are significantly reduced, the root mean square value of the dynamic deflection of the suspension was not improved. However, on the whole, the ride comfort of the vehicle has been improved. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate a non‐resorbable implant for the focal repair of chondral defects in eight adult horses with 12‐month follow‐up. The bi‐layered construct composed of a polycarbonate‐urethane‐urea biomaterial which was printed in 3D fashion onto a bone anchor was implanted into surgically created osteochondral defects into the femoropatellar joints of eight horses. The analysis of post‐mortem outcomes were compared to defects treated with microfracture in the same animal on the contralateral femoropatellar jointfemoropatellar joint. The overall macroscopic scoring after 12 months yielded higher scores in the OCI‐treated stifles compared to MF treatment (p = 0.09) with better quality and filling of the defect. Histology revealed good anchorage of repair tissue growing into the 3D structure of the implant and histopathology scoring for adjacent native cartilage showed no difference between groups. MRI and micro‐CT showed overall less sclerotic reactions in the surrounding bone in the implant group and no foreign body reaction was detected. Biomechanical analysis of the repair tissue revealed a significantly higher peak modulus (p < 0.05) in the implant group (0.74 ± 0.45) compared to the microfracture control group (0.15 ± 0.11). Dynamic loading yielded higher values for the repair tissue overgrowing the implant group (0.23 ± 0.17) compared to the microfracture control (0.06 ± 0.06) (p < 0.05). The bi‐layered osteochondral implant provided a safe implant for focal repair of full‐thickness osteochondral defects, as no adverse reaction was seen within the joints and the level of degeneration of adjacent cartilage to the repair site was not different compared to that seen in defects treated with microfracture after 12 months. [ABSTRACT FROM AUTHOR]

Effective identification of dynamic loads on vehicle systems is crucial for evaluating the structural integrity of railway vehicles. The inverse problem method has been proposed for dynamic load identification to determine the impact load on the carbody. Due to the sparse nature of the impact load, the combination of the l1-norm and TwIST (two-step iterative threshold shrinkage method) methods is used to reconstruct the impact load, taking into account the influence of sensor placement on the identification results. The MOHBA (Multi-objective Optimisation Honey Badger Algorithm) was proposed to simultaneously select the regularisation and iteration parameters. This algorithm aims to improve the accuracy of subsequence load reconstruction by considering the influence of noise levels when selecting the measured data. The impact load experiment was conducted on the scale carbody, and the single-point impact load and multi-point impact load matched well with the actual load. Satisfactory load identification results can still be achieved when the noise level is within 15%. When arranging measurement points on the boundary of the vehicle body, satisfactory load identification results can also be achieved. [ABSTRACT FROM AUTHOR]

Load distribution is a very important indicator that has a great effect on bearing service performance. Unreasonable load distribution is likely to accelerate the bearing failures. The dynamic effects of the moving parts of the rolling bearing have significant influence on the load distribution. In order to study the load distribution of rolling bearings, the dynamic interaction between raceways and balls is considered in detail and a dynamic model of ball bearings subjected to radial loads is presented. The results of the proposed model are compared with those of the traditional static model and the quasi‐static model. The dynamic load coefficient and the dynamic angular extent coefficient are defined to show the characteristics of the dynamic load distribution. The effects of radial clearance, the radial load, and the rotational speed on the dynamic load distribution are studied. Through the above research, this paper concludes that the load distribution is greatly influenced by the dynamic effects of moving parts, especially under the conditions of large clearance, light load, or high speed. [ABSTRACT FROM AUTHOR]

Purpose: Limited nutrient transport is hypothesized to be involved in intervertebral disc (IVD) degeneration. It is widely recognized that the dominant mode of transport of small molecules such as glucose is via diffusion, rather than convection. However, recent findings suggest a role for convection-induced by fast (motion-related) and slow (diurnal) dynamic loading in molecular transport of even such small solutes. The aim of this study was to investigate whether fluid exchange induced by simulated physiological loading (composed of both fast cyclic or slower diurnal loading) can influence the molecular transport of a small molecule through the cartilage endplate (CEP) into the nucleus pulposus (NP) of IVDs. Methods: The molecular transport of fluorescein through the CEP and into the NP was studied in a bovine CEP/NP explant model and loading was applied by an axial compression bioreactor. The loaded explants (convection and diffusion) were compared to unloaded explants (diffusion alone). Results: In the initial 24 h, there were no differences between loaded and unloaded explants, indicating that convection did not enhance molecular transport of small solutes over diffusion alone. Notably, after 48 h which corresponds to two complete diurnal cycles of tissue compression, fluid exudation/imbibing and redistribution, the fluorescein concentration was significantly increased in the top and bottom layer of the explant, when compared to the unloaded explant. Conclusions: Slower diurnal cyclic compression of the IVD might enhance the transport of small molecules into the IVD although it could not be discerned whether this was due to diffusion/convection or a combination. [ABSTRACT FROM AUTHOR]

In this study, we introduce a machine learning-based method to predict the modeling parameters of superelastic shape memory alloys (SMAs). Our goal is to simultaneously determine and fine-tune all internal and material-related parameters, including thermodynamic ones, for a specific constitutive model using only cyclic tensile tests. We employ feedforward neural networks (FNNs) for their versatile structure. First, we sample the searched parameters within a predefined parameter space using the Latin hypercube sampling method. Then, using the constitutive model with the sampled parameters and representative strain loading, we generate the corresponding stress responses and finally train the FNN. To address the ill-posed nature of this inverse parameter identification problem and ensure a unique parameter set, during training, we use a dual network architecture with an additional FNN-based surrogate of the constitutive model. We also utilize transfer learning to accelerate the training process through knowledge transfer and handle multiple load cases simultaneously, ensuring consistent parameter identification across different scenarios. We validate the method by comparing the numerical results with the experimental data and demonstrate the importance of accurately identified parameter sets by numerical investigations on a SMA-retrofitted frame structure. [ABSTRACT FROM AUTHOR]

Accurate prediction of the dynamic response of a structure is crucial for its system identification, reliability analysis, and health monitoring. However, uncertainties in physics-based models and parameters may cause a significant discrepancy between predictions and actual responses. The neural network–augmented physics (NNAP) model aims to address this issue by augmenting physics-based models with deep-learning models trained by real data. While promising, such an approach has yet to be applied to large multi-degree-of-freedom (MDOF) structures under response-dependent forces. This paper presents a novel method incorporating modal truncation into the NNAP model for more accurate prediction of the dynamic responses of nonlinear MDOF systems. The proposed NNAP-m uses modal truncation to describe a physics-based model by lower-dimension coordinates and augments it with a neural network representing phenomena with more significant epistemic uncertainties. This hybrid modeling approach relies on information about mode shapes and natural frequencies to improve prediction capability. The proposed method is successfully verified using a numerical example of the Lysefjord bridge structure exhibiting nonlinear behaviors, including the interaction between wind loads and dynamic responses. The proposed approach is expected to provide accurate response predictions of real-world structures using measurement data and to promote the development of physics-based deep-learning approaches for complex structures with large DOFs. [ABSTRACT FROM AUTHOR]

In medium and high voltage DC microgrids, the input series output parallel dual active bridge (ISOP-DAB) converter, as one of the key devices, has received more and more attention from experts and researchers. This is due to the power imbalance and poor dynamic performance of each module of ISOP-DAB converters. Based on the double-loop decoupling strategy, this paper proposes a hybrid control strategy of a super twisting sliding mode considering backflow power optimization. First, the power model and ZVS characteristics of the DAB converter in two modes under extended phase-shift modulation are analyzed, and a reduced-order model of the DAB converter is established on the basis of the transmitted power model. Second, an output voltage loop super twisting sliding mode controller and a backflow power optimization module are designed based on the established mathematical model. Finally, simulation results show that the ISOP-DAB system has good dynamic performance in load switching and input voltage mutation, can ensure the input voltage of each sub-module, and can effectively reduce the backflow power. [ABSTRACT FROM AUTHOR]

The Hoek–Brown strength criterion is commonly employed to anticipate rock mass failure, considering influential factors including rock mass quality and static stress conditions. Nevertheless, extensive experiments have revealed that the strength of intact rock also depends on the loading rate. Since rock masses frequently experience dynamic loading in practical scenarios, extending the application of this criterion into the dynamic domain is both valuable and challenging. This paper initiates an exploration into the dynamic strength criterion of rock masses, drawing from experimental studies on the dynamic mechanical response of jointed rock specimens. A dynamic three-dimensional strength test was carried out on artificially jointed rock specimens using SHPB equipment with confining pressure. Specimens contain a set of sub-horizontal joint and a set of sub-vertical joint. The research shows that the dynamic compressive strength and Young's modulus of jointed rock specimens increase with the increase of loading rate. The dynamic scale effect of rocks is more related to the structure, rather than being solely dictated by scale. Discussion is undertaken regarding the fundamental form of dynamic strength criterion of rock mass, which is modified from the Hoek–Brown (H–B) criterion. Subsequently, the dynamic compressive strength and Young's modulus of jointed rock specimens are analyzed. By accounting for dynamic size effects, the geological strength index (GSI) was evaluated, which is closely consistent with GSI calculated through dynamic Young's modulus. The relationship between GSI and loading rate is discussed. According to the GSI chart, the joint spacings of rock masses as reflected by the specimen's structures under different loading rates are derived. These findings contribute valuable guidance on utilizing laboratory-scale jointed rock specimens to assess the mechanical behavior and strength characteristics of rock masses under dynamic loads such as blasting. Highlights: Dynamic experiment on jointed rock specimens using SHPB equipment Dynamic mechanical properties of jointed rock specimens Dynamic Hoek-Brown strength criterion for rock masses Dynamic size effect of jointed rock mass and dynamic GSI [ABSTRACT FROM AUTHOR]

Android malware has been emerged as a significant threat, which includes exposure of confidential information, misrepresentation of facts and execution of applications without the knowledge of the users. Malware analysis plays an essential role in dealing with the unlawful behaviour of such malicious applications. Android malware analysis involves examining and understanding malware behaviour and its characteristics. It also includes potential adversarial impacts on Android devices. This paper presents a quick understanding and a holistic view of malware detection and analysis. The current investigation conducted a systematic literature review (SLR) to recognize the salient shifts in malware detection by examining a range of scholarly journals and conference papers. The SLR investigated 99 articles published between the years 2018 and 2023. The key observation of this SLR is that static analysis is the most implemented approach for detecting Android malware; Apktool and Androguard are the most frequently used tools. This study also conceded that deep learning and machine learning models have more potential to analyse the malicious behaviour of malware. Certain challenges are faced in Android malware analysis, that is, obfuscation techniques, dynamic code loading, and issues related to experimented datasets. Further, this study focuses on the following areas: the definition of the sample set, data optimisation and processing, feature extraction, machine learning application, and classifier validation. This investigation differs from previous analyses of Android malware detection by emphasizing additional methods based on machine learning. [ABSTRACT FROM AUTHOR]

Research on the evolutionary behavior of the particle breakage processes in coarse-grained soil under the action of train load is of practical significance for subgrade construction and maintenance. However, existing studies have not addressed the prediction of particle size distribution evolution. In this paper, the MTS loading system is used to simulate the dynamic train load effect on coarse-grained soil fillers. The study analyzes the influence of dynamic stress amplitude, loading frequency, and vibration times on both the macro-characteristics and micro-characteristics of particle breakage. The characteristics of particle fragmentation in coarse soil filler under high-speed train load are elucidated. Furthermore, a predictive model for the evolution of particle size distribution curves in relation to particle content and relative particle size is established using the ZHU continuous grading curve equation. This model captures the evolution process of particle breakage characteristics in coarse-grained soil fillers subjected to high-speed train loads. The applicability of this model has been verified. Based on the grading prediction model, an integral expression for the breakage rate index is derived, and the evolution characteristics of particle breakage in coarse-grained soil fillers under the action of train load are analyzed. The results indicate that during filling, the particle breakage mode of coarse-grained soil fillers during filling is primarily characterized by fracture and fragmentation; conversely, under dynamic cyclic loading conditions, it is predominantly characterized by fracture and grinding. The breakage rate aligns with the measured results, suggesting that the breakage rate index established in this study can effectively describe the evolution process of particle breakage in railway subgrade coarse-grained soil. After the reaching one million loading cycles, both deformation and particle breakage degree in coarse-grained soil fillers tend to stabilize. Under the action of dynamic stress amplitudes ranging from 10 to 200 kPa and loading frequencies between 2 and 12 Hz, the particle breakage index stabilizes below 1.1%. These research findings contribute to a deeper understanding of the evolutionary processes affecting engineering characteristics of railway subgrade coarse-grained soils and provide a theoretical as well as experimental foundation for railway subgrade construction and maintenance. [ABSTRACT FROM AUTHOR]

Despite the significant research on the seismic stability of earth structures, critical gaps remain in understanding the dynamic response of soil slopes with varying reinforcements. These gaps were addressed in this study by using a small shake table to investigate the dynamic behavior of soil slopes under different conditions. The research examines responses at various frequencies, the effect of reinforcement methods, and the impact of slope height. Results indicate that the higher frequencies and amplitudes lead to increased displacements, while reinforcement reduces crest displacement by 21 to 45%. Steeper slopes (35° and 40°) also show increased displacements by 9 to 65%, compared to a 30° slope. The importance of reinforcement in improving the seismic resilience of soil slopes is highlighted in this study, offering practical insights for engineering design. [ABSTRACT FROM AUTHOR]

This paper presents the results of a laboratory investigation into the response of stone column–improved soft clay under dynamic traffic load conditions. Six reduced-scale model tests were performed with vertical traffic load composed of three consecutive stages: initial static load, cyclic load, and postcyclic load. The principal parameters were comprehensively investigated, such as loading frequency (1, 3, and 5 Hz), bearing stratum, and reinforcement conditions. The results show that dynamic settlement of a floating geosynthetic-encased stone column (F-ESC) increases rapidly with the increase in the time of cyclic loading at high loading frequency (5 Hz), accounting for 36.8% of total settlement. The geogrid encasement showed great benefits to the settlement improvement of stone columns under traffic loading. High-frequency traffic load generally decreased the bearing capacity and load transfer efficiency of F-ESC. Excess pore-water pressure (EPWP) is sensitive to the load frequency, and the value in F-ESC under the 5 Hz cyclic load is 1,420.5% larger than that under 1 Hz cyclic load. Rapid increase and accumulation of EPWP may cause significant foundation settlement at high loading frequency. The end-bearing geosynthetic-encased stone column shows a high strain increment ratio (up to 96.2%) under cyclic loads, which should be duly considered in the selection and design of reinforcement materials. [ABSTRACT FROM AUTHOR]

With only a few floating offshore wind turbine (FOWT) farms deployed anywhere in the world, FOWT technology is still in its infancy, building on a modicum of real‐world experience to advance the nascent industry. To support further development, engineers rely heavily on modeling tools to accurately portray the behavior of these complex systems under realistic environmental conditions. This reliance creates a need for verification and validation of such tools to improve reliability of load and dynamic response prediction and analysis capabilities of FOWT systems. The Offshore Code Comparison Collaboration, Continued with Correlation and unCertainty (OC6) project was created under the framework of the International Energy Agency to address this need and considers a three‐sided verification and validation between engineering level models, computational fluid dynamics (CFD), and experimental results. In this paper, a novel floating offshore wind platform, the Stiesdal TetraSpar, is simulated using CFD under the load conditions defined by Phase IV of the OC6 project. The comparison of these CFD results against the experimental results demonstrated the ability to predict the platform response to waves when imposing the measured wave signals as input. Although validation versus experiment was largely successful, the damping behavior was impacted by uncertainties likely originating from the mooring system and sensor umbilical cable. This extensive comparison effort with multiple CFD practitioners offers insight into best practices to achieve reliable results. [ABSTRACT FROM AUTHOR]

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To address the optimal scheduling of islanded microgrids under extreme operating conditions, this paper proposes a demand response (DR) economic optimization scheduling strategy based on model predictive control (MPC). The strategy improves the utilization of photovoltaic (PV) and energy storage systems while ensuring stable power supply to critical loads through a dynamic load shedding approach based on load priority and power system constraints. By incorporating time-of-use electricity pricing and load importance assessment, an innovative demand response incentive policy is designed to optimize consumer behavior and reduce grid load pressure. Experimental results demonstrate that the DR-MPC-based method reduces operating costs and increases renewable energy utilization compared to traditional methods. This approach is broadly applicable to pre-emptive load shedding and energy storage optimization in islanded microgrids during emergencies and is expected to be extended to the optimal scheduling of microgrid clusters in the future. [ABSTRACT FROM AUTHOR]

The mechanical response of the Ti-4.5Al-2.9V-3Fe alloy demonstrates a significant strain rate strengthening effect and strong ductility at high strain rates (3.0 × 103/s), contrary to the typical behavior of titanium and its alloys which exhibit a trade-off between these properties. Our recent studies have revealed that this unusual improvement can be attributed to a transformation in the plastic deformation mechanism, specifically from slip-dominating to twinning–slipping combination, under dynamic loading conditions compared to quasi-static loading conditions. Microstructure characterization before and after loading confirms this change in deformation mechanism. Furthermore, simulation predicts a dramatic adiabatic temperature rise in the necking region, which may contribute to strain softening effects observed experimentally. These findings provide valuable insights for manufacturing strategies and enhance our understanding of the mechanical behavior exhibited by titanium alloys. [ABSTRACT FROM AUTHOR]

Inspired by nature's self-similar designs, novel honeycomb-spiderweb based self-similar hybrid cellular structures are proposed here for efficient energy absorption in impact applications. The energy absorption is enhanced by optimizing the geometry and topology for a given mass. The proposed hybrid cellular structure is arrived after a thorough analysis of topologically enhanced self-similar structures. The optimized cell designs are rigorously tested considering dynamic loads involving crush and highvelocity bullet impact. Furthermore, the influence of thickness, radial connectivity, and order of patterning at the unit cell level are also investigated. The maximum crushing efficiency attained is found to be more than 95%, which is significantly higher than most existing traditional designs. Later on, the first and second-order hierarchical self-similar unit cell designs developed during crush analysis are used to prepare the cores for sandwich structures. Impact tests are performed on the developed sandwich structures using the standard 9-mm parabellum. The influence of multistaging on impact resistance is also investigated by maintaining a constant total thickness and mass of the sandwich structure. Moreover, in order to avoid layer-wise weak zones and hence, attain a uniform out-of-plane impact strength, off-setting the designs in each stage is proposed. The sandwich structures with first and second-order self-similar hybrid cores are observed to withstand impact velocities as high as 170 m/s and 270 m/s, respectively. [ABSTRACT FROM AUTHOR]