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Arc devices are among the receivers with the highest power connected to power systems. Due to dynamic load changes, these receivers generate a number of disturbances that affect the quality of electric power. The most important disturbances include voltage fluctuations. It is also worth mentioning the asymmetry and deformation of the supply voltage curve. This article discusses the mutual interaction of receivers operating in parallel, operating stably, and devices with dynamic current consumption. Calculations based on model tests and the results of parameters characterizing the quality of energy, which were recorded in the line supplying the steelworks, are presented. The power supply conditions (power of the short-circuit network) were assessed to influence the degree of suppression of voltage fluctuations by loads with stable current consumption. [ABSTRACT FROM AUTHOR]

In a multi-fed DC environment, the UHV DC recipient grid faces significant challenges related to DC phase shift failure and voltage instability due to the high AC/DC coupling strength and low system inertia level. While the new large-capacity synchronous condensers (SCs) can provide effective transient reactive power support, the associated investment and operation costs are high. Therefore, it is valuable to investigate the optimization of SC configuration at key nodes in the recipient grid in a scientific and rational manner. This study begins by qualitatively and quantitatively analyzing the dynamic characteristics of DC reactive power and induction motors under AC faults. The sub-transient and transient reactive power output model is established to describe the SC output characteristics, elucidating the coupling relationship between the SC's reactive power output and the DC reactive power demand at different time scales. Subsequently, a critical stabilized voltage index for dynamic loads is defined, and the SC's reactive power compensation target is quantitatively calculated across different time scales, revealing the impact of transient changes in DC reactive power on the transient voltage stability of the multi-fed DC environment with dynamic load integration. Finally, an optimal configuration model for the large-capacity SC is proposed under the critical stability constraint of dynamic loads to maximize the SC's reactive power support capability at the lowest economic cost. The proposed model is validated in a multi-fed DC area, demonstrating that the optimal configuration scheme effectively addresses issues related to DC phase shift failures and voltage instability resulting from AC bus voltage drops. [ABSTRACT FROM AUTHOR]

As part of the Ultra High Aspect Ratio Wing Advanced Research and Designs (U-HARWARD) project, funded by CS2JU, various gust load alleviation (GLA) technologies have been developed and studied. GLA plays a crucial role in the development of new generation ultra-high aspect ratio wings (UHARWs), as it reduces gust loads, thereby decreasing the structural weight of the wing and, consequently, the entire aircraft. This weight reduction enhances overall aircraft efficiency, enabling a higher aspect ratio. GLA technologies are categorized into passive systems, which require no active intervention, and active systems, where control surfaces redistribute the aerodynamic loads. In this study, passive GLA was implemented using a folding wing tip (FWT) developed by the University of Bristol, while active GLA employed a Static Output Feedback controller developed by Politecnico di Milano. Both approaches were compared against a baseline aircraft configuration. A flutter assessment confirmed that FWT does not introduce aeroelastic instabilities, ensuring the aircraft remains flutter-free across its flight envelope. A thorough comparison of load envelopes, based on nearly 2000 load cases across different flight points and mass configurations, was conducted in compliance with CS25 regulations, examining both positive and negative gust conditions. The results show a possible 15% reduction in the dynamic load envelope for both passive and active solutions. Using NeOPT, a hybrid finite element (FE) model was developed, with a detailed global FEM (GFEM) for the wingbox and stick elements for other components. Linear gust analyses in Nastran, with the hinge locked and released, provided high-fidelity results, comparing wing failure indexes and demonstrating the effectiveness of the FWT solution. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on the dynamic modeling of distribution power systems with a focus on the integration of renewable energy sources (RESs) for stability analysis. Our research delves into the static and dynamic behavior of distribution systems, emphasizing the need for enhanced load modeling to mitigate planning and operational uncertainties. Using MATLAB/Simulink®, we simulate four distinct study cases characterized by varying load types and levels of distributed generation (DG), particularly solar PV, under both balanced and unbalanced conditions. Our findings highlight the critical role of DG in influencing voltage stability, revealing that deviations in voltage and current during grid imbalances remain within acceptable limits. The study underscores the importance of DG-based inverters in maintaining grid stability through reactive power support and sets the stage for future research on microgrid simulations and battery storage integration to further enhance system stability and performance. [ABSTRACT FROM AUTHOR]

Saturated sand foundations are susceptible to liquefaction under dynamic loads. This can result in roadbed subsidence, flotation of underground structures, and other engineering failures. Compared with the traditional foundation reinforcement technology, enzyme-induced calcium carbonate precipitation technology (EICP) is a green environmental protection reinforcement technology. The EICP technology can use enzymes to induce calcium carbonate to cement soil particles and fill soil pores, thus effectively improving soil strength and inhibiting sand liquefaction damage. The study takes EICP-solidified standard sand as the research object and, through the dynamic triaxial test, analyzes the influence of different confining pressure (σ3) cementation times (CT), cyclic stress ratio (CSR), dry density (ρd), and vibration frequency (f) on dynamic strength characteristics. Then, a modified dynamic strength model of EICP-solidified standard sand was established. The results show that, under the same confining pressure, the required vibration number for failure decreases with the increase in dynamic strength, and the dynamic strength increases with the rise in dry density. At the same number of cyclic vibrations, the greater the confining pressure and cementation times, the greater the dynamic strength. When the cementation times are constant, the dynamic strength of EICP-solidified sand decreases with the increase in the vibration number. When cementation times are 6, the dynamic strength of the specimens with CSR of 0.35 is 25.9% and 32.4% higher than those with CSR of 0.25 and 0.30, respectively. The predicted results show that the model can predict the measured values well, which fully verifies the applicability of the model. The research results can provide a reference for liquefaction prevention in sand foundations. [ABSTRACT FROM AUTHOR]

The stress environments of gob-side roadways (GSRs) are becoming increasingly complex during deep coal mining under thick and hard roofs. This leads to strong strata behaviors, including roadway floor heave, roof subsidence, and even coal bursts. Among them, coal bursts pose the greatest threat to production safety in coal mines. Coal bursts in a GSR strongly correlate with the load characteristics and stress-energy evolution laws of the roadway. This study analyzes the roof structures of double working faces (DWFs) during the initial weighting stage (IWS) and full mining stage (FMS) of gob-side working faces (GSWFs). This study also explores how varying roof structures affect the stability of GSRs. Three-dimensional roof structure models of DWFs and mechanical models of dynamic and static loads superposition on a GSR throughout the IWS and FMS of a GSWF were developed. An analysis identified the primary stress sources affecting the GSR throughout various mining stages of the GSWF. Subsequently, the principle of "three-load" superposition was developed. A novel method was proposed to quantify the stress state in the GSR surrounding rock across different mining stages of the GSWF. The method quantitatively characterizes the load of the GSR surrounding rock. Based on this, the criterion for judging the burst failure of the roadway was established. Numerical simulations are used to analyze the stress-energy evolution laws of the working face, coal pillar, and GSR surrounding rock during the mining process of the GSWF. These findings offer valuable references for studying and preventing coal bursts in GSRs under equivalent geological situations. [ABSTRACT FROM AUTHOR]

Aiming at the problem of system controller performance failure caused by improperly setting the value of each weighting coefficient of the model predictive control (MPC), a fractional-order MPC strategy with Takagi–Sugeno fuzzy optimization (T–SFO MPC) is proposed for a vehicle active suspension system. Firstly, the fractional-order model predictive control framework for active suspension systems is designed based on a 1/4 vehicle model. Then, we analyze the influence of different weighting coefficients on the suspension performance and introduce the Takagi–Sugeno fuzzy optimization theory to adaptively adjust the weighting coefficients of the fractional-order MPC controller. Finally, the system responses of the T–SFO MPC, traditional MPC, linear quadratic regulator (LQR), and passive suspension control are numerically analyzed under various road conditions. Simulation results show that suspension response with the T–SFO MPC is significantly improved compared with passive suspension control, traditional MPC control, and LQR control, and the weight coefficients of the T–SFO MPC can be adaptively adjusted according to the dynamic changes of suspension response. Compared with passive suspension, the root mean square (RMS) value of the vertical acceleration of the T–SFO MPC under various roads decreased by a maximum of 37.97%, and the RMS value of suspension dynamic deflection and tire dynamic load decreased by a maximum of 32.94% and 37.8%, respectively. These results validate that the proposed control method can achieve coordinated optimization of vehicle comfort and handling stability. [ABSTRACT FROM AUTHOR]

Spacecraft recovery technology is crucial in the field of aerospace, in which the parachute plays a key role in slowing down the descent speed of the spacecraft and realizing a smooth landing. In order to construct a dynamically adjustable parachute deployment strategy, it is necessary to measure the parachute dynamic load accurately in real-time. However, the existing sensor measurement scheme makes it difficult to meet the measurement requirements due to its large structure and complex wiring. In order to meet the current demand for real-time measurement of parachute cords dynamic load, a miniature measuring instrument is designed. According to the function and technical requirements of the miniature measuring instrument, the hardware modules of the acquisition system are selected and designed, and the integration debugging and performance optimization of the microcontroller module, A/D sampling module, signal acquisition circuit, and power supply module are carried out. The software of the parachute cords tension acquisition system based on the miniature measuring instrument is developed. The Load Cell is modeled by using SolidWorks 2022 and statically analyzed by using Ansys 2022 R1 Workbench finite element analysis software. Then the final structure of the Load Cell and the pasting position of the strain gauge are determined through the results analysis as well as experimental verification. The hardware module of the signal acquisition system for the miniature measuring instrument is then encapsulated. The force value of the miniature measuring instrument is calibrated and tested many times by using the microcomputer-controlled electronic universal testing machine. The experimental results show that the designed miniature measuring instrument has accurate data, strong stability, and good real-time performance, which meets the demand for real-time accurate measurement of miniature measuring instruments, and can provide reliable data for parachute cords parameter validation and stepless unfolding design. [ABSTRACT FROM AUTHOR]

The curvic coupling, as one of the common connecting structures for gas turbine combined rotors, is more susceptible to various dynamic and static loads at extreme operating conditions. But, traditional combined rotor models tend to neglect the influence of the connection structure, especially failing to consider the contribution of the curvic coupling interfaces. To address this problem, this paper establishes a solid geometric model of the combined rotor with curvic couplings considering the rough three-dimensional interfaces. The effectiveness of the proposed model method is indirectly verified through the compression tests and modal tests. Subsequently, combined with finite element calculations, the mechanical properties of the rotor with curvic couplings considering the rough interface are analyzed under static and dynamic load conditions. The results indicate that the roughness of the interface significantly affects the deformation of the contact surface under static load, but its impact on the overall deformation of the rotor is relatively insignificant. The dynamic stress at the interface exhibits periodic variations at the resonance speed. At the maximum operating speed, the dynamic stress is influenced by the magnitude of imbalance. The aforementioned methods and conclusions provide a reference for the design research and engineering application of combined rotors. [ABSTRACT FROM AUTHOR]

Technological progress is leading to the incorporation of digital twinning and artificial intelligence, causing engineering design and scientific procedures to transition into an AI-driven age. Digital twinning and modeling have been increasingly included into engineering design optimization, particularly via processes like topology optimization and generative design, to provide modern design solutions efficiently. The integration of topology optimization with additive manufacturing is revolutionizing the design optimization process in the automotive industry, where there is a pressing demand for lightweight design and improving production efficiency. A design optimization methodology has been developed to optimize an Automotive Seatbelt Bracket subjected to dynamic load and fatigue. The innovative design is lighter and consolidates the entire assembly into a single body that can be manufactured using additive manufacturing. [ABSTRACT FROM AUTHOR]

This paper studies the effect of schistosity on the dynamic mechanical properties and failure pattern of thin-layered schist. Wudang Group schist with thin layers is selected as the research object, and the influence of the dynamic mechanical properties and failure pattern of schist under different angles and spacing is studied by combining an SHPB test and numerical simulation. The results indicate that under dynamic loading, the stress–strain curve demonstrates elastic compression, plastic deformation, and strain softening stages. Moreover, it is observed that the dynamic critical failure strength of schist exhibits typical "U"-type strength anisotropy. Specimens with a schistosity angle of 0° or 90° exhibit higher dynamic compressive strength under dynamic loading, with axial splitting and schistosity splitting as predominant failure modes. Conversely, when the schistosity angles are 30°, 45° or 60°, there is a noticeable decrease in compressive strength accompanied predominantly by shear failure along with local compressive shear failure. We additionally noted that as the spacing between schists decreases from 22 mm to 7 mm, there is a gradual reduction in dynamic compressive strength by approximately 20.3%. [ABSTRACT FROM AUTHOR]

Shipping impact and wave loads impose dynamic loads on jetties and platforms in the sea, which cause the vibration of structures. Recently, many advanced viscous damper devices have been developed for implementation in structures to diminish structural vibration due to earthquakes or wind. However, the longitudinal configuration of conventional viscous damper devices requires adequate space to locate the damper device within the frame structure, which limits the application of viscous dampers for use in jetties or platforms to dissipate the vibrations imposed by ship impact or wave force. For this reason, in this study, an attempt has been made to develop a new viscous plane damper device applicable in limited space positions where the longitudinal damper device is not able to fit. For this purpose, the initial design for the viscous plane damper device is proposed, and the prototype of the device is manufactured. Then, the performance of the fabricated viscous plane damper is examined through experimental tests by applying cyclic loads using a dynamic actuator. In order to investigate the effect of the diameter and configuration of the piston's orifices, five different diameters for the orifices of 1, 2, 5, 8, and 10 mm are included, and three different distribution configurations of the orifices in the piston plate as Configurations A, B, and C are manufactured and tested experimentally. The lab testing is conducted by applying cyclic loads with different frequencies to evaluate the performance of the developed plane damper device under various load velocities. Accordingly, the dynamic performance of the damper device, including the damping force, effective damping and stiffness and the energy dissipation capacity obtained from the hysteresis response (force–displacement result), is investigated. The results of the experimental tests prove the functionality of the developed device to generate the desired damping force and vibration energy dissipation during applied cyclic loads. Therefore, the new plane damper device can be implemented in any structure to dissipate the effect of imposed vibration. [ABSTRACT FROM AUTHOR]

To investigate the applicability and differences in wave loads and the dynamic response calculation principles for SFT on an entire-length scale, two numerical models of entire-length SFT with identical dimensions and parameters were established. These models are employed by a 3D diffraction method based on rigid-body assumptions, the potential flow theory and the Dummy-Connection-Mass (DCM) method based on the lumped mass method and Morison equation while considering hydroelasticity effects. The applicability of the potential flow theory and Morison equation for wave load calculation of SFT is presented along with the differences in their dynamic response calculation, which aim to explore the impact on SFT dynamic responses considering hydroelasticity by comparing the numerical calculation results. Furthermore, a comparison between free-end boundary and fixed-end boundary models, established using the DCM method, is conducted to examine the reasonableness of the commonly adopted free-end boundary condition. [ABSTRACT FROM AUTHOR]

Pier structures in port and fishing harbor facilities require dynamic analyses during the design phase to account for external dynamic forces because of their high flexibility. Dynamic forces are frequently approximated as equivalent static forces for design purposes in practical engineering applications, but the fluctuational effects induced by these dynamic forces can be neglected. As the frequency range of wave forces acting on pier structures (0.05–1.0 Hz) significantly overlaps with the typical natural frequency range of pier structures (0.25–4.0 Hz), the response of a pier structure can be amplified because of the dynamic effects of the waves. In this study, we conducted a dynamic analysis by applying wave forces—a representative dynamic load—to a pier structure. The results were compared with those from a static analysis. A fatigue life assessment, which is often overlooked in static analyses, was also performed. The findings indicated that the concrete at the connection between the upper pier and steel piles exhibited a fatigue life of 27.3 years. The steel piles exhibited fatigue lives of 27.1 and 8.3 years depending on the weld details, falling short of the expected structural durability. Based on these results, recommendations for pier structures are proposed. [ABSTRACT FROM AUTHOR]

Historical seismic events have repeatedly highlighted the susceptibility of above-ground liquid storage steel tanks, underscoring the critical need for their proper design to minimize potential damage due to seismic forces. A significant failure mechanism in these structures, which play essential roles in the extraction and distribution of various raw or refined materials—many of which are flammable or environmentally hazardous—is the dynamic buckling of the tank walls. This study introduces a numerical framework designed to assess the earthquake-induced hydrodynamic pressures exerted on the walls of cylindrical steel tanks. These pressures result from the inertial forces generated during seismic activity. The computational framework incorporates material and geometric nonlinearities and models the tanks using four-node shell elements with two-point integration, specifically Belytschko shell elements. The Arbitrary Lagrangian–Eulerian (ALE) method is employed to accommodate substantial structural and fluid deformations, enabling a full simulation of fluid–structure interaction through highly nonlinear algorithms. Experimental test data are utilized to validate the proposed modeling approach, particularly in replicating sloshing phenomena and identifying stress concentrations that may lead to wall buckling. The study further presents results from a parametric analysis that varies the height-to-radius and radius-to-thickness ratios of a typical anchored flat-bottomed tank, examining the seismic performance of this common storage system. These results provide insights into the relationship between tank properties and mechanical behavior under dynamic loading conditions. [ABSTRACT FROM AUTHOR]

This research aims to develop principles for assessing the impact of mega-cyclic vibrodynamic loads on the reliability of construction structures. The relevance of the reasons for the development and improvement of algorithms for numerical modeling of multicycle dynamic loads on building structures is due to the steadily increasing intensity of such loads on buildings and structures in megacities, as well as the acute practical problem of significant differences in the dynamic characteristics of buildings and structures obtained as a result of mathematical modeling and determined by experimental methods. The article presents research materials on computational equivalent models of dynamic load sources for numerical modeling of the behavior of construction structures under their influence, using the method of vibroacoustic analogies. The article examines models of sources of dynamic impact on construction sites. Algorithms and final formulas for computational modeling of the simplest sources of dynamic load are developed using the method of vibroacoustic analogies. The dynamic properties of the simplest dynamic load sources were analyzed. A significant difference between the computational models of real and ideal dynamic load sources. The article presents research and development results intended for calculating the distribution of dynamic loads on elements of construction structures in industrial and civil engineering projects located in areas with high levels of transport vibrodynamic impacts. An important property of the proposed computational equivalent models of sources of dynamic impact on building structures is the possibility of computational verification of critical elements, points, or nodes of load-bearing structures of buildings and structures under dynamic overloads. The position of these critical elements, points, and nodes of load-bearing structures under dynamic loads can differ significantly from their position determined using static and quasistatic computational modeling methods. [ABSTRACT FROM AUTHOR]

To address the issues of high computational load and slow dynamic performance in traditional fractional-order sliding mode control for LCL-type grid-connected inverters, this paper proposes a fixed-time robust fractional-order sliding mode control strategy based on weighted average current control. Firstly, the weighted average current control (WACC) is used to reduce the third-order LCL filter to the first order, which simplifies the system model; secondly, in order to suppress the disturbance caused by the filter parameter perturbation to the weighted average current accuracy, a fixed-time disturbance observer (FTDO) is used to quickly estimate the disturbance caused by the filter parameter perturbation in a fixed time, so as to improve the anti-interference ability of the system; moreover, a fixed-time fractional-order sliding mode controller (FTFOSMC) is designed to achieve rapid tracking of the incoming reference current, and the stability of the proposed control strategy is confirmed by the strict Lyapunov method, which proves that the upper bound of the stability time is independent of the initial state of the system. Finally, simulation and experimental results show that the proposed method has better steady-state performance and a higher dynamic performance. [ABSTRACT FROM AUTHOR]

It is imperative to conduct experimental studies on the seepage behavior of gas-bearing coal under cyclic dynamic loading conditions. This paper focuses on the evolution of coal permeability under the combined effects of dynamic loading, static loading, and gas adsorption. The principal conclusions are as follows: (1) As the frequency and amplitude of dynamic loading increase, the development of pore and fissure structures within the coal body becomes increasingly pronounced during dynamic loading cycles, resulting in a gradual rise in permeability. Notably, as the coal approaches its yielding stage, the permeability can increase by up to 47%. (2) The permeability curve is divided into four regions: the compaction reduction zone, the oscillation zone, the gradual recovery zone, and the abrupt failure increase zone. Ultimately, in the failure phase, the permeability surges dramatically, potentially reaching four to five times the initial permeability. (3) When the static loading stage and dynamic load are constant, the rate of change in coal permeability decreases with increasing adsorption amounts. When the adsorption amount is constant, the rate of change in permeability of the coal under dynamic loading increases with the increase in the static loading stress stage, with the maximum increase reaching 75.2%. It can be concluded from the rate of change in permeability and the dynamic loading sensitivity coefficient that the permeability of coal is highly sensitive to cyclic dynamic loading, with increased sensitivity associated with larger static loading stages and decreased sensitivity with greater adsorption amounts. [ABSTRACT FROM AUTHOR]

Discarded rubber tires (DSRTs) have become a significant landfill and environmental problem that needs to be solved to reduce health risks, fires, and other environmental issues. The inclusion of such rubber can enhance the ductility of concrete and increase its resistance to dynamic loads, as well as enhancing the concrete's durability and lifespan by modifying its impact resistance (IR). However, the smooth surface and low bond strength with cement pastes directly lead to a decrease in the strength of the proposed concrete, restricting its range of use in the construction industry. The inclusion of pozzolanic materials with high hydraulic capacity in the concrete matrix as partial cement replacements, such as granulated blast furnace slag (GBFS), has led to enhanced performance of the modified rubberized concretes (MRCs) in terms of bond strength and other mechanical properties. Based on these facts, this study aimed to evaluate the effects of including 20% GBFS and various levels (5–25%) of metakaolin (MK) as replacements for ordinary Portland cement (OPC), on the engineering properties of newly designed rubberized concretes. For this purpose, twenty-two mixes of MRCs were prepared by replacing the OPC and natural aggregates with various contents of GBFS, MK, and DSRTs. The results indicated that the MRC specimens prepared with a ternary blend of OPC-GBFS-MK illustrated significant improvements in strength performance, wherein the compressive strength (CS) after the curing age of 56 days (46.5 MPa) was higher than that of the OPC control mix (41.2 MPa). Moreover, the mix designed with high amounts of MK-GBFS-DSRTs significantly enhanced the engineering properties of the proposed MRCs by increasing the IR and reducing the total porosity. It can be asserted that, by using MK, GBFS, and DSRTs as renewable resources for construction materials, the environmental problems can significantly be reduced, with excellent benefits in the engineering properties of the designed rubberized concretes. [ABSTRACT FROM AUTHOR]

The fractal theory can effectively describe the complexity and multi-scale of concrete under impact load and provide a scientific basis for evaluating concrete's impact resistance. Therefore, based on the fractal theory, this study carried out the fragmentation size analysis by weighing the quality of SFRRAC fragments, disclosed the distribution characteristics of impact fragmentation size of steel fiber reinforced recycled aggregate concrete (SFRRAC) specimens under different recycled coarse aggregate (RCA) replacement ratio, different steel fiber (SF) contents and different impact pressures. The results indicate that the fractal dimension can describe the degree of fragmentation of the specimen. The greater the fractal dimension, the more the amount of fragmentation of the specimen subjected to impact load, the lesser the fragmentation size, and the greater the degree of fragmentation. Under the impact load, the fractal dimension of SFRRAC is between 1.36 and 2.28. As the impact pressure increases, the energy consumption increases, and the fractal dimension decreases. With the growth in replacement ratio, the fractal dimension gradually increases, and the energy consumption is negatively correlated with the fractal dimension. Along with the growth of SF content, the energy consumption gradually increases, and the fractal dimension continuously decreases. A new metric angle is provided to explore the inherent law between the impact-crushing characteristics of SFRRAC and the dynamic load, thereby offering foundational support for the application of SFRRAC in practical engineering. [ABSTRACT FROM AUTHOR]

Induction motors are the most common type of motor in power systems, constituting approximately 70–90% of the dynamic loads, making them significant contributors to system dynamics. In transient voltage stability analysis, dynamic equivalent models are commonly used to simplify the representation of a group of induction motors. This paper presents a method for the grouping and aggregation of induction motors at a common bus. Firstly, grouping rules are provided for clustering induction motors into several subgroups based on the mechanical principles of rotor force and motion, and aggregation rules are provided for aggregating a motor subgroup into a single-unit model based on the relationship between voltage drop and power transmission in distribution networks. Secondly, guided by the grouping rules, high-speed remaining electromagnetic torque and low-speed remaining electromagnetic torque are defined as new clustering indicators, and an adaptive K-means clustering method using silhouette coefficient verification is introduced to obtain the optimal motor subgroups. Thirdly, guided by the aggregation rules, a dynamic equivalent method is further introduced to obtain the equivalent single-unit model from a motor subgroup. Lastly, a transient voltage stability simulation in a typical distribution network is presented to illustrate that the proposed clustering and equivalent methods are more reasonable, accurate, and effective than traditional methods, as the obtained model has better dynamic characteristics and can more accurately reproduce the process of voltage collapse. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive analysis of the electric-drive-wheel (EDW) with idler gear. From the perspective of automotive engineering, the EDW is an integrated execution unit that combines the function of powertrain and suspension. As a result, the research on EDW involves the intersection of multiple disciplines. The evolution of idler gear configuration requires some geometric constraints. Under this premise, the longitudinal and vertical dynamic characteristics of the system were studied, respectively. There are several factors that influence the system performance, such as the gear parameters, the position of the electric motor, and the suspension K&C value. The principles of each parameter on the output indicators were studied, with an optimized plan and simulation comparison to check the correctness of theory. In the end, the prototype was equipped with a test bench, covering a wide range of working operations to examine the expected performance of EDW design. The step response test of the EDW result showed a balanced performance in transmission smoothness and responsiveness agility. [ABSTRACT FROM AUTHOR]

This article presents the methodology and process of the modeling, designing, and testing of a research station enabling the identification, tuning, and verification of Digital Twin (DT) in control systems in power hydraulics. The concept of the station is presented, the main part of which is a subsystem forcing a dynamic, variable load using a hydraulic actuator controlled by a proportional valve, together with data acquisition and processing systems and software. The load application subsystem can subject the tested power hydraulic system, usually consisting of an actuator with its own control system, to controlled dynamic loads, which allows for the determination of its characteristics and tuning of the DT. This article describes the electro-hydraulic elements used to adjust the position of the actuators and the designed hydraulic and electrical diagrams of the station. The process of identifying, modeling, and selecting a controller for a subsystem simulating an external load is presented. The test station is built and tested. The identification, modeling, and tuning of DTs, for example, actuators and controllers, are described. A satisfactory convergence of the simulation and modeling results with the operation of the real system is achieved, which allows the obtaining of a reliable DT for actuator control systems operating under variable load. [ABSTRACT FROM AUTHOR]

Dynamic load forecasting is essential for effective energy management and grid operation. The use of GRU (Gated Recurrent Unit) and Long Short-Term Memory (LSTM) networks for precise load prediction is investigated in this paper. This research examines dynamic load patterns by innovatively integrating heterogeneous information from several datasets. The results show that the LSTM and GRU models are equally good at making predictions and that this holds true across a variety of datasets. Furthermore, the models' ability to accurately capture the temporal relationships in the load data is demonstrated by their low Mean Absolute Percentage Error (MAPE) and Mean Squared Error (MSE) values. Additionally, the comparative analysis results, which highlight flexibility in model selection, can aid energy sector decision makers. The significance of precise load projections for maintaining grid dependability and optimizing resources is further highlighted by this work, which also elucidates the effects of forecast inaccuracies on decision-making procedures. Our research study provides important information for power system management strategy planning, which in turn promotes the continuous innovation of smart grids in dynamic load forecasting to keep up with changing energy consumption patterns. [ABSTRACT FROM AUTHOR]

This study investigates bidirectionally sinusoidal corrugated steel shells using finite element analysis (FEA) software, primarily ABAQUS 2017, supplemented by RFEM 6.05 for an initial result comparison. The research aims to establish a robust numerical solution to understand the structural behaviour of these shells under static and dynamic loading. Starting with meticulous calculations for a selected structural element, the paper emphasises a comparative analysis between ABAQUS and RFEM, offering valuable insights into simulating the responses of corrugated steel shells. A distinctive contribution of this research lies in its novel and comprehensive parametric analysis of these shells under static and dynamic loading, an area that has not been explored in previous studies. The study systematically explores various model parameters, including geometrical and mechanical properties, with detailed analyses revealing their influences on deformation, stress distribution, dynamic properties, and behaviour. Another key feature is the development of a coded script that systematically generates diverse numerical models, allowing for a thorough exploration of the structural system's response. This study advances our understanding of the structural behaviour of bidirectionally sinusoidal corrugated steel shells. These findings are set to enhance structural analysis and design practices by optimising parameters for improved performances in various engineering applications. [ABSTRACT FROM AUTHOR]

The behaviour of a structural component, such as the spreader installed on an aeroplane passenger seat made of the magnesium alloy Elektron® 43, is evaluated under a variety of load conditions. The purpose of this research project is to considerably reduce weight by employing the new alloy while keeping the strength and ductility necessary to meet the dynamic standards for both the 16 g forward and 14 g downward tests. A comprehensive campaign of static and dynamic testing on coupons was conducted to characterise the mechanical behaviour of the E43 magnesium alloy, from quasi-static to dynamic loading, and across a wide range of deformation rates. The elastic–plastic and strain rate sensitive material model of E43 is then calibrated using an FEA approach and LS-DYNA software, utilising stress–strain curves and properties determined from standardised experimental tensile and compression trials at varied strain rates. Finally, this material model was used to perform a finite element structural study of a major component of an aeroplane seat built using Elektron® 43 under typical in-flight stresses. [ABSTRACT FROM AUTHOR]

The vehicle load on a bridge is a critical and dynamic variable. It adversely affects bridges, especially when overloading occurs. Bridges are prone to fatigue damage or collapse. Therefore, identifying the size and type of dynamic vehicle loads on bridges is critical for theoretical studies and practical applications, such as health monitoring, daily maintenance, safety assessment, and traffic planning. The paper proposes a method for identifying the dynamic load parameters based on a convolutional neural network (CNN) and dynamic strain data. The model is implemented in MATLAB. An initial finite-element model of a three-span precast beam bridge is established in the software ABAQUS and modified by combining the modal and experimental data derived from a segmental girder bridge. The dynamic strain response of the bridge under a moving vehicle load is simulated under different working conditions. The results are used as the training data of the CNN to identify the vehicle's position, speed, and load on the bridge. The high prediction accuracy indicates the proposed model's suitability for identifying the dynamic load parameters. [ABSTRACT FROM AUTHOR]

This article proposes the use of a three-phase induction generator (IG), connected through a single-phase connection (Fukami configuration), to be used as a rotating exciter for synchronous generators. This proposal aims at presenting an alternative to replace the permanent magnet generators (PMGs) used in the rotating exciters for synchronous generators (SGs). In order to obtain the results, a six-pole IG and a four-pole SG were used, a DC motor (DCM) was employed as the primary machine, and the speed control for the aforementioned primary machine is presented and described in this work. To carry out performance tests of the rotating exciter with the IG and the terminal voltage control of the SG, a voltage controller was proposed. The performance of the voltage regulator was tested when the SG supplied a dynamic load, as established by the NEMA MG-1 standard. This article validates its proposal by comparing the results obtained through computational simulation and experimental testing of the SG terminal voltage waveform when faced with a sudden load change. [ABSTRACT FROM AUTHOR]

The unique combination of the high data rates, ultra-low latency, and massive machine communication capability of 5G networks has facilitated the development of a diverse range of applications distinguished by varying connectivity needs. This has led to a surge in data traffic, driven by the ever-increasing number of connected devices, which poses challenges to the load distribution among the network cells and minimizes the wireless network performance. In this context, maintaining network balance during congestion periods necessitates effective interaction between various network components. This study emphasizes the crucial role that mobility management plays in mitigating the uneven load distribution across cells. This distribution is a significant factor impacting network performance, and effectively managing it is essential for ensuring optimal network performance in 5G and future networks. The study investigated the complexities associated with congested cells in wireless networks to address this challenge. It proposes a Dynamic Distance-based Load-Balancing (DDLB) algorithm designed to facilitate efficient traffic distribution among contiguous cells and utilize available resources more efficiently. The algorithm reacts with congested cells and redistributes traffic to its neighboring cells based on specific network conditions. As a result, it alleviates congestion and enhances overall network performance. The results demonstrate that the DDLB algorithm significantly improves key metrics, including load distribution and rates of handover and radio link failure, handover ping-pong, and failed attached requests. [ABSTRACT FROM AUTHOR]

A flexible telescopic boom is a multi-body system composed of several hollow booms nestled into each other. For this kind of system, due to the limitation of the elemental size being fixed, it is necessary to divide it into many small-sized elements and judge which two elements are in a contact state in real time using the traditional finite element methods. This complex operation often requires calculations on enormous scales and can even result in simulation failure. In view of the above difficulties, an efficient dynamic contact analysis model of flexible telescopic boom systems with a moving boundary is proposed in this study. Firstly, on the deformable axis of the boom, some crucial points are defined as inner and outer contact points, and spatial points are selected as nodes for describing the motion of the system. Secondly, in contrast to the traditional solid finite element method, the assumption that elemental nodes are fixed with the material points is removed, and on this basis, a geometrical nonlinear dynamic element with moving nodes is constructed, which can describe the moving boundary problem effectively and is used to model each boom. Thirdly, to better cooperate with the moving boundary conditions, a contact model and its corresponding discretization method are developed on the premise of not removing the sliding joint constraints, which are used for dynamic contact analysis considering the friction effect between adjacent booms. Finally, experiments were conducted to evaluate the accuracy of the modeling, wherein the dynamic response properties of the supported beam under the action of a moving load and the dynamic behavior of the telescopic boom being extracted were analyzed. [ABSTRACT FROM AUTHOR]

Carbon-fiber-reinforced polyetheretherketone (CF/PEEK) composites are widely utilized in aerospace, medical devices, and automotive industries, renowned for their superior mechanical properties and high-temperature resistance. Despite these advantages, the thermomechanical coupling behavior of CF/PEEK under dynamic loading conditions is not well understood. This study aims to explore the thermomechanical coupling effects of CF/PEEK at elevated strain rates, employing Hopkinson bar impact tests and scanning electron microscopy (SEM) for detailed characterization. Our findings indicate that an increase in temperature led to significant reductions in the yield strength, peak stress, and specific energy absorption of CF/PEEK, while fracture strain had no significant effect. For instance, at 200 °C, the yield strength, peak stress, and specific energy absorption decreased by 39%, 37%, and 38%, respectively, compared to their values at 20 °C. Furthermore, as the strain rate increased, the yield strength, peak stress, specific energy absorption, and fracture strain all exhibited strain-hardening effects. However, as the strain rate further increased, above 4000 s−1, the enhancing effect of the strain rate on the yield strength and peak stress gradually diminished. The interaction of the temperature and strain rate significantly affected the mechanical performance of CF/PEEK under high-speed impact conditions. While the strain rate generally enhanced these properties, the strain-hardening effect on the yield strength weakened as the temperature increased, and both the temperature and strain rate contributed to the increase in specific energy absorption. Microdamage mechanism analysis revealed that interface debonding and sliding between the fibers and the matrix were more pronounced under static compression than under dynamic compression, thereby diminishing the efficiency of stress transfer. Additionally, higher temperatures caused the PEEK matrix to soften and exhibit increased viscoelastic behavior, which in turn affected the material's toughness and the mechanisms of stress transfer. These insights hold substantial engineering significance, particularly for the optimization of CF/PEEK composite design and applications in extreme environments. [ABSTRACT FROM AUTHOR]

In this paper, a new linear-based closed-loop control method for a Solid-State Transformer (SST) has been proposed. In this new control method, individual current and voltage loops for each of the power conversion stages (AC-DC, DC-DC, DC-AC) are implemented. The feedback between the input and output control signals for each loop is achieved through the voltage on the DC link capacitors and the current transferred between the converters. This enables the SST to be controlled easily in a linear-based closed-loop manner without the need for complex computations. In order to evaluate the performance analysis of the proposed control system, a simulation of an SST with approximately 10 kVA apparent power was performed. Based on the obtained simulation results, the response time of the proposed control method for dynamic load variations was proved to be in the range of 40 milliseconds, and it has been observed that this method allows electrical power to be transferred from the load to the grid. The power factor value of SST under inductive load is measured to be approximately 99%, and the overall system efficiency is 96% and above, indicating that this proposed new control method has very high performance. [ABSTRACT FROM AUTHOR]

In order to solve the problem of large dynamic load and low loading accuracy prevailing in traditional fatigue testing machines, and to meet the fatigue test loading demand of alternating small-load microelectromechanical devices and bionic devices, a high-frequency resonant piezoelectric fatigue tester that can apply alternating small loads in the range of 0.1 N~100 N was designed and manufactured, with a piezoelectric oscillator as the driving source of the system. Firstly, the structure of this fatigue testing machine is designed, and a dynamic model is established for the fatigue testing machine to theoretically study the influence of the system mass and stiffness on the change in the resonance frequency of the fatigue testing machine. Then, numerical calculations and experiments are carried out to verify the effect of system mass and stiffness changes on the intrinsic frequency of the fatigue testing machine. Finally, the fatigue testing machine was used to carry out fatigue test on the dog-bone-shaped specimens, and the failure process of specimen fatigue was verified by analysing the load applied to the specimen by the fatigue testing machine, and at the same time, it was proved that the performance of the present fatigue testing machine complied with the requirements. It provides a new technical means to meet the fatigue test loading demand of small-load electromechanical devices and bionic devices. [ABSTRACT FROM AUTHOR]

Estimating line impedance is relevant in transmission and distribution networks, in particular for planning and control. The large number of deployed PMUs has fostered the use of passive indirect methods based on network model identification. Electrified railways are a particular example of a distribution network, with moving highly dynamic loads, that would benefit from line impedance information for energy efficiency and optimization purposes, but for which many of the methods used in industrial applications cannot be directly applied. The estimate is carried out onboard using a passive method in a single-point perspective, suitable for implementation with energy metering onboard equipment. A comparison of two methods is carried out based on the non-linear least mean squares (LMS) optimization of an over-determined system of equations and on the auto- and cross-spectra of the pantograph voltage and current. The methods are checked preliminarily with a simulated synthetic network, showing good accuracy, within 5%. They are then applied to measured data over a 20 min run over the Swiss  16.7  Hz railway network. Both methods are suitable to track network impedance in real time during the train journey; but with suitable checks on the significance of the pantograph current and on the values of the coefficient of determination, the LMS method seems more reliable with predictable behavior. [ABSTRACT FROM AUTHOR]

Dual–motor drive is commonly used in heavy–duty robotic joint servo systems. However, the backlash inevitably affects joint accuracy. In this article, a variable bias torque control method is proposed for a dual–motor–driven robotic joint. The variable bias torque varies directly according to the motor current, and the conversion method of the bias compensation torque is presented. A simulation model of the dual–motor drive system in MATLAB/Simulink is established based on the dynamic modeling of a dual–motor drive system, and a robotic joint prototype is also established. The variable bias torque control can achieve a reasonable distribution of the output torque for the whole servo cycle and can effectively reduce the energy consumption of the system to maintain static backlash elimination; the dynamic loading of the bias voltage can be achieved through the setting of the conversion function to complete the smooth transition between the two states of backlash elimination control and common drive control; the dynamic loading of the bias torque improves the torque output capability of the dual–motor system. In the experiment, the steady–state error of the servo system is less than 0.05°, and the error is much smaller than the internal backlash angle (about 2°) of the system, which indicates that the internal backlash of the robot joint has been eliminated. The static backlash elimination bias current of the joint is reduced from about 250 mA to about 110 mA, reducing the energy consumption of the servo system effectively. [ABSTRACT FROM AUTHOR]

In milling processes in which material removal is performed periodically from solid material, dynamic effects are generally considered to be responsible for instabilities and subsequent productivity limits. Usually, in such applications, the process-inherent complex dynamic load spectrum on machines, tools and workpieces is considered together with vibration-based relative displacements that can be attributed to the regenerative effect. There are numerous techniques in the literature addressing the suppression of these dynamic effects, but they require a large amount of analysis and implementation effort as well as specific expert knowledge. The approach presented here, however, provides a universally applicable method for suppressing chatter vibrations and deflections. By applying structure elements to the flanks of the minor cutting edges of HSS end mills, it was possible to increase the chatter-free limiting depth of cut ap,crit in the milling processes of the aluminum alloy EN AW-7075. Structured tools were used in ramp milling tests to investigate various effects, such as the influence of certain geometric design features on the stabilization potential compared to a reference tool. Furthermore, the effects of varied process parameter configurations and wear-related effects on the performance of the tool concept were focused on as well. The three key design features of the cutting edge and the structured profiles were identified from the results of the investigation, which, when combined in the most efficient design, in each case led to the development of an optimized structure and process configuration with cumulative potential for increasing the stability limit up to 200%. [ABSTRACT FROM AUTHOR]

Adequate vertical track support is essential for safe and efficient railway operations. Insufficient support leads to distorted track geometry, increased dynamic loads, component stress, poor ride quality, rolling stock damage, and derailment risks. Current inspection practices focus on assessing the condition of the track components and geometry, rather than the root causes of degradation. To improve this condition, this study presents the use of a methodology that utilizes an autonomous vertical track deflection measurement system mounted on a loaded rail car (36 tonnes/axle) to support track maintenance decisions in a heavy haul railroad located in southeast Brazil. The system continuously measured substructure stiffness along the railway line. Over one year, data were collected from over 8000 km of track. The study highlighted seasonal effects on track degradation over time, identifying areas with significant deflections and high deflection rates, which contribute to issues such as differential settlement and reduced lifespan of track components. Additionally, the study revealed seasonal effects, with deflections peaking during wet weather and decreasing during dry cycles. A method to classify weak track areas was developed, facilitating monitoring and enabling more effective maintenance planning, contributing to the reduction of overall track maintenance costs and enhancing safety and operational efficiency. [ABSTRACT FROM AUTHOR]

To address the frequent occurrence of rock burst disasters in areas with wide coal pillars during mining in the western mining area of China, the wide coal pillar area of the Tingnan coal mine in Shanxi Province was used as the research background. Theoretical analysis, numerical simulation, and field tests were used to establish the mechanical criterion and the energy criterion for the dynamic instability of wide coal pillars. The process and mechanism of wide coal pillar dynamic instability under dynamic and static load disturbances were revealed, and a wide coal pillar rock burst prevention and control scheme was proposed. The results indicated that when the load above a coal pillar reached the stress failure index and the energy failure index was met, the coal pillar reached the critical conditions for rock burst. With increasing static load, the stress, energy, and range of the plastic zone all showed increasing trends on both sides of the coal pillar. Under a given dynamic load, the stress and plastic zone range of the coal pillar significantly increased compared to those without a dynamic load. Under a given static load, the greater the dynamic load, the more likely the coal pillar was to undergo dynamic instability. The evolution of coal pillar dynamic instability was divided into three stages: energy accumulation, local instability, and dynamic instability. When the critical stress and energy conditions for coal pillar dynamic instability are exceeded, rock burst will occur. To reduce the static and dynamic loads of coal pillars, a rock burst prevention and control scheme of energy release and load reduction was proposed and applied onsite. The monitoring results showed that this control plan effectively reduced the stress of the coal pillar and the dynamic load generated by the fracture of the overlying rock layer, indicating safe mining in this area of wide coal pillars. [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]

In construction projects, conducting dynamic load tests on all piles proves impractical. Selective testing estimates bearing capacity, while the remaining piles rely on penetration depth for management. This approach, however, faces reliability issues due to varying conditions among piles. Technological advancements, such as non-contact hammers and sensors, have enhanced the accuracy of penetration depth measurements during final driving. Nonetheless, relying solely on penetration depth for construction and quality management remains problematic. This study, therefore, focuses on enhancing the use of driving formulas to improve pile quality management, particularly for the widely used pre-stressed high-strength concrete (PHC) piles. To improve pile quality management, existing driving formulas underwent review and refinement. Utilizing 258 dynamic load test data from various sites, the Hiley, Gates, and Danish formulas underwent validation through statistical analysis and graphical comparison. Enhancements to the Gates formula, achieved through curve fitting with actual data and the application of segment-based coefficients, demonstrated increased accuracy in bearing capacity estimation. These improvements offer a more reliable approach to pile quality management in construction projects. [ABSTRACT FROM AUTHOR]

This paper investigates the secondary control problem of shipboard microgrids (SMGs) with a high percentage of new energy sources under general noise. Firstly, a polymorphic SMG model is constructed, which enables the software-defined functionality of the control strategy and allows heterogeneous distributed generators (DGs) in AC SMGs to exchange packets of different types. Secondly, due to the presence of highly dynamic and high-power loads in the SMGs, a containment-based distributed secondary control strategy is proposed to improve the flexibility of the DG voltage regulation. Then, considering the complexity and diversity of disturbances during ship navigation, general noise is introduced instead of white noise to describe various disturbances. Furthermore, based on the random differential equations (RDEs), the NOS stability of the proposed strategy is proved using Lyapunov theory, which proves the effectiveness of the containment-based distributed secondary control strategy under general noise. And, the containment error is obtained to prove that the voltage and frequency of the system converge to the convex hull spanned by the virtual leaders, ensuring the high quality of the power supply. Finally, the validity of the proposed containment-based strategy is verified by an AC SMG model with four DGs in three cases. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of long, large-diameter bored piles' behavior under static and dynamic load tests for a megaproject located in El Alamein, on the northern shoreline of Egypt. Site investigations depict an abundance of limestone fragments and weak argillaceous limestone interlaid with gravelly, silty sands and silty, gravelly clay layers. These layers are classified as intermediate geomaterials, IGMs, and soil layers. The project consists of high-rise buildings founded on long bored piles of 1200 mm and 800 mm in diameter. Forty-four (44) static and dynamic compression load tests were performed in this study. During the pile testing, it was recognized that the pile load–settlement behavior is very conservative. Settlement did not exceed 1.6% of the pile diameter at twice the design load. This indicates that the available design manual does not provide reasonable parameters for IGM layers. The study was performed to investigate the efficiency of different approaches for determining the design load of bored piles in IGMs. These approaches are statistical, predictions from static pile load tests, numerical, and dynamic wave analysis via a case pile wave analysis program, CAPWAP, a method that calculates friction stresses along the pile shaft. The predicted ultimate capacities range from 5.5 to 10.0 times the pile design capacity. Settlement analysis indicates that the large-diameter pile behaves as a friction pile. The dynamic pile load test results were calibrated relative to the static pile load test. The dynamic load test could be used to validate the pile capacity. Settlement from the dynamic load test has been shown to be about 25% higher than that from the static load test. This can be attributed to the possible development of high pore water pressure in cohesive IGMs. The case study analysis and the parametric study indicate that AASHTO LRFD is conservative in estimating skin friction, tip, and load test resistance factors in IGMs. A new load–settlement response equation for 600 mm to 2000 mm diameter piles and new recommendations for resistance factors φ qp, φ qs, and φ load were proposed to be 0.65, 0.70, and 0.80, respectively. [ABSTRACT FROM AUTHOR]

This study aims to investigate the behaviour of reinforced concrete (RC) beams strengthened by Carbon Fibre-Reinforced Polymer (CFRP) under static and impact loads. A series of RC beams were tested and categorized into four groups, namely, unstrengthened RC beams (B1), RC beams strengthened with a CFRP longitudinal strip in the tension zone (B2), RC beams wrapped with CFRP fabric (B3), and RC beams strengthened with a combination of both CFRP longitudinal strips and wraps (B4). The results show that the average load–displacement capacity of RC beam group (B4) was improved by 84.88% as compared with the unstrengthened beam (B1) under static loads. The dynamic test results demonstrated an increase in the deflection resistance of RC beam group (B4) by −57.89% as compared with unstrengthened RC beam group (B1) under identical drop weights of 1 m. In addition, a collapse failure mode was noticed in the unstrengthened beams, while minor damage was recorded mainly in the case of RC beam group (B4). Furthermore, the numerical analysis conducted using LS-DYNA software (V 971 R6.0.0) proved that the adopted numerical models can efficiently predict the behaviour of RC beams under dynamic loads, with maximum differences reaching up to −12.5% compared with the experimental test results. [ABSTRACT FROM AUTHOR]

The wheels of decelerating vehicles in braking mode roll with increased slip, up to complete lock-up, which is a negative phenomenon. This is effectively managed by the anti-lock braking system (ABS). However, in the course of braking, especially before the system activation, self-excited oscillatory processes with high amplitudes may occur, causing increased dynamic loads on the drive system. The paper studies the braking processes of a vehicle with an electromechanical individual traction drive in both electrodynamic regenerative and combined braking modes, utilizing the drive and the primary braking system. The theoretical framework is provided for identifying the self-excited oscillation onset conditions and developing a technique to detect wheel slips during braking to suppress these oscillations. To check the functionality of the wheel-slip observer in braking mode, the performance of the self-excited oscillation pulse suppression algorithm was studied in the MATLAB Simulink 2018b software package. The study results can be used to develop control systems equipped with the function of suppressing self-excited oscillations by vehicle motion. [ABSTRACT FROM AUTHOR]

To overcome the issue of unstable speed output encountered by cotton pickers operating in harsh environments and subject to frequent external load fluctuations, a hydraulic–mechanical transmission (HMT) for cotton pickers is proposed in this study. By analyzing the driving system of the cotton picker, a Lavira-based HMT scheme is developed. The matching characteristics of the HMT speed ratio are analyzed, a continuity and smoothness test of the speed ratio of the changing segment is carried out, and the influence law of smoothness of the HMT changing segment is discussed. The results show that the HMT system effectively satisfies the driving speed requirements for both field harvesting and road transportation of cotton pickers. The HMT speed ratio is continuously controllable and the design is reasonable. The HMT load torque and the oil pressure in the main oil circuit have a significant impact on the smoothness indicators of speed reduction and dynamic load. Additionally, the flow rate of the governor valve has a notable effect on the smoothness indicator of sliding friction power. However, the engine's output speed has no significant influence on the HMT's smoothness. This research can provide theoretical support for the development and design of cotton picker gearboxes and the transmission characteristics and experimental research of off-road vehicle gearboxes. [ABSTRACT FROM AUTHOR]

The warning of the potential faults occurring in the future in a sucker rod well can help technicians adjust production strategies in time. It is of great significance for safety during well production. In this paper, the key characteristic parameters of dynamometer cards were predicted by a temporal neural network to implement the warning of different working conditions which might result in failures. First, a one-dimensional damped-wave equation was used to eliminate the dynamic loads' effect of surface dynamometer cards by converting them into down-hole dynamometer cards. Based on the down-hole dynamometer cards, the characteristic parameters were extracted, including the load change, the position of the valve opening and closing point, the dynamometer card area, and so on. The mapping relationship between the characteristic parameters and working conditions (classification model) was obtained by the Xgboost algorithm. Meanwhile, the noise in these parameters was reduced by wavelet transformation, and the rationality of the results was verified. Second, the Encoder–Decoder and multi-head attention structures were used to set up the time series prediction model. Then, the characteristic parameters were predicted in a sequence-to-sequence way by using historical characteristic parameters, date, and pumping parameters as input. At last, by inputting the predicted results into the classification model, a working conditions warning method was created. The results showed that noise reduction improved the prediction accuracy significantly. The prediction relative error of most characteristic parameters was less than 15% after noise reduction. In most working conditions, their F1 values were more than 85%. Most Recall values could be restored to over 90% of those calculated by real parameters, indicating few false negative cases. In general, the warning method proposed in this paper can predict faulty working conditions that may occur in the future in a timely manner. [ABSTRACT FROM AUTHOR]

During the mode-switching process of a hybrid tractor equipped with a hydraulic-mechanical continuously variable transmission (HMCVT) device, the separation and combination of the clutch will cause transient shocks, affecting the smoothness and driving comfort of the entire vehicle. This article conducts simulation and experimental research on the impact problem when switching from pure electric drive mode to hybrid-power speed coupling mode. Firstly, establish a system dynamics model in SimulationX 3.5 software and build a hardware-in-the-loop (HIL) experimental platform. Secondly, a strategy of "clutch oil pressure fuzzy control + motor torque compensation" is proposed to solve the problem of the slow dynamic response of the engine. Finally, the orthogonal experiment range analysis method and variance analysis method are used to optimize the quality of mode switching, with six clutch-switching time sequences as experimental factors. The simulation results show that adopting the strategy of "clutch oil pressure fuzzy control + motor torque compensation" and optimizing the clutch-switching timing can effectively reduce the amplitude of output shaft speed reduction, dynamic load coefficient, and impact, and shorten the switching time. The comparison between the HIL test results and the simulation results shows that there is a certain difference between the two, but the overall trend is consistent, which verifies the effectiveness of the proposed control strategy and method. [ABSTRACT FROM AUTHOR]

The primary goal of enhancing automatic generation control (AGC) in interconnected multi-area power systems is to ensure high-quality power generation and reliable distribution during emergencies. These systems still struggle with consistent stability and effective response under dynamic load conditions despite technological advancements. This research introduces a secondary controller designed for load frequency control (LFC) to maintain stability during unexpected load changes by optimally tuning the parameters of a Proportional–Integral–Derivative (PID) controller using pelican optimization algorithm (POA). An interconnected power system for ith multi-area is modeled in this study; meanwhile, for determining the optimal PID gain settings, a four-area interconnected power system is developed consisting of thermal, reheat thermal, hydroelectric, and gas turbine units based on the ith area model. A sensitivity analysis was conducted to validate the proposed controller's robustness under different load conditions (1%, 2%, and 10% step load perturbation) and adjusting nominal parameters (R, Tp, and Tij) within a range of ±25% and ±50%. The performance response indicates that the POA-optimized PID controller achieves superior performance in frequency stabilization and oscillation reduction, with the lowest integral time absolute error (ITAE) value showing improvements of 7.01%, 7.31%, 45.97%, and 50.57% over gray wolf optimization (GWO), Moth Flame Optimization Algorithm (MFOA), Particle Swarm Optimization (PSO), and Harris Hawks Optimization (HHO), respectively. [ABSTRACT FROM AUTHOR]

Titanium parts fabricated by additive manufacturing, i.e., laser or electron beam-powder bed fusion (L- or EB-PBF), usually exhibit columnar grain structures along the build direction, resulting in both microstructural and mechanical anisotropy. Post-heat treatments are usually used to reduce or eliminate such anisotropy. In this work, Ti-6Al-2Zr-1Mo-1V (TA15) alloy samples were fabricated by L-PBF to investigate the effect of post-heat treatment and load direction on the dynamic response of the samples. Post-heat treatments included single-step annealing at 800 °C (HT) and a hot isotropic press (HIP). The as-built and heat-treated samples were dynamically compressed using a split Hopkinson pressure bar at a strain rate of 3000 s−1 along the horizontal and vertical directions paralleled to the load direction. The microstructural observation revealed that the as-built TA15 sample exhibited columnar grains with fine martensite inside. The HT sample exhibited a fine lamellar structure, whereas the HIP sample exhibited a coarse lamellar structure. The dynamic compression results showed that post-heat treatment at 800 °C led to reduced flow stress but enhanced uniform plastic strain and damage absorption work. However, the HIP samples exhibited both higher stress, uniform plastic strain, and damage absorption work owing to the microstructure coarsening. Additionally, the load direction had a subtle influence on the flow stress, indicating the negligible anisotropy of flow stress in the samples. However, there was more significant anisotropy of the uniform plastic strain and damage absorption. The samples had a higher load-bearing capacity when dynamically compressed perpendicular to the build direction. [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]