Average Speed Research Articles

Enhancing the Mobility of Small-Scale Robots Via Nonlinear Structural Springs Exhibiting Negative Stiffness

Abstract Compared to traditional robotic systems, small-scale robots, ranging from several millimeters to micrometres in size, are capable of reaching narrower and vulnerable regions with minimal damage. However, conventional small-scale robots’ limited maneuverability and controlability hinder their ability to effectively navigate in the intricate environments, such as the gastrointestinal tract. Self-propelled capsule robots driven by vibrations and impacts emerge as a promising solution, holding the potentials to enhance diagnostic accuracy, enable targeted drug delivery, and alleviate patient discomfort during gastrointestinal endoscopic procedures. This paper builds upon our previous work on self-propelled capsule robots, exploring the potential of nonlinear connecting springs to enhance its propulsion capabilities. Leveraging a mathematical model for self-propelling robots with a von Mises truss spring, which is verified using a finite element model, we investigate the effects of negative stiffness and snap-back within the nonlinear structural spring on the robots’ propelling speed. Our analysis reveals that the negative stiffness of the von Mises truss can significantly reduce the sensitivity of the propelling speed to excitation frequency. As a result, the capsule robot exhibits a remarkably wider operational band where it maintains a high average propelling speed, surpassing its linear counterpart. This work sheds light on the potential for developing customized nonlinear structural systems for diverse scenarios in small-scale robot applications, opening up new possibilities for enhanced functionality and maneuverability in various biomedical applications.

Single-pixel imaging for a high-speed rotating object with varying rotation speed

We report a single-pixel imaging method that can capture high-quality images of a high-speed rotating object with varying rotation speed. Recently, single-pixel imaging methods for high-speed rotating objects were proposed, but the methods commonly require the object should rotate at a constant speed, which limits their practical use. Here we report an improved method that adopts synchronized rotation angle detection to ease the requirement of constant rotation speed of the target object. With the synchronized rotation angle detection, the single-pixel measurements at the same rotation angle can be extracted in the data post-processing, so that the target object and the structured patterns remain relatively motionless. We successfully demonstrate the reported method in imaging a central-process-unit cooling fan whose average rotation speed is 14,402 revolutions per minute (rpm) with a varying speed from 14,357.50 to 14,436.96 rpm. The method provides continuous and high-resolution imaging of a high-speed rotating object with a practical and robust solution. It might find various potential applications such as health monitoring of high-speed rotating machines in operation.

Cooperative lane-changing for connected autonomous vehicles merging into dedicated lanes in mixed traffic flow

Connected and automated vehicles (CAVs) have enormous potential to enhance traffic safety, efficiency, and emissions reduction. However, in the initial phases of CAV development, mixed traffic comprising CAVs and human-driven vehicles (HDVs) will inevitably coexist in the traffic system. To fully exploit the benefits of CAVs, dedicated lanes with independent rights of way will be established. This paper proposes an optimal control strategy for coordinating the mandatory lane-changing of CAVs from ordinary lanes to dedicated lanes. The strategy develops a centralized two-stage cooperative optimal control model to optimize the lane-changing sequence and trajectories of CAVs. In the first stage, a dynamic programming formulation is designed to determine the lane-changing sequence decisions. The model predictive control (MPC) controller is adopted to dynamically solve the optimal control problem with a fixed terminal state. In the second stage, we dynamically and cooperatively designed the longitudinal trajectories of related CAVs. The lateral trajectories of lane-changing CAVs are planned with a cubic polynomial. The objective function considers driving comfort and state tracking to ensure traffic smoothness. Simulation results show that: (1) the proposed strategy can improve the negative impact of lane-changing behavior under different traffic demand levels. (2) Compared to the benchmark approach, the proposed strategy can significantly enhance traffic efficiency and driving comfort, particularly in medium-traffic demand. The strategy can improve the average speed of CAVs by approximately 12 % and decrease the average acceleration by over 45 %. (3) The average fuel consumption is positively correlated with traffic demands and the difference in arrival speeds between lane-changing and dedicated lane CAVs. (4) The effectiveness of the strategy increases with the length of the lane-changing segment. However, the marginal benefit becomes negligible when the segment exceeds 300 m. Therefore, the findings of this paper can provide theoretical support for the cooperative control of CAVs in dedicated lanes of highways in the future.

Study on the Impact of Design Factors of Piloti Forms on the Thermal Environment in Residential Quarters

Study on the Impact of Design Factors of Piloti Forms on the Thermal Environment in Residential Quarters

Toxicity evaluation of neonicotinoids to earthworm (Eisenia fetida) behaviors by a novel locomotion tracking assay

Pesticides are substances used for controlling, preventing, and repelling pests in agriculture. Among them, neonicotinoids have become the fastest-growing class of insecticides because of their efficiency in targeting pests. They work by strongly binding to nicotinic acetylcholine receptors (nAChRs) in the central nervous system of insects, leading to receptor blockage, paralysis, and death. Despite their selectivity for insects, these substances may be hazardous to non-target creatures, including earthworms. Although earthworms may be invasive in some regions like north America, they contribute to the development of soil structure, water management, nutrient cycling, pollution remediation, and cultural services, positively impacting the environment, particularly in the soil ecosystem. Thus, this study aimed to develop a novel earthworm behavior assay since behavior is a sensitive marker for toxicity assay, and demonstrated its application in evaluating the toxicity of various neonicotinoids. Here, we exposed Eisenia fetida to 1 and 10 ppb of eight neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram pestanal, thiacloprid, thiametoxam, and sulfoxaflor) for 3 days to observe their behavior toxicities. Overall, all of the neonicotinoids decreased their locomotion, showed by a reduction of average speed by 24.94–68.63% and increment in freezing time movement ratio by 1.51–4.25 times, and altered their movement orientation and complexity, indicated by the decrement in the fractal dimension value by 24–70%. Moreover, some of the neonicotinoids, which were acetamiprid, dinotefuran, imidacloprid, nitenpyram, and sulfoxaflor, could even alter their exploratory behaviors, which was shown by the increment in the time spent in the center area value by 6.94–12.99 times. Furthermore, based on the PCA and heatmap clustering results, thiametoxam was found as the neonicotinoid that possessed the least pronounced behavior toxicity effects among the tested pesticides since these neonicotinoid-treated groups in both concentrations were grouped in the same major cluster with the control group. Finally, molecular docking was also conducted to examine neonicotinoids' possible binding mechanism to Acetylcholine Binding Protein (AChBP), which is responsible for neurotransmission. The molecular docking result confirmed that each of the neonicotinoids has a relatively high binding energy with AChBP, with the lowest binding energy was possessed by thiametoxam, which consistent with its relatively low behavior toxicities. Thus, these molecular docking results might hint at the possible mechanism behind the observed behavior alterations. To sum up, the present study demonstrated that all of the neonicotinoids altered the earthworm behaviors which might be due to their ability to bind with some specific neurotransmitters and the current findings give insights into the toxicities of neonicotinoids to the environment, especially animals in a soil ecosystem.

Image Guided Interpedicular Screw Placement Simulation System for Training and Skill Evaluation. Proof of Concept

IntroductionPresent work introduces SpineST-01 system, an image guided vertebrae cannulation training system. During task execution, the computer calculates performance based metrics displaying different visual perspectives (LV, AV, APV) with the position of the instrument inside it. Finally, a report with the metrics is generated as performance feedback. MethodsA training box holds a 3D printed spine section. The computer works with two orthogonal disposed cameras, tracking passive markers placed on the instrument. Eight metrics were proposed to evaluate the surgical task’s execution performance. A preliminary study, with 25 participants divided into three groups: 12 Novices, 10 intermediates and 3 Experts, was conducted to determine the feasibility of the system to evaluate and assess the performance differences of each group using Kruskal-Wallis analysis and U Mann-Whitney. In both, Kruskal-Wallis analysis and U Mann-Whitney, a p-value ≤0.05 was considered statistically significant. ResultsWhen comparing Experts vs Novices and the three groups, the statistical analysis showed significant differences in six of the eight metrics. (Axial angle error (°), Lateral angle error (°), Average Speed (mm/s), Progress between shots (mm), Time (s), Shots) The metrics that did not show any statistically significant difference were time between shots (s), and speed between shots (mm/s). As well the average result comparison placed the Experts as the best performance group. ConclusionOn the SpineST-01 presentation, initial testing demonstrated potential for the system to practice image guided cannulation task on lumbar vertebrae. Results show objective differences between Experts, Intermediates, and Novices on the proposed metrics. Making this system a feasible option for developing basic navigation system skills, without the risk of radiation exposure and objectively evaluate task performance.

Can zigzag marking improve pedestrian safety at unsignalized crosswalks? An observational before-after study in Israel

Zigzag road marking near unsignalized pedestrian crosswalks is common in some countries but not yet allowed in Israel. An observational before-after study was conducted to explore its impacts on pedestrian crossing conditions. The measure was applied at three midblock urban crosswalks, on dual-carriageway and two-lane roads. The study examined changes in safety-related behaviors by comparing three periods: before the installation, and two weeks and two months afterwards. Shortly after the zigzag application, a significant decrease in average vehicle speeds, of 9%-16%, was observed at all study sites, but in a longer-term a decrease of 7%-8% remained at the dual-carriageway sites only. A relative increase in yielding rates to pedestrians was of 19%-20% in the short-term and of 13%-14% after two months, at dual-carriageway sites, with no change at the two-lane site. Overall, zigzag marking may improve pedestrian safety. However, as the effects were inconsistent, it was not recommended for widespread use.

Machine Learning-Based Approach to Predict Last-Minute Cancellation of Pediatric Day Surgeries.

The last-minute cancellation of surgeries profoundly affects patients and their families. This research aimed to forecast these cancellations using EMR data and meteorological conditions at the time of the appointment, using a machine learning approach. We retrospectively gathered medical data from 13 440 pediatric patients slated for surgery from 2018 to 2021. Following data preprocessing, we utilized random forests, logistic regression, linear support vector machines, gradient boosting trees, and extreme gradient boosting trees to predict these abrupt cancellations. The efficacy of these models was assessed through performance metrics. The analysis revealed that key factors influencing last-minute cancellations included the impact of the coronavirus disease 2019 pandemic, average wind speed, average rainfall, preanesthetic assessments, and patient age. The extreme gradient boosting algorithm outperformed other models in predicting cancellations, boasting an area under the curve value of 0.923 and an accuracy of 0.841. This algorithm yielded superior sensitivity (0.840), precision (0.837), and F1 score (0.838) relative to the other models. These insights underscore the potential of machine learning, informed by EMRs and meteorological data, in forecasting last-minute surgical cancellations. The extreme gradient boosting algorithm holds promise for clinical deployment to curtail healthcare expenses and avert adverse patient-family experiences.

Ankle movement alterations during gait in children with acute lymphoblastic leukemia with suspected peripheral mononeuropathy. A cross-sectional study

BackgroundPeripheral neuropathy due to chemotherapeutic drugs causes alterations in ankle movement during gait. This study aimed to describe the spatiotemporal parameters and ankle kinematics during gait in schoolchildren with acute lymphoblastic leukemia with clinically suspected peripheral neuropathy. MethodsIn children with acute lymphoblastic leukemia in the maintenance phase, we calculated spatiotemporal and kinematic parameters of the ankle during gait using Kinovea® software. Furthermore, we identified alterations in the parameters obtained considering the values of the normality data from a stereophotogrammetry system as the reference values. Finally, we represented the kinematic parameters of the ankles calculated with Kinovea® compared to the normality values of the stereophotogrammetry. FindingsWe evaluated 25 schoolchildren; 13 were male (52.0%) with a median age of 88.0months and a median of 60.0 weeks in the maintenance phase, and 54.8% were classified as standard risk. Spatiotemporal parameters: cadence (steps/min), bilateral step length (m), and average gait speed (m/s) in ALL children were significantly lower than reference values (p < 0.001). Except for right mid-stance and bilateral foot strike, initial swing showed that both ankles maintained plantar flexion values during gait, significantly lower in ALL patients (p < 0.05). InterpretationWe identified spatiotemporal and kinematics alterations in schoolchildren with acute lymphoblastic leukemia during all phases of the gait suggestive of alteration in ankle muscles during movement, probably due to peripheral neuropathy; nevertheless, our results should be taken with caution until the accuracy and reliability of Kinovea® software as a diagnostic test compared to the stereophotogrammetric system in children with ALL and healthy peers is proven.

Different strategies between queens and workers against fungal pathogens in the termite Reticulitermes chinensis

AbstractSocial insects are prone to pathogen infection because of high exposure rates from social interactions. However, it remains unclear whether queens have enhanced pathogen resistance, because reproduction is largely confined to queens. Here, we used a natural host–pathogen system, the subterranean termite Reticulitermes chinensis and the entomopathogenic fungus Metarhizium anisopliae, to investigate the differences in allogrooming, locomotion, and immune gene expression between queens and workers against pathogen infection. We found that fungal infection significantly reduced survival in both queens and workers. Infected queens received significantly more grooming time from sanitary nestmates than infected workers, but they returned much less grooming time to sanitary nestmates than infected workers. Infection resulted in a reduction in the average locomotion speed and distance of queens but had no effect on worker locomotion. Infection resulted in upregulated expression of two immune genes (termicin and transferrin), two antioxidant genes (CAT and SOD), and phosphate genes CYP450 in queens but not in workers. Our results indicated that eusocial termites evolved strategies that prioritize the reproductive castes' welfare in defending against the pathogen infection to ensure continued reproduction and colony persistence.

Synthetic wind speed time series generation by dynamic factor model

The global transition to renewable energy is driven by the fight against climate change. Wind power plays a crucial role in reducing dependence on fossil fuels and greenhouse gas emissions. Therefore, addressing uncertainties in wind speed variations requires innovative solutions. This study proposes a Bayesian-based approach using a Dynamic Factor Model to generate synthetic monthly average wind speed series. The Dynamic Factor Model framework captures temporal and spatial correlations, improving wind resource representation in operational planning models. The model's autoregressive configuration with common factors, prior distributions, and Bayesian inference techniques enhances predictive capabilities. Validation exercises confirm the model's reliability, accurately capturing seasonal oscillations and spatial correlations across eight wind farms. The study highlights the usefulness of the Dynamic Factor Model in evaluating wind projects and optimizing energy generation strategies, effectively mitigating wind uncertainty, and facilitating renewable energy integration in Brazil's power mix.

A ray-inspired flexible robot fish with stable controllability actuated by photo -responsive composite hydrogels with poly(N-isopropylacrylamide) and multi-walled carbon nanotubes

Drawing inspiration from the movement behaviour of rays in nature, we have successfully developed a ray-inspired flexible robot fish driven by visible light. A composite made of poly(N-isopropylacrylamide) (PNIPAM) and multi-walled carbon nanotubes (MWCNTs) has excellent biocompatibility and photo-responsive deformability. The PNIPAM hydrogel flexible material of the robot fish was prepared by light curing printing technology. Under the control of visible light, the robot fish swims in a straight line at an average speed of about 0.42 mm/s. The photoinduced asymmetric deformation mechanism is used to control the deformation of the fins on both sides of the robot fish, so that the robot fish can turn and realize directional swimming control. These findings have important implications for the development of flexible bionic robots and provide valuable insights for the research of bionic robots driven by visible light.

THE PHYSIOLOGICAL VALIDITY OF CRITICAL SPEED DERIVED FROM A 3-MINUTE ALL-OUT SWIM TEST

INTRODUCTION AND AIMS The boundary between heavy and severe exercise domains is one of the most consistent predictors of swimming performance. The gold standard approach to assessing this physiological threshold (numerous 30-minute constant-load trials) is complex and time-consuming, leading practitioners to explore other methodologies, which has left coaches questioning the validity of testing outcomes and reducing testing implementation. The recent proposal of a modified 3-minute all-out swim test has produced reliable estimates of critical speed (CS), however the estimates have not been validated against physiological measures. The aim of this study was to establish the physiological validity of CS derived from the modified 3-minute all-out swim test in elite swimmers. METHODS 16 elite swimmers completed a 3-minute test consisting of 12 maximal 25-m efforts separated by 5s of rest. CS was calculated as the average speed of the slowest two 25-m efforts from the last four completed. To identify MLSS, swimmers completed a 30-minute trial broken into 6 x 5-minute intervals. Blood lactate concentration collected at each interval determined the subsequent interval speed. Over two additional visits, participants completed a 30-minute constant speed trial – at 2% above and 2% below CS to determine the physiology surrounding CS. Statistical analyses were conducted to compare CS and MLSS and determine their association, and to compare physiological measures within the two constant load trials. RESULTS MLSS and CS were not statistically different (p&amp;gt;0.05) and had a strong positive correlation (r=0.98). A physiological steady state was verified in the below CS trial (p&amp;gt;0.05). A physiological steady state was not obtained in the above CS trial (p&amp;lt;0.05). CONCLUSIONS These findings suggest the modified 3-minute all-out swim test as a valid methodology to assess the CS of elite swimmers. Implementation of this methodology could enable critical insight into how athletes are adapting to training and contribute significantly to swimming talent identification.

Street Crowdedness and Urban Congestion Level by MAC and GPS Data

Wi-Fi is one of the emerging technologies today. Wi-Fi refers to MAC (Media Access Control) address data. A MAC address represents a device number. In other words, it represents the number of people. The system uses MAC address data to determine road traffic congestion and land use, detects the number of terminals using a Wi-Fi scanner, and analyzes vehicle speed using GPS. The purpose of this research is to understand city-level services from traffic services and road congestion status and degree of congestion using Wi-Fi data (MAC addresses). This method was used for this study by providing a Wi-Fi scanner and a GPS scanner inside the bus. A Wi-Fi scanner that collects MAC address data and GPS for calculating bus speed. The congestion hypothesis in this study is that the bus is slow, and the total number of MAC addresses is high at the same time, or vice versa. The results show that the maximum correlation value between speed and total number of MAC addresses is -0.629. Negative correlation leads to slower bus speeds, higher total MAC addresses, and different. The numbers indicate the congested sections around the bus route during the bus operating hours. Several parameters such as travel time, travel speed and standard deviation/variance were analyzed for congestion level. Analyze aspects that link road conditions to good or bad service. Congestion levels can be determined based on RI, which is derived from the standard deviation and average speed of each road link.

A Comparison of Elite and Sub-elite Match-Play Running Performance of Gaelic Football Players.

Donnelly, S, Collins, K, Burns, C, O'Neill, C, and Mangan, S. A comparison of elite and sub-elite match-play running performance of Gaelic football players. J Strength Cond Res 38(5): 912-923, 2024-This research aimed to examine differences in match-play running performance between elite and sub-elite Gaelic football players. Global Positioning System devices were used to record the match-play running performance of sub-elite and elite players during the 2018 and 2019 seasons, respectively. In total, 783 samples were collected from 31 sub-elite and 30 elite players, from 1 elite and 1 sub-elite team. Comparisons were made on a team and positional level. Statistical significance was accepted at p ≤ 0.05. Significant positional differences were present between all positions with varying effect sizes (ESs) and p-values. Effect size was used to determine the magnitude of statistical difference. On a team level, the elite covered significantly more relative distance (p = 0.021, ES = 0.007) and elicited significantly higher average speed (p = 0.023, ES = 0.007) in quarters 2, 3, and 4 than the sub-elite. The elite covered significantly more relative distance high-intensity running (17-21.9 km·h-1; p = 0.002, ES = 0.012) in quarter 3 and performed significantly more power events per minute (p = 0.006, ES = 0.009) in quarter 4. In quarter 1, the sub-elite performed significantly more power events per minute (p = 0.006, ES = 0.009), relative high-speed running (≥17 km·h-1; p = 0.011, ES = 0.009), and relative distance high-intensity running (17-21.9 km·h-1; p = 0.002, ES = 0.012). Power events were defined as the estimation of the number of events that depend on anaerobic processes. The present study indicates that elite players possess superior conditioning, ability to read match-play, pacing, and anaerobic capacity. Sub-elite teams may use the present study to inform their training to potentially improve conditioning, pacing, and anaerobic capacity.

The effect of chronic leg press exercises on hamstring muscle length and different vertical jump performance

Background and Study Aim. As it is known, chronic resistance exercises cause limitations in some joints and this negatively affects the normal range of motion. In the present study, it was aimed to analyse the quadriceps-hamstring balance by analysing different vertical jump performances after six weeks of leg press exercise. Material and Methods. Eleven university students aged between 18-30 years were included in this study. The hamstring muscle length, 1 repetition maximum (1-RM) leg press performance were analysed before and after six weeks of leg press exercise. In addition, the vertical jump performances of the participants were analysed with My Jump 2 software programme. In this study, counter movement jumps (CMJ) and squat jump (SJ) performances of the participants were determined. Results. According to the findings, 1 repetition maximum (1-RM) leg press performance and hamstring length of the participants improved significantly (t=-7.609, ES: -2.29, p&lt;.001; t=-2.540, -0.76, p=.029, respectively). CMJ and SJ parameters of the participants did not change (p&lt;0.05). It was concluded that the lengthened hamstring length after the leg press exercise programme had a positive relationship with vertical jump height (r=0.656, p=0.028), flight duration (r=0.663, p=0.026), speed (r=0.657, p=0.028), and average speed (r=0.669, p=0.024). These relationships were observed among CMJ parameters following the exercise programme. Likewise, a positive correlation was found between hamstring length, which lengthened after the leg press exercise programme, and vertical jump height (r=0.625, p=0.040), flight duration (r=0.646, p=0.032), speed (r=0.646, p=0.032), and average speed (r=0.637, p=0.035). These correlations were identified among the SJ parameters after the exercise. Conclusions. As a result, it was determined that chronic leg press exercises positively affected hamstring muscle length and muscle strength. Different vertical jump performances such as CMJ and SJ did not change. However, the relationship between hamstring length and vertical jump parameters is interesting.

Experimental Study on the Distribution Law of Wind Speed in Rectangular Section Tunnels of Coal Mines

Ventilation is the cornerstone of coal mine safety production, and accurate monitoring of ventilation parameters is the fundamental guarantee for ventilation technology decision-making. A calculation model for the average wind speed line position in rectangular section tunnels of coal mines was established based on the Boussinesk theory and Prandtl turbulence theory to address the issue of difficulty in meeting decision-making needs in wind speed monitoring accuracy. The airflow field of rectangular section tunnels under different wind speed conditions was measured at the coal mine site, and the average position of the measured average wind speed line was obtained. The comparison and verification with the theoretical calculation results were carried out, with an absolute error of less than 5%.

Deep Q-Network Algorithm-Based Cyclic Air Braking Strategy for Heavy-Haul Trains

Cyclic air braking is a key element for ensuring safe train operation when running on a long and steep downhill railway section. In reality, the cyclic braking performance of a train is affected by its operating environment, speed and air-refilling time. Existing optimization algorithms have the problem of low learning efficiency. To solve this problem, an intelligent control method based on the deep Q-network (DQN) algorithm for heavy-haul trains running on long and steep downhill railway sections is proposed. Firstly, the environment of heavy-haul train operation is designed by considering the line characteristics, speed limits and constraints of the train pipe’s air-refilling time. Secondly, the control process of heavy-haul trains running on long and steep downhill sections is described as the reinforcement learning (RL) of a Markov decision process. By designing the critical elements of RL, a cyclic braking strategy for heavy-haul trains is established based on the reinforcement learning algorithm. Thirdly, the deep neural network and Q-learning are combined to design a neural network for approximating the action value function so that the algorithm can achieve the optimal action value function faster. Finally, simulation experiments are conducted on the actual track data pertaining to the Shuozhou–Huanghua line in China to compare the performance of the Q-learning algorithm against the DQN algorithm. Our findings revealed that the DQN-based intelligent control strategy decreased the air braking distance by 2.1% and enhanced the overall average speed by more than 7%. These experiments unequivocally demonstrate the efficacy and superiority of the DQN-based intelligent control strategy.

Performance of soccer players under acute physical fatigue: An approach based on cognitive, tactical and physical aspects

This study aimed to verify whether peripheral perception, tactical behaviour, and physical performance are influenced by acute physical fatigue in soccer players. The study included 24 trained soccer players (18.6 ± 1.5 years) from two Brazilian clubs. The TSAFT90 test was used to induce acute physical fatigue. The results showed that physical fatigue did not affect peripheral perception (p = 0.360). Regarding tactical behaviour, improved efficiency was observed for the principles of offensive coverage (p = 0.029), width and length with the ball (p = 0.044), and concentration (p = 0.008). On the other hand, a reduction was observed in the number of tactical actions of offensive coverage (p = 0.020) and recovery balance (p = 0.042). Also, improved accuracy in the principles of defensive balance (p = 0.009), recovery balance (p = 0.021) and defensive unity (p = 0.003) occurred under physical fatigue. A reduction in the physical performance outcomes total distance covered (p < 0.001), average speed (p < 0.001), sprints (p = 0.029), number of accelerations (p = 0.008) and decelerations (p = 0.008) were also detected. The internal (p < 0.01) and external (p < 0.01) workload was higher under physical fatigue. Overall, acute physical fatigue did not influence peripheral perception. However, physical performance was reduced under fatigue, the perceived effort increased, and tactical behaviours were affected by decreasing tactical actions performed near the ball, increasing errors in defensive movements in the lateral corridors and the last defensive line, and improving offensive tactical actions performance.

Numerical simulation of optimizing the swing curve of a 3DOF biomimetic pectoral fin in drag mode

In response to the optimization problem of the motion law of the pectoral fins of biomimetic robotic fish, this paper uses computational fluid dynamics (CFD) methods to achieve the CFD optimization of two types of rigid biomimetic pectoral fins with three degrees of freedom (DOF): elliptical and 8-shaped swing curves. By analyzing the hydrodynamic characteristic curve of the pectoral fins, pressure distribution upstream and downstream of the fin surface, velocity vector of the surrounding flow field during pectoral fin swing, and three-dimensional vortex structure, it is found that when the pectoral fins are pushed forward in an elliptical swing curve, the resistance peak value decreases after two optimizations. However, at the same time, a certain amount of thrust is lost. When the pectoral fin advances in an 8-shaped swinging curve, after two optimizations, the pectoral fins resistance decreases while maintaining an enormous thrust, comprehensively improving the propulsive effect of the pectoral fin on the robotic fish. By substituting the optimized 8-shaped pattern into the robotic fish model, it is found that the flapping angle of 35° has better drag reduction performance, and the average swimming speed of the robotic fish is the fastest at this angle.