Body Acceleration Research Articles

Numerical Analysis of the Influence of Prestressed Steel Wires on Vehicle-Bridge Coupling Vibration of Simply Supported Beams on High-Speed Railway

By the theory of vehicle-bridge coupled vibration analysis in railways, the dynamic analysis model for space of the train-track-bridge-steel wires coupled system was established. Moreover, a corresponding program was compiled based on the train-track-bridge-steel wires coupling vibration analysis method. Taking a 32 m simple beam which is in high-speed railways as the subject of study, the influence of effective prestress, steel wires eccentricity and vehicle speed on the dynamic response of the vehicle-bridge coupled vibration was analysed. The results show that the bridge dynamic response is remarkably influenced by prestressed steel wires. With the prestress increasing, the crest of the vertical dynamic response at the midspan decreased first, then increased. Moreover, the minimum peak value appeared when the prestress was 1300 MPa. When the steel wires were deflected downward relative to the design position, the vertical displacement of the bridge decreased by more than when the downshift occurred. The extreme values of the bridge lateral dynamic response and the train body acceleration response appeared when the train ran at 300 km/h. Prestressed steel wires had little effect on the dynamic response in the transverse direction of the bridge and train body.

CONSTRUCTION OF THE EXACT SOLUTION OF BLOOD FLOW OF OLDROYD-B FLUIDS THROUGH ARTERIES WITH EFFECTS OF FRACTIONAL DERIVATIVE MAGNETIC FIELD AND HEAT TRANSFER

In this paper, we construct the exact solution of blood flow of Oldroyd-B fluids to represent the non-Newtonian characteristics of biofluids and to study the unsteady flow of blood and heat transfer through arterial segment with external magnetic field applied normal to the flow direction in the presence of thermal radiation and body acceleration. In the study, we investigate the influence of Caputo time-fractional parameter, heat transfer, external body acceleration, and magnetic field on the blood velocity and temperature distribution in a straight circular cylindrical vessel. The constitutive partial differential equation and temperature equation governing blood flow in the arterial wall are solved using Laplace and finite Hankel transforms. In addition, Gaver Stehfest’s algorithm is used for the inverse Laplace transform. The results obtained are interpreted graphically and discussed from the physiological point of view. The graphs show that the rate of heat transfer and blood velocity become less with the increase in the external magnetic field strength which is very good in regulating blood flow as well as temperature distribution during treatment. Based on the graphical representations, blood velocity and temperature distribution both decrease in ascending order of the fractional parameter as memory effect. Further, owing to the dissipation of energy caused by blood viscoelasticity and magnetic field effect, during pulsatile flow of blood, the heat transfer rate at the wall of the artery is enhanced. The significance of this study can be found in the application fields such as biomedical engineering, medicine and pathology.

Research on CNN-BiLSTM Fall Detection Algorithm Based on Improved Attention Mechanism

Falls are one of the significant causes of accidental injuries to the elderly. With the rapid growth of the elderly population, fall detection has become a critical issue in the medical and healthcare fields. In this paper, we propose a model based on an improved attention mechanism, CBAM-IAM-CNN-BiLSTM, to detect falls of the elderly accurately and in time. The model includes a convolution layer, bidirectional LSTM layer, sampling layer and dense layer, and incorporates the improved convolutional attention block module (CBAM) into the network structure so that the one-dimensional convolution layer replaces the dense layer to aggregate the information from channels, which allows the model to accurately extract different behavior characteristics. The acceleration and angular velocity data of the human body, collected by wearable sensors, are respectively input into the convolution layer and bidirectional LSTM layer of the model and then classified and identified by softmax after feature fusion. Based on comparison with models such as CNN and CNN-BiLSTM, as well as with different attention mechanisms such as squeeze-and-excitation (SE), efficient channel attention (ECA) and the convolutional block attention module (CBAM), this model improves the accuracy, sensitivity and specificity to varying degrees. The experimental results showed that the accuracy, sensitivity and specificity of the CBAM-IAM-CNN-BiLSTM model proposed in this paper were 97.37%, 97.29% and 99.56%, respectively, which proves that the model has good practicability and strong generalization ability.

Effects of heat transfer, body acceleration and hybrid nanoparticles (Au–Al2O3) on MHD blood flow through a curved artery with stenosis and aneurysm using hematocrit-dependent viscosity

The present study investigates the heat transfer and body acceleration effects on unsteady MHD blood flow through a curved artery in the presence of stenosis and aneurysm using hybrid nanoparticles (). For realistic behavior of blood flow, blood is assumed to be a pulsatile, laminar, incompressible, viscous fluid with hematocrit-dependent viscosity. A uniform magnetic field is applied in the radial direction to the blood flow with radiation effect. The governing momentum and energy equations are solved using Crank-Nicolson Finite difference method through an accurate mesh using rectangular mesh units. The obtained data for both stenotic and aneurysm segments are graphically depicted and analyzed for various physical parameters. To examine the overall behavior of blood flow patterns, velocity contours for several emergent parameters have been displayed. Using clinically realistic hemodynamic data, comprehensive solutions for gold and gold- aluminium oxide hybrid mediated blood flow are presented. It is observed that the velocity profile rises as the volume fraction of gold () nanoparticles increases, while, the velocity profile decreases as the volume fraction of aluminium oxide () nanoparticles increases. It is noted that impedance of the flow decreases with increment in body acceleration parameter , while, WSS increases with increment in . The resistive impedance is higher for curved arteries than straight artery. The findings show that hybrid nanoparticles () reduce the values of hemodynamic parameters such as wall shear stress and resistive impedance, and blood flow rate decreases with an increment in and magnetic field strength. The current findings are consistent with recent findings in other studies. The outcomes of the study may be helpful in the diagnosis and treatment of plaque rupture, cancer, infections, brain aneurysms, and blood clot removal. Results may also be used to design and analyze biomedical devices for great potential treatment modalities, the anticancer drug industry, and nano-drug delivery systems.

Studies of Acceleration of the Human Body during Overturning and Falling from a Height Protected by a Self-Locking Device.

The use of individual fall protection equipment is one of the most commonly applied methods of protecting workers whose worksites are located above the floor level. The safety of the user in such a situation depends on both the proper selection and correct use of such equipment. Additionally, aspects such as minimizing the free-fall distance before the fall arrest, as well as quick notification of an accident and efficient rescue operation, are important factors influencing safety. This paper presents a new testing method for fall arrest equipment using a test stand consisting of the Hybrid III 50th Pedestrian ATD anthropomorphic manikin and measuring set with three-axis acceleration transducers. The proposed method and test stand were developed for the design and testing of new fall protection devices equipped with electronic detection and alarm systems, for which it is necessary to determine acceleration limits in order to determine the alarm threshold. The proposed method is based on the measurement of accelerations that occur during tipping and falling from the height of an anthropomorphic manikin secured by a self-locking device. Two places of attachment of the measuring set with a three-axis acceleration sensor were analyzed at the waist belt of the manikin (abdomen and back). Moreover, the self-locking device lanyard was attached to the two points of the safety harnesses (the front and back point). The aim of the research was to check whether the acceleration values depend on the places of attachment of the measuring and anchored system, as well as to determine their maximum values. Acceleration values corresponding to fall arrest and tipping were analyzed. Limits of acceleration have been established in order to determine the threshold of alarm triggering. The non-parametric Mann–Whitney U test was used to check whether the location of the three-axis acceleration transducer and the position of the self-locking device lanyard attachment affect the value of the recorded acceleration. For results of acceleration measurements when testing the behavior of the manikin during fall arrest, no statistically significant differences were found. For results of acceleration measurements when testing the tipping behavior of the manikin, statistically significant differences occurred. This means that during fall arrest, the location of the three-axis acceleration transducer and the position of the self-locking device lanyard attachment do not matter. This work is a continuation of previous research on accelerations characterizing human body positions occurring during normal physical activities (ADL—activities of daily living).

A vehicle-bridge interaction vibration model considering bridge deck pavement

The bridge pavement subjected to vehicle loads is the most vulnerable component in the highway bridge and overloaded vehicles can result in serious damage to the bridge pavement more easily. Therefore, it is necessary to consider the pavement in vehicle-bridge interaction (VBI) system. However, the bridge pavement is not considered in the traditional VBI system or the viscoelasticity of bridge pavement is ignored. In this study, a new vehicle-pavement-bridge interaction (VPBI) system is established. The viscoelastic asphalt pavement is simulated with the continuously and uniformly distributed spring-damper. The equivalent stiffness coefficient and equivalent damping coefficient of the pavement are determined through dynamic mechanical analysis (DMA) test and finite element method. The equations of motion for VPBI system can be derived using Lagrange equation and the modal superposition method. Then the crucial parameters such as displacement at mid-span of bridge, acceleration of vehicle body, tire contact force, and pavement deformation are obtained. The effects of vehicle velocity, bridge span, tire contact area, pavement stiffness coefficient, and pavement damping coefficient on VPBI responses are analyzed. The results show that (1) The pavement is compressive during vehicle passing bridge and its dynamic deformation fluctuates around initially static deformation of pavement. (2) Increasing the stiffness of pavement can rapidly reduce the deformation of pavement, while the pavement damping has the opposite effect. (3) The increase of bridge span can conduct exponentially growth of dynamic responses of VPBI system. The pavement deformation will increase by 7.9% if the bridge span is lengthened by 5 m. This study provides a reliability response analysis method for VPBI system.

Video Validation of Tri-Axial Accelerometer for Monitoring Zoo-Housed Tamandua tetradactyla Activity Patterns in Response to Changes in Husbandry Conditions.

Simple SummaryIn recent years, the use of technologies to remotely monitor animal behaviour has increased. However, when they are used for the first time in a new species, validation is needed. Therefore, a tri-axial accelerometer was used to monitor lesser anteater (Tamandua tetradactyla) behaviour. First, the influence of using a vest on the animals’ behaviour was evaluated. Second, correlations between video recordings and accelerometer data were made, allowing the researchers to obtain summary measures for each behaviour and a threshold to discriminate activity/inactivity events. Sensitivity and precision variables revealed the robustness of accelerometer monitoring. Third, animals responded to a reduction in enclosure complexity by increasing their activity. The relevance of the accelerometer was determined comparing data (activity level and activity cycle) with video recordings. The results indicate that an accelerometer attached to a vest is a reliable technology for monitoring the activity pattern of T. tetradactyla under semi-controlled environmental conditions.Accelerometers are a technology that is increasingly used in the evaluation of animal behaviour. A tri-axial accelerometer attached to a vest was used on Tamandua tetradactyla individuals (n = 10) at Biodiversity Park. First, the influence of using a vest on the animals’ behaviour was evaluated (ABA-type: A1 and A2, without a vest; B, with a vest; each stage lasted 24 h), and no changes were detected. Second, their behaviour was monitored using videos and the accelerometer simultaneously (experimental room, 20 min). The observed behaviours were correlated with the accelerometer data, and summary measures (X, Y and Z axes) were obtained. Additionally, the overall dynamic body acceleration was calculated, determining a threshold to discriminate activity/inactivity events (variance = 0.0055). Then, based on a 24 h complementary test (video sampling every 5 min), the sensitivity (85.91%) and precision (100%) of the accelerometer were assessed. Animals were exposed to an ABA-type experimental design: A1 and A2: complex enclosure; B: decreased complexity (each stage lasted 24 h). An increase in total activity (%) was revealed using the accelerometer (26.15 ± 1.50, 29.29 ± 2.25, and 35.36 ± 3.15, respectively). Similar activity levels were detected using video analysis. The results demonstrate that the use of the accelerometer is reliable to determine the activity. Considering that the zoo-housed lesser anteaters exhibit a cathemeral activity pattern, this study contributes to easily monitoring their activities and responses to different management procedures supporting welfare programs, as well as ex situ conservation.

Optimal Design and Dynamic Performance Analysis of Vehicle Suspension Employing an Eccentric Inerter

This paper concerns the dynamic performance analysis of the vehicle ISD (inerter-spring-damper) suspension employing an eccentric inerter. Firstly, the quarter car model of the two basic vehicle suspension layouts involving an eccentric inerter, namely, the series-connected layout and the parallel-connected layout, is established. Then, by considering the overall performance such as the vehicle body acceleration, the suspension working space, and the dynamic tire load, the key parameters of the two suspensions are optimized by using the genetic algorithm. Simulation analysis results indicate that the series-connected vehicle ISD suspension is superior to the parallel-connected one, and all of the RMS values of the body acceleration, the suspension working space, and the dynamic tire load are decreased significantly by comparing to the conventional suspension, while the improvement of the parallel-connected vehicle ISD suspension is relatively poor. At last, the impact of the flywheel eccentricity and the screw pitch on the dynamic performance indices of the two suspensions is discussed, and the trade-offs among the three performances are analyzed, which will provide a guide method for the suspension design when considering the eccentric factor.

Vibration Response Analysis of Overhead System Regarding Train-Track-Bridge Dynamic Interaction

Based on the paucity of studies on the analysis of the coupled vibration response of the train-track-overhead System, in this article, finite element software ABAQUS was integrated with multi-body dynamics software, Universal Mechanism (UM), to construct a joint simulation model of the train-track overhead system under a railway line, with the focus on the investigation of the influence of different track irregularity levels, speeds and damping coefficients on the coupled vibration response of the vehicle-track-overhead system. The findings demonstrate that the response of the train body is sensitive to track irregularity, which primarily impacts the safety index of train operation. The results also suggest that the level of track irregularity should be rigorously regulated above AAR5 during construction. The train-track-overhead system functions well and satisfies the overhead system’s design requirements when the train travels through the reinforced line at a speed of no more than 60 km/h. When the train speed is 100 km/h, the vertical acceleration exceeds the limit for the “I” overhead system. There is a possibility of excessive lateral acceleration of the train body and excessive lateral force of the wheel and rail when the train speed is greater than 60 km/h, which endangers the safety of the driver. While it has little effect on the mid-span and vertical displacements, the damping factor of the bridge has a substantial impact on the vertical acceleration and mid-span acceleration of the vertical and horizontal beams. The study’s findings provide useful guidance.

Dynamic Analysis of a Steel–Concrete Composite Box-Girder Bridge–Train Coupling System Considering Slip, Shear-Lag and Time-Dependent Effects

A dynamic computational program considering slip, shear-lag and time-dependent effects of composite box-girder bridge–train coupling system is firstly proposed based on the authors’ previous studies. In the program, the long-term vertical displacement of a composite bridge is firstly calculated. The calculated vertical displacement is then superimposed on the existing uneven track as the new excitation of the composite box-girder bridge–train coupling system to obtain the dynamic responses of the bridge–train coupling system. A 3 × 40 m simply supported steel–concrete composite box-girder bridge is selected to investigate the influence of its time-dependent behavior on its dynamic responses. The results showed that the time-dependent effect will amplify the dynamic characteristics of the composite box-girder bridge and the high-speed train. The maximum vertical displacement and acceleration of the composite bridge increase by 8.82% and 13.64%, and the maximum vertical acceleration of the train body increases by 144.78%. Additionally, the slip and shear-lag effects have an impact on the dynamic responses of the composite box-girder bridge–train coupling system at different operation times. The dynamic responses of the coupling system strengthen with the decrease in shear connection stiffness. The dynamic responses of the system may be underestimated when the shear-lag effect is not neglected. Therefore, these conclusions should be given sufficient attention in the design, construction and operation of high-speed railway composite bridges.

Fatigue Affects Body Acceleration During Vertical Jump And Agility Performance In Elite Young Badminton Players

PURPOSE: Ability of change of direction and explosive power of lower extremity during jumping are important competency for badminton players. Declines in physical fitness during games could easily influence sports performance. Therefore, the purpose of this study was to investigate the influence of fatigue on body accelerations during vertical jump and agility drill in elite young badminton players. METHODS: A total of 38 elite badminton players were recruited from a high-school team. For obtaining the changes of the whole-body acceleration, a nine-axes inertial measurement unit (MTw Awinda System, Xsens, Netherlands) was secured on the level of L4-L5. Participants were requested to perform three best vertical jumps and agility-T test before and after a fatigue protocol. Mean (root mean square), peak, and rate of acceleration change were calculated for time-domain analysis, and median frequency was identified after Fast Fourier Transform for frequency-domain analysis. In addition, height of vertical jumping and total finish duration and duration of each direction of the agility-T test were also recorded. RESULTS: The jumping height significantly decreased (p < 0.001), and duration of left side-shuffle running significantly increased (p = 0.021) after fatigue. For the vertical jump test, both mean and rate of change in downward acceleration during squatting subphase significantly increased after fatigue (p = 0.006 and p = 0.026, respectively). Both mean and peak in upward acceleration during jumping subphase significantly increased after fatigue (p = 0.018 and p = 0.010, respectively). No changes were observed in frequency-domain analysis. For the agility-T test, peak, range of change and mean of mediolateral acceleration significantly increased during the leftward shuffle running (p = 0.039, p = 0.038 and p = 0.002, respectively). Median frequency also significantly increased in this direction (p = 0.042). CONCLUSIONS: Fatigue could affect body accelerations in both vertical and horizontal directions during vertical jump and agility-T tests as well as sports performance for badminton players. Current findings imply declined neuromuscular control of the lower extremity might be occurred after fatigue which provides a rationale for specific training programs in badminton players.

Influence of Body Acceleration and Slip Velocity on Fluid Flow in a Multi-Stenotic Artery

Blockage of arteries by the formation of plaques causing stenosis is a major health problem among human beings.In this study, a model is developed for the flow through a multi-stenosed elastic artery segment under the effect of body acceleration and slip velocity. Fluid is regarded as Non-Newtonian Bingham Plastic Fluid. The equations representing the model are solved analytically using Perturbation Method. Result is discussed for velocity, wall shear stress and volumetric flow rate by varying several parameters like pulse frequency, slip parameter and Womersley Frequency parameter graphically.

Blood Flow Modeling in Constricted Arteries Under Body Acceleration and Wall Slip Using Two-Layered Bingham Plastic Fluid

Analysis is done on a two-layered Bingham Plastic model of restricted, thin arteries with periodic body acceleration. The model essentially consists of a centre layer with a core of suspended red blood cells and an outer layer with a peripheral plasma layer. It has been assumed that the rheology of blood in the core region has been classified as a Newtonian fluid with the PPL and a non-Newtonian fluid obeying the law of Bingham plastic model. This model has been used to investigate how blood flow in stenotic arteries is affected by body acceleration, the non-Newtonian character of blood, and a velocity slip at the wall. Analytical equations for axial velocity, flow rate, wall shear stress, and apparent viscosity are produced by using the perturbation method, and their variations with respect to various parameters are shown in the figures and explained in this article. Due to a wall slip, it is seen that while velocity and flow rate rise, effective viscosity falls. The impact of body acceleration significantly increases flow rates and speed. The physiological effects of this theoretical modelling for blood flow conditions are also briefly looked at.

基于液体晃动等效力学模型的喷雾机侧倾稳定性分析

In order to analyze the influence of liquid sloshing on roll stability of the sprayer, the equivalent mechanical model of liquid sloshing was introduced. A multi-degree-of-freedom model of the sprayer was established that includes the effect of liquid sloshing. An E-level road spectrum was constructed based on sinusoid superposition method according to the grade of the field ground unevenness, and the roll stability of the sprayer under these excitations was investigated. The effects of liquid filling ratio and driving speed were analyzed. The results show that the roll angle decreases with the increase of filling ratio at low speed, but the situation is opposite at high speed. The vertical acceleration of the vehicle body decreases to some extent under some situations due to the presence of the liquid. In general, both the roll angle and the vertical acceleration increase with the increase of the driving speed, especially in the case of existing liquid sloshing.

Influence of temperature gradient of slab track on the dynamic responses of the train-CRTS III slab track on subgrade nonlinear coupled system

Temperature is an important load for ballastless track. However, there is little research on the system dynamic responses when a train travels on a ballastless track under the temperature gradient of ballastless track. Considering the moving train, temperature gradient of slab track, gravity of slab track, and the contact nonlinearity between interfaces of slab track, a dynamic model for a high-speed train runs along the CRTS III slab track on subgrade is developed by a nonlinear coupled way in ANSYS. The system dynamic responses under the temperature gradient of slab track with different amplitudes are theoretically investigated with the model. The results show that: (1) The proportions of the initial force and stress caused by the temperature gradient of slab track are different for different calculation items. The initial fastener tension force and positive slab bending stress have large proportions exceeding 50%. (2) The maximum dynamic responses for slab track are not uniform along the track. The maximum slab bending stress, slab acceleration, concrete base acceleration appear in the slab middle, at the slab end, and at the concrete base end, respectively. (3) The maximum accelerations of track components appear when the fifth or sixth wheel passes the measuring point, and at least two cars should be used. (4) The temperature gradient of slab track has a small influence on the car body acceleration. However, the influences on the slab acceleration, concrete base acceleration, fastener tension force are large, and the influence on the slab bending stress is huge.

Influence of the turbulence conditions of crosswind on the aerodynamic responses of the train when running at tunnel-bridge-tunnel

High-speed trains (HSTs) often encounter crosswinds with complex pulsating components when running at a tunnel-bridge-tunnel section (TBTS), and their running safety may deteriorate sharply due to the complex terrain conditions in mountainous areas. This study aims to discuss the influence relationship of different turbulent conditions of the crosswind on the aerodynamic response of the HST passing through the TBTS. On the basis of the measured wind field data of a typical TBTS site, the pulsating wind field is numerically reconstructed by large eddy simulation, and the influence of the incoming flow dimension, the turbulence intensity and the average wind speed on the aerodynamic loads of the HST running at the TBTS are analysed. The corresponding influence mechanisms are explained in terms of the pressure distribution and flow field structure of the HST. The influence of the loading dimension of aerodynamic load and incoming turbulence intensity on the dynamic response index of the train body and wheel-rail contact is further discussed by establishing a wind-vehicle-bridge-tunnel coupling dynamic calculation model. The main conclusions are as follows: At the TBTS, the 1D pulsating incoming flow simulation scheme can be used rather than the 3D incoming flow scheme in calculating the aerodynamic response of the HST. The influence of the incoming turbulence intensity on the aerodynamic load of the HST is mainly reflected at the bridge section (BS), The fluctuation extent of the aerodynamic load of the HST increases with the increase in the turbulent intensity of the incoming flow. When the incoming flow turbulence intensity increases from 0 to 0.09, at the BS, the pitching acceleration of the train body and the vertical contact force of the wheel-rail on the leeward side increase by 18% and 16%, respectively. The average wind speed of the incoming flow has an important effect on the aerodynamic load of the HST, especially the head train, running at the TBTS. A linear positive correlation is found between the average wind speed of the incoming flow and the corresponding change amplitude of the aerodynamic load coefficient of the head train. When the HST runs at the TBTS, the five aerodynamic loads should be loaded in the calculation process of the aerodynamic response index of the HST, and the calculated wheel-rail response results are conservative when only two aerodynamic loads are applied to the train body.

The damage to model concrete gravity dams subjected to water explosions

Over the past century, the safety of dams has gradually attracted attention from all parties. Research on the dynamic response and damage evolution of dams under extreme loads is the basis of dam safety issues. In recent decades, scholars have studied the responses of dams under earthquake loads, but there is still much room for improvement in experimental and theoretical research on small probability loads such as explosions. In this paper, a 50-m-high concrete gravity dam is used as a prototype dam, and a water explosion model test of a 2.5-m-high concrete gravity dam is designed. The water pressure and the acceleration response of the dam body in the test are analysed. The pressure characteristics and dynamic response of the dam body are assessed. Taking the dam damage test as an example, a numerical model of concrete gravity dam damage is established, and the damage evolution of the dam body is analysed. By combining experiments and numerical simulations, the damage characteristics of the dam body under the action of different charge water explosions are clarified. The integrity of the dam body is well maintained under the action of a small-quantity water explosion, and the dynamic response of the dam body is mainly caused by the shock wave. Both the shock wave and the bubble pulsation cause the dam body to accelerate, and the peak acceleration of the dam body under the action of the bubble pulsation is only one percent of the peak acceleration of the dam body under the action of the shock wave. When subjected to explosions in large quantities of water, the dam body is seriously damaged. Under the action of a shock wave, the dam body produces a secondary acceleration response, which is generated by an internal interaction after the dam body is damaged. The damage evolution process of the dam body under the action of a large-scale water explosion is analysed, and it is found that the shock wave pressure of the water explosion causes local damage to the dam body facing the explosion. After the peak value of the shock wave, the impulse continues to act on the dam body, causing cumulative damage and damage inside the dam body.

Highlighting when animals expend excessive energy for travel using dynamic body acceleration

SummaryTravel represents a major cost for many animals so there should be selection pressure for it to be efficient – at minimum cost. However, animals sometimes exceed minimum travel costs for reasons that must be correspondingly important. We use Dynamic Body Acceleration (DBA), an acceleration-based metric, as a proxy for movement-based power, in tandem with vertical velocity (rate of change in depth) in a shark (Rhincodon typus) to derive the minimum estimated power required to swim at defined vertical velocities. We show how subtraction of measured DBA from the estimated minimum power for any given vertical velocity provides a “proxy for power above minimum” metric (PPAmin), highlighting when these animals travel above minimum power. We suggest that the adoption of this metric across species has value in identifying where and when animals are subject to compelling conditions that lead them to deviate from ostensibly judicious energy expenditure.

Personality drives activity and space use in a mammalian herbivore

BackgroundAnimal personality has emerged as a key concept in behavioral ecology. While many studies have demonstrated the influence of personality traits on behavioral patterns, its quantification, especially in wild animal populations, remains a challenge. Only a few studies have established a link between personality and recurring movements within home ranges, although these small-scale movements are of key importance for identifying ecological interactions and forming individual niches. In this regard, differences in space use among individuals might reflect different exploration styles between behavioral types along the shy-bold continuum.MethodsWe assessed among-individual differences in behavior in the European hare (Lepus europaeus), a characteristic mammalian herbivore in agricultural landscapes using a standardized box emergence test for captive and wild hares. We determined an individuals’ degree of boldness by measuring the latencies of behavioral responses in repeated emergence tests in captivity. During capture events of wild hares, we conducted a single emergence test and recorded behavioral responses proven to be stable over time in captive hares. Applying repeated novel environment tests in a near-natural enclosure, we further quantified aspects of exploration and activity in captive hares. Finally, we investigated whether and how this among-individual behavioral variation is related to general activity and space use in a wild hare population. Wild and captive hares were treated similarly and GPS-collared with internal accelerometers prior to release to the wild or the outdoor enclosure, respectively. General activity was quantified as overall dynamic body acceleration (ODBA) obtained from accelerometers. Finally, we tested whether boldness explained variation in (i) ODBA in both settings and (ii) variation in home ranges and core areas across different time scales of GPS-collared hares in a wild population.ResultsWe found three behavioral responses to be consistent over time in captive hares. ODBA was positively related to boldness (i.e., short latencies to make first contact with the new environment) in both captive and wild hares. Space use in wild hares also varied with boldness, with shy individuals having smaller core areas and larger home ranges than bold conspecifics (yet in some of the parameter space, this association was just marginally significant).ConclusionsAgainst our prediction, shy individuals occupied relatively large home ranges but with small core areas. We suggest that this space use pattern is due to them avoiding risky, and energy-demanding competition for valuable resources. Carefully validated, activity measurements (ODBA) from accelerometers provide a valuable tool to quantify aspects of animal personality along the shy-bold continuum remotely. Without directly observing—and possibly disturbing—focal individuals, this approach allows measuring variability in animal personality, especially in species that are difficult to assess with experiments. Considering that accelerometers are often already built into GPS units, we recommend activating them at least during the initial days of tracking to estimate individual variation in general activity and, if possible, match them with a simple novelty experiment. Furthermore, information on individual behavioral types will help to facilitate mechanistic understanding of processes that drive spatial and ecological dynamics in heterogeneous landscapes.

Dynamic body acceleration improves mapping of at‐sea foraging behavior in black‐tailed gulls Larus crassirostris

Areas at which seabirds forage intensively can be discriminated by tracking the individuals' at‐sea movements. However, such tracking data may not accurately reflect the birds' exact foraging locations. In addition to tracking data, gathering information on the dynamic body acceleration of individual birds may refine inferences on their foraging activity. Our aim was to classify the foraging behaviors of surface‐feeding seabirds using data on their body acceleration and use this signal to discriminate areas where they forage intensively. Accordingly, we recorded the foraging movements and body acceleration data from seven and ten black‐tailed gulls Larus crassirostris in 2017 and 2018, respectively, using GPS loggers and accelerometers. By referring to video footage of flying and foraging individuals, we were able to classify flying (flapping flight, gliding and hovering), foraging (surface plunging, hop plunging and swimming) and maintenance (drifting, preening, etc.) behaviors using the speed, body angle and cycle and amplitude of body acceleration of the birds. Foraging areas determined from acceleration data corresponded roughly with sections of low speed and area‐restricted searching (ARS) identified from the GPS tracks. However, this study suggests that the occurrence of foraging behaviors may be overestimated based on low‐speed trip sections, because birds may exhibit long periods of reduced movement devoted to maintenance. Opposite, the ARS‐based approach may underestimate foraging behaviors since birds can forage without conducting an ARS. Therefore, our results show that the combined use of accelerometers and GPS tracking helps to adequately determine the important foraging areas of black‐tailed gulls. Our approach may contribute to better discriminate ecologically or biologically significant areas in marine environments.