Absolute Velocity Research Articles

Radial velocities: Direct application of Pierre Connes’ shift-finding algorithm to cross-correlation functions

Context. Pipelines of state-of-the-art spectrographs dedicated to planet detection provide, for each exposure, series of cross-correlation functions (CCFs) built with a binary mask (BM), as well as the absolute radial velocity (RV) derived from the Gaussian fit of a weighted average CCFtot of the CCFs. Aims. Our aim was to test the benefits of the application of the shift-finding algorithm developed by Pierre Connes directly to the total CCFtot, and to compare the resulting RV shifts (DRVs) with the results of the Gaussian fits. In a second step, we investigated how the individual DRV profiles along the velocity grid derived from the shift-finding algorithm can be used as an easy tool for detection of stellar line shape variations. Methods. We developed the corresponding algorithm and tested it on 1151 archived spectra of the K2.5 V star HD 40307 obtained with ESO/ESPRESSO during a one-week campaign in 2018. Tests were performed based on the comparison of DRVs with RVs from Gaussian fits. DRV profiles along the velocity grid (DRV(i)) were scrutinized and compared with direct CCFtot ratios. Results. The dispersion of residuals from a linear fit to RVs from 406 spectra recorded within a single night, a measure of mean error, was found to be σ = 1.03 and 0.83 m s−1 for the Gaussian fit and the new algorithm, respectively, which is a significant 20% improvement in accuracy. The two full one-week series obtained during the campaign were also fitted with a three-planet system Keplerian model. The residual divergence between data and best-fit model is significantly smaller for the new algorithm than for the Gaussian fit. Such a difference was found to be associated in a large part with an increase of ≃1.3 m s−1 in the difference between the two types of RV values between the third and fourth nights. Interestingly, the DRV(i) profiles reveal at the same time a significant variation of line shape. Conclusions. The shift-finding algorithm is a fast and easy tool that provides additional diagnostics on the RV measurements in series of exposures. For observations made in the same instrumental configuration, and if line shapes are not varying significantly, it increases the accuracy of velocity variation determinations. On the other hand, departures from constancy of the DRV(i) profiles, as well as varying differences between RVs from this new method and RVs from a Gaussian fit can detect and report in a simple way line shape variations due to stellar activity.

Influence of Different Breathing Strategies on Plantar Pressure Distribution in Ballet Movements

PURPOSE This study investigated the differences in plantar pressure distribution when using three breathing techniques during heel raises.METHODS The subjects were 29 professional dancers aged 20 to 30 years with more than 10 years of experience. Pressure distribution according to breathing method during heel raise was measured for 10 seconds while controlling the raise speed and gaze. The three breathing techniques were randomly ordered. Peak pressure, contact area and time, displacement, and absolute velocity of the center of pressure trajectory were measured using Emed<sup>®</sup>-le from Novel GMBH. Plantar pressure was analyzed by dividing it into a total of 12 areas (masks): five toes, five metatarsals, the midfoot, and the hindfoot.RESULTS Using the teeth occlusion breathing technique, the peak pressure on the first metatarsal was significantly reduced, the contact time of the second metatarsal was significantly longer, and the displacement of the center of pressure trajectory was significantly shorter. Additionally, during the phase of the forefoot retainer, the velocity of the center of pressure trajectory was significantly reduced.CONCLUSIONS The teeth occlusion technique reduces peak pressure, increases contact time and area, and decreases the displacement and velocity of the center of pressure trajectory, demonstrating an efficient method for maintaining balance in ballet movements. This technique can potentially enhance stability and prevent injuries in ballet dancers.

Substantiating the rational shape of a drum-type working tool for surface soil treatment

The working bodies of agricultural implements should minimize resistance to movement. The shape of a curved tooth, which is fixed between two cylindrical disks, has been considered in this paper. Several such sections on the shaft form a drum similar to a harrow roller or a needle harrow. When rolling, the tooth sinks into the soil, followed by its loosening. The task was to find such a shape of the tooth, which at the first stage of immersion in the soil would slide over it as much as possible with minimal deformation, and at the second stage would balance it and turn it over. The object of the study is a drum-type working body. The work of a straight tooth with its transformation into a curved tooth was analyzed. As a result of such an analysis and subsequent search, a rational shape of a drum-type tillage working body was obtained for the purpose of reducing resistance when it is buried in the soil. The involute of a circle turned out to be such a curve. A tooth in the form of an involute of a circle has a peculiarity: at the moment of contact of the tooth with the ground, the absolute velocity vector is directed perpendicular to it. The result is explained by the fact that as the disks roll, the tooth sinks into the soil, and the point of entry remains unchanged, and the tooth itself slides practically along itself, especially in the upper layers of the soil. In known working bodies, their curvilinear form was selected experimentally. The proposed shape of the working body was obtained analytically. To reduce the resistance of the teeth entering the soil, the ratio of the tillage depth to the radius of the drum is important. The immersion of the blade to the full depth should correspond to a 30° rotation of the drum. After diving to the maximum depth, it begins to weigh the soil to the surface or loosen it. The field of application of such a tooth shape can be the improvement of the working bodies of tillage implements

Absolute velocity estimation of UAVs based on phase correlation and monocular vision in unknown GNSS‐denied environments

AbstractThis paper proposes a novel approach for absolute velocity estimation of unmanned aerial vehicles in unknown and unmapped GNSS‐denied environments. The proposed method leverages the advantages of Fourier‐based image phase correlation and utilizes off‐the‐shelf onboard sensors, including a downward‐facing monocular camera, an inertial sensor, and a sonar. The non‐matching tracking approach is particularly appealing, offering accurate estimation while remaining robust against frequency‐dependent noise, significant intensity variations, and time‐varying illumination disturbances. In the proposed method, the first step involves computing global pixel motion from consecutive images using phase correlation, which utilizes the shift property of the Fourier transform. This pixel motion estimation serves as the basis for creating a closed‐loop solution for absolute velocity estimation. To further enhance accuracy, a Kalman filter is implemented to fuse all available data and provide a reliable velocity estimate. Validation of the proposed visual‐inertial technique is conducted through simulation experiments using AirSim and real‐world flight tests. The results demonstrate the practicality and effectiveness of the approach across a range of challenging scenarios.

Gas and powder flow characteristics of packed bed: A two-way coupled CFD-DEM study

A two-way coupled Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) calculation was performed to numerically investigate the gas and powder flow characteristics within a packed bed. The analysis and discussion focused on the effects of gas phase velocity, particle shape, and size on the flow behavior of the powders. The results revealed that the average absolute velocity of the powder increased with an increase in the inlet gas flow rate. Conversely, the average dimensionless velocity exhibited the opposite trend. Particle shape significantly impacted the flowability of the powders. A critical value of sphericity equal to 0.96 was observed. For powders with sphericity less than 0.96, the average velocity fluctuated around a progressively decreasing value over time, and the powders tended to accumulate in the inlet region. In contrast, powders with a sphericity greater than 0.96 exhibited average velocities fluctuating around a constant value throughout the simulation. Additionally, a smaller number of these particles remained within the fluid domain, indicating a higher flow rate through the packed bed and ultimately exiting the fluid domain. Regarding the influence of particle size, the flowability reached a minimum value at a radius of 0.14 mm, with the average powder velocity mirroring this trend. Powders with a radius exceeding 0.14 mm demonstrated increasing flowability and average velocity. The observed impact on flowability was likely due to a combination of mechanisms. The findings presented in this paper offer valuable insights into the dynamics of powders within a packed bed. This knowledge can be instrumental in the design and analysis of packed bed reactors.

Quantifying near-fault motion effects on soil liquefaction through effective stress site response analysis

Near-fault (NF) pulse-like ground motions have a significant impact on the performance of structures, but their effects on soil liquefaction potential have been relatively understudied. This paper uses 1D effective stress site response analysis capable of modeling porewater pressure (PWP) generation to investigate the seismic site response under NF and general ground motions. The aim is to assess the effects of NF motions on soil liquefaction by considering different soil models and PWP generation models. The results show that NF ground motions generally induce larger ground responses in terms of PWP generation, especially when the durations of the motions are short. This is due to the higher cumulative absolute velocity associated with NF ground motions compared with general ground motions due to a high-velocity pulse under the same peak ground acceleration. However, this effect diminishes as the duration of motion increases. To avoid underestimating seismic demand, especially for small to moderate earthquakes, a preliminary magnitude scale factor modified for the NF effect is suggested for use in conventional soil liquefaction triggering analysis.

Hafele and Keating revisited: A novel interpretation of the results of the Hafele‐Keating experiment

The Hafele‐Keating experiment showed the occurrence of time dilation in clocks placed on two airplanes, one moving eastward and one moving westward relative to the Earth’s rotation. However, the application of the special theory of relativity failed to account for the significant differences in the data. This problem is solved by a novel approach that focuses on the absolute velocities of the clocks with reference to the Earth’s rotation and uses space as a fixed reference point. The basic idea here is that time dilatation is an experimental fact and, therefore, independent from the theory behind it, so it is independent from relativism. Time dilatation also can occur under absolute conditions. Up until now, it is not clear if the concept of relativism is correct or not. The existence of time dilatation cannot be proofs for relativism as time dilatation also can occur under absolute conditions. Here, it is established that the eastbound plane had a higher absolute velocity than its westbound counterpart, resulting in time dilation figures of 50 and 140 ns, respectively.

The effect of inlet profiles on the repeatability in the single-stage compressor

A novel method has been proposed to design inlet gauzes in single-stage low-speed simulation compressor experiments. The aim is to investigate the method for designing inlet profiles and understand how they affect the repeatability of the compressor. Based on the inlet gauzes, the effect of the inlet profile on the compressor repeatability and its flow mechanisms was investigated by the experiments. The experiment results show that, for the single-stage low-speed compressor, as the inlet flow coefficient decreases, the loss and blockage near the rotor casing caused by the tip leakage flow are enhanced, resulting in an increase in the local absolute velocity and the total pressure. Meanwhile, the radial migration of the secondary cross flow in the stator is enhanced, leading to a thinner boundary layer at the stator outlet near casing region. Consequently, the flow capacity near the casing at the compressor outlet is enhanced with a decrease in the inlet flow coefficient. Given that the flow structure and the local loss of the compressor are not sensitive to the inlet profile at the near-choked condition, employing the inlet profile generated based on the compressor outlet profile at the near-stall condition can simulate the repeating stage environment accurately in the single-stage low-speed compressor experiment.

Cumulative Absolute Velocity (CAV) parameter estimation in earthquake emergency response based on a support vector machine

Cumulative Absolute Velocity (CAV) parameter estimation in earthquake emergency response based on a support vector machine

Modeling cerebrospinal fluid dynamics across the entire intracranial space through integration of four-dimensional flow and intravoxel incoherent motion magnetic resonance imaging

BackgroundBidirectional reciprocal motion of cerebrospinal fluid (CSF) was quantified using four-dimensional (4D) flow magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) MRI. To estimate various CSF motions in the entire intracranial region, we attempted to integrate the flow parameters calculated using the two MRI sequences. To elucidate how CSF dynamics deteriorate in Hakim’s disease, an age-dependent chronic hydrocephalus, flow parameters were estimated from the two MRI sequences to assess CSF motion in the entire intracranial region.MethodsThis study included 127 healthy volunteers aged ≥ 20 years and 44 patients with Hakim’s disease. On 4D flow MRI for measuring CSF motion, velocity encoding was set at 5 cm/s. For the IVIM MRI analysis, the diffusion-weighted sequence was set at six b-values (i.e., 0, 50, 100, 250, 500, and 1000 s/mm2), and the biexponential IVIM fitting method was adapted. The relationships between the fraction of incoherent perfusion (f) on IVIM MRI and 4D flow MRI parameters including velocity amplitude (VA), absolute maximum velocity, stroke volume, net flow volume, and reverse flow rate were comprehensively evaluated in seven locations in the ventricles and subarachnoid spaces. Furthermore, we developed a new parameter for fluid oscillation, the Fluid Oscillation Index (FOI), by integrating these two measurements. In addition, we investigated the relationship between the measurements and indices specific to Hakim’s disease and the FOIs in the entire intracranial space.ResultsThe VA on 4D flow MRI was significantly associated with the mean f-values on IVIM MRI. Therefore, we estimated VA that could not be directly measured on 4D flow MRI from the mean f-values on IVIM MRI in the intracranial CSF space, using the following formula; e0.2(f−85) + 0.25. To quantify fluid oscillation using one integrated parameter with weighting, FOI was calculated as VA × 10 + f × 0.02. In addition, the FOIs at the left foramen of Luschka had the strongest correlations with the Evans index (Pearson’s correlation coefficient: 0.78). The other indices related with Hakim’s disease were significantly associated with the FOIs at the cerebral aqueduct and bilateral foramina of Luschka. FOI at the cerebral aqueduct was also elevated in healthy controls aged ≥ 60 years.ConclusionsWe estimated pulsatile CSF movements in the entire intracranial CSF space in healthy individuals and patients with Hakim’s disease using FOI integrating VA from 4D flow MRI and f-values from IVIM MRI. FOI is useful for quantifying the CSF oscillation.

Muscle-Tendon Unit Properties in Mice Bred for High Levels of Voluntary Running: Novel Physiologies, Coadaptation, Trade-Offs, and Multiple Solutions in the Evolution of Endurance Running.

AbstractMuscle-tendon unit (MTU) morphology and physiology are likely major determinants of locomotor performance and therefore Darwinian fitness. However, the relationships between underlying traits, performance, and fitness are complicated by phenomena such as coadaptation, multiple solutions, and trade-offs. Here, we leverage a long-running artificial selection experiment in which mice have been bred for high levels of voluntary running to explore MTU adaptation, as well as the role of coadaptation, multiple solutions, and trade-offs, in the evolution of endurance running. We compared the morphological and contractile properties of the triceps surae complex, a major locomotor MTU, in four replicate selected lines to those of the triceps surae complex in four replicate control lines. All selected lines have lighter and shorter muscles, longer tendons, and faster muscle twitch times than all control lines. Absolute and normalized maximum shortening velocities and contractile endurance vary across selected lines. Selected lines have similar or lower absolute velocities and higher endurance than control lines. However, normalized shortening velocities are both higher and lower in selected lines than in control lines. These findings potentially show an interesting coadaptation between muscle and tendon morphology and muscle physiology, highlight multiple solutions for increasing endurance running performance, demonstrate that a trade-off between muscle speed and endurance can arise in response to selection, and suggest that a novel physiology may sometimes allow this trade-off to be circumvented.

A mesoscale non-dimensional lattice Boltzmann model for self-sustained structures of swimming microbial suspensions

A new mesoscale two-phase flow non-dimensional lattice Boltzmann model (NDLBM) is developed for dynamical simulations of emergence and dispersion of self-sustained vortex and energy structures in microbial suspensions. Microbial fluids are treated as two-phase fluids with interaction forces between the biofluid phase and the base fluid phase, and the bioforces are based on transient local relative velocities. Microbial concentrations, sizes, shapes, densities, viscosities, surface tensions, active indexes, self repelling coefficients, and the nonlinear drag between the two phases are included in the present model. Base fluid properties and temperatures are also included. Both macroscopic and mesoscopic governing parameters are expressed with physical means for each coefficient. Compared to previous single-phase fluid mixture absolute velocity based models, the present two-phase fluid model based on the relative velocity shows faster convergence and more stable results. Parametric studies have been performed for intensities and group sizes of active flow structures in wide ranges of physical properties and governing parameters. Vorticity and energy structure patterns and scales are illustrated to show the underlying mechanism.

The Analytical Validity of Stride Detection and Gait Parameters Reconstruction Using the Ankle-Mounted Inertial Measurement Unit Syde®.

The increasing use of inertial measurement units (IMU) in biomedical sciences brings new possibilities for clinical research. The aim of this paper is to demonstrate the accuracy of the IMU-based wearable Syde® device, which allows day-long and remote continuous gait recording in comparison to a reference motion capture system. Twelve healthy subjects (age: 23.17 ± 2.04, height: 174.17 ± 6.46 cm) participated in a controlled environment data collection and performed a series of gait tasks with both systems attached to each ankle. A total of 2820 strides were analyzed. The results show a median absolute stride length error of 1.86 cm between the IMU-based wearable device reconstruction and the motion capture ground truth, with the 75th percentile at 3.24 cm. The median absolute stride horizontal velocity error was 1.56 cm/s, with the 75th percentile at 2.63 cm/s. With a measurement error to the reference system of less than 3 cm, we conclude that there is a valid physical recovery of stride length and horizontal velocity from data collected with the IMU-based wearable Syde® device.

Evaluation of liquefaction‐induced lateral spread displacement based on ensemble learning

Liquefaction‐induced lateral spread is a kind of ground deformation caused by soil liquefaction, which is a danger to houses, roads and other infrastructures. In order to systematically investigate the influence law of different parameters on lateral displacement, this paper establishes a numerical model of the seismic responses of gently sloping grounds through the open‐source finite element software OpenSees and carries out a large number of calculations considering various working conditions. Based on the calculation results, eXtreme Gradient Boosting (XGBoost) and random forest (RF) regression are used to build the proxy models for lateral spread displacement prediction. The finite element model was verified by using the multiple VELACS No. 2 centrifuge experiments. Finally, the model was interpreted using SHapley Additive exPlanation (SHAP) method. The results of the model training showed that both models were able to achieve a good fit to the numerical calculation results, with the RF model having a smaller prediction error for the centrifuge experiments. The model interpretation results showed that the modified cumulative absolute velocity (CAV5) was the most important input variable in the model, and the importance of ground slope (S), relative density (Dr) and thickness of liquefiable soil layer (HL) was relatively high. In addition, the influence of each parameter on the lateral displacement is consistent with the actual situation, reflecting the rationality of the model prediction process. In addition, the results showed that there is a threshold for the modified cumulative absolute velocity (CAV5) and Arias intensity (Ia) that leads to a significant increase in lateral displacement. The thresholds of CAV5 and Ia are 1.3 g s and 1.0 m/s, respectively. These thresholds are in good agreement with the thresholds for triggering the overall initial liquefaction of the soil layer determined by related studies, which provides a reference for the evaluation of liquefaction‐induced lateral displacement.

Influence of pulse-like motions and extreme environmental loads on the seismic foundation response of offshore wind turbines on layered liquefiable soils

Monopile foundations are known as the most common foundation solution for offshore wind turbines (OWTs). However, the state of practice for designing monopile foundations in high seismicity areas is still limited. In particular, the impact of soil liquefaction on the seismic soil-foundation-OWT interaction is not yet well understood. In this paper, three-dimensional (3D), fully-coupled, nonlinear finite-element analyses performed in the OpenSees numerical platform were used to evaluate the seismic performance of a series of hypothetical 5 MW OWTs on monopile foundations in layered, liquefiable sites. A suite of earthquake recordings with and without strong velocity pulses (i.e., near fault, pulse-like and ordinary motions, respectively) was used to investigate the impact of ground motion characteristics on the seismic response of the OWT system. Also, the influence of soil-structure interaction and earthquake shaking coupled with extreme environmental loading (i.e., wind and wave loads) on the seismic performance of soil-OWT systems was evaluated. The numerical results showed pile movements induced by extreme climate loading led to a bias in permanent settlement accumulation across the foundation area and accumulation of soil deformations in the proximity of the pile. Ground motion velocity pulses increased the cyclic stress demand in soil and, therefore, the potential for the occurrence of soil liquefaction. A subsequent, limited numerical sensitivity study showed that the foundation rotations of the OWT system were influenced by ground motion characteristics such as polarity and velocity pulses, and the presence of the wind and wave loads. The cumulative absolute velocity (CAV) was identified as the optimum ground motion intensity measure for permanent foundation settlement and tilt as well as for peak transient foundation tilt of the OWT system under extreme environmental loadings. The net outcome of these factors determined the magnitude and orientation of the foundation rotations at the end of shaking. This study highlights the importance of considering the effects of extreme loadings and pulse-like motions in the design and performance of OWT systems.

Classification of set-net fish catch volumes in Iwate Prefecture, Japan using machine learning with water temperature and current distribution images at migration depth

Efficient management of set-net fisheries can be achieved by predicting fish catches in advance. We aimed to estimate fish catch volumes using machine learning based on the data obtained from past set-net fisheries. We also suggested that the estimation can be conducted without the installation of special sensors, such as fish finders, sonars, and cameras, in the set nets. Therefore, a special feature of this study is the construction of a machine learning model using marine environmental images around the set net. In particular, the distribution images of water temperature and current at a certain water depth were applied to the model. In set-nets where migratory fish are caught, ocean data related to migration routes can be useful for estimation. The images used in this study included the water temperature at a depth of 100 m, absolute velocity at a depth of 50 m, and sea surface temperature for comparison. We then classified the fish catch into three classes as follows: chum salmon, yellowtail, and Japanese common squid in Iwate Prefecture, Japan. Consequently, our results achieved an accuracy of approximately 70–80% compared with the validation and test dataset with the water temperature at depths of 100 m. They showed higher accuracy than the sea surface temperature and absolute velocity at a depth of 50 m. This study indicates the usefulness of image-based classification for predicting the volumes of fish caught by set nets.

High accuracy ranging for space debris with spaceborne single photon Lidar.

The increasing risk posed by space debris highlights the need for accurate localization techniques. Spaceborne single photon Lidar (SSPL) offers a promising solution, overcoming the limitations of traditional ground-based systems by providing expansive coverage and superior maneuverability without being hindered by weather, time, or geographic constraints. This study introduces a novel approach leveraging non-parametric Bayesian inference and the Dirichlet process mixture model (DPMM) to accurately determine the distance of space debris in low Earth orbit (LEO), where debris exhibits nonlinear, high dynamic motion characteristics. By integrating extended Kalman filtering (EKF) for range gating, our method captures the temporal distribution of reflected photons, employing Markov chain Monte Carlo (MCMC) for iterative solutions. Experimental outcomes demonstrate our method's superior accuracy over conventional statistical techniques, establishing a clear correlation between radial absolute velocity and ranging error, thus significantly enhancing monostatic space debris localization.

Sensor-Fusion-Based Simultaneous Positioning and Vibration Suppression Method for a Three-Degrees-of-Freedom Isolator.

For vibration isolation systems, vibration suppression and platform positioning are both important. Since absolute velocity feedback causes difficulty in achieving positioning while suppressing vibration, an H∞ control strategy based on sensor fusion feedback is proposed in this paper. The signals of inertial and displacement sensors are fused through a pair of complementary filters. Thus, active control based on the fusion signal could concurrently achieve vibration and position control since it is a displacement signal. In addition, the obtained fusion signals have a lower noise level. In this way, simultaneous positioning and vibration suppression can be established using the sensor fusion strategy. On this basis, in order to obtain an optimal H∞ controller, system damping can be maximized by using the performance weight function to attenuate noise; the system bandwidth is determined by the uncertainty weight function, which can avoid the effect of high-frequency modes of the system. The effectiveness of the proposed strategy is verified by comparing it with the conventional absolute velocity feedback strategy on a 3-DOF isolator.

The MEGARA view of outflows in LINERs

Context. Feedback processes, in particular those driven by outflows, are believed to play a major role in galaxy evolution. Outflows are believed to be ubiquitous in all active galactic nuclei (AGNs), although their presence in low luminosity AGNs, in particular for Low-Ionisation Nuclear Emission line Regions (LINERs), has only started to be explored. Their properties (geometry, mass, and energetics) are still far from being properly characterised. Aims. The main goal is to use integral field spectroscopic data from the MEGARA instrument at the Gran Telescopio Canarias (GTC) to analyse a small sample of nine LINERs, candidates of hosting ionised gas outflows. We aim to study the main emission lines in the optical wavelength range to identify their properties and physical origin. Methods. We obtained data cubes in several bands at the lowest (R ∼ 6000) and highest (R ∼ 20 000) spectral resolution of MEGARA. We modelled and subtracted the stellar continuum to obtain the ionised gas contribution, and then fitted the emission lines to extract their kinematics (velocity and velocity dispersion). We identified outflows as a secondary component in the emission lines and obtained their main properties. Results. The primary component of the emission lines was typically associated with gas in the galactic disc. For some objects, there is an enhanced-σ region typically co-spatial with the secondary component. We associated it to turbulent gas produced due to the interaction with the outflows. We find signatures of outflows in six LINERs, with mass outflow rates ranging from 0.004 to 0.4 M⊙ yr−1 and energy rates from ∼1038 to ∼1040 erg s−1. Their mean electronic density is 600 cm−3, extending to distances of ∼400 pc at an (absolute) velocity of ∼340 km s−1 (on average). They tend to be compact and unresolved, although for some sources they are extended with a bubble-like morphology. Conclusions. Our results confirm the existence of outflows in the best LINER candidates identified using previous long-slit spectroscopic and imaging data. These outflows do not follow the scaling relations obtained for more luminous AGNs. For some objects we discuss jets as the main drivers of the outflows.

Modeling the repetitions-in-reserve-velocity relationship: a valid method for resistance training monitoring and prescription, and fatigue management.

Establishing a relationship between repetitions left in reserve and the mean absolute velocity (RIR-velocity relationship) during resistance training (RT) could allow for objective monitoring, prescription, and real-time adjustment of the training load and set-volume. Therefore, we examined the goodness of fit and prediction accuracy of general and individual RIR-velocity relationships in the free-weight back squat exercise. The effects of sex, training status and history, as well as personality traits, on the goodness of fit and the accuracy of these relationships were also investigated. Forty-six resistance-trained people (15 females and 31 males) performed a one-repetition maximum (1RM) test, and two repetitions to failure (RTF) tests 72 h apart. We found greater goodness of fit of individual RIR-velocity relationships compared to general RIR-velocity relationships. Individual, but not general RIR-velocity relationships established in the first testing session yielded acceptable prediction accuracy of RIR (mean error <2 repetitions) in the subsequent testing session, regardless of the load used. Similar results were obtained when both general and individual RIR-velocity relationships were averaged across the loads, suggesting that a single RIR-velocity relationship covering a range of loads can be used instead of traditional RT methods, potentially allowing for better fatigue management and more efficient adaptation.