Velocity Variables Research Articles

Finite-time adaptive neural network event-triggered output feedback control for PMSMs

This article investigates the finite-time adaptive neural network event-triggered output feedback control for the permanent magnet synchronous motor (PMSM) systems. The addressed PMSM systems include unknown nonlinear dynamics and immeasurable states. The neural networks are utilized to approximate the unknown nonlinear dynamics and an equivalent control design model is established, by which a neural network state observer is given to estimate the immeasurable states. By constructing an event-triggered mechanism and under the framework of adaptive backstepping control design technique and finite-time stability theory, a finite-time adaptive event-triggered output feedback control scheme is developed. It is proved that the proposed control scheme ensures the closed-loop system to be stable and the angular velocity, stator current and other state variables remain bounded in a finite time. Finally, the computer simulation is provided to confirm the effectiveness of the presented controllers.

Changes of Impact Force During Performance of Straight Punch With Two Boxing Techniques – Case Study

PURPOSE: Performance in boxing is a combination of strength, speed, and stability to create maximum impact. One of the types of punches commonly used in boxing is the straight punch. The magnitude of force exerted at the point of impact is influenced by a number of factors. Therefore, some biomechanical parameters can have greater effect than others during punch performance. Likewise, different technique modalities influence punch force. This study aims to determine differences between kinetic and kinematic parameters of punches performed with two different techniques (with and without weight shifting). METHODS: Overall, 20 straight punches were performed (10 for each observed technique) by a top-level female boxer (26.1 years old, height 170.3 cm, weight 63.2 kg). Afterwards, four kinematic variables (shoulder, upper arm, forearm, and hand velocities) were analyzed together with the position of center of mass (Xsens, Awinda). Also, overall foot pressure force of both feet (Novel pressure insoles) was analyzed for each technique, as well as the impact force of each punch (Punchsensor). Differences between the techniques were determined by MANOVA. RESULTS: Significant differences were found in foot pressure force and impact force, with higher values of punch force determined in the straight punch performance that includes weight shifting (p=0.00). Regarding kinematic parameters, there were significant differences in shoulder velocity, forearm velocity, and center of mass position (p=0.00). Upper arm and hand velocity variables did not differ significantly. This result indicates that different punch preparation can exhibit greater force and better performance. CONCLUSION: The understanding of movement pattern in punching could provide insightful instruction to coaches and boxers on how to generate powerful straight punches. The presented data objectively determined differences between two approaches in performing a straight punch which could help in correcting technical performance.

Geographic and hydromorphologic controls on interactions between hyporheic flow and discharging deep groundwater

Hyporheic exchange flow (HEF) at the streambed–water interface (SWI) has been shown to impact the pattern and rate of discharging groundwater flow (GWF) and the consequential transport of heat, solutes and contaminants from the subsurface into streams. However, the control of geographic and hydromorphological catchment characteristics on GWF–HEF interactions is still not fully understood. Here, the spatial variability in flow characteristics in discharge zones was investigated and averaged over three spatial scales in five geographically different catchments in Sweden. Specifically, the deep GWF discharge velocity at the SWI was estimated using steady-state numerical models, accounting for the real multiscale topography and heterogeneous geology, while an analytical model, based on power spectral analysis of the streambed topography and statistical assessments of the stream hydraulics, was used to estimate the HEF. The modeling resulted in large variability in deep GWF and HEF velocities, both within and between catchments, and a regression analysis was performed to explain this observed variability by using a set of independent variables representing catchment topography and geology as well as local stream hydromorphology. Moreover, the HEF velocity was approximately two orders of magnitude larger than the deep GWF velocity in most of the investigated stream reaches, indicating significant potential to accelerate the deep GWF velocity and reduce the discharge areas. The greatest impact occurred in catchments with low average slope and in reaches close to the catchment outlet, where the deep GWF discharge velocity was generally low.

Seasonal variations in total deposition velocity and washout ratio of fine aerosols revealed from beryllium-7 (7Be) measurements in Sevastopol, the Black Sea region

Washout ratios and deposition velocities are crucial in fine aerosols as they affect their atmospheric concentration, which in turn impacts human health. The only method to estimate the total (dry and wet) aerosol deposition velocity or washout ratio is by using a tracer such as beryllium-7 (7Be). This study collected field data on the temporal variability of monthly total deposition flux of 7Be and monthly mean 7Be activity in Sevastopol station, the Black Sea region from March 2011 to December 2013. From these data, the washout ratio and deposition velocity of fine aerosol particles were derived. The monthly mean values of the washout ratio and deposition velocity ranged from 388 to 3533 (mean 1112 ± 793) and from 0.1 to 1.5 cm s−1 (mean 0.6 ± 0.4 cm s−1), respectively. The dry deposition velocity in the four precipitation-free months varied between 0.10 and 0.15 cm s−1 with an average of 0.13 ± 0.02 cm s−1. The precipitation amount and frequency strongly influenced the seasonal variability of the deposition velocity, whereas the seasonal variability of the washout ratio was controlled only by the precipitation amount. The reduced washout ratio and the increased deposition velocity were associated with the increased precipitation. Thus, the results obtained allowed for parameterizations to estimate the monthly mean values of the washout ratio and deposition velocity from the data of the monthly precipitation amount.

One-Leg Stance Postural Sway Is Not Benefited by Bicycle Motocross Practice in Elite Riders.

Balance has been positioned as an important performance skill in sport. Differences in postural control have been found between levels of expertise. However, this statement remains unanswered in some cyclic sports. This work aimed to describe the one-leg balance performance of a sample of elite BMX riders-racing and freestyle-compared to a control group formed by recreational athletes. The center of pressure (COP) of nineteen international BMX riders (freestyle, n = 7; racing, n = 12) and twenty physically active adults was analyzed in a 30-s one-leg stance test on both legs. COP dispersion and velocity variables were analyzed. Non-linear dynamics of postural sway were evaluated through Fuzzy Entropy and Detrended Fluctuation Analysis. BMX athletes did not show differences between legs in any of the variables. The control group did show differences between the dominant and non-dominant leg in the magnitude of variability of the COP in the mediolateral axis. Group comparison revealed non-significant differences. International BMX athletes did not show better balance parameters than the control group in a one-leg stance balance task. The adaptations derived from BMX practice do not have a significant impact in one-leg stance balance performance.

Pulse Wave Velocity and Blood Pressure Variability as Prognostic Indicators in Very Elderly Patients

There is scarce evidence for the prognostic importance of hemodynamic measures, such as blood pressure (BP), BP variability, and arterial stiffness, in the very elderly population with advanced chronic conditions. We aimed to evaluate the prognostic importance of 24 h BP, BP variability, and arterial stiffness in a cohort of very elderly patients admitted to the hospital due to a decompensated chronic disease. We studied 249 patients older than 80 (66% women; 60% congestive heart failure). Noninvasive 24 h monitoring was used to determine 24 h brachial and central BP, BP and heart rate variabilities, aortic pulse wave velocity, and BP variability ratios during admission. The primary outcome was 1-year mortality. Aortic pulse wave velocity (3.3 times for each SD increase) and BP variability ratio (31% for each SD increase) were associated with 1-year mortality, after adjustments for clinical confounders. Increased systolic BP variability (38% increase for each SD change) and reduced heart rate variability (32% increase for each SD change) also predicted 1-year mortality. In conclusion, increased aortic stiffness and BP and heart rate variabilities predict 1-year mortality in very elderly patients with decompensated chronic conditions. Measurements of such estimates could be useful in the prognostic evaluation of this specific population.

Modelling the dispersion in residence time of size-dispersed particles with fluctuating axial velocity falling through a fluid

The residence time of a spherical particle falling in a stationary, Newtonian liquid is examined. The diameter of the particle is taken to be a described by the Log-Normal distribution which leads to a variation in residence time. Additionally, the complexity of the particle-fluid interaction introduces further dispersion into the residence time by causing particle velocity to fluctuate about its nominal value. Experiments were conducted at two ranges of Reynolds Numbers with a variety of particle-liquid systems to examine this phenomenon. The variability in velocity can be characterised by a dispersion parameter and a corresponding particle Peclet number. Using probability theory, a novel expression is developed that permits the effect of both the dispersion in particle diameter and the irregular nature of particle motion on particle residence time to be simultaneously quantified. Such an approach permits the relative influence of systematic size dispersion and fluctuations in motion on residence time to be determined. It provides new insights into settling behavior which can be used to promote greater uniformity in residence time.

Solutions to the non-cutoff Boltzmann equation in the grazing limit

It is known that in the parameters range $-2 \leq \gamma <-2s$ spectral gap does not exist for the linearized Boltzmann operator without cutoff but it does for the linearized Landau operator. This paper is devoted to the understanding of the formation of spectral gap in this range through the grazing limit. Precisely, we study the Cauchy problems of these two classical collisional kinetic equations around global Maxwellians in torus and establish the following results that are uniform in the vanishing grazing parameter $\epsilon$: (i) spectral gap type estimates for the collision operators; (ii) global existence of small-amplitude solutions for initial data with low regularity; (iii) propagation of regularity in both space and velocity variables as well as velocity moments without smallness; (iv) global-in-time asymptotics of the Boltzmann solution toward the Landau solution at the rate $O(\epsilon)$; (v) continuous transition of decay structure of the Boltzmann operator to the Landau operator. In particular, the result in part (v) captures the uniform-in-$\epsilon$ transition of intrinsic optimal time decay structures of solutions that reveals how the spectrum of the linearized non-cutoff Boltzmann equation in the mentioned parameter range changes continuously under the grazing limit.

Kinetic and Kinematic Assessment of the Band-Assisted Countermovement Jump.

Fernandes, JFT, Arede, J, Clarke, H, Garcia-Ramos, A, Perez-Castilla, A, Norris, JP, Wilkins, CA, and Dingley, AF. Kinetic and kinematic assessment of the band-assisted countermovement jump. J Strength Cond Res 37(8): 1588-1593, 2023-This study sought to elucidate kinetic and kinematic differences between unloaded and band-assisted countermovement jumps (CMJs). In a randomized order, 20 healthy subjects (mass 84.5 ± 18.6 kg) completed 3 repetitions of CMJs across 3 conditions: unloaded (at body mass), low, and moderate band (8.4 ± 1.9 and 13.3 ± 3.3 kg body mass reduction, respectively). For all repetitions, a force platform and linear position transducer were used to record and calculate kinetic and kinematic data. Body mass was significantly different between the unloaded, low, and moderate band conditions ( p < 0.05). Peak velocity, absolute peak, and mean force and movement duration displayed a trend that was mostly related to the condition (i.e., unloaded > low > moderate) ( p < 0.05). The opposing trend (i.e., moderate > low > unloaded) was generally observed for relative peak and mean force, reactive strength index modified, and flight time ( p < 0.05). No differences were observed for mean velocity, movement duration, and absolute and relative landing forces ( p > 0.05). The use of band assistance during CMJs can alter force, time, and velocity variables. Practitioners should be aware of the potential positive and negative effects of band assistance during CMJs.

Settling dynamics of cohesive sediments in a highly turbid tidal river

An optical settling column was used in the Garonne Tidal River to estimate the settling velocity of suspended matter in surface waters over a period characterized by contrasting hydrological conditions. A time and space variability of settling velocity was observed during this study. The settling velocities of surface suspended matter ranged from 0.018 to 0.268 mm. s−1, and the median diameter of dispersed particles varied from 4.74 to 14.38 μm. The data revealed the physical processes influencing the sediment settling dynamics throughout different time scales in a highly turbid tidal river. On tidal and fortnightly time scales, resuspension, deposition and advection mechanisms were the major drivers of the settling velocity variability, while it is likely that the estuarine turbidity maxima (ETM) was responsible for seasonal variations. The findings of this work suggest that in tidal rivers, salinity is too low to promote flocculation, whereas ETM can play a key role in enhancing this process. The stronger variability in settling velocity occurs on a tidal timescale, with median values up to four times higher at the end of the ebb tide than at high water. These variations cannot be correlated to salinity or sediment concentration. On a seasonal timescale, flocculation appears to be strongly correlated with the presence of the ETM and associated fluid mud layer. A simple correlation based on tidal variations seems to be a better predictor than the relationships based on the sediment concentration.

Variability of Glacier Velocity and the Influencing Factors in the Muztag-Kongur Mountains, Eastern Pamir Plateau

Glacier velocity is the key to understanding the nature of glaciers. Its variation plays an important role in glacier dynamics, mass balance, and climate change. The Muztag-Kongur Mountains are an important glacier region in the Eastern Pamir Plateau. Under the background of global warming, the glacier velocity variation has been widely considered, but details of the inter-annual and intra-annual changes have not been clear. In this study, we explored the inter-annual and intra-annual variations in the glacier velocity from 1990 to 2021, and the influencing factors, based on Landsat images, Inter-Mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE), and Karakoram Highway (KKH) data product analysis. The results showed the following: (1) the glacier velocity has increased since 1990, and significant growth occurred in 1995–1996. (2) A transverse profile of two typical glaciers was used to analyze the monthly variation in glacier velocity during the year. The peaks of monthly velocity occurred in May and August. (3) Since 1990, the inter-annual precipitation has increased, and the temperature increase slowed down from 2000 to 2013. The trend of inter-annual glacier velocity variation was consistent with that of the precipitation. The glacier velocity peaked in 1996/1997 due to increased precipitation in 1995. The glacier velocity over the year was consistent with the monthly precipitation trends, which indicates that precipitation has a significant influence on the change in glacier velocity. (4) In addition to temperature and precipitation, the glacier velocity variation was moderately correlated with the glacier size (length and area) and weakly correlated with the slope. The spatial distribution of glaciers shows that the spatial heterogeneity of glaciers in the Muztag-Kongur Mountains is affected by the westerly circulation. The long-term glacier velocity variation research of the Muztag-Kongur Mountains will contribute to a better understanding of glacier dynamics within the context of climatic warming, and the different influencing factors were analyzed to further explain the glacier velocity variation.

Deep Learning-Based Prediction of Unsteady Reynolds-Averaged Navier-Stokes Solutions for Vertical-Axis Turbines

The following study investigates the effectiveness of a deep learning-based method for predicting the flow field and flow-driven rotation of a vertical-axis hydrokinetic turbine operating in previously unseen free-stream velocities. A Convolutional Neural Network (CNN) is trained and tested using the solutions of five two-dimensional (2-D), foil-resolved Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations, with free-stream velocities of 1.0, 1.5, 2.0, 2.5, and 3.0 m/s. Based on the boundary conditions of free-stream velocity and rotor position, the flow fields of x-velocity, y-velocity, pressure, and turbulent viscosity are inferred, in addition to the angular velocity of the rotor. Three trained CNN models are developed to evaluate the effects of (1) the dimensions of the training data, and (2) the number of simulations used as training cases. Reducing data dimensions was found to diminish mean relative error in predictions of velocity and turbulent viscosity, while increasing it in predictions of pressure and angular velocity. Increasing the number of training cases from two to three was found to reduce relative error for all predicted unknowns. With the best achieved CNN model, the variables of x-velocity, y-velocity, pressure, turbulent viscosity, and angular velocity were inferred with mean relative errors of 6.93%, 9.82%, 10.7%, 7.48%, and 0.817%, respectively.

A multi-spatiotemporal scale strategy to evaluate factors controlling pebble mobility and its interactions with bedforms in a lowland gravel-bed river

This work analysed the factors controling the spatiotemporal variability in bedload mobility in a low-energy gravel-bed meandering river, with a particular focus on interactions between bedload transport distance and bedforms (bar-riffle-pool units). We first addressed the influence of pre-existing morphology, especially bars, on event transport distance, and examined to what extent the maintenance of bedforms requires hydrological events that can move bedload over distances at least equivalent to the length of two successive identical geomorphic units. Specifically, we tracked the displacement of passive integrated transponder (PIT)-tag particles 10 years after their injection, and applied bedload formulae to reconstruct the event transport distance for a 32-year study period. The results showed that event bedload distances for bed surface median size sediments (D50) could not exceed an active channel width, roughly equivalent to 0.3 times the median distance between riffles and between pools. This has two main implications; first, trapping by bars is rare, or perhaps even absent, at the scale of competent events for most particles located at a distance greater than an active channel width from a bar; second, because no event is able to transport bedload over distances at least equal to the length of one riffle-pool unit, maintenance of bedforms must arise from successive minor changes. Furthermore, our data reveal important variability in bedload velocity at the decadal scale according to the year of injection, type of geomorphic unit of injection, and method of injection. This highlights the long-term effects in low-energy rivers of location, timing, and method of injection on velocity estimate. Lastly, we inferred the long-term bedload velocity from PIT-tag data and applied it to bedload formulae. The resulting velocity of 0.95–1.3 km century-1 is considered an overestimate because the slowdown of tracers seeded at the bed surface due to their progressive mixing in the active layer and their trapping in bars is still ongoing.

Differences in Tridimensional Shoulder Kinematics between Asymptomatic Subjects and Subjects Suffering from Rotator Cuff Tears by Means of Inertial Sensors: A Cross-Sectional Study.

Background: The aim of this study was to analyze differences in three-dimensional shoulder kinematics between asymptomatic subjects and patients who were diagnosed with rotator cuff tears. Methods: This cross-sectional study recruited 13 symptomatic subjects and 14 asymptomatic subjects. Data were obtained from three inertial sensors placed on the humerus, scapula and sternum. Kinematic data from the glenohumeral, scapulothoracic and thoracohumeral joints were also calculated. The participants performed shoulder abductions and flexions. The principal angles of movements and resultant vectors in each axis were studied. Results: The glenohumeral joint showed differences in abduction (p = 0.001) and flexion (p = 0.000), while differences in the scapulothoracic joint were only significant during flexion (p = 0.001). The asymptomatic group showed higher velocity values in all sensors for both movements, with the differences being significant (p < 0.007). Acceleration differences were found in the scapula during abduction (p = 0.001) and flexion (p = 0.014), as well as in the sternum only during shoulder abduction (p = 0.022). Conclusion: The results showed kinematic differences between the patients and asymptomatic subjects in terms of the mobility, velocity and acceleration variables, with lower values for the patients.

Educational Mechatronics Training System Based on Computer Vision for Mobile Robots

Boosting by the world’s context, several efforts have been maiden toward the digital transformation of Education. Technology-based active learning has become pivotal in pursuing a more flexible education system. This work presents the development of an Educational Mechatronics (EM) training system based on computer vision that performs as a positioning system for mobile robots in the 2D plane. The results show that the obtained precision, exactitude, and resolution of the EM training system are suitable for robotics applications comprising position, velocity, and acceleration variables. Moreover, an instructional design aligned with the EM conceptual framework, using the EM training system and a LEGO mobile robot, is presented to construct the mechatronic concept: line segment.

Plant phenology drives seasonal changes in shear stress partitioning in a semi-arid rangeland

Accurate representation of surface roughness in predictive models of aeolian sediment transport and dust emission is required for model accuracy and for models to inform wind erosion management. While past wind tunnel and field studies have examined roughness effects on drag partitioning, the spatial and temporal variability of surface shear velocity and the shear stress ratio remain poorly described. Here, we use a four-month dataset of total shear velocity (u*) and soil surface shear velocity (us*) measurements to examine the spatiotemporal variability of the shear stress ratio (R) before, during, and after vegetation green-up at a honey mesquite (Prosopis glandulosa Torr.) shrub-invaded grassland in the Chihuahuan Desert, New Mexico, USA. Results show that vegetation green-up, the emergence of leaves, led to increased drag and surface aerodynamic sheltering and a reduction in us* and R magnitude and variability. We found that us* decreased from 20% to 5% of u* as the vegetation form drag and its sheltering effect increased. Similarly, the spatiotemporal variability of R was found to be linked directly to plant phenological phases. We conclude that drag partition schemes should incorporate seasonal vegetation change, via dynamic drag coefficients and/or R, to accurately predict the timing and magnitude of seasonal aeolian sediment fluxes. The drag partition response to mesquite phenological phases also provided insight to potential mesquite herbicide treatment effects which, if successful, could increase wind erosivity and the onsite and downwind impacts of wind erosion unless protection by herbaceous plants is maintained.

Evaluating Note Frequency and Velocity During Improvised Active Music Therapy in Clients With Parkinson's Disease.

The purpose of this article was to report on the findings of the note frequency and velocity measures during Improvised Active Music Therapy (IAMT) sessions with individuals with Parkinson's disease (PD). In this single-subject multiple baseline design across subjects, the article reports the note frequency (note count) and velocity of movement (mean note velocity) played by three right-handed participants while playing uninterrupted improvised music on a simplified electronic drum-set. During baseline, the music therapist played rhythmic accompaniment on guitar using a low-moderate density of syncopation. During treatment, the Music Therapist introduced rhythms with a moderate-high density of syncopation. The music content of the sessions was transformed into digital music using a musical instrument digital interface. Results of this study indicated that all participants exhibited an increase in note count during baseline until reaching a plateau at treatment condition and were found to be significantly positively correlated with the Music Therapist's note count. All participants played more notes with upper extremity (UE) across conditions than with lower extremity. All participants also scored similar total mean velocity across conditions. Two participants demonstrated higher mean note velocity with UE than right foot, whereas the other participant did not demonstrate this difference. Two participants also exhibited greater mean note velocity variability with left foot within and across conditions. More research is required to identify commonalities in note count and mean note velocity measures in individuals with PD during IAMT sessions.

Characterization of proven Late Cretaceous Reservoir rocks in the Gulf of Gabes: Integrated case study

Microstructural features control the petrophysical properties of rocks. Of these, pore size is particularly sensitive when non-wetting fluids saturate the reservoir. The pore networks and physical properties (helium, water and mercury saturation porosity, bulk density, nitrogen permeability, P-wave velocity and thermal conductivity) of different rock types from a productive Upper Cretaceous (Coniacian) reservoir in the tunisian offshore are measured on hydrocarbon-washed samples. The facies sampled of Douleb Member are wackestone, packstone and grainstone textures as well as dolostone, dolomitized packstone and anhydrite textures. Based mainly on the results obtained by mercury injection, the porous facies of the Coniacian Douleb Member are characterized by a complex pore system with a large morphological and pore size variability in the rock. Porosity values range from 0.3 to 23.6%, bulk densities vary from 2.05 to 2.92 g.cm−3. The permeability is variable from 3760 mD to values below 0.01 mD (measurement limit of the device). P-wave propagation velocity values range from 2060 to 6084 m.s−1 and thermal conductivity varies from 1.43 to 3.77 W.m−1.K−1. The oil-impregnated facies with the best petrophysical characteristics are mainly the rudist-rich limestones and dolomites of the first unit (U1) of the Douleb Member. The well-sorted grainstones with small rudist debris and peloids have the best reservoir qualities. Porosity is the first order characteristic that controls petrophysical properties. The variability of permeability values around this first-order relationship is attributed to variations in the size of the pore access thresholds and connectivity. The variability in velocities is due to the shape of the voids, while the variability in thermal conductivity measurements is due to the nature of the contacts between the grains.

Free weight training vs. elastic band training

The aim of this study was to assess the effectiveness of two resistance training (RT) programs (free weight [FW] and elastic band [EB]) on velocity variables (handball throwing velocity [HTV] and maximal theoretical velocity [V0]) using load-velocity (L-V) relationship modelling. Both programs lasted 6 weeks and consisted of performing bench press and overarm dumbbell pull-over using free weights (FW group) or elastic bands (EB group). Nineteen male sports science students were randomly assigned to EB (n=10) or FW group (n=9). Both RT programs increased HTV and V0, although the increment was greater in the FW (&amp;gt;2 m·s-1) compared to the EB group (&amp;lt;1 m·s-1). RT programs had selective effects on the strength variables being FW more effective in increasing 1-repetition maximum, while EB in increasing maximal isometric force. Very large correlations were observed between two-point (L-V relationship modelled through two pairs of L and V data) and multiple-point methods (L-V relationship modelled through six pairs of L and V data) (V0: r=0.96; HTV: r=0.93). All coefficients of variation showed high validity both for V0 and HTV (≤6.2%). Altogether, FW training should be used for increasing the velocity of the throwing performance, while the two-point method for following training-induced changes.

Monitoring debris flows in the Gadria catchment (eastern Italian Alps): Data and insights acquired from 2018 to 2020

This work analyses seven debris flows recorded between 2018 and 2020 in the Gadria instrumented catchment (South Tirol). We focus on three aspects not previously explored in this catchment: (i) the debris-flow transfer times between the headwaters and the outlet; (ii) the longitudinal variability of debris-flow velocity between the three downstream monitored cross-sections, and (iii) the characteristics of the secondary surges observed in three debris flows. In most cases, the mean velocity of the debris flow estimated from the upper to the lower channel reaches (for travel distance of 2155 m) is rather low, ranging between 1.9 and 3.9 m/s. This result could indicate a progressive slowing down, and possibly even temporary stops of debris flows along the path. Some variability in flow velocity was observed between two channel reaches in the lower part of the catchment (0.7 – 2.3 m/s in the upstream reach, and 1.4 – 4.7 in the downstream one). Regarding the secondary surges, these have been noted to occur superimposed on slow-moving slurry-type phases. The mean velocity of the secondary surges varied between 3.5 and 8.9 m/s, with an average value close to 6 m/s for all three events. Their regular shape, duration, and depth suggest that such surges were generated by flow instabilities, with no external forcing.