High-speed Video Research Articles

Behavior and morphology combine to influence energy dissipation in mantis shrimp (Stomatopoda).

Animals deliver and withstand physical impacts in diverse behavioral contexts, from competing rams clashing their antlers together to archerfish impacting prey with jets of water. Though the ability of animals to withstand impact has generally been studied by focusing on morphology, behaviors may also influence impact resistance. Mantis shrimp exchange high-force strikes on each other's coiled, armored telsons (tailplates) during contests over territory. Prior work has shown that telson morphology has high impact resistance. I hypothesized that the behavior of coiling the telson also contributes to impact energy dissipation. By measuring impact dynamics from high-speed videos of strikes exchanged during contests between freely moving animals, I found that approximately 20% more impact energy was dissipated by the telson as compared with findings from a prior study that focused solely on morphology. This increase is likely due to behavior: because the telson is lifted off the substrate, the entire body flexes after contact, dissipating more energy than exoskeletal morphology does on its own. While variation in the degree of telson coil did not affect energy dissipation, proportionally more energy was dissipated from higher velocity strikes and from strikes from more massive appendages. Overall, these findings show that analysis of both behavior and morphology is crucial to understanding impact resistance, and suggest future research on the evolution of structure and function under the selective pressure of biological impacts.

Postural Change of the Annual Cicada (Tibicen linnei) Helps Facilitate Backward Flight.

Cicadas are heavy fliers well known for their life cycles and sound production; however, their flight capabilities have not been extensively investigated. Here, we show for the first time that cicadas appropriate backward flight for additional maneuverability. We studied this flight mode using computational fluid dynamics (CFD) simulations based on three-dimensional reconstructions of high-speed videos captured in a laboratory. Backward flight was characterized by steep body angles, high angles of attack, and high wing upstroke velocities. Wing motion occurred in an inclined stroke plane that was fixed relative to the body. Likewise, the directions of the half-stroke-averaged aerodynamic forces relative to the body (local frame) were constrained in a narrow range (<20°). Despite the drastic difference of approximately 90° in body posture between backward and forward flight in the global frame, the aerodynamic forces in both flight scenarios were maintained in a similar direction relative to the body. The forces relative to the body were also oriented in a similar direction when observed during climbs and turns, although the body orientation and motions were different. Hence, the steep posture appropriated during backward flight was primarily utilized for reorienting both the stroke plane and aerodynamic force in the global frame. A consequence of this reorientation was the reversal of aerodynamic functions of the half strokes in backward flight when compared to forward flight. The downstroke generated propulsive forces, while the upstroke generated vertical forces. For weight support, the upstroke, which typically generates lesser forces in forward flight, is aerodynamically active in backward flight. A leading-edge vortex (LEV) was observed on the forewings during both half strokes. The LEV's effect, together with the high upstroke velocity, increased the upstroke's force contribution from 10% of the net forces in forward flight to 50% in backward flight. The findings presented in this study have relevance to the design of micro-aerial vehicles (MAVs), as backward flight is an important characteristic for MAV maneuverability or for taking off from vertical surfaces.

Convolutional neural networks for image analysis of high-speed videos from two slab burners

High-speed video recordings of slab burner experiments were analyzed using a machine learning approach with convolutional neural networks in order to compute the regression rate of hybrid rocket fuels over time. Combustion tests of paraffin-based fuel grains performed in two different hybrid rocket slab burners were recorded with high-speed video cameras and the resulting image data are analyzed in order to determine the height of the fuel in each frame. To this end, a deep neural network with U-net architecture is trained in a supervised fashion to segment the shape of the fuel slab. It is demonstrated that this approach is more capable to segment combustion images in unsteady flow conditions than classical computer vision methods based on thresholding or edge detection. Furthermore, methods in the area of uncertainty quantification of neural networks are applied to estimate the errors in the neural network prediction to new previously unseen data. Finally, the regression rate of the fuel is computed as the rate of change of this height. This method enables automatic analysis of a large amount of video data, taking full advantage of the optical access capabilities of slab burners. Additionally, the method delivers not only the time and space average values of the fuel regression rate, but also quantifies its variation over time and over the length of the slab, providing deeper insights into the combustion mechanics of hybrid rockets.

Using Pose Estimation and 3D Rendered Models to Study Leg-Mediated Self-righting by Lanternflies.

The ability to upright quickly and efficiently when overturned on the ground (terrestrial self-righting) is crucial for living organisms and robots. Previous studies have mapped the diverse behaviors used by various animals to self-right on different substrates, and proposed physical models to explain how body morphology can favor specific self-righting methods. However, to our knowledge, no studies have quantified and modeled all of an animal's limb motions during these complicated behaviors. Here, we studied terrestrial self-righting by immature invasive spotted lanternflies (Lycorma delicatula), an insect species that must frequently recover from being overturned after jumping and falling in its native habitat. These nymphs self-righted successfully in 92-100% of trials on three substrates with different friction and roughness, with no significant difference in the time or number of attempts required. They accomplished this using three stereotypic sequences of movements. To understand these motions, we combined 3D poses tracked on multi-view high-speed video with articulated 3D models created using photogrammetry and Blender rendering software. The results were used to calculate the mechanical properties (e.g., potential and kinetic energy, angular speed, stability margin, torque, force, etc.) of these insects during righting trials. We used an inverted physical pendulum model (a "template") to estimate the kinetic energy available in comparison to the increase in potential energy required to flip over. While these insects began righting using primarily quasistatic motions, they also used dynamic leg motions to achieve final tip-over. However, this template did not describe important features of the insect's center of mass trajectory and rotational dynamics, necessitating the use of an "anchor" model comprising the 3D rendered body model and six articulated two-segment legs to model the body's internal degrees of freedom and capture the role of the legs' contribution to inertial reorientation. This anchor elucidated the sequence of highly coordinated leg movements these insects used for propulsion, adhesion, and inertial reorientation during righting, and how they frequently pivot about a body contact point on the ground to flip upright. In the most frequently used method, diagonal rotation, these motions allowed nymphs to spin their bodies to upright with lower force with a greater stability margin compared to the other less frequently used methods. We provide a concise overview of necessary background on 3D orientation and rotational dynamics, and the resources required to apply these low-cost modeling methods to other problems in biomechanics.

Cavitation and jetting from shock wave refocusing near convex liquid surfaces

We study the physical mechanisms behind the ejection of a liquid jet from a curved free surface, specifically a free-falling water drop. The jet is produced after a spherical shock wave emitted from a micro-explosion created by a focused laser pulse is refocused on the opposite side of its source. The analysis of high-speed videos of the liquid jet formation revealed that it originates from a larger, prolate cavitation bubble created by the strong tension produced after the reflection of the original wave on the air–liquid interface. The shock wave propagation and jet formation are modeled separately with finite volume simulations in OpenFOAM. Initially we study the pressure evolution inside the drop by comparing the numerical simulations with the distribution of bubbles nucleated after the passage of the negative pressure wave. The jet formation dynamics is explained by comparing the experiments with numerical results. The jet velocity is higher if the laser focus is closer to the drop surface.

Modular multi-channel high voltage arbitrary waveform generator and imaging setup for dielectric elastomer actuator characterisation

Various applications require multi-channel high-voltage sources for their control, e.g. electrostatic adhesion, electrophoresis and artificial muscles such as piezoelectric, hydraulically amplified self-healing electrostatic(HASEL) and dielectric elastomer actuators(DEAs). Further, the ability to simultaneously monitor the state of the actuators either with images, or voltage and current sensing is crucial to characterise their behaviour. In this work, we present the design of a versatile characterisation setup, capable of generating eight HV (15 kV) arbitrary waveforms(rise time of 8 ms and fall time of 80 ms for 60 MΩ load), while synchronously monitoring voltage and current, and record high-speed (120 fps) video. The setup ensures modularity and customisability by consisting of three independent modules: (1) The imaging module includes a Raspberry Pi and a Pi Camera; (2) A 3.3 V analogue interface 16-bit resolution data acquisition module on a PCB that accommodates a microcontroller board, two 8-channel analogue-to-digital converters, and an 8-channel digital-to-analogue converter; (3) Up to 8 DC-to-HVDC converter boards powered by 12 V DC, with 3.3 V analogue interface.

Neuroethology: Decoding the waggle dance

A new study combining high-speed video recordings and computational modeling has revealed an overlooked feature of the famous honeybee waggle dance, yielding the first biologically plausible neural circuit model of how the information transmitted via the waggle dance could be assimilated by the follower bees.

Condensation shock topologies in carbon dioxide and a non-condensable gas mixture in supersonic nozzles

Condensation shock waves may occur in many flow expansion devices such as turbomachinery, gas ejectors, micro thrust-nozzles, and supersonic gas flow separators. However, their experimental analysis has been barely addressed as condensation shocks comprise complex phenomena such as compressible flow behavior, a shock-like phase transition, and a two-phase flow expansion. This work characterizes experimentally some condensation shock topologies of a mixture of carbon dioxide and dry air at several compositions in a Laval nozzle. Experiments were carried out in a test-rig instrumented with high-response pressure transducers installed along the Laval nozzle wall along with a Schlieren setup equipped with a high-speed video camera imaging the flow behavior within the nozzle. The nozzle wall profile was built by using the method of characteristics developed from a real equation-of-state suited for the testing mixture. Results revealed the influence of the nozzle wall profile on the condensation shock location and topology. Moreover, there types of flow behavior were captured and named as conventional, transition, and Mach wave condensation shocks. The transition from one topology to another occurred due to the interaction between cancelation waves originated from the nozzle wall and the phase-change phenomenon, giving rise to two distinct regions characterized by certain observable droplet population density. The current investigation presents an in-depth phenomenological discussion of the three types of condensation shock topologies as such assessment has not been previously developed.

The impact of changing drum rotation direction on fabric motion and drying performance in clothes dryers

Fabric motion in tumble dryers, particularly the motion observed from the cross-section of the rotating drum, contributes significantly to the heat and mass transfer between textiles and the surrounding hot airflow. However, the wider picture for this process is not yet clear and requires further study. In this article, fabric motion with different drum rotation direction settings was analyzed experimentally to determine the effect of drum rotation direction on drying performance. A high-speed video camera was used to record the fabric motion during the entire drying process. The recorded movies were then processed, and the velocity and occupancy distributions of the tracer fabric and several motion indexes were analyzed by using OpenCV and Matlab. The results indicated that changes in the drum rotation mode cause significant variations in the dynamics of fabric motion in domestic tumble dryers across different drying conditions with variations in fabric size, drum rotation speed and load size. Constantly changing drum rotation direction plays an important role in enlarging the motion area and reducing the passive motion area, lifting the textiles up to a higher place and agitating the mixture inside the rotating drum. This means that the fabrics can be effectively scattered instead of tangling together, and because this drying condition provides more opportunities for them to be exposed to the surrounding hot airflow, it enhances convective heat and mass transfer within the drying chamber and reduces the formation of wrinkles on fabrics. This study could lead to new guidance for obtaining effective fabric motion patterns that lead to an optimal drying performance.

Simultaneous High-Speed Video Laryngoscopy and Acoustic Aerodynamic Recordings during Vocal Onset of Variable Sound Pressure Level: A Preliminary Study.

Three healthy males and three healthy females were studied by simultaneous high-speed video laryngoscopy and recording with the production of the gesture [pa:pa:] at soft, medium, and loud voices. The fiber optic endoscope was threaded through a pneumotachograph mask for the simultaneous recording and analysis of acoustic and aerodynamic data. The average increase in the sound pressure level (SPL) for the group was 15 dB, from 70 to 85 dB. The fundamental frequency increased by an average of 10 Hz. The flow was increased in two subjects, reduced in two subjects, and remained the same in two subjects as the SPL increased. There was a steady increase in the subglottic pressure from soft to loud phonation. Compared to soft to medium phonation, a significant increase in glottal resistance was observed with medium-to-loud phonation. Videokymogram analysis showed the onset of vibration for all voiced tokens without the need for full glottis closure. In loud phonation, there is a more rapid onset of a larger amplitude and prolonged closure of the glottal cycle; however, more cycles are required to achieve the intended SPL. There was a prolonged closed phase during loud phonation. Fast Fourier transform (FFT) analysis of the kymography waveform signal showed a more significant second- and third-harmonic energy above the fundamental frequency with loud phonation. There was an increase in the adjustments in the pharynx with the base of the tongue tilting, shortening of the vocal folds, and pharyngeal constriction. Voice onset occurs in all modalities, without the need for full glottal closure. There was a more significant increase in glottal resistance with loud phonation than that with soft or middle phonation. Vibration analysis of the voice onset showed that more time was required during loud phonation before the oscillation stabilized to a steady state. With increasing SPL, there were significant variations in vocal tract adjustments. The most apparent change was the increase in tongue tension with posterior displacement of the epiglottis. There was an increase in pre-phonation time during loud phonation. Patterns of muscle tension dysphonia with laryngeal squeezing, shortening of the vocal folds, and epiglottis tilting with increasing loudness are features of loud phonation. These observations show that flexible high-speed video laryngoscopy can reveal observations that cannot be observed with rigid video laryngoscopy. An objective analysis of the digital kymography signal can be conducted in selected cases.

Using a hall sensor with GoGo board to determine angular speed and angular frequency

This research focuses on modifying two physics experiments, a rotating wheel and a simple harmonic oscillator, to train pre-service physics teachers with an emphasis on digital and maker skills. The primary aims are twofold: first, to demonstrate the application of a Hall sensor, combined with the GoGo Board, in determining the angular speed in the rotating-wheel experiment and the angular frequency in the oscillation experiment. The second aim involves comparing these results with those obtained from high-speed video analysis using the Tracker software. To measure the period, a neodymium magnet was attached to both the wheel and mass. A block-based code was developed to control the Hall sensor and record the time when the magnet entered the detectable range of the sensor. In both experiments, high-speed videos at 250 fps were recorded and analysed using Tracker software. The study revealed that while the Hall sensor yields accurate measurements at lower speeds, its performance declines at higher speeds owing to limitations in accurately detecting the position of the magnet. In a simple harmonic oscillation experiment, the Hall sensor proved to be more effective at slower speeds. Although the Hall sensor approach resulted in a higher percentage error, it significantly enhanced students’ learning experience in terms of computational thinking and digital/maker skills.

Numerical simulation of two-phase gas-liquid flowthrough horizontal annulus pipe

Chemical, petroleum and nuclear systems are only a few of the industrial processes that utilize gas-liquid flow in annular closed channels. However, concentric horizontal annuli flow patterns have received little attention. The ability to precisely characterize two-phase flow patterns using computational techniques is crucial for the production, transportation, and optimization of designs. This current research aims to establish the accuracy of the computational fluid dynamics (CFD) model in predicting the gas-liquid flow pattern in the concentric annulus pipe and validating the flow pattern of liquid holdup with experimental results from the literature. The simulations were done on a test section of a 12.8 m length pipe with a hydraulic diameter of 0.0168 m using air and water as the working fluids. The volume of fluid (VOF) model in Ansys Fluent based on the Eulerian- Eulerian approach in conjunction with the realizable k-ε turbulence model was used to model the gas-liquid flow pattern, i.e. dispersed bubble, elongated bubble, and slug in a horizontal annulus. A comparison of the model with the experimental high-speed video images shows a reasonable agreement for the flow pattern and liquid holdup data.

Dopamine lesions alter the striatal encoding of single-limb gait.

The striatum serves an important role in motor control, and neurons in this area encode the body's initiation, cessation, and speed of locomotion. However, it remains unclear whether the same neurons also encode the step-by-step rhythmic motor patterns of individual limbs that characterize gait. By combining high-speed video tracking, electrophysiology, and optogenetic tagging, we found that a sizable population of both D1 and D2 receptor expressing medium spiny projection neurons (MSNs) were phase-locked to the gait cycle of individual limbs in mice. Healthy animals showed balanced limb phase-locking between D1 and D2 MSNs, while dopamine depletion led to stronger phase-locking in D2 MSNs. These findings indicate that striatal neurons represent gait on a single-limb and step basis, and suggest that elevated limb phase-locking of D2 MSNs may underlie some of the gait impairments associated with dopamine loss.

Dopamine lesions alter the striatal encoding of single-limb gait

The striatum serves an important role in motor control, and neurons in this area encode the body’s initiation, cessation, and speed of locomotion. However, it remains unclear whether the same neurons also encode the step-by-step rhythmic motor patterns of individual limbs that characterize gait. By combining high-speed video tracking, electrophysiology, and optogenetic tagging, we found that a sizable population of both D1 and D2 receptor expressing medium spiny projection neurons (MSNs) were phase-locked to the gait cycle of individual limbs in mice. Healthy animals showed balanced limb phase-locking between D1 and D2 MSNs, while dopamine depletion led to stronger phase-locking in D2 MSNs. These findings indicate that striatal neurons represent gait on a single-limb and step basis, and suggest that elevated limb phase-locking of D2 MSNs may underlie some of the gait impairments associated with dopamine loss.

Advancing Primary Ciliary Dyskinesia Diagnosis through High-Speed Video Microscopy Analysis.

Primary ciliary dyskinesia (PCD) is an inherited disorder that impairs motile cilia, essential for respiratory health, with a reported prevalence of 1 in 16,309 within Hispanic populations. Despite 70% of Puerto Rican patients having the RSPH4A [c.921+3_921+6del (intronic)] founder mutation, the characterization of the ciliary dysfunction remains unidentified due to the unavailability of advanced diagnostic modalities like High-Speed Video Microscopy Analysis (HSVA). Our study implemented HSVA for the first time on the island as a tool to better diagnose and characterize the RSPH4A [c.921+3_921+6del (intronic)] founder mutation in Puerto Rican patients. By applying HSVA, we analyzed the ciliary beat frequency (CBF) and pattern (CBP) in native Puerto Rican patients with PCD. Our results showed decreased CBF and a rotational CBP linked to the RSPH4A founder mutation in Puerto Ricans, presenting a novel diagnostic marker that could be implemented as an axillary test into the PCD diagnosis algorithm in Puerto Rico. The integration of HSVA technology in Puerto Rico substantially enhances the PCD evaluation and diagnosis framework, facilitating prompt detection and early intervention for improved disease management. This initiative, demonstrating the potential of HSVA as an adjunctive test within the PCD diagnostic algorithm, could serve as a blueprint for analogous developments throughout Latin America.

Primary and secondary breakup of molten Ti64 in an EIGA atomizer for metal powder production

Electrode Induction melting Gas Atomization (EIGA) is a free-fall gas atomization process used to produce metal powders, where a swirling supersonic gas jet hits a molten metal stream atomizing it into droplets through various fragmentation mechanisms. Fragmentation mechanisms of molten Ti64 are investigated by high-speed video visualization. The role of gas pressure and melting chamber overpressure on the fragmentation mechanisms and on the particle size distribution is determined. The mechanisms observed are fiber breakup, bag breakup and Rayleigh breakup for primary fragmentation and bag breakup and shear breakup for secondary fragmentation. Increasing the gas pressure promotes shear breakup and creates finer droplets. A model based on log-stable law is proposed to fit the mass distribution according to the dominant fragmentation regime. A good agreement is observed between the different analysis (dominant atomization regime, mass cumulative distribution evolution, parameters of log-stable law). A criterion for prediction of nozzle clogging is devised.

Comparing region of interest selection and whole-field analysis for measurement of ciliary beat frequency in high-speed video analysis

BackgroundCiliary beat frequency (CBF) is crucial in mucociliary clearance. High-speed video analysis (HSVA) is commonly used to measure CBF but lacks standardization. We compared visual observation and computer-assisted calculation using fast Fourier transformation (FFT) in freshly collected bronchial ciliary epithelial cells and cultured cells. MethodsBronchial epithelial cells were obtained from 12 patients who required bronchoscopic examination. Eighty-five videos of ciliary movement of freshly collected and cultured cells were recorded and used to calculate CBF using manual observation, region of interest (ROI) selection, and whole-field analysis. ResultsCBF measured by the ROI selection method strongly correlated with that measured using manual observation, especially in freshly collected cells. However, 27.8% of the manual observation method values were doubled in the ROI selection method, probably because a round trip of cilia was calculated as two cycles and needed to be corrected to 1/2 value. Upon increasing the number of ROIs, the results of the ROI selection method came closer to that of WFA. ConclusionsComputer-assisted calculation using FFT can aid in measuring CBF; however, current methods require visual confirmation. Further automated evaluation techniques are needed to establish more standardized and generalized CBF measurement methods using HSVA.

Analyzing Vocal Fold Frequency Dynamics Using High-Speed 3D Laser Video Endoscopy.

To examine changes in lateral and vertical vibratory motion along the anterior, middle, and posterior sections of the vocal folds, as a function of vocal frequency variations. Absolute measurements of vocal fold surface dynamics from high-speed videoendoscopy with custom laser endoscope were made on 23 vocally healthy adults during sustained /i:/ production at 10%, 20%, and 80% of pitch range. The 3D parameters of amplitude (mm), maximum velocity opening/closing (mm/s), and mean velocity opening/closing (mm/s) were computed for the lateral and vertical vibratory motion along the anterior, middle, and posterior sections of the vocal folds. Linear mixed model analysis was conducted to evaluate the differences in (a) vocal frequency levels (high vs. normal vs. low pitch), (b) axis level (vertical vs. lateral), (c) position level (anterior vs. middle vs. posterior), and (d) gender differences (male vs. female). Overall, the superior surface vertical motion of the vocal fold is greater compared with the lateral motion, especially in males. Along the superior surface, the mean and maximum closing velocities are greater posteriorly for low pitch. The location (anterior, middle, and posterior) along the superior surface is relevant only for vocal fold closing rather than opening, as the dynamics are different along the various locations. The study highlights the significance of assessing the vertical motion of the superior surface of the vocal fold to understand the complex dynamics of voice production. NA Laryngoscope, 134:3267-3276, 2024.

Experimental heat transfer results and flow visualization of horizontal Near-Saturated liquid nitrogen flow boiling in uniformly heated circular tube under Earth gravity

This study investigates 1-ge horizontal flow boiling of liquid nitrogen with a near-saturated inlet along a circular tube of dimensions 8.5-mm inner diameter and 680-mm heated length. Experiments are conducted using a payload developed for eventual parabolic flight experiments. The operating parameters varied are mass velocity of 406.76–1572.77 kg/m2s, inlet quality of −0.05 to −0.01, and inlet pressure of 336.29–493.07 kPa. High speed video recordings are presented to explain two-phase flow structure and regime transitions which are visualized through a transparent tube in a visualization section situated downstream of the heated tube. Recognized flow patterns are bubbly, plug, slug, stratified annular, and annular. Heat transfer results are presented and discussed in terms of flow boiling curve trends, streamwise wall temperature profiles, streamwise heat transfer coefficient (HTC) profiles, and average HTCs. Previous HTC correlations are evaluated against the measured HTC data, of which two are identified for superior accuracy in predicting cryogen data. Finally, this study confirms the reliability and readiness of the payload for subsequent parabolic flight experiments intended for acquisition of microgravity data.

Kinematic analysis of swimming ontogeny in seabass (Dicentrarchus labrax)

Swimming has been investigated in multiple species, but few studies consider the establishment of swimming through ontogeny. This study describes the establishment of cyclical swimming in Dicentrachus labrax, a marine fish from cold, temperate waters. The data were compared with results from previous studies on two subtropical freshwater catfish species (Clarias gariepinus and Corydoras aeneus). The three species have different modes of locomotion each during their adult stage (anguilliform, subacarangiform and carangiform). The swimming of Dicentrarchus labrax was recorded with a high-speed video camera (500 fps) from 0 to 288 hours and from 960 to 2496 hours post-hatching. Three indices, i.e. coefficient of determination (r²), coefficient of variation (CV), and Strouhal number (St), were used to investigate the establishment and efficiency of swimming. Important differences in the timing of swimming establishment were observed between the seabass and the two catfish species. The two catfish species display a sine-shaped swimming mode immediately or soon after hatching, and the efficiency of movement substantially improves during the first days of life. For seabass, however, establishment of swimming is slower during the same developmental period. These differences may be related to a faster developmental rate in the catfishes that allows them to swim rapidly in an intermediate regime flow and to develop the required morphology to establish efficient movements earlier.