High-speed Video Recording Research Articles

Динамическая твердость и образование полос Портевена-Ле Шателье при ударном индентировании

The effect of shock indentation on the formation and propagation of the Portevin-Le Chatelier deformation bands in an aluminum-magnesium alloy was studied experimentally using acoustic emission and high-speed video recording methods. Dynamic and nonlinear responses to shock indentation are revealed: the first include high values of dynamic hardness and local strain and loading rates, and the second - threshold and multiple nature of force and acoustic responses. It is shown that the bands of macrolocalized deformation represent a latent volumetric type of erosion damage, which reduces the mechanical stability and durability of the alloy.

TRANSFER OF A DROP MATERIAL DURING THE PRIMARY CAVERN FORMATION

The transfer of a freely falling drop matter in the bulk of a target fluid at rest at the stage of primary cavity formation was traced by high-speed video recording for the first time. In the experiments, drops of water, ink solution (diluted in a ratio of 1:100) or a saturated solution of baking soda with a diameter of D = 0.43 cm fell with velocity of U = 3.1 m/s into fresh water or a 20% ammonium thiocyanate solution in the splash formation mode. In all experiments, the wall of the growing cavity was penetrated by thin fibers containing drop matter, which form an intermediate fine-structured layer. After the end of the fiber growth stage with a duration of 7–8 ms, the diffusion smoothed the concentration gradients, a liquid shell of intermediate density with a thickness of 1.5 to 0.7 mm was formed around the growing cavity. The shell is separated by a sharp boundary from the target fluid. A new group of inclined fibrous loops was formed in the wake of the collapsing cavity.

Development of a universal binary classifier of the state of artillery barrels by the physical fields of shots

An artillery shot is accompanied by the release of combustion products of powder gases from the barrel. It is proposed to usemuzzle ejection to classify the level of barrel wear during firing. A full-scale experiment was carried out with high-speed video recording in the visible and infrared ranges of the dynamics of the development of muzzle ejection when firing guns with a defect-free and worn barrel. Muzzle ejection when fired from a large-caliber gun consists of three spatial regions: frontal and two side, associated with the emission of powder gases through the openings of the compensators. A technique for analyzing three synchronized video streams has been developed. The technique made it possible to quite fully investigate the processes of muzzle ejectiondevelopment dynamics in defect-free and worn barrels. Informative signs are chosen, which are different for the dynamics of muzzle ejection from defect-free and worn barrels. This madeit possible to build a binary classifier of the condition of the trunks by the level of wear based on the support vector machine with least squares. In contrast to the classical SVM classifier, thisallowed us to reduce the calculation time and reduce the required size of the training set. To assess the quality of classification, it is proposed to rely on only errors of the first and second kind, but also an integral indicator –the probability of error-free classification. To increase the reliability of the classification, the concept of a universal binary classifier is proposed, which uses both video recording of the muzzle ejection and acoustic fields of the shot –ballistic and muzzle waves –to diagnose the state of the barrel. On the basis of experimental data, it is shown that the use of all physical fields accompanying an artillery shot for the binary SVM classification allows obtaining a high value of the error-free classification probability.

Deep learning study of induced stochastic pattern formation in the gravure printing fluid splitting process

We use deep learning (DL) algorithms for the phenomenological classification of Saffman-Taylor-instability-driven spontaneous pattern formation at the liquid meniscus in the fluid splitting in a gravure printing press. The DL algorithms are applied to high-speed video recordings of the fluid splitting process between the rotating gravure cylinder and the co-moving planar target substrate. Depending on rotation velocity or printing velocity and gravure raster of the engraved printing cylinder, a variety of transient liquid wetting patterns, e.g., a raster of separate drops, viscous fingers, or more complex, branched liquid bridges appear in the printing nip. We discuss how these patterns are classified with DL methods, and how this could serve the identification of different hydrodynamic flow regimes in the nip, e.g., point or lamella splitting.

Surface Damage Analysis on the Application of Abrasion and Slurry Erosion in Targeted Steels Using an Erosion Test Rig

The research focuses on slurry abrasion and erosion of martensitic steels used in the mining and agricultural industries. A traditionally constructed slurry pot tester with corundum abrasives in slurry form was used for wear characterisation. Wear testing was performed on each specimen for 180 h. Every 20 h, pauses were taken to characterise the specimen size, weight, hardness, and surface roughness. The worn zone’s damage progression was studied using optical microscopy. As the test period rose, the mass loss due to the wear, which was governed by the impact angle of the slurry flow, followed a linear pattern. The impact of specimen orientation on the wear rate was more pronounced than that of abrasive flow velocity. High-speed video recordings highlighted the varied contact conditions that caused the wear mechanism to shift from abrasion to slurry erosion. Slurry abrasion was seen at the bottom of the specimen as a result of pure sliding conditions, while pitting was observed at the top of the specimen as a result of fatigue from particle impact. Studies of 3D surfaces demonstrated a decrease in wear rate while transitioning from the abraded zone, which witnessed polishing and minor hardness, to the pitting zone. The wear performance of the materials was rated, with tempered martensitic steel coming out on top.

Complex gravity-acoustic impact on M-flame structure

Ensuring fire safety is one of the most important problems in the creation of habitable spacecraft. It is necessary to thoroughly study the issues of the reliability of the functioning of space systems, including those using chemical fuel. The paper studies experimentally the dynamics of an M-shaped premixed methane-air flame under normal and reversed gravity at various external acoustic excitation. The stable M-shaped flame is studied experimentally by means of high-speed video recording of flame chemoluminescence and PIV-methods. The paper shows that at low frequencies of acoustic excitation, the flame front remains practically undisturbed. At a 160 Hz frequency, the oscillatory motion is energetically more saturated than the main gas flow. With a further frequency increase, the main flow again becomes dominant in terms of energy, and the effect on the flame structure decreases.

Experimental modeling of bed morphological changes and toe erosion of emerged breakwaters due to wave-structure interactions in a deltaic coast

Large-scale coastal erosion in the Mekong Delta has been dramatically increasing in severity in recent decades. There are several effective hard engineering solutions that have been implemented in this delta to efficiently prevent coastal erosion and stimulate sedimentation while supporting the local ecosystem conservation. These measures include Pile-Rock Breakwaters (PRBW), Hollow Triangle Breakwaters (HTB) and Semicircular Breakwaters (SBW). However, research on the sediment transport, morphological changes and toe erosion for these offshore breakwaters is very limited and is currently in the initial stages of understanding the specific conditions of sediment characteristics and foundations. The objective of this study was to reproduce the morphological changes and toe erosion of three breakwaters due to wave-structure interactions. This was investigated using 2D physical models with 3000 irregular waves during 8 experimental hours (equal to 15,000*Tp). To extract the bed morphological changes and toe erosion both specialized laser measurements (SW50M laser ruler) and analysis of high-speed video recording by images digitalization were applied. The experimental results show that the shape and structural design of offshore breakwaters can have a significant influence on the bed morphology on both the seaside and the leeside. We found that generally the toe of the construction on the seaside was eroded due to the occurrence of reflected waves, and that the flow is narrowed while passing through the construction, increasing the flow velocity and causing toe erosion. Additionally, the accretion of sediment at the leeside of the breakwaters was found to be mainly driven by the transport of sediment through the construction. Comparing the breakwater designs the experimental results showed that the HTB has the maximum accretion rate behind the structure, as well as the fastest accretion rate behind the breakwater. The SBW has high wave energy dissipation efficiency, although the toe erosion rate is faster than the other classes of breakwaters. The PRBW shows the fastest toe erosion rate in front of the structure and causes accretion at the leeside of the construction but at a lower rate than the HTB. The findings from this study will help practical designers to reinforce the foot of construction during real breakwater designing and inform stability calculations. We recommendation is to apply these three classes of breakwaters, especially the HTB and SBW, for stimulating sedimentation for mangrove restoration in the mangrove mud-coast delta.

Functional morphology of cirri in the barnacle Amphibalanus improvisus (crustacea: Balanidae).

Barnacles rely heavily on their mobile cirri for food capture because of the sessile lifestyle. These filamentous food capturing devices are extended into the water current and perform undulating movements. Cuticular structures with corresponding musculature work together, to allow these highly repetitive movements. This paper studies the interplay between structure and function of the cirri using scanning electron microscopy (SEM), microcomputed tomography (µCT) and high-speed video recordings (HSV) in Amphibalanus improvisus. Barnacles use the external cuticle structures (denticles and setae) for efficient grooming, food capturing, and providing support for the muscular system responsible for movement control. Entanglement of the cirri during extension is probably avoided through an interlocking of the serrate setae on cirri IV-VI, creating a "zipper-like" effect, which was recorded here using the HSV. We analyzed the muscular arrangement using µCT and found a new flexor muscle in both the endo- and exopod of cirrus II. Supported by the intrinsic cirral muscles, the new flexor muscles may provide variable movements of the anterior cirri (cirri I-III), which is important for further food handling. Our results provide a foundation for further comparative studies of the feeding apparatus of barnacles and for possible implications in the area of bio-inspired robotics.

Functional morphology of prey capture in stream-dwelling sailfin silversides (Telmatherinidae) based on high-speed video recordings

Understanding how ecology shapes the evolution of morphological traits is a major goal in organismal biology. By quantifying force of motion, hypotheses on the function of fundamental tasks of animals like feeding can be tested. Ray-finned fishes use various feeding strategies, classified into three main feeding modes: suction, ram and manipulation. While manipulation feeders are usually distinct in morphology and feeding behavior, differentiation between suction and ram feeders is often fine-scaled and transitional. Previous studies have identified different feeding modes and biomechanical adaptations on interspecific and intersexual levels in lake-dwelling sailfin silversides, species of a Sulawesi freshwater radiation. Functional feeding morphology of stream-dwelling species remained in contrast unstudied. We hypothesized that different requirements of riverine habitats favor the evolution of alternative functional adaptations in stream-dwelling sailfin silversides. To test this hypothesis, we investigated feeding of two phenotypically distinct riverine species, Telmatherina bonti and Marosatherina ladigesi, and their sexes, by high-speed videos and biomechanical models. The kinematic approaches identify T. bonti as ram feeder and M. ladigesi as suction feeder. Surprisingly, the biomechanical models of the jaw apparatus provide contradicting results: only one out of three studied parameters varies between both species. Contrarily to lake-dwelling Telmatherina, sexes of both species do not differ in feeding biomechanics. We conclude that T. bonti predominantly uses ram feeding while M. ladigesi primarily uses suction feeding as its main hunting strategy. Feeding biomechanics of stream-dwelling sailfin silversides are less distinct compared to lake-dwelling species, likely due to different trophic ecologies or less stable ecological conditions.

Examination of Haines Jump in Microfluidic Experiments via Evolution Graphs and Interface Tracking

This work examines a type of rapid pore-filling event in multiphase flow through permeable media that is better known as Haines Jump. While existing microfluidic experiments on Haines Jump mostly seek to maintain quasi-steady states through very low bulk flow rates over long periods of time, this work explores the combined use of a highly structured microscale transport network, high-speed fluorescent microscopy, displacement front segmentation algorithms, and a tracking algorithm to build evolution graphs that track displacement fronts as they evolve through high-speed video recording. The resulting evolution graph allows the segmentation of a high-speed recording in both space and time, potentially facilitating topology-cognitive computation on the transport network. Occurrences of Haines Jump are identified in the microfluidic displacement experiments and their significance in bulk flow rates is qualitatively analyzed. The bulk flow rate has little effect on the significance of Haines Jump during merging and splitting, but large bulk flow rates may obscure small bursts at the narrowest part of the throat.

Towards phase-based defect detection: A feasibility study in vibrating panels

This work discusses the possibility of using phase-based motion magnification as a non-destructive inspection tool for defect detection and identification in vibrating panels. Phase-based motion magnification has recently emerged as a potentially disruptive technology in the field of optical methods for vibration engineering. In fact, the method allows to post-process high-speed video recordings in order to magnify small motions happening in a prescribed bandwidth. In particular, our strategy relies on measuring the full-field low-frequency eigen-shapes, and extracting their aberration as resulting from small defects. Effects of defects are usually very localized in space but may appear even at lower frequencies, making the approach particularly suitable for any kind of high-resolution full-field optical technique. Within this work, a novel phase-based processing pipeline for defect detection is described, and a set of preliminary tests is discussed to assess the feasibility and advantages of the methodology. All validations were carried out by means of numerical simulations relying upon a photo-realistic dynamic finite element model of a rectangular plate.

Preliminary Evaluation of a Blast Sprayer Controlled by Pulse-Width-Modulated Nozzles.

Precision spraying relies on the response of the spraying equipment to the features of the targeted canopy. PWM technology manages the flow rate using a set of electronically actuated solenoid valves to regulate flow rate at the nozzle level. Previous studies have found that PWM systems may deliver incorrect flow rates. The objective of the present study was to characterize the performance of a commercial blast sprayer modified with pulse-width-modulated nozzles under laboratory conditions, as a preliminary step before its further field validation. Four different duty cycles (25 percent, 50 percent, 75 percent and 100 percent) and four different pressures (400 kPa, 500 kPa, 600 kPa and 700 kPa) were combined to experimentally measure the flow rate of each nozzle. Results showed that the PWM nozzles mounted in the commercial blast sprayer, under static conditions, were capable of modulating flow rate according to the duty cycle. However, the reduction of flow rates for the tested duty cycles according to pressure was lower than the percentage expected. A good linear relation was found between the pressure registered by the control system feedback sensor and the pressure measured by a reference conventional manometer located after the pump. High-speed video recordings confirmed the accurate opening and closing of the nozzles according to the duty cycle; however, substantial pressure variations were found at nozzle level. Further research to establish the general suitability of PWM systems for regulating nozzle flow rates in blast sprayers without modifying the system pressure still remains to be addressed.

Temporal super-resolution high-speed holographic video recording based on switching reference lights and angular multiplexing in off-axis digital holography

We develop a temporal super-resolution high-speed holographic video recording method based on the angular multiplexing in off-axis digital holography that can achieve an acquisition rate greater than the frame rate of image sensors. We realize a high-speed switching of reference lights with different incident angles using two acousto-optic modulators. We successfully double the frame rate of the hologram recording using a rotating circular protractor and demonstrate its practical application in compressed gas flow injection; we achieve a frame rate of 175,000 fps using a high-speed image sensor triggered at 87,500 Hz.

An experimental method for evoking and characterizing dynamic color patterning of cuttlefish during prey capture.

Cuttlefish are active carnivores that possess a wide repertoire of body patterns that can be changed within milliseconds for many types of camouflage and communication. The forms and functions of many body patterns are well known from ethological studies in the field and laboratory. Yet one aspect has not been reported in detail: the category of rapid, brief and high-contrast changes in body coloration (“Tentacle Shot Patterns” or TSPs) that always occur with the ejection of two ballistic tentacles to strike live moving prey (“Tentacles Go Ballistic” or TGB moment). We designed and tested a mechanical device that presented prey in a controlled manner, taking advantage of a key stimulus for feeding: motion of the prey. High-speed video recordings show a rapid transition into TSPs starting 114 ms before TGB (N = 114). TSPs are then suppressed as early as 470–500 ms after TGB (P < 0.05) in unsuccessful hunts, while persisting for at least 3 s after TGB in successful hunts. A granularity analysis revealed significant differences in the large-scale high-contrast body patterning present in TSPs compared to the camouflage body pattern deployed beforehand. TSPs best fit the category of secondary defense called deimatic displaying, meant to briefly startle predators and interrupt their attack sequence while cuttlefish are distracted by striking prey. We characterize TSPs as a pattern category for which the main distinguishing feature is a high-contrast signaling pattern with aspects of Acute Conflict Mottle or Acute Disruptive Pattern. The data and methodology presented here open opportunities for quantifying the rapid neural responses in this visual sensorimotor set of behaviors.

КОНЦЕПТУАЛЬНЫЕ ОСНОВЫ СОЗДАНИЯ СОВРЕМЕННЫХ ТЕХНОЛОГИЙ НАПЛАВКИ ПОКРЫТИЙ

The paper presents a conceptual approach to improving the durability of the working surfaces of products using new materials and technologies for their application, including various methods of spraying and surfacing based on the analysis of modern ways of forming high characteristics on the surfaces of structural steels used under extreme operating conditions.&#x0D; The study objective is to find ways to increase the operational performance of wearing products operating under conditions of extreme loads and intensive wear, through the use of new materials and modern technologies for their application, spraying and surfacing methods.&#x0D; The problem to which the paper is devoted deals with justifying the physical principles of reinforcing coating engineering on the basis of applying the most effective ways to improve the performance of wearing products in the conditions of increased wear and extreme loads.&#x0D; Research methods: Based on an analytical review of existing approaches to reinforcing wearing surfaces, the application of modern research methods is justified including: high-speed video recording, oscillography of the main mode energy parameters, performed synchronously with the recording of video images, thermal imaging of thermal fields during experiments.&#x0D; The novelty of the work is connected with the complex application of a new generation of sprayed and surfaced materials, and promising methods of their application, including additional shock and mechanical treatment of the surface layers, as well as methods of controlled heat deposition, contributing to controlled crystallization of the melt on the treated surfaces, using pulse and arc surfacing methods.&#x0D; Research results:&#x0D; Based on the research carried out, a conceptual approach is proposed to develop modern coating technologies, including the most effective combinations of materials, both practically known because of their effective application, and new technologies, including methods of adaptive pulse surfacing technologies.&#x0D; Conclusions:&#x0D; Improving the operational properties of products used under conditions of intense wear and corrosion can be achieved by the complex application of a new generation of surfacing and sprayed materials, technologies for their application to the working bodies of rapidly wearing products, new methods of surfacing based on adaptive pulse technologies.

Investigation of the effect of electron beam parameters on the characteristics of the steam-gas channel during welding of nickel and titanium alloys

The article presents the developed technique of high-speed video recording of the combined-cycle gas channel and subsequent frame processing to obtain the dimensional characteristics of the combined-cycle gas channel. On the basis of this technique, dependences of the width of the weld at different depths were obtained depending on the current and welding speed. A pattern of dimensional characteristics of the steam-gas channel depending on the running energy and the dependence of the frequency of collapse of the steam-gas channel on the electron beam current at a constant welding speed of 40 m/h by the example of nickel and titanium alloys was revealed.

Wave spectroscopy in a driven granular material

Driven granular media constitute model systems in out-of-equilibrium statistical physics. By assimilating the motions of granular particles to those of atoms, by analogy, one can obtain macroscopic equivalent of phase transitions. Here, we study fluid-like and crystal-like two-dimensional states in a driven granular material. In our experimental device, a tunable magnetic field induces and controls remote interactions between the granular particles. We use high-speed video recordings to analyse the velocity fluctuations of individual particles in stationary regime. Using statistical averaging, we find that the particles self-organize into collective excitations characterized by dispersion relations in the frequency-wavenumber space. These findings thus reveal that mechanical waves analogous to condensed matter phonons propagate in driven granular media. When the magnetic coupling is weak, the waves are longitudinal, as expected for a fluid-like phase. When the coupling is stronger, both longitudinal and transverse waves propagate, which is typically seen in solid-like phases. We model the dispersion relations using the spatial distribution of particles and their interaction potential. Finally, we infer the elastic parameters of the granular assembly from equivalent sound velocities, thus realizing the spectroscopy of a granular material.

Citrus Fruit Movement Assessment Related to Fruit Damage during Harvesting with an Experimental Low-Frequency–High-Amplitude Device

The profitability of fresh citrus crops outlines the possibility of using mechanical systems to reduce the high cost of the manual harvesting operation. In this line, an experimental light shaker with low frequency and high amplitude and a hydraulic arm was developed. This device had been successfully used for harvesting ornamental citrus trees. In previous studies, it was proven that the removal percentage was adequate, but the percentage of slightly damaged fruit increased compared to a traditional fruit trunk shaker. Visualizing the fruit movements in high-speed video recording images during harvesting, a higher impact level was observed due to the higher amplitude. The aim of this study was to analyze the fruit movement during the vibration with the experimental shaker compared to the movement when vibrating with an orchard tractor mounted trunk shaker related to the increase of slightly damaged fruit when using the experimental shaker. Fruit movement parameters (fruit distance, fruit displacement, speed and acceleration) when using the two harvesting systems (experimental shaker and trunk shaker) were compared analyzing the high-speed video recordings. Results showed that the higher vibration amplitude produced a maximum distance experienced by the fruits (maximum displacement of 0.135 m with the experimental shaker compared to 0.078 m with the trunk shaker) that could cause a higher damage level (74% of slightly damaged fruits using the experiemntal shaker compared to 14% using the trunk shaker).

Activation of Combustion Process of Anthracite by Metal Nitrates

ABSTRACT The effect of metal nitrates on the activation of anthracite combustion process has been studied. Fe(NO3)2 · 9H2O and Cu(NO3)2 · 3H2O were used as nitrates in an amount of 5 wt% applied to anthracite powder (fraction less than 0.1 mm) by incipient wetness impregnation. Using scanning electron microscopy and EDX mapping, it was found that using this method of applying the additive makes it possible to achieve high dispersion and uniform distribution in the fuel composition. The characteristics of oxidation, ignition, and combustion were studied using thermal analysis methods and high-speed video recording in the combustion chamber at a temperature of 800°C. It was found that the use of metal nitrates contributes to an increase in the reactivity of anthracite as evidenced by a decrease in the temperature of the intensive oxidation beginning (ΔTi) by 23–84°C and the ignition delay time (Δti) by 0.9–2.2 seconds. The greatest effect of changing the reactivity of anthracite was recorded in the case of using copper nitrate additive. The use of nitrates also contributed to the decrease in the resulting fuel underburning (from 3.5 to 0.4 wt%) and gas-phase CO compounds (by 31–53%). At the early stages, combustion process of modified samples was accompanied by periodic formation of micro-explosions, which led to the activation and development of the particle surface.

Visualization in a Ranque-Hilsch vortex tube using high-speed video recording

Visualisation via video recording was carried out in a Ranque-Hilsch vortex tube with a square cross-section. Video files were captured at recording speeds from 1000 to 10 000 frames per second. The best video files were obtained at a shooting frequency of 7800 frames per second with an input pressure of 1 bar. The video confirmed the presence of a double helix in the flow core in the second section of the tube. Video files showed the presence of a circulation zone between the flow core and the periphery, which is constantly changing over time. The angle at which the particles move in the peripheral flow is clearly visible on it. The resulting video files show how the core of the flow precesses on the axis of a square-section vortex tube.