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Image‐based measurements of underwater infrastructure dynamics is challenging due to the refractive nature of the environment. To mitigate this problem, a multimedia high‐speed videogrammetric technique is proposed. The approach monitors the motion states of the underwater object and introduces a virtual refracting interface compensation model. The spatial expression of the virtual refracting interface is first found as a convex surface. Through the proposed compensation model, the complex multimedia refraction imaging can be easily transformed to simple dual‐media refraction imaging. Combined with high‐speed videogrammetry, this multimedia imaging analysis approach can measure underwater deformation. Simulated and experimental testing confirmed the feasibility and reliability of the proposed approach with sub‐millimetre positioning accuracy. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusions Physical vascular phantoms are instrumental in studying intracranial aneurysms and testing relevant imaging tools and training systems to provide improved clinical care. Current vascular phantom production methods have major limitations in capturing the biophysical and morphological characteristics of intracranial aneurysms with good fidelity and multi‐modal imaging capacity. With stereolithography (SLA) 3D printing technology becoming more accessible, newer flexible and transparent printing materials with higher precision controls open the door for improving the efficiency and quality of producing anthropomorphic vascular phantoms but have rarely been explored for the application.This technical note intends to report the feasibility of using SLA 3D printing technology to manufacture flexible intracranial aneurysm phantoms with similar scales to the real anatomy, as well as their capacity for multi‐modal flow imaging and analysis, including ultrasound flow imaging, high‐speed filming, and particle image velocimetry analysis.We designed and 3D‐printed two intracranial aneurysm phantoms with an SLA 3D printer using Formlabs Elastic 50A resin. By using a micropump to introduce cyclical flows in the phantoms, we first employed conventional Doppler and vector flow ultrasonography to observe and measure different fluidic properties. Then, a high‐speed camera was used to record particles flowing within the phantom, and we further conducted a particle image velocimetry analysis, including the distribution of mean 2D velocity vectors, average velocity magnitudes, and the mean vorticity fields in the phantom for the high‐speed imaging data.We successfully 3D‐printed flexible intracranial aneurysm phantoms with similar dimensions to the real anatomy. Additionally, we validated the phantoms’ ability to allow visualization, measurement, and analysis of flow dynamics based on both real‐time ultrasound and optical imaging.Our proof‐of‐concept study illustrates that SLA 3D printing using commercial elastic resins can significantly contribute towards facilitating the fabrication of flexible intracranial aneurysms phantoms for training, research, and preoperative planning. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Spray systems in agriculture serve essential roles in the precision application of pesticides, fertilizers, and water, contributing to effective pest control, nutrient management, and irrigation. These systems enhance efficiency, reduce labor, and promote environmentally friendly practices by minimizing chemical waste and runoff. The efficacy of a spray is largely determined by the characteristics of its droplets, including their size and velocity. These parameters are not only pivotal in assessing spray retention, i.e., how much of the spray adheres to crops versus becoming environmental runoff, but also in understanding spray drift dynamics. This study introduces a real-time deep learning-based approach for droplet detection and tracking which significantly improves the accuracy and efficiency of measuring these droplet properties. Our methodology leverages advanced AI techniques to overcome the limitations of previous tracking frameworks, employing three novel deep learning-based tracking methods. These methods are adept at handling challenges such as droplet occlusion and varying velocities, ensuring precise tracking in real-time potentially on mobile platforms. The use of a high-speed camera operating at 2000 frames per second coupled with innovative automatic annotation tools enables the creation of a large and accurately labeled droplet dataset for training and evaluation. The core of our framework lies in the ability to track droplets across frames, associating them temporally despite changes in appearance or occlusions. We utilize metrics including Multiple Object Tracking Accuracy (MOTA) and Multiple Object Tracking Precision (MOTP) to quantify the tracking algorithm's performance. Our approach is set to pave the way for innovations in agricultural spraying systems, offering a more efficient, accurate, and environmentally responsible method of applying sprays and representing a significant step toward sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the laser directed energy deposition (LDED) process, the in-flight thermal dynamics of metal powders lead to the formation of detrimental by-products such as fumes, flames, and metal vapors. In this work, we use a high-speed camera to investigate the nuanced thermal stage changes of the powders, examining how gas flow rates and laser beam powers influence them. We identify distinct stages in the powder's journey: heating up, fusion and vaporization, flaming, tailing, and accelerated falling. Notably, the latter stages adversely affect both the processing environment and surface quality. Control over gas flow rate and laser beam power dictates the trajectory, duration, and intensity of tailing. Additionally, laser irradiation accelerates the falling speed of particles by 6.8–22.8% compared to non-irradiated ones. Higher laser beam powers increase vaporization-induced propulsion, culminating in escalated particle velocities. Optimal gas flow rates enhance the surface quality by significantly minimizing high-temperature spatter. Through this work, the in-flight thermal dynamic behaviors of metal particles and their impact on LDED processing are explained.

Invasive plant species pose ecological threats to native ecosystems, particularly in areas adjacent to roadways, considering that roadways represent lengthy corridors through which invasive species can propagate. Traditional manual survey methods for monitoring invasive plants are labor-intensive and limited in coverage. This paper introduces a high-speed camera system, named CamAlien, designed to be mounted on vehicles for efficient invasive plant species monitoring along roadways. The camera system captures high-quality images at rapid intervals, to monitor the full roadside when following traffic speed. The system utilizes a global shutter sensor to reduce distortion and geotagging for precise localistion. The camera system makes it possible to collect extensive data sets, which can be used for a digital library of the invasive species and their locations, but also subsequent training of machine learning algorithms for automated species recognition.

The Event‐based Vision Sensor (EVS) is a bio‐inspired sensor that captures detailed motions of objects, aiming to become the 'eyes' of machines like self‐driving cars. Compared to conventional frame‐based image sensors, the EVS has an extremely fast motion capture equivalent to 10,000‐fps even with standard optical settings, plus high dynamic ranges for brightness and also lower consumption of memory and energy. Here, we developed 22 characteristic features for analysing the motions of aquatic particles from the EVS raw data and tested the applicability of the EVS in analysing plankton behaviour. Laboratory cultures of six species of zooplankton and phytoplankton were observed, confirming species‐specific motion periodicities up to 41 Hz. We applied machine learning to automatically classify particles into four categories of zooplankton and passive particles, achieving an accuracy up to 86%. At the in situ deployment of the EVS at the bottom of Lake Biwa, several particles exhibiting distinct cumulative trajectory with periodicities in their motion (up to 16 Hz) were identified, suggesting that they were living organisms with rhythmic behaviour. We also used the EVS in the deep sea, observing particles with active motion and periodicities over 40 Hz. Our application of the EVS, especially focusing on its millisecond‐scale temporal resolution and wide dynamic range, provides a new avenue to investigate organismal behaviour characterised by rapid and periodical motions. The EVS will likely be applicable in the near future for the automated monitoring of plankton behaviour by edge computing on autonomous floats, as well as quantifying rapid cellular‐level activities under microscopy. [ABSTRACT FROM AUTHOR]

In this study, underwater explosion tests with 2.5 g trinitrotoluene explosive under different fixed plates with prefabricated holes were conducted. The experimental results showed that the air inflow from the prefabricated hole caused the bubble to collapse earlier with an increase in the hole diameter. In addition, the deformation mode of the thin plate transitioned from "convex" to "concave" (up to down). Next, the coupled Eulerian-Lagrangian method was used to perform the corresponding numerical simulation. The accuracy of the numerical simulation method was verified through a comparison with the experimental data. In addition, a series of numerical simulations were conducted with different prefabricated-hole diameters, blast distances, and prefabricated-hole shapes. The results showed that the bubble-pulsating water jet substantially influenced the deformation of the thin plate when the diameter of the prefabricated hole was within the theoretical maximum bubble radius. When the blast distance was within the theoretical maximum bubble radius, the thin plate was subjected to only a single bubble pulsation owing to the air inflow from the prefabricated hole. [ABSTRACT FROM AUTHOR]

To study the fracture speed of power turbine blades in aero-engine and its variation law with the proportion of bending stress, a total of 32 simulated blades with 4 different ratios of bending stress were designed and processed based on the principle of equivalence. The fracture speed of the simulated blades was calculated by finite element method. The simulated blades were grouped and fracture speed measurement experiments were conducted to obtain the actual fracture speed and fracture form of the blades. The simulated blade fracture test process was recorded by high-speed camera technology, and the variation law of blade fracture speed with the proportion of blade bending stress was obtained. The research results show that the error between the actual fracture speed and the calculated speed of the simulated blades are not greater than 1. 10%. Within a certain range, as the bending stress decreases, the fracture speed of the blade generally shows a downward trend, and as the proportion of bending stress in the blade increases, the fracture speed of the blade decreases faster. The research provides a reference for the strength design and blade fracture test methods of real blades, which has important engineering application value. [ABSTRACT FROM AUTHOR]

In this study, a stable and high-speed vision-based self-position estimation method was proposed that improves upon the existing method of lane detection by recognizing the lighting facilities that are installed in tunnels on Japanese expressways where GNSS cannot be used. In addition, we proposed a method for inspecting multiple cracks at once by estimating the self-position with the successful rate 75% in the traveling direction by counting the lighting with the successful rate 99.85%. The effectiveness of the method was verified by capturing images of cracks in an actual tunnel. The proposed method will enable more frequent inspections for tunnel cracks that lead to flaking while maintaining infrastructure safety, reducing costs, and improving tunnel visual inspection flow efficiency. [ABSTRACT FROM AUTHOR]

Invasive plant species pose ecological threats to native ecosystems, particularly in areas adjacent to roadways, considering that roadways represent lengthy corridors through which invasive species can propagate. Traditional manual survey methods for monitoring invasive plants are labor-intensive and limited in coverage. This paper introduces a high-speed camera system, named CamAlien, designed to be mounted on vehicles for efficient invasive plant species monitoring along roadways. The camera system captures high-quality images at rapid intervals, to monitor the full roadside when following traffic speed. The system utilizes a global shutter sensor to reduce distortion and geotagging for precise localistion. The camera system makes it possible to collect extensive data sets, which can be used for a digital library of the invasive species and their locations, but also subsequent training of machine learning algorithms for automated species recognition.

This work investigates the effectiveness of using convolutional neural networks (CNNs) and instantaneous displacement measurements for damage identification in beams. The study involves subjecting laboratory beams to eight distinct damage scenarios and capturing the vertical positions of 60 points along the beam length during free-vibration tests using a high-speed camera. The data obtained was subsequently used to train a CNN in a supervised manner to estimate the level of damage at each point. Results showed that the CNN models were able to correctly localize and quantify the damage levels when trained on data from all damage scenarios. The soundness of the proposed methodology was demonstrated in a robustness assessment, where all eight damage scenarios were correctly identified even when two of them were excluded from the training dataset. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Mechatronics. Armament, Aviation, Safety Engineering / Problemy Mechatroniki. Uzbrojenie, lotnictwo, Inżynieria Bezpieczeństwa is the property of Index Copernicus International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pellet ablation mechanism is an interesting subject for plasma fuelling in fusion plasmas. In GAMMA 10/PDX, pellet injection experiments for higher density plasma production are planned to conduct detached plasma experiments in the higher density plasma condition. We measured the pellet ablation cloud by using the two-directional simultaneous photography system in GAMMA 10/PDX. The tomography reconstruction technique was used for considering the pellet trajectory in the plasma and pellet ablation. The three-dimensional pellet trajectory and pellet ablation images in the plasma were clearly obtained for the first time, to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Abstract The Event‐based Vision Sensor (EVS) is a bio‐inspired sensor that captures detailed motions of objects, aiming to become the ‘eyes’ of machines like self‐driving cars. Compared to conventional frame‐based image sensors, the EVS has an extremely fast motion capture equivalent to 10,000‐fps even with standard optical settings, plus high dynamic ranges for brightness and also lower consumption of memory and energy. Here, we developed 22 characteristic features for analysing the motions of aquatic particles from the EVS raw data and tested the applicability of the EVS in analysing plankton behaviour. Laboratory cultures of six species of zooplankton and phytoplankton were observed, confirming species‐specific motion periodicities up to 41 Hz. We applied machine learning to automatically classify particles into four categories of zooplankton and passive particles, achieving an accuracy up to 86%. At the in situ deployment of the EVS at the bottom of Lake Biwa, several particles exhibiting distinct cumulative trajectory with periodicities in their motion (up to 16 Hz) were identified, suggesting that they were living organisms with rhythmic behaviour. We also used the EVS in the deep sea, observing particles with active motion and periodicities over 40 Hz. Our application of the EVS, especially focusing on its millisecond‐scale temporal resolution and wide dynamic range, provides a new avenue to investigate organismal behaviour characterised by rapid and periodical motions. The EVS will likely be applicable in the near future for the automated monitoring of plankton behaviour by edge computing on autonomous floats, as well as quantifying rapid cellular‐level activities under microscopy.

Particle dampers (PD) can be embedded in structures fabricated via selective laser melting (SLM) because the raw powder (particle diameter : several tens of micrometers) remains in closed spaces during SLM. However, most PD studies have focused on coarse particle sizes larger than 1 mm and low frequencies below 100 Hz; there is insufficient evaluation of PD attenuation characteristics and particle behavior for particle sizes from tens of micrometers to sub-millimeters and in the 100 to 1000 Hz band. In this study, the equivalent viscous damping coefficients of spherical zirconia balls with nominal sizes of 0.05, 0.10, 0.20, and 0.40 mm are measured under different vibration accelerations (from 9 to 148 m/s2(rms)) and frequencies (from 100 to 800 Hz) to experimentally investigate the effect of fine particle diameters on the damping properties. It is deduced that in the frequency range above 200 Hz, the equivalent viscous damping coefficients of the coarse particle diameter are greater than those of fine particles at accelerations below the range of 15.7–22.4 m/s2(rms). In contrast, the equivalent viscous damping coefficients of the fine particles are greater than those of the coarse particles at accelerations above the 15.7–22.4 m/s2(rms) range. In addition, to determine the reason for these tendencies, the behavior of particles with a nominal size of 0.05 mm, which is close to the raw powder, is observed through a window using a high-speed microscope camera. The results reveal that in the low acceleration range, the inertial force does not overcome the static friction force owing to poor flowability caused by adhesion force, and the particles are always stationary with respect to the sealed container.

This study proposes a positive pressure re-acceleration assisted seeding mechanism and analyzes the motion mechanism of corn seeds during the seeding process. By employing the CFD-EDEM gas-solid coupling simulation analysis method, the fluid characteristics, initial ejection velocity of seeds, seed dropping time difference, and sowing position difference in the seeding mechanism under different structural parameters of the air pressure valve body were investigated. The optimal structural parameters of the air pressure valve body were determined (nozzle gap c = 0.6 mm, throat constriction diameter d = 16 mm, and throat constriction length l = 44 mm). A multi-factor experimental method was used to explore the effects of airflow pressure, forward speed during sowing, and sowing distance on sowing performance, aiming to identify the optimal working parameters for the positive pressure re-acceleration seeding mechanism. High-speed camera technology was used to record and analyze the seed movement process. The results indicate that an increase in positive pressure within the seed guide tube shortens the sowing time of corn seeds, reduces the coefficient of variation of seed dropping time difference, and effectively improves the consistency of sowing distance. The optimal parameters are a forward speed of 8 km/h, sowing distance of 20 cm, airflow pressure of 10 kPa, with a sowing distance coefficient of variation of 7.56%, and a seed dropping time difference coefficient of variation of 5.35%.

Spray systems in agriculture serve essential roles in the precision application of pesticides, fertilizers, and water, contributing to effective pest control, nutrient management, and irrigation. These systems enhance efficiency, reduce labor, and promote environmentally friendly practices by minimizing chemical waste and runoff. The efficacy of a spray is largely determined by the characteristics of its droplets, including their size and velocity. These parameters are not only pivotal in assessing spray retention, i.e., how much of the spray adheres to crops versus becoming environmental runoff, but also in understanding spray drift dynamics. This study introduces a real-time deep learning-based approach for droplet detection and tracking which significantly improves the accuracy and efficiency of measuring these droplet properties. Our methodology leverages advanced AI techniques to overcome the limitations of previous tracking frameworks, employing three novel deep learning-based tracking methods. These methods are adept at handling challenges such as droplet occlusion and varying velocities, ensuring precise tracking in real-time potentially on mobile platforms. The use of a high-speed camera operating at 2000 frames per second coupled with innovative automatic annotation tools enables the creation of a large and accurately labeled droplet dataset for training and evaluation. The core of our framework lies in the ability to track droplets across frames, associating them temporally despite changes in appearance or occlusions. We utilize metrics including Multiple Object Tracking Accuracy (MOTA) and Multiple Object Tracking Precision (MOTP) to quantify the tracking algorithm’s performance. Our approach is set to pave the way for innovations in agricultural spraying systems, offering a more efficient, accurate, and environmentally responsible method of applying sprays and representing a significant step toward sustainable agricultural practices.

Invasive plant species pose ecological threats to native ecosystems, particularly in areas adjacent to roadways, considering that roadways represent lengthy corridors through which invasive species can propagate. Traditional manual survey methods for monitoring invasive plants are labor-intensive and limited in coverage. This paper introduces a high-speed camera system, named CamAlien, designed to be mounted on vehicles for efficient invasive plant species monitoring along roadways. The camera system captures high-quality images at rapid intervals, to monitor the full roadside when following traffic speed. The system utilizes a global shutter sensor to reduce distortion and geotagging for precise localistion. The camera system makes it possible to collect extensive data sets, which can be used for a digital library of the invasive species and their locations, but also subsequent training of machine learning algorithms for automated species recognition.

In order to solve the problems of poor hole-filling performance and the high seed-breakage rate of conventional rice bud seed precision hole direct seed-metering devices, a side-filled rice precision hole direct seed-metering device was developed, and the mechanism and force analyses for seeding operations were carried out. The key factors affecting seeding quality were determined: rotation speed, seeding angle and seeding height. By coupling the discrete element method (DEM) and multi-rigid body dynamics (MBD), the seed breakage rate and seeding performance at different rotation speeds were analyzed. Single-factor bench testing was used to analyze the effect of a duckbill unit on seeding performance under different factor levels. The three-factor and five-level quadratic regression orthogonal rotation center combination test methods were used to obtain the optimal working parameter combination. The test results showed that when the rotation speed was 47 r/min, the seeding angle was 19°, and the seeding height was 180 mm, the qualified index of seeding was 92.03%, the hole diameter qualified index was 91.62%, and the hole distance variation index was 7.17%. This study provides a reference for the research of mechanical rice sprouting seed-metering devices. [ABSTRACT FROM AUTHOR]

This study was designed as a preliminary experiment for missions at the electrostatic levitation furnace in the International Space Station (ISS-ELF) such as Hetero-3D. The objective of this study was to employ a high-speed camera to determine the recalescence time of undercooled Ti6Al4V alloy with TiC heterogeneous nucleation site particles more accurately compared to measurements using a pyrometer. The sample was melted and solidified in the ground-based electrostatic levitation (ESL) furnace. The changes in the luminescence emitted from the sample surface due to recalescence were recorded using a high-speed camera, and the intensity at the center of each captured image was analyzed with MATLAB® software. As a result, the intensity of the undercooled samples increased significantly during recalescence. The maximum change in the intensity was 101 per 256 gray levels in the recording at 7,200 frames per second (fps) and the noise was at most only 3. Therefore, the recalescence time could be obtained using the high-speed camera. At 15,000 fps, the recalescence time was within 6.7 × 10-5 s, which was much more accurate than the time (0.11 s) measured using a pyrometer at a sampling rate of 120 Hz in the ESL furnace. For enhanced measurement accuracy, it is crucial to establish an appropriate exposure time to prevent the intensity from reaching the lower limit of 0 just before recalescence and the upper limit of 255 immediately after that. This study suggests that the high-speed camera newly installed in the ISS-ELF in 2023 may have the potential to achieve a more accurate recalescence time than the pyrometer at a sampling rate of 100 Hz in the ISS-ELF. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the potential of capture systems in improving high school students' dancing skills through the use of experimental design. The major findings were as follows: First, using a MoCap system and high-speed camera to document dancers' movements can provide reference materials for students to improve their skills through self-practice. Second, using a MoCap system and high-speed camera as teaching aids at dance studio can enhance the effectiveness of dancing teaching. Third, incorporating MoCap and high-speed camera technologies into dance art is becoming necessary for achieving peak performance. [ABSTRACT FROM AUTHOR]

The deep coal mine blasting is the combined action of the initial ground stress field and the explosion load. By using the unidirectional dynamic and static combined loading test platform and the dynamic caustic experimental system, the expansion law of the initial stress field intensity on the blasting crack is explored under the horizontal or vertical unidirectional confining pressure applied to the blasthole notch on the plexiglass plate. The test results show that the grooving of the blasthole can effectively control the distribution range of the initial stress field, promote the concentrated release of energy, and improve the directional blasting effect. At the same time, the dynamic effect of explosion and the static effect of confining pressure are dominant in the near and far areas of the blasthole, respectively. The horizontal initial stress field increases the stress concentration at the crack tip and promotes the growth of the main crack. With the increase of the stress field, the promotion effect is more obvious, and the occurrence of secondary cracks is inhibited. In contrast, the vertical initial stress field reduces the stress concentration at the notch tip, inhibits the crack propagation, and transforms the crack from type I fracture to type I-II mixed fracture. With the increase of stress field, the shear fracture is more obvious, and the crack propagates along the direction of the maximum principal stress. [ABSTRACT FROM AUTHOR]

Invasive plant species pose ecological threats to native ecosystems, particularly in areas adjacent to roadways, considering that roadways represent lengthy corridors through which invasive species can propagate. Traditional manual survey methods for monitoring invasive plants are labor-intensive and limited in coverage. This paper introduces a high-speed camera system, named CamAlien, designed to be mounted on vehicles for efficient invasive plant species monitoring along roadways. The camera system captures high-quality images at rapid intervals, to monitor the full roadside when following traffic speed. The system utilizes a global shutter sensor to reduce distortion and geotagging for precise localistion. The camera system makes it possible to collect extensive data sets, which can be used for a digital library of the invasive species and their locations, but also subsequent training of machine learning algorithms for automated species recognition.

The study of clastic rock failure evolution under true triaxial stress is an important research topic; however, it is rarely studied systematically due to the limitation of monitoring technology. In this study, true triaxial compression tests were conducted on clastic rock specimens to investigate the effect of cementation and intermediate principal stress (σ2) on the failure mechanism. The complete stress–strain curves were obtained, while the acoustic emission (AE) was monitored to indirectly evaluate the evolution of tensile and shear cracks, and crack evolution under true triaxial compression was imaged in real time by a high-speed camera. The results showed that the deformation and failure characteristics of clastic rock were closely related to the cementation type and intermediate principal stress. On the basis of the distribution characteristics of the ratio of rise time to amplitude (RA) and the average frequency (AF) of AE signals, tensile cracks of the contact cementation specimen propagated preferentially. Meanwhile, the enhancement of specimen cementation promoted the evolution of shear cracks, and the increase in σ2 promoted the evolution of tensile cracks. Moreover, the mesoscale cracking mechanism of clastic rock caused by cementation and σ2 under true triaxial compression was analyzed. The failure patterns of clastic rock under true triaxial compression were divided into three modes: structure-induced, structure-stress-induced and stress-induced failures. This study confirms the feasibility of high-speed camera technology in true triaxial testing, and has important implications for elucidating the disaster mechanism of deep tunnels in weak rocks.

The liquid film coverage over the tube wall is important in flow hydrodynamics, and flow hydrodynamics are important in heat transfer performance in falling-film systems as well. An experimental setup is used with the aid of a high-speed camera to visualize the flow behavior, which is challenging to see with the naked eye. The set of experiments are carried out by varying the important working parameters such as Reynolds number (250−458) and inter tube distance (20/30/40 mm). The Sobel image analysis method is developed to quantify flow parameters such as jet diameter and axial film thickness. The liquid jet diameter increases with increasing tube spacing for the same Reynolds number and decreases with increasing inter tube distance for the same Reynolds number. The formation of connected droplets causes disturbances near the liquid jet head. The connected droplet phenomenon causes the liquid jet diameter to increase and decrease in this region. Furthermore, there is a distinct pattern in the axial film coverage beneath and above the tube wall. Three data sets are generated for each parameter using an image analysis approach, which can then be used to train and develop machine learning models. The findings indicated that the Decision Tree, Random Forest, and Gradient Boosting models consistently better performed the other models on all features. Although a few models have lower error percentages below the datum line, consistency in each feature is still required. The results of the flow visualization experiments, as well as the machine learning models developed, can be used to quantify flow parameters and improve flow characteristics for better design. [Display omitted] • Falling-film column flow characteristics over horizontal tubes are investigated experimentally. • The Sobel edge detection algorithm is implemented to quantify the flow parameters. • The liquid jet diameter increases with Re for the same tube spacing and decreases with increased tube spacing for the same Re. The film coverage beneath and above the tube wall showed a distinct pattern. • The findings show that the Decision Tree, Random Forest, and Gradient Boosting models consistently beat the other models on all features. [ABSTRACT FROM AUTHOR]

Deep filtration is an important technology for the separation of fine particle pollutants in industrial wastewater. The theoretical core of microchannel separation is the interaction between channel interface and pollutants. Here, microchannels with different shapes and sizes were designed by microfluidic technology and the particle migration process in microchannels was visualized by high-speed camera. This paper studied the effects of apparent depth, inlet structure and channel angle of the interception channel on fluid flow and particle interception. When apparent depth of the interception channel was equidistantly distributed, the flow rate in each channel was uniform, but interception efficiency gradually decreased with the increase of apparent depth. Interception efficiency of the first layer was 16.7 %, while for the 14th layer was only 0.4 %. Interception performance of the upper wall of the inlet of the interception channel was substantially higher than that of the lower wall. The smoother the angle between the interception channel and the mainstream channel was, the better the interception performance. When the angle between the upper and lower walls of the inlet and the mainstream channel was 30° and 60°, respectively, interception efficiency was the optimal, and cumulative interception efficiency of the three filtrations was 92.4 %. Additionally, flow rate and interception efficiency of the interception channel increased with decreasing channel angle. The total interception performance of the 30°–45° group was the optimal, and the total split ratio and total interception efficiency were 65.5 % and 85.5 %, respectively. This provides reference for the change of microchannel structure and the mechanism of particle migration and deposition. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper presents an enhanced version of an arc electron source designed for air ionization applications in a self-neutralizing air-breathing plasma thruster. The arc electron source is specifically suited for the air-breathing plasma thruster, as it allows precise control of mean electron energy levels. This paper focuses on the ionization aspects of air-breathing thrusters through the development of axially magnetized arc electron sources. The sources consist of a circular and coaxial configuration of a metallic arc plasma source coupled with a positively biased grid to extract electrons and control mean electron energy. The average mean electron energy of electrons in the arc electron source is regulated by adjusting the bias voltage of the grid within the range of 0 V – 300 V. To investigate the behavior of ion current density and electron density concerning pressure and mean electron energy, the current probe and magnetic filter were utilized. It was demonstrated that the circular electron source leads to enhanced ionization of airflow by achieving plasma densities greater than 1018 m−3. By utilizing a high-speed camera for the circular arc electron source, the arc spot was seen to move azimuthally due to the magnetic field. Furthermore, scanning electron microscopy and a conductance measurement system were employed for the coaxial arc electron source to examine the deposition and conductance of the electron extraction grid. While the grid underwent deposition of about 600 microns, the conductance was observed to increase/saturate with time and bias voltage, indicating an electrically "self-healing material". [ABSTRACT FROM AUTHOR]

The paper presents a proposition of the theoretical-experimental method of determination of power losses in the transversely vibrating rubber V-belt of continuously variable transmission. The article comprises the results of experimental tests conducted on a special test stand with a complete scooter drivetrain powered by a small two-stroke internal combustion engine. Such a configuration allows ensuring real CVT working conditions. A high-speed camera was used for the contactless measurement of belt vibrations and time-lapse image analysis was performed in dedicated software. An axially moving Euler-Bernoulli beam was assumed as the mathematical model. Longitudinal vibrations and nonlinear effects were omitted. Additionally, it was assumed that the belt material behaves according to the Kelvin-Voigt rheological model. Analysis of the damped free vibrations of the cantilever beam, made of the belt segment, allowed to determine the equivalent bending damping coefficient. The CVT power losses, due to bending in the rubber transmission belt, were obtained for the fixed working conditions after numerical calculations. The proposed methodology is a new approach in this research area, which allows to obtain results impossible to achieve with other measurement methods. [ABSTRACT FROM AUTHOR]

Simple Summary: The feeding relationship between copepods and phytoplankton has immense ecological significance. The feeding behavior of copepods may be affected by the ingestion of toxic algae. This study investigated the feeding behavior of copepods via study of the feeding selectivity of Paracalanus parvus, a key small copepod species, using a high-speed camera. The study demonstrates that toxic dinoflagellates alter the feeding behavior of copepods and describes the variations in their feeding response to different algal species and concentrations. The findings provide crucial insights for further studies on the feeding relationship between copepods and phytoplankton and the functional assessment of plankton ecosystems. The feeding relationship between copepods and phytoplankton has immense ecological significance. This study investigated the feeding behavior of copepods by studying the feeding selectivity of Paracalanus parvus, a key small copepod species, using a high-speed camera. The feeding behavior of P. parvus separately fed on three algae, Prorocentrum minimum, Alexandrium minutum, and Thalassiosira weissflogii, was studied at five different concentrations. The factors characterizing feeding behavior, including the beating frequency (BF), beating time (BT), and rejection behavior, were analyzed. The average BT and BF of P. parvus fed on toxic algae were significantly lower than those of copepods fed on nontoxic algae, indicating that the toxic algae negatively affected their feeding behavior. There were no significant differences in feed rejection among the three algae during the short period of experimentation, indicating that the rejection behavior was insignificant in the early period (within 20 min) of feeding on toxic algae. The feeding behavior was inhibited when the concentration reached 250 cells/mL. The BT was initially affected at increasing concentrations followed by the BF, and P. minimum and A. minutum reduced the BF at concentrations of 250 and 1000 cells/mL, respectively. Analysis of the average BFs revealed that P. parvus was more significantly affected by P. minimum containing diarrheal shellfish poison than by A. minutum containing paralytic shellfish poison. The BF of copepods fed on P. minimum was significantly lower than that of copepods fed on A. minutum at 250–500 cells/mL but was not significantly different from that at 1000 cells/mL. This indicated that the inhibitory effect of P. minimum on the feeding behavior was more significant at concentrations observed at the onset of red tide blooms (0.25–0.5 × 102 cells/mL), but insignificant at concentrations reaching those in advanced red tides (>103 cells/mL). This study demonstrates that toxic dinoflagellates alter the feeding behavior of copepods and describes the variations in their feeding response to different algal species and concentrations. The findings provide crucial insights for further studies on the feeding relationship between copepods and phytoplankton and on functional assessment of plankton ecosystems. [ABSTRACT FROM AUTHOR]

Background: The assessment of masticatory performance (MP) is conducted in hospitals, but is difficult to perform in nursing facilities that lack specialists in dysphagia. To select the appropriate food textures in nursing practice, a simple method of evaluating the MP should be developed. Objective: The purpose of this study was to investigate motion parameters that influence MP by motion capture analysis of maxillofacial movement on chewing gummy jelly in healthy adults. Methods: The subjects were 50 healthy adults. The state of chewing gummy jelly was photographed using a high‐speed camera. Simultaneously, we evaluated the amount of glucose extracted (AGE) obtained with gummy jelly as a reference value for MP. The subjects were divided into two groups: normal and low masticatory groups (NG and LG, respectively) based on the AGE. The cycle of mastication was classified into three phases: closing phase (CP), transition phase (TP) and opening phase (OP) through motion capture analysis of the video photographed. Parameters of jaw movement and their associations with the AGE were examined. Results: The transition phase rate (TR) and opening phase rate (OR) were correlated with the AGE. Furthermore, the TR in the NG was significantly higher than in the LG, whereas the OR was significantly lower than in the LG. The age, TR and opening velocity were significant independent variables. Conclusion: Motion capture technology facilitated the analysis of jaw movement. The results suggested that MP can be evaluated by analysing the TP and OP rates. [ABSTRACT FROM AUTHOR]

The requirement of micro holes or features on the additively manufactured (AM) components attract machinability investigations on Laser Powder Bed Fused (L -PBF) components, and directional anisotropy is one of the critical problems with parts made using L -PBF. As a result, the current study compares the machinability properties during the micro-drilling of several samples, including cast and L -PBF-produced AlSi10Mg. Moreover, the impact of T6 solution heat treatment and build orientation on microstructure, thrust force, cutting torque, surface roughness, and cutting temperature is analyzed. It was found that at a feed of 8 µm/rev and 5000 rpm, the force requirement perpendicular to the build direction (PPBD) was 23.11 % higher than parallel to the build plane direction (PBD). The force required is reduced after heat treatment because of the reduction in hardness. Similarly, a difference of 31.36 % in cutting torque requirement was observed, which increased to 46.82 % after heat treatment. At the same time, the difference in chip temperature in the as-built AlSi10Mg was less between PPBD and PBD. It was also observed that there is a reduction in the chip temperature with feed rate. The chip formation was further studied using a high-speed camera, and four stages of chip formation were identified. From the SEM analysis of the chips, microchips of different lengths and morphology can be identified, which are dissimilar to one another. [ABSTRACT FROM AUTHOR]

It was difficult to measure the volume change of alloy at high temperature, especially for undercooled solidification. In this paper, a novel method is proposed to measure the volume change of high temperature melt by high-frequency induction combined with the high-speed camera. The changes of liquid and solid volume of binary Ni–B and ternary Fe–Ni–B alloy with temperature were studied. The influence of the undercooling of the primary transition and eutectic transition on the volume change before and after solidification is discussed. It is found that both the solid and liquid volumes of Ni–B and Fe–Ni–B alloys decrease with decreasing temperature. For the primary transition (dendritic phase forms), the larger the undercooling, the more serious the volume shrinkage. For eutectic transformation (eutectic forms), the volume shrinkage decreases with the increase of undercooling. [ABSTRACT FROM AUTHOR]

X-ray radiography and computed tomography have become well-established methods for investigation of internal structure of objects and for defectoscopy. Recently, the methods have even been used for in-situ analysis of materials under mechanical loading. Although the techniques would be very suitable for analysis during dynamic events, their application is constrained by typical achievable frame rates. Therefore, fast imaging is usually limited to facilities providing sufficient flux like particle accelerators. In this paper, we test imaging performance of a laboratory-based setup with a high-power X-ray tube, a scintillation panel, and an optical camera. Fast-rotating object and typical specimens for impact testing are irradiated with different power settings and quality of captured images is evaluated and analyzed. It is found out that the system can be successfully used for imaging at several hundred frames per second allowing for inspection of slow impact dynamics experiments.

This study encompasses the impact of fabric construction, seam angle, and impact force on the behaviour of the parachute canopy. The ripstop and plain-woven fabric stitched at 0° and 45° seam angles have been subjected to the three levels of tensile impact forces derived through a scale-down approach of the C-9 parachute and the behaviour is analysed using a high-speed digital camera. Results indicate that seam angle has a major influence on the performance of the specimen under impact load. The plain-woven samples showed more ability to absorb impact force but higher damage, especially at seam lines of 0° seamed specimen than the ripstop samples. Both the fabric specimens of 0° seam angle induce a form of seam line damage due to the corresponding higher impact force. In contrast, the 45° seam bias angles are quite stable at seam lines and also produce higher work done under varying impact forces. [ABSTRACT FROM AUTHOR]

Printability on thin heterogeneous media using ink is related to the spreadability of ink. Thus, this study focused on quantifying the spread of ink droplets by performing amorphous morphology measurements using a measurement system that generated uniform ink droplets while simultaneously acquiring high-speed images of the ink spread on a thin medium. The directions of the droplet and camera inspection were unified to ensure measurement accuracy. Back-light illumination was adopted to increase visibility and distinguish the ink spread during image acquisition. The spreadability was assessed using digital filters, a boundary detector, nonlinear regression, and statistical analysis. Digital filters removed atypical patterns caused by the heterogeneity and porosity of the medium from the images. Subsequently, boundary points were extracted from the binarized images using a Canny edge detector. The ink spread was represented by a radial model to identify the overall movement, whereby a shaded region was considered for the kinematic structure of the measurement system. The radial model was estimated from the boundary points using nonlinear regression and a simplex search. Various spreadability indices were derived from the geometric and statistical relationships between the radial model and boundary points. The proposed measurement method was verified using predefined test images. The measurement error was at the sub-pixel level. The spreadability of ink droplets with 10–100% density was further measured, and the physical properties were investigated. [ABSTRACT FROM AUTHOR]

The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study. The results were defined by Reynolds number, which focuses on the breakup of liquid film, droplet size, velocity, and liquid volume flux under different Reynolds numbers at the near-field spray. The spray structure was visualized using a high-speed camera, and the characteristics of droplets were measured using a Phase Doppler Anemometer (PDA) in both the radial and axial directions. The tests were carried out at varying spray pressures (0.2 to 1.0 MPa), corresponding to different Reynolds numbers (5369 to 12 006). It was found that when the Reynolds number rises, the liquid became more unstable after leaving the nozzle, causing the liquid film to break up faster. According to the measurements of PDA, the coalescence of droplets increased due to the centrifugal effect. What's more, the velocity of the droplets fluctuates significantly in the radial direction, and the droplets with a smaller particle size had a higher average velocity. From the perspective of liquid distribution, the increase in Reynolds number caused the spray liquid to move in the radial direction gradually. In contrast, the liquid volume distribution changed in the radial direction more obviously than in the axial direction, growing to the maximum along the radial direction and gradually reducing. It can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics. [ABSTRACT FROM AUTHOR]

X-ray radiography and computed tomography have become well-established methods for investigation of internal structure of objects and for defectoscopy. Recently, the methods have even been used for in-situ analysis of materials under mechanical loading. Although the techniques would be very suitable for analysis during dynamic events, their application is constrained by typical achievable frame rates. Therefore, fast imaging is usually limited to facilities providing sufficient flux like particle accelerators. In this paper, we test imaging performance of a laboratory-based setup with a high-power X-ray tube, a scintillation panel, and an optical camera. Fast-rotating object and typical specimens for impact testing are irradiated with different power settings and quality of captured images is evaluated and analyzed. It is found out that the system can be successfully used for imaging at several hundred frames per second allowing for inspection of slow impact dynamics experiments. [ABSTRACT FROM AUTHOR]