High-speed Image Acquisition Research Articles

The structural-mechanical damage behavior of rice bran layer under tensile processing for moderate milling

Bran layer moderate removal during rice milling is a crucial process for reducing rice broken rate and nutrient loss. The bran layer structural-cracking behavior is analyzed using a self-developed in-situ observation tensile tester with high-speed image acquisition. The rice bran tissue microstructure, chemical composition, cracking morphology are in-depth investigated. The results show that rice bran pericarp cells are of reticulate network, cell shape with rectangular or elliptical.significant differences in cell distribution and density across rice varieties, with Japonica rice (NJ5055) with a denser and more uniform structure, exhibiting higher ductility and tensile strength. The rice bran exhibited linear elastic rheological behavior. The bran tensile property is different under tensing directions, the tensile strength shows longitudinal (Y) > radial (X). Cracking along the cell long axis is Y direction, showing orderly line cracking path. Cracking along cell short axis is X direction, showing zigzag cracking path. Pericarp cells geometrical structure determines the mechanical strength and cracking-removal resistance ability of rice bran. The pericarp layer significantly enhances the ductility of the bran layer, allowing it to stretch and deform under stress, thereby improving overall mechanical performance. Rice bran structural-mechanical properties are affected by micro-structure and components.

Line-field dynamic optical coherence tomography platform for volumetric assessment of biological tissues.

Dynamic optical coherence tomography (dOCT) utilizes time-dependent signal intensity fluctuations to enhance contrast in OCT images and indirectly probe physiological processes in cells. Majority of the dOCT studies published so far are based on acquisition of 2D images (B-scans or C-scans) by utilizing point-scanning Fourier domain (spectral or swept-source) OCT or full-field OCT respectively, primarily due to limitations in the image acquisition rate. Here we introduce a novel, high-speed spectral domain line-field dOCT (SD-LF-dOCT) system and image acquisition protocols designed for fast, volumetric dOCT imaging of biological tissues. The imaging probe is based on an exchangeable afocal lens pair that enables selection of combinations of transverse resolution (from 1.1 µm to 6.4 µm) and FOV (from 250 × 250 µm2 to 1.4 × 1.4 mm2), suitable for different biomedical applications. The system offers axial resolution of ∼ 1.9 µm in biological tissue, assuming an average refractive index of 1.38. Maximum sensitivity of 90.5 dB is achieved for 3.5 mW optical imaging power at the tissue surface and maximum camera acquisition rate of 2,000 fps. Volumetric dOCT images acquired with the SD-LF-dOCT system from plant tissue (cucumber), animal tissue (mouse liver) and human prostate carcinoma spheroids allow for volumetric visualization of the tissues' cellular and sub-cellular structures and assessment of cellular motility.

Development of an Optical System for Strain Drop Measurement of Osteosarcoma Cells on Substrates with Different Stiffness.

Adherent cells perceive mechanical feedback from the underlying matrix and convert it into biochemical signals through a process known as mechanotransduction. The response to changes in the microenvironment relies on the cell's mechanical properties, including elasticity, which was recently identified as a biomarker for various diseases. Here, we propose the design, development, and characterization of a new system for the measurement of adherent cells' strain drop, a parameter correlated with cells' elasticity. To consider the interplay between adherent cells and the host extracellular matrix, cell stretching was combined with adhesion on substrates with different stiffnesses. The technique is based on the linear stretching of silicone chambers, high-speed image acquisition, and feedback for image centering. The system was characterized in terms of the strain homogeneity, impact of collagen coating, centering capability, and sensitivity. Subsequently, it was employed to measure the strain drop of two osteosarcoma cell lines, low-aggressive osteoblast-like SaOS-2 and high-aggressive 143B, cultured on two different substrates to recall the stiffness of the bone and lung extracellular matrices. Results demonstrated good substrate homogeneity, a negligible effect of the collagen coating, and an accurate image centering. Finally, the experimental results showed an average strain drop that was lower in the 143B cells in comparison with the SaOS-2 cells in all the tested conditions.

Experimental study on gas and coal dust explosive overpressure and flame dynamic characteristics in an engineering-level test roadway

The continuous development of coal science and technology has made gas and coal dust explosion disasters an important factor that restricts efficient and intelligent coal mining, which seriously threatens the safe production process of coal mines. To explore the gas and coal dust explosive overpressure and flame propagation characteristics in an actual roadway, the dynamic characteristics of gas and coal dust mixed explosion propagation and evolution laws of explosion flames were investigated using an integrated explosion test system and a high-speed image acquisition system in an engineering-level test roadway with a length of about 700 m and a cross-sectional area of 7.2 m2. Experimental results showed that the peak overpressure measured at each measuring point during the propagation process of explosion shock wave in the roadway did not rise or fall monotonously but fluctuated. The power of explosion shock wave was significantly strengthened by adding coal dust, while the flame propagation speed sharply increased in a certain zone, which generally showed a first increasing and then declining trend. In addition, the flame was blue white after the gas in the roadway was ignited, developed in an irregular shape, and ignited the surrounding combustible gas soon, which further ignited the coal dust under the combined action of pressure wave and flame front. In this case, the flame was deep yellow on the whole. The gas and coal dust explosion flame propagated along the longitudinal section above the roadway, and the flame propagated at an accelerated speed on the transverse section due to the disturbance of obstacles. The study results will provide an important theoretical basis for the R&D of technical active explosion suppression equipment in coal mines and the improvement in their installation technologies.

Bulk material influence on the aggressiveness of cavitation – Questioning the microjet impact influence and suggesting a possible way to erosion mitigation

In a study conducted over 10 years ago (Petkovsek and Dular, 2013) [1] we noticed that the thin metal sheet sustains less cavitation damage when it is attached to an acrylic glass (PMMA) than in the case when we attached it to quartz glass (SiO2). The reason for this was not explored at the time.In the present paper we present a systematic study of single cavitation bubble erosion of a thin aluminum foil, which was attached to either PMMA or SiO2 plate. We show that the damage sustained on the foil attached to PMMA plate is significantly smaller regardless of the bubble collapse distance from the boundary. The result is surprising since one would expect the weak foil to be severely damaged regardless of the material it is attached to.By femtosecond illumination and high-speed image acquisition we were able to capture the formation and progression of the shock waves, which are emitted at cavitation bubble collapse and observed that they are reflected on SiO2 boundary but that they traverse the PMMA bulk material. We offer an explanation that to achieve less damage the bulk material needs to have acoustic impedance similar to the one of the liquid medium in which cavitation occurs.Further on, we constructed a simple composite material where PMMA was attached to the SiO2 and showed that we can partially mitigate the damage. This was further confirmed by ultrasonic cavitation erosion tests.The results also imply that the cavitation damage originates solely from the shock wave, which is emitted at cavitation bubble collapse – consequently putting the idea of microjet impact mechanism under question. Finally, the study offers a new exciting approach to mitigate cavitation erosion by fine tuning the acoustic impedance of the coatings.

Label-free multiphoton imaging flow cytometry.

Label-free imaging flow cytometry is a powerful tool for biological and medical research as it overcomes technical challenges in conventional fluorescence-based imaging flow cytometry that predominantly relies on fluorescent labeling. To date, two distinct types of label-free imaging flow cytometry have been developed, namely optofluidic time-stretch quantitative phase imaging flow cytometry and stimulated Raman scattering (SRS) imaging flow cytometry. Unfortunately, these two methods are incapable of probing some important molecules such as starch and collagen. Here, we present another type of label-free imaging flow cytometry, namely multiphoton imaging flow cytometry, for visualizing starch and collagen in live cells with high throughput. Our multiphoton imaging flow cytometer is based on nonlinear optical imaging whose image contrast is provided by two optical nonlinear effects: four-wave mixing (FWM) and second-harmonic generation (SHG). It is composed of a microfluidic chip with an acoustic focuser, a lab-made laser scanning SHG-FWM microscope, and a high-speed image acquisition circuit to simultaneously acquire FWM and SHG images of flowing cells. As a result, it acquires FWM and SHG images (100 × 100 pixels) with a spatial resolution of 500 nm and a field of view of 50 μm × 50 μm at a high event rate of four to five events per second, corresponding to a high throughput of 560-700 kb/s, where the event is defined by the passage of a cell or a cell-like particle. To show the utility of our multiphoton imaging flow cytometer, we used it to characterize Chromochloris zofingiensis (NIES-2175), a unicellular green alga that has recently attracted attention from the industrial sector for its ability to efficiently produce valuable materials for bioplastics, food, and biofuel. Our statistical image analysis found that starch was distributed at the center of the cells at the early cell cycle stage and became delocalized at the later stage. Multiphoton imaging flow cytometry is expected to be an effective tool for statistical high-content studies of biological functions and optimizing the evolution of highly productive cell strains.

Experimental Study of the Microscopic Visualization of Gas Clogging during Groundwater Recharge

Clogging is one of the most important factors that restricts the development and popularization of artificial groundwater recharge technology. Gas clogging is an important but often overlooked form of clogging. In this study, a high-speed image acquisition system was used to obtain high-resolution images of the migration of water and gas in the pore. The bypass flow, trapped bubbles in the H-shaped pore channel, blind end, and corner of the pore were directly observed and their clogging mechanisms were analyzed. The influences of the pore structure and gas content on the degree of gas clogging were quantified. The pore–throat size has a certain controlling effect on the movement of the gas and liquid phases. As the diameter of the pore–throat increases, the clogging effect of the gas decreases, and the relative permeability of the water (krw) increases. The pore–throat ratio exhibits a negative correlation with the relative permeability of the liquid phase, and the pore–throat sorting coefficient exhibits a positive correlation with krw. As the gas content increases, the degree of gas clogging increases, and the effect is more significant at low gas-to-liquid ratios (<1:2). These results provide theoretical support for the scientific quantitative evaluation and prediction of the occurrence of gas clogging in groundwater recharge projects.

Viscosity Measurement in Biocondensates Using Deep-Learning-Assisted Single-Particle Rotational Analysis.

Viscoelastic characterization is of great importance for the investigation of biomolecular condensates. Single-particle-tracking-based rotational diffusion analysis of single nanorods is an effective approach for quantitative viscosity measurement. However, in the case of high background and noise with high-speed image acquisition, accurate extraction of diffusivity from the data is a challenging task. Here, we develop a novel frequency-domain-based deep learning (DL) method for single nanorod rotational tracking analysis. We synthesized Brownian rotational time-series data for training, designed a data preprocessing module to reduce the effect of noise, and extracted rotational diffusion coefficient using recurrent neural networks in the frequency domain. Compared with the traditional curve-fitting-based methods, our method shows higher accuracy and a wider detection range for viscosity measurement. We verified our method using experimental data from plasmonic imaging of single gold nanorods (AuNRs) in glycerol solution and PGL droplets. Our method can be potentially applied to the viscosity measurement of different biomolecular condensates in vitro and in vivo.

High-speed image acquisition system and image acquisition method of ferroelectric liquid crystal light valve film

As one of the new high-performance products, the ferroelectric liquid crystal light valve has entered people's daily lives and has been widely used. Because of its excellent characteristics, it is widely used in various aspects such as industry and commerce. This paper adopts an experimental analysis method and data analysis method, and aims to break through the existing image acquisition methods by studying ferroelectric liquid crystal light valve film and high-speed image acquisition system, and develop an image acquisition system with faster speed and high-quality performance. According to the experimental results, the system can meet the functional requirements and technical indicators proposed by the design and can operate safely and stably, achieving the expected effect of the design.

Effects of He content in shielding gases on high-efficient hybrid laser arc welding with C-276 filler metal

High-efficient welding technology with rotating arc assisted by laser under shielding gases with different He content was investigated for the application of 9% Ni steel in LNG storage. High-speed image and electrical signal acquisition were adopted to investigate arc stability and metal transfer behavior during hybrid laser arc welding. The results indicated that with increasing content of He, the weld formation became better first and then worse. Ar+30 %He improved the formation of welding seam. The He content had a significant influence on the electric signal waveforms. With the addition of 30 %He, the waveforms had the minimal fluctuation. It was rotating spray transfer with pure Ar, Ar+30 %He and Ar+50 %He. The difference was that with the He content increase, transfer mode shifted from unstable rotating spray transfer to stable rotating spray transfer, to irregular rotating spray transfer. With pure He, it was large droplet transfer, resulting in the formation of large spatters. The research of rotating spray transfer trajectory showed that the rotation velocity was relatively constant and one rotation time was 3.19 ms in one pulse period under Ar+30 %He. The trajectory equation was obtained for describing the rotating spray transfer. This indicated that the addition of 30 %He improved the coupling effect of laser and arc, enhanced the matching degree between rotating spray transfer and arc pulse period. It was meaningful to understand the effects of shielding gases on 9% Ni steel hybrid laser arc welding, providing theoretical basis for LNG storage efficient and reliable manufacturing.

Custom control system for Split Hopkinson Pressure bars

In order to ensure the necessary usage safety in structures that withstand extreme loading conditions, it is necessary to perform high-strain rate tests for the used materials, in order to be able to predict their behaviour. A common apparatus for these tests is the Split Hopkinson Pressure Bar (SHPB).This type of test is currently performed in the Advanced Monitoring and Structural Integrity unit of INEGI with a custom-built pneumatic setup, comprising two compression and two tension bars. Originally, these bars were manually controlled using a couple of buttons and a pressure gauge and thus the system was somewhat more prone to user error and required manual synchronization of the multiple acquisition systems.Thus, this work reports the development of a custom control system for an SHPB, not only to ensure good repeatability in the firing mechanism, but also to synchronize the data acquisition, namely the acquired voltage signals with the high-speed image acquisition for use with Digital Image Correlation (DIC).The developed system was already implemented, being capable of successfully controlling the trigger pressure through a computer user interface.

Influence of residual pressure on the melting of a powder bed induced by a laser beam

The laser beam melting (LBM) process is a powder-based additive manufacturing able to produce parts layer-by-layer in a hermetic chamber. Selection of the appropriate process parameters and fabrication conditions plays a fundamental role in the final properties. Investigating the interaction between the laser and the powder bed helps to understand the melt-pool behavior. In fact, even if additive manufacturing processes offer appreciable advantages, some processing parameters have to be studied to improve the properties of the products. The conventional LBM process is carried out in a chamber filled with an inert gas, at approximately atmospheric pressure. During the melting of a metal powder, gas can be caught in the liquid and may cause pores to form. This work investigates the effect of vacuum pressure in the chamber (up to 10−2 mbar) on avoiding oxidation and improving the quality of the welding of stainless steel 316L. However, by modifying the residual pressure of the chamber, physical phenomena such as surface tension, Marangoni convection, and recoil pressure are amplified, creating more instabilities in the melt pool. This paper presents an initial analysis of the behavior of the powder under combinations of different residual pressures and laser speeds/powers. High-speed image acquisition brings to light the evolution of the spatters in vacuum compared to atmospheric pressure. Particle recovery coupled with Scanning Electron Microscopy (SEM) analyses shows the organization and morphologies of the ejections. Then, sectional views of single scan tracks are compared and related to the spattering. A considerable evolution in the results of the melting is found as one passes from atmospheric pressure to residual pressure. Hence, a powder pre-sintering solution is investigated in order to remedy the instabilities in vacuum and improve the process.

Development of High-Speed Image Acquisition and Processing System for Real-Time Plasma Control on EAST

In order to realize advanced plasma control based on visible cameras, a high-speed image acquisition and processing system has been developed recently on Experimental Advanced Superconducting Tokamak (EAST). This system is optimized in many ways to achieve high-speed, real-time, low-latency performance, and to load multiple acquisition cards simultaneously. The acquisition rate of this system can be close to 10 000 FPS when the frame size is set as 320 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times240$ </tex-math></inline-formula> and the pixel depth is set as 8 bits. DMA is used for high-speed data transmission; the memory copy function is optimized for reducing the time cost on data memory reading and writing. Besides, the visualization subsystem based on the Python web can communicate with the acquisition machines and also can synthesize data of multiple acquisition machines in real time to perform image fusion and access display. In addition, a thermal event recognition function based on visible imaging is also included in this system. The convolutional neural network (CNN) model of hot spots and multifaceted asymmetric radiation from the edge (MARFE) detection for EAST plasma discharge has been developed so far. The detection results can be visualized in quasi-real time. In terms of data storage, a new data storage format is designed; a GUI for off-line data analysis and processing based on MATLAB is provided.

Experimental research on the law of flame spreading in the charge bed of a central ignition tube

In order to investigate the development of flame spreading in the charge bed of a central ignition tube, a visualized ignition experiment platform was designed, and experiments were carried out with different ignition charge masses and charge structures. A high-speed image acquisition system was used to record the propagation process of ignition flame in the propellant bed at 10000 frames per second, and a transient pressure recorder was used to obtain the variation of pressure with time and position in the chamber. In addition, a synchronous trigger was used to connect the high-speed image acquisition system, the transient pressure recorder and the ignition system of the experimental platform, giving the system a trigger zero point, which is convenient for the statistical analysis of subsequent experimental phenomena. The experimental results show that the time of flame-appearing from the ignition tube into the combustion chamber is 0.6 ms when the mass of the black powder is 20 g. However, the time increases to 1.5 ms when the mass of the black powder is 30 g. The average flame-spreading time of the stick charge structure is 2.2 ms, the average flame-spreading time of the granular charge structure is 3.4 ms, and the average flame-spreading time of the mixed charge structure is 3.1 ms. The results indicate that the mass of the black powder in an ignition tube has a significant effect on the time of flame-appearing from the ignition tube, and the higher black powder mass lead to the longer flame-appearing time. The performances of flame-spreading in different charge bed structures are quite different. The performance of flame-spreading in the stick charge structures is better than that in the granular charge structures and mixed charge structures. In addition, the pressure fluctuations will appear in the chamber due to gas choking in the granular charge structures. A mathematical model of the flame-spreading process was established by fitting the first-order exponential decay function according to the time sequence of the position of flame, and the goodness of fit is greater than 0.98.

Full-field motion and deformation measurement of high speed rotation based on temporal phase-locking and 3D-DIC

The full-field and non-contact measurement of three-dimensional motion and deformation of high-speed rotating machinery is a very challenging task in the engineering field. Two issues, the cost of high-speed camera and the decorrelation between rotated images, are hard to avoid for investigators. In this paper, a systematic solution is presented, which combines high-speed rotation image acquisition using low-speed camera with 3D digital image correlation, both low-cost, flexible and accurate. Firstly, the frequency and initial phase of high-speed rotation are calculated by FFT, and temporal phase-locked signal is generated to trigger the dual-camera asynchronously to collect the circumferential images with equal phase interval. Then a layer-by-layer matching method is proposed to search uncoded targets between two rotated images, while a binocular rotation correlating strategy to correlate the speckle subsets. Finally, the corresponded uncoded targets and speckle subsets are reconstructed in three dimension via the camera calibration results, furtherly the 3D motion and deformation fields can be obtained. Five experiments, including two measurement repeatability tests, an accuracy test, a rigid motion measurement of rotating table and a dynamic deformation measurement of ventilation fan, prove the accuracy and effectiveness of the proposed method.

Spark Analysis Based on the CNN-GRU Model for WEDM Process.

Wire electrical discharge machining (WEDM), widely used to fabricate micro and precision parts in manufacturing industry, is a nontraditional machining method using discharge energy which is transformed into thermal energy to efficiently remove materials. A great amount of research has been conducted based on pulse characteristics. However, the spark image-based approach has little research reported. This paper proposes a discharge spark image-based approach. A model is introduced to predict the discharge status using spark image features through a synchronous high-speed image and waveform acquisition system. First, the relationship between the spark image features (e.g., area, energy, energy density, distribution, etc.) and discharge status is explored by a set of experiments). Traditional methods have claimed that pulse waveform of “short” status is related to the status of non-machining while through our research, it is concluded that this is not always true by conducting experiments based on the spark images. Second, a deep learning model based on Convolution neural network (CNN) and Gated recurrent unit (GRU) is proposed to predict the discharge status. A time series of spark image features extracted by CNN form a 3D feature space is used to predict the discharge status through GRU. Moreover, a quantitative labeling method of machining state is proposed to improve the stability of the model. Due the effective features and the quantitative labeling method, the proposed approach achieves better predict result comparing with the single GRU model.

Segmentor: a tool for manual refinement of 3D microscopy annotations

BackgroundRecent advances in tissue clearing techniques, combined with high-speed image acquisition through light sheet microscopy, enable rapid three-dimensional (3D) imaging of biological specimens, such as whole mouse brains, in a matter of hours. Quantitative analysis of such 3D images can help us understand how changes in brain structure lead to differences in behavior or cognition, but distinguishing densely packed features of interest, such as nuclei, from background can be challenging. Recent deep learning-based nuclear segmentation algorithms show great promise for automated segmentation, but require large numbers of accurate manually labeled nuclei as training data.ResultsWe present Segmentor, an open-source tool for reliable, efficient, and user-friendly manual annotation and refinement of objects (e.g., nuclei) within 3D light sheet microscopy images. Segmentor employs a hybrid 2D-3D approach for visualizing and segmenting objects and contains features for automatic region splitting, designed specifically for streamlining the process of 3D segmentation of nuclei. We show that editing simultaneously in 2D and 3D using Segmentor significantly decreases time spent on manual annotations without affecting accuracy as compared to editing the same set of images with only 2D capabilities.ConclusionsSegmentor is a tool for increased efficiency of manual annotation and refinement of 3D objects that can be used to train deep learning segmentation algorithms, and is available at https://www.nucleininja.org/ and https://github.com/RENCI/Segmentor.

Ship engine detection based on wavelet neural network and FPGA image scanning

This paper uses wavelet neurons instead of traditional neurons, and uses wavelet multi-resolution analysis to decompose the FPGA image scan of the ship engine. Because the neural network has the approximation ability of arbitrary functions, the wavelet transform is connected to the neural network to form a wavelet neural network. To test ship engines. The hardware design of GigE image acquisition and processing system based on FPGA was started. FPGA was used as the main control chip and Gigabit Ethernet was used as the transmission medium. The hardware circuit of the image data acquisition and image processing system was designed. It mainly includes the FPGA main control circuit and the FPGA Peripheral circuits. The high-speed image acquisition, transmission, storage, and display module circuit design is realized. Real-time monitoring and fault analysis of the engine's condition is performed by the FPGA image scanning method, and data of the engine's running state is pre-processed with the help of step tracking technology to make it a standard signal. The data is transmitted to the computer through NI's data acquisition card. Combining feature extraction such as information entropy, Fourier transform, EMD and wavelet neural network technology. The accuracy of the diagnosis results and the actual fault state is improved. It can enable the staff to monitor the running status of the engine in real time, improve the efficiency of engine fault diagnosis, reduce labour costs and maintenance costs, and thus realize intelligent, real-time and accurate status monitoring of the engine.

Hardware Design of an Image Acquisition Device for Target Observation and Tracking

In order to observe and track the separated targets in the air, This paper presents a hardware image acquisition platform based on three-way camera + FPGA + two-way DSP, Xilinx artix-7 series xc7a200t-2fbg676i FPGA is used as the main processor. It is mainly responsible for high-speed image acquisition, preprocessing, transmission and display, TMS320DM368 DSP of Texas Instruments is used as image compression processor. After receiving the image transmitted by artix-7 FPGA, the image H.264 is compressed. This architecture solves the delay problem of traditional image acquisition system in hardware architecture level, and realizes the real-time and high-speed image acquisition and processing. At the same time, the hardware has the basis of multi-channel image acquisition, multi-channel image compression, visible light and infrared camera acquisition data fusion.

Volume holographic optical element for light sheet fluorescence microscopy.

Three-dimensional (3D) imaging of living organisms requires fine optical sectioning and high-speed image acquisition, which can be achieved by light sheet fluorescence microscopy (LSFM). However, orthogonal illumination and detection arms in the LSFM system make it bulky. Here, we propose and demonstrate the application of a volume holographic optical element (photopolymer-based volume holographic grating) for designing a compact LSFM system, called a volume holographic LSFM (VHLSFM). Using the VHLSFM, we performed in vivo imaging of Caenorhabditis elegans (C. elegans) and observed high-contrast optically sectioned fluorescence images of the oocytes and embryonic development in real time for 3D imaging.