High-speed Image Acquisition System Research Articles

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.

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.

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.

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.

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.

Dynamic Visual Measurement of Driver Eye Movements.

Vibrations often cause visual fatigue for drivers, and measuring the relative motion between the driver and the display is important for evaluating this visual fatigue. This paper proposes a non-contact videometric measurement method for studying the three-dimensional trajectories of the driver’s eyes based on stereo vision. The feasibility of this method is demonstrated by dynamic calibration. A high-speed dual-camera image acquisition system is used to obtain high-definition images of the face, and the relative trajectories between the eyes and the display are obtained by a set of robust algorithms. The trajectories of the eyes in three-dimensional space are then reconstructed during the vehicle driving process. This new approach provides three-dimensional information and is effective for assessing how vibration affects human visual performance.

Automated Machine Vision System for Liquid Particle Inspection of Pharmaceutical Injection

The particle matter inspection for pharmaceutical injection is inevitable in the field of pharmaceutical manufacturing, as it has the direct impact on the quality of the drugs. It is a challenge to inspect the contaminated injection online using an imaging system. This paper introduces a novel and effective inspection machine consisting of three modules, a mechanical system with 120 carousel grips, an image acquisition system with multihigh resolution cameras and a multilight sources station, and a distributed industrial electrical computer control system. Particle visual inspection machine first acquires image sequence using the high-speed image acquisition system. The image capture process at each camera module is alternately synchronized with different LED illumination techniques (light transmission method and light reflection method), enabling independent capture of particle images from the same container. Then, a set of novel algorithms for image registration and fast segmentation are proposed to minimize false rejections even in sensitive conditions, which enable the identification of all the tiny potential defects. Finally, a particle tracking and classification algorithm based on an adaptive local weighted-collaborative sparse model is also presented. The experiments demonstrate that the proposed inspection system can effectively detect the particles in the pharmaceutical infusion solution online, and achieve a performance rate of above 97% average accuracy.

High-Speed Visible Image Acquisition and Processing System for Plasma Shape and Position Control of EAST Tokamak

Currently, the fast evolution of cameras in recent years has made them promising tools for diagnostics of Tokamak. The solution presented in this paper consists of a prototype of high-speed visible image acquisition and processing system (HVIAPs) dedicated for experimental advanced superconducting tokamak shape and position control. Graphics processing unit (GPU) and field-programmable gate array (FPGA) are typically used as accelerators or co-processors in addition to a CPU. Such a heterogeneous computing system can combine the advantages of its individual components. The main imaging equipment components used for this system are four high-resolution fast cameras equipped with fiber interface. Image data from the cameras are received by the frame grabber card based on the FPGA and transmitted to the GPU via the peripheral component interconnect express interface. The software support for the system includes low-level drivers and application programming interface libraries for all components and the algorithm developed for image processing. The offline image process results are compared to equilibrium fitting code, which is a commonly used reconstruction method, with an average error of 1.5 cm. The total processing time for one frame is less than 0.3 ms.

Data characterizing compressive properties of Al/Al2O3 syntactic foam core metal matrix sandwich.

Microstructural observations and compressive property datasets of metal matrix syntactic foam core sandwich composite at quasi-static and high strain rate (HSR) conditions (525–845 s−1) are provided. The data supplied in this article includes sample preparation procedure prior to scanning electron and optical microscopy as well as the micrographs. The data used to construct the stress–strain curves and the derived compressive properties of all specimens in both quasi-static and HSR regions are included. Videos of quasi-static compressive failure and that obtained by a high speed image acquisition system during deformation and failure of HSR specimen are also included.

Syntactic foam core metal matrix sandwich composite: Compressive properties and strain rate effects

The present work is the first attempt to study metal matrix syntactic foam core sandwich composites. The sandwich is studied for microstructure and compressive properties at quasi-static and high strain rates. Under quasi-static compressive conditions, specimens were tested in the flatwise and edgewise orientations. The compressive strength, yield strength and plateau stress were higher in the flatwise orientation. Furthermore, both orientations for the sandwich composites showed a higher specific compressive strength and specific yield strength than the foam core alone. Failure initiated in the particles in the flatwise orientation, but in the carbon fabrics in the edgewise orientation. The results show that the fabric had a reinforcing effect under quasi-static conditions. The high strain rate (HSR) characterization was conducted in the strain rate range 525–845s−1 using a split-Hopkinson pressure bar set-up equipped with a high speed image acquisition system. Within this strain rate range, the compressive strength of the sandwich is similar to that of the syntactic foam core alone. Upon review, the syntactic foam core metal matrix sandwich outperforms most of the syntactic foams in terms of energy absorption and compressive strength at comparable density levels.

The Design and Realize on the Circuit Board of High-Speed Image Acquisition System

On the aim of the designs and realizes of the high-speed image acquisition of FPGA and DSP systematic hardware platform, combine the actual requirement for the subject, on the basis of confirming systematic scheme and design of the system hardware circuit, finishing the design of the systematic printed circuit board and measure the realization of the algorithm on the edge. Including the overall arrangement of the circuit board, designs of the power and ground, design of electric capacity of decoupling, design of transmission line, etc. at last, provided the intact systematic circuit board picture, put forward a method to expand matrix outside, i.e. measure algorithms on the edge that holds the matrix law again. The systematic circuit is simple, dependability is good, the performance-cost ratio is fine, and has certain innovation and common.

A Design of Image Acquisition System Based on FPGA and USB2.0

The paper introduces a realization method of high-speed image acquisition system based on FPGA and USB2.0. After introducing the CMOS chip MT9T001 of Micron Technology, Inc. and the universal interface chip CY7C68013 of Cypress Semiconductor Corporation, we design the hardware platform of image acquisition system and the control program written by Verilog HDL language through which FPGA can simulate I2C bus to configure CMOS. Then we introduce the development of firmware, driver and application of the USB interface. This paper completed the design and the experiment of image acquisition system well. In the test, the system achieves the requirement of real-time display. The collected images are clear, which can satisfy design requests.

Liquid–liquid extraction in microchannels with Zinc–D2EHPA system

Liquid–liquid extraction experiments have been carried out in two different types of microchannels using water (Zn) D2EHPA+dodecane system, a standard reactive extraction system recommended for evaluation of liquid–liquid extraction equipment. The microchannels used in the experiments are a t-junction serpentine microchannel and a split and recombine microchannel. Effects of O/A ratio and residence time on overall volumetric mass transfer coefficient have been studied and an attempt has been made to explain the experimental trends with the help of liquid–liquid flow patterns observed by using a high speed image acquisition system. Correlations relating overall volumetric mass transfer coefficients to O/A ratio and velocity are reported for both the microchannels.

Transesterification of Sunflower Oil in Microreactors

AbstractKOH catalyzed transesterification of sunflower oil using methanol has been studied in different types of microreactors. All the microreactors consist of a serpentine microchannel etched in a glass chip but have different types of microfluidic junctions (dispersing devices). First microreactor consists of a T-type microfluidic junction. The second microreactor has a †-type microfluidic junction. The third microreactor uses a split and recombine micromixer to generate the dispersion. Effects of temperature, flow rate, and feed molar ratio on the conversion of triglyceride (TG) have been studied. In some cases, conversion of TG is not found to change monotonically with change in flow rate. An attempt has been made to explain this seemingly unusual trend, and the explanations are substantiated using the liquid–liquid two-phase flow patterns observed using a high-speed image acquisition system. The results from the experiments conducted in this study indicate that it is possible to get very high TG conversion (&gt;90%) with residence time less than a minute.

Design and Implementation of High Speed Image Data Protocol Conversion System

This paper presented a high-speed image acquisition system based on PXI bus and Low Voltage Differential Signaling (LVDS) technology, with the characteristics of mass data, high-speed of data acquisition in the field of modem technology and scientific research. It expatiated the whole frame, and emphasized the design and implement of the system. It simulated the Ping-Pong operation of image data transmission, and tested the performance of the system. The results of test indicate that the high-speed image acquisition system has good ability of acquisition and transmission, and it can satisfy the engineering applied demand.

Fractal Structure in Gas–Liquid–Solid Circulating Fluidized Beds with Low Solid Holdups of Macroporous Resin Particles

The fractal structures of flow images of gas–liquid–solid circulating fluidized beds (GLSCFBs) with low solid holdups of macroporous resin particles at different operating conditions and liquid physical properties were investigated by the fractal analysis method. The images were obtained with the high-speed image acquisition and treatment system of complementary metal oxide semiconductor (CMOS). The results show that the structure of the gas–liquid–solid circulating flow exhibits certain fractal behavior and the fractal dimension D can be used to describe the multiphase self-organization flow structure from the point of view of geometry. The fractal dimension changes with the phase holdup and the agglomeration degree of bubbles or/and particles. Generally, higher solid or gas holdup leads to larger fractal dimension and more extensive aggregation or self-organization degree results in lower entropy and thus lower fractal dimension. In order to avoid the appearance of the aggregation in the GLSCFB riser, higher superficial velocity of primary liquid flow, lower superficial velocity of auxiliary liquid flow, and lower liquid surface tension may be exerted.

Study of 3D Reconstruction of Laser Welding Pool Surface Based on Shape from Shading

Shape from shading (SFS) is one of the critical techniques in 3D shape recovery in computer vision. The task of SFS is to reconstruct 3D shape of the visible surface of an object from one single picture using its gray variation. Analyzing the 3D shape of welding pool is important to evaluate the welding quality. During the disk laser welding experiments, a high-power laser was used as the auxiliary illuminant, and a high-speed image acquisition system with infrared filter was applied to capture the welding pools in real time. The slant and tilt of illuminant source were estimated by statistics to reconstruct the 3D shape of welding pool visible surface by using the localization method of SFS. Methods of median filter and cubic spline interpolation were used to denoise images and smooth the image shapes. Experimental results showed that the proposed technique could reconstruct parts of welding pool effectively.

High-Speed Image Measurement Technology and its Application under Toner Drop Impact Test

A transport package cushioning property evaluation test system is established to achieve the goal of high-precision, real-time, non-contact, and full-field measurement. It consists of a shock testing machine, a shock measuring instrument and a high-speed image acquisition and processing system. High-speed imaging measurement techniques and digital image processing method are used to make a comprehensive assessment on the cushioning properties of air-cushion package. In this paper, the developed system was used to measure the drop shock responses of the toner and air cushion deformation under drop impact test.

BioThreads: A Novel VLIW-Based Chip Multiprocessor for Accelerating Biomedical Image Processing Applications

We discuss BioThreads, a novel, configurable, extensible system-on-chip multiprocessor and its use in accelerating biomedical signal processing applications such as imaging photoplethysmography (IPPG). BioThreads is derived from the LE1 open-source VLIW chip multiprocessor and efficiently handles instruction, data and thread-level parallelism. In addition, it supports a novel mechanism for the dynamic creation, and allocation of software threads to uncommitted processor cores by implementing key POSIX Threads primitives directly in hardware, as custom instructions. In this study, the BioThreads core is used to accelerate the calculation of the oxygen saturation map of living tissue in an experimental setup consisting of a high speed image acquisition system, connected to an FPGA board and to a host system. Results demonstrate near-linear acceleration of the core kernels of the target blood perfusion assessment with increasing number of hardware threads. The BioThreads processor was implemented on both standard-cell and FPGA technologies; in the first case and for an issue width of two, full real-time performance is achieved with 4 cores whereas on a mid-range Xilinx Virtex6 device this is achieved with 10 dual-issue cores. An 8-core LE1 VLIW FPGA prototype of the system achieved 240 times faster execution time than the scalar Microblaze processor demonstrating the scalability of the proposed solution to a state-of-the-art FPGA vendor provided soft CPU core.